[PATCHSET driver-core-next] sysfs: separate out kernfs, take #3

[PATCHSET driver-core-next] sysfs: separate out kernfs, take #3

[Tejun Heo]

Hey,

This is the third take of the patchset to separate out kernfs from
sysfs.

Changes between the second[S] and third take are

* cb26a311578e ("sysfs: drop kobj_ns_type handling") had a bug in
  symlink handling incorrectly enabling tag filtering in a directory
  which contains a symlink pointing to a tagged directory and got
  reverted.  0001-sysfs-drop-kobj_ns_type-handling-take-2.patch added
  to try it again.

* 0001 adds SYSFS_NS_FLAG and testing code in sysfs.
  0040-sysfs-kernfs-implement-kernfs_ns_enabled.patch added to
  encapsulate the flag access.

Changes between the first[F] and second[S] take are

* Patches applied to driver-core-next are dropped and the rest are
  refreshed.

* Mount portion of kernfs implemented.  kernfs now supports multiple
  sysfs_dirent hierarchies and sysfs is just one of them.

* Dummy interface for kernfs for !CONFIG_SYSFS updated to return
  -ENOSYS / ERR_PTR(-ENOSYS) where applicable.

* Several bug fixes.

This patchset contains 41 patches to separate out core sysfs features
into kernfs.  kernfs exclusively deals with sysfs_dirent, which will
be later renamed to kernfs_node, and kernfs_ops.  sysfs becomes a
wrapping layer over sysfs which interfaces kobject and
[bin_]attribute.

The goal of these changes is to allow other users to make use of the
core features of sysfs instead of rolling their own pseudo filesystem
implementation which usually fails to deal with issues with file
shutdowns, locking separation from vfs layer and so on.  This patchset
refactors sysfs and separates out core functionalities to kernfs.
After the patchset, kernfs is fully functional - multiple sysfs_dirent
hierarchies can be created and mounted and sysfs is just one user of
kernfs.

This patchset shouldn't introduce any behavior differences and
contains the following patches.

 0001-sysfs-drop-kobj_ns_type-handling-take-2.patch
 0002-sysfs-make-__sysfs_add_one-fail-if-the-parent-isn-t-.patch
 0003-sysfs-kernfs-add-skeletons-for-kernfs.patch
 0004-sysfs-kernfs-introduce-kernfs_remove-_by_name-_ns.patch
 0005-sysfs-kernfs-introduce-kernfs_create_link.patch
 0006-sysfs-kernfs-introduce-kernfs_rename-_ns.patch
 0007-sysfs-kernfs-introduce-kernfs_setattr.patch
 0008-sysfs-kernfs-replace-sysfs_dirent-s_dir.kobj-and-s_a.patch
 0009-sysfs-kernfs-introduce-kernfs_create_dir-_ns.patch
 0010-sysfs-kernfs-prepare-read-path-for-kernfs.patch
 0011-sysfs-kernfs-prepare-write-path-for-kernfs.patch
 0012-sysfs-kernfs-prepare-mmap-path-for-kernfs.patch
 0013-sysfs-kernfs-prepare-open-release-poll-paths-for-ker.patch
 0014-sysfs-kernfs-move-sysfs_open_file-to-include-linux-k.patch
 0015-sysfs-kernfs-introduce-kernfs_ops.patch
 0016-sysfs-kernfs-add-sysfs_dirent-s_attr.size.patch
 0017-sysfs-kernfs-remove-SYSFS_KOBJ_BIN_ATTR.patch
 0018-sysfs-kernfs-introduce-kernfs_create_file-_ns.patch
 0019-sysfs-kernfs-remove-sysfs_add_one.patch
 0020-sysfs-kernfs-add-kernfs_ops-seq_-start-next-stop.patch
 0021-sysfs-kernfs-introduce-kernfs_notify.patch
 0022-sysfs-kernfs-reorganize-SYSFS_-constants.patch
 0023-sysfs-kernfs-revamp-sysfs_dirent-active_ref-lockdep-.patch
 0024-sysfs-kernfs-introduce-kernfs-_find_and-_get-and-ker.patch
 0025-sysfs-kernfs-move-internal-decls-to-fs-kernfs-kernfs.patch
 0026-sysfs-kernfs-move-inode-code-to-fs-kernfs-inode.c.patch
 0027-sysfs-kernfs-move-dir-core-code-to-fs-kernfs-dir.c.patch
 0028-sysfs-kernfs-move-file-core-code-to-fs-kernfs-file.c.patch
 0029-sysfs-kernfs-move-symlink-core-code-to-fs-kernfs-sym.patch
 0030-sysfs-kernfs-drop-unused-params-from-sysfs_fill_supe.patch
 0031-sysfs-kernfs-make-sysfs_super_info-ns-const.patch
 0032-sysfs-kernfs-no-need-to-kern_mount-sysfs-from-sysfs_.patch
 0033-sysfs-kernfs-introduce-sysfs_root_sd.patch
 0034-sysfs-kernfs-implement-kernfs_create-destroy_root.patch
 0035-sysfs-kernfs-make-inode-number-ida-per-kernfs_root.patch
 0036-sysfs-kernfs-make-super_blocks-bind-to-different-ker.patch
 0037-sysfs-kernfs-prepare-mount-path-for-kernfs.patch
 0038-sysfs-kernfs-move-mount-core-code-to-fs-kernfs-mount.patch
 0039-sysfs-kernfs-make-sysfs_dirent-definition-public.patch
 0040-sysfs-kernfs-implement-kernfs_ns_enabled.patch
 0041-sysfs-kernfs-remove-cross-inclusions-of-internal-hea.patch

 0001 retries removing kobj_ns_type handling.

 0002 is prep patch.

 0003 preps fs/kernfs/ directory with skeleton files.

 0004-0024 refactor various code paths so that all externally visible
 interfaces are split to core kernfs interface which deals with
 sysfs_dirent and kernfs_ops and sysfs wrapping it to provide the
 existing interface.

 0025-0029 move kernfs part of the implementation under fs/kernfs.

 0030-0036 update mount logic so that it can support multiple
 sysfs_dirent hierarchies instead of assuming single sysfs hierarchy.

 0037-0038 refactor mount code path for kernfs and moves kernfs
 interface and implementation to fs/kernfs.

 0039-0041 cut the remaining entanglement between sysfs and kernfs and
 make the former proper user of the latter.

Multiple hierarchy support tested with the attached module (needs
adding EXPORT_SYMBOL to kernfs interface).  Works as expected.

This patchset is on top of

  v3.13-rc1 6ce4eac1f600 ("Linux 3.13-rc1")
+ [1] sysfs: handle duplicate removal attempts in sysfs_remove_group()
+ [2] sysfs: use a separate locking class for open files depending on mmap

The patches are also available in the following git branch.

 git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git review-separate-out-kernfs

diffstat follows.  Thanks.

 fs/Makefile                 |    2 
 fs/kernfs/Makefile          |    5 
 fs/kernfs/dir.c             | 1014 +++++++++++++++++++++++++++++++++++++++++++
 fs/kernfs/file.c            |  814 ++++++++++++++++++++++++++++++++++
 fs/kernfs/inode.c           |  337 ++++++++++++++
 fs/kernfs/kernfs-internal.h |  115 ++++
 fs/kernfs/mount.c           |  165 +++++++
 fs/kernfs/symlink.c         |  149 ++++++
 fs/namespace.c              |    2 
 fs/sysfs/Makefile           |    2 
 fs/sysfs/dir.c              | 1030 --------------------------------------------
 fs/sysfs/file.c             |  931 +++++++--------------------------------
 fs/sysfs/group.c            |   59 +-
 fs/sysfs/inode.c            |  331 --------------
 fs/sysfs/mount.c            |  182 -------
 fs/sysfs/symlink.c          |  179 -------
 fs/sysfs/sysfs.h            |  228 ---------
 include/linux/kernfs.h      |  348 ++++++++++++++
 include/linux/sysfs.h       |   43 -
 lib/kobject.c               |   27 -
 20 files changed, 3252 insertions(+), 2711 deletions(-)

--
tejun

[F] https://lkml.kernel.org/g/1382629780-10006-1-git-send-email-tj@kernel.org
[S] https://lkml.kernel.org/g/1383472398-17812-1-git-send-email-tj@kernel.org
[1] https://lkml.kernel.org/g/20131123183508.GA28162@mtj.dyndns.org
[2] https://lkml.kernel.org/g/20131123183540.GB28162@mtj.dyndns.org

[PATCH 01/41] sysfs: drop kobj_ns_type handling, take #2

[Tejun Heo]

The way namespace tags are implemented in sysfs is more complicated
than necessary.  As each tag is a pointer value and required to be
non-NULL under a namespace enabled parent, there's no need to record
separately what type each tag is.  If multiple namespace types are
needed, which currently aren't, we can simply compare the tag to a set
of allowed tags in the superblock assuming that the tags, being
pointers, won't have the same value across multiple types.

This patch rips out kobj_ns_type handling from sysfs.  sysfs now has
an enable switch to turn on namespace under a node.  If enabled, all
children are required to have non-NULL namespace tags and filtered
against the super_block's tag.

kobject namespace determination is now performed in
lib/kobject.c::create_dir() making sysfs_read_ns_type() unnecessary.
The sanity checks are also moved.  create_dir() is restructured to
ease such addition.  This removes most kobject namespace knowledge
from sysfs proper which will enable proper separation and layering of
sysfs.

This is the second try.  The first one was cb26a311578e ("sysfs: drop
kobj_ns_type handling") which tried to automatically enable namespace
if there are children with non-NULL namespace tags; however, it was
broken for symlinks as they should inherit the target's tag iff
namespace is enabled in the parent.  This led to namespace filtering
enabled incorrectly for wireless net class devices through phy80211
symlinks and thus network configuration failure.  a1212d278c05
("Revert "sysfs: drop kobj_ns_type handling"") reverted the commit.

This shouldn't introduce any behavior changes, for real.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/sysfs/dir.c        | 92 ++++++++++++++++++++-------------------------------
 fs/sysfs/mount.c      | 24 ++++----------
 fs/sysfs/symlink.c    | 26 ++++-----------
 fs/sysfs/sysfs.h      | 25 ++++----------
 include/linux/sysfs.h |  2 ++
 lib/kobject.c         | 27 ++++++++++++---
 6 files changed, 79 insertions(+), 117 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 5e73d66..b3cf61d 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -279,7 +279,6 @@ static int sysfs_dentry_delete(const struct dentry *dentry)
 static int sysfs_dentry_revalidate(struct dentry *dentry, unsigned int flags)
 {
 	struct sysfs_dirent *sd;
-	int type;
 
 	if (flags & LOOKUP_RCU)
 		return -ECHILD;
@@ -300,13 +299,9 @@ static int sysfs_dentry_revalidate(struct dentry *dentry, unsigned int flags)
 		goto out_bad;
 
 	/* The sysfs dirent has been moved to a different namespace */
-	type = KOBJ_NS_TYPE_NONE;
-	if (sd->s_parent) {
-		type = sysfs_ns_type(sd->s_parent);
-		if (type != KOBJ_NS_TYPE_NONE &&
-				sysfs_info(dentry->d_sb)->ns[type] != sd->s_ns)
-			goto out_bad;
-	}
+	if (sd->s_parent && (sd->s_parent->s_flags & SYSFS_FLAG_NS) &&
+	    sysfs_info(dentry->d_sb)->ns != sd->s_ns)
+		goto out_bad;
 
 	mutex_unlock(&sysfs_mutex);
 out_valid:
@@ -423,13 +418,14 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt)
 int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
 		    struct sysfs_dirent *parent_sd)
 {
+	bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS;
 	struct sysfs_inode_attrs *ps_iattr;
 	int ret;
 
-	if (!!sysfs_ns_type(parent_sd) != !!sd->s_ns) {
+	if (has_ns != (bool)sd->s_ns) {
 		WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
-			sysfs_ns_type(parent_sd) ? "required" : "invalid",
-			parent_sd->s_name, sd->s_name);
+		     has_ns ? "required" : "invalid",
+		     parent_sd->s_name, sd->s_name);
 		return -EINVAL;
 	}
 
@@ -610,12 +606,13 @@ struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
 				       const void *ns)
 {
 	struct rb_node *node = parent_sd->s_dir.children.rb_node;
+	bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS;
 	unsigned int hash;
 
-	if (!!sysfs_ns_type(parent_sd) != !!ns) {
+	if (has_ns != (bool)ns) {
 		WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
-			sysfs_ns_type(parent_sd) ? "required" : "invalid",
-			parent_sd->s_name, name);
+		     has_ns ? "required" : "invalid",
+		     parent_sd->s_name, name);
 		return NULL;
 	}
 
@@ -667,7 +664,6 @@ struct sysfs_dirent *sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd,
 EXPORT_SYMBOL_GPL(sysfs_get_dirent_ns);
 
 static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
-		      enum kobj_ns_type type,
 		      const char *name, const void *ns,
 		      struct sysfs_dirent **p_sd)
 {
@@ -681,7 +677,6 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
 	if (!sd)
 		return -ENOMEM;
 
-	sd->s_flags |= (type << SYSFS_NS_TYPE_SHIFT);
 	sd->s_ns = ns;
 	sd->s_dir.kobj = kobj;
 
@@ -701,33 +696,7 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
 int sysfs_create_subdir(struct kobject *kobj, const char *name,
 			struct sysfs_dirent **p_sd)
 {
-	return create_dir(kobj, kobj->sd,
-			  KOBJ_NS_TYPE_NONE, name, NULL, p_sd);
-}
-
-/**
- *	sysfs_read_ns_type: return associated ns_type
- *	@kobj: the kobject being queried
- *
- *	Each kobject can be tagged with exactly one namespace type
- *	(i.e. network or user).  Return the ns_type associated with
- *	this object if any
- */
-static enum kobj_ns_type sysfs_read_ns_type(struct kobject *kobj)
-{
-	const struct kobj_ns_type_operations *ops;
-	enum kobj_ns_type type;
-
-	ops = kobj_child_ns_ops(kobj);
-	if (!ops)
-		return KOBJ_NS_TYPE_NONE;
-
-	type = ops->type;
-	BUG_ON(type <= KOBJ_NS_TYPE_NONE);
-	BUG_ON(type >= KOBJ_NS_TYPES);
-	BUG_ON(!kobj_ns_type_registered(type));
-
-	return type;
+	return create_dir(kobj, kobj->sd, name, NULL, p_sd);
 }
 
 /**
@@ -737,7 +706,6 @@ static enum kobj_ns_type sysfs_read_ns_type(struct kobject *kobj)
  */
 int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
 {
-	enum kobj_ns_type type;
 	struct sysfs_dirent *parent_sd, *sd;
 	int error = 0;
 
@@ -751,9 +719,7 @@ int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
 	if (!parent_sd)
 		return -ENOENT;
 
-	type = sysfs_read_ns_type(kobj);
-
-	error = create_dir(kobj, parent_sd, type, kobject_name(kobj), ns, &sd);
+	error = create_dir(kobj, parent_sd, kobject_name(kobj), ns, &sd);
 	if (!error)
 		kobj->sd = sd;
 	return error;
@@ -767,13 +733,12 @@ static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry,
 	struct sysfs_dirent *parent_sd = parent->d_fsdata;
 	struct sysfs_dirent *sd;
 	struct inode *inode;
-	enum kobj_ns_type type;
-	const void *ns;
+	const void *ns = NULL;
 
 	mutex_lock(&sysfs_mutex);
 
-	type = sysfs_ns_type(parent_sd);
-	ns = sysfs_info(dir->i_sb)->ns[type];
+	if (parent_sd->s_flags & SYSFS_FLAG_NS)
+		ns = sysfs_info(dir->i_sb)->ns;
 
 	sd = sysfs_find_dirent(parent_sd, dentry->d_name.name, ns);
 
@@ -1029,6 +994,21 @@ int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
 	return sysfs_rename(sd, new_parent_sd, sd->s_name, new_ns);
 }
 
+/**
+ * sysfs_enable_ns - enable namespace under a directory
+ * @sd: directory of interest, should be empty
+ *
+ * This is to be called right after @sd is created to enable namespace
+ * under it.  All children of @sd must have non-NULL namespace tags and
+ * only the ones which match the super_block's tag will be visible.
+ */
+void sysfs_enable_ns(struct sysfs_dirent *sd)
+{
+	WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
+	WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));
+	sd->s_flags |= SYSFS_FLAG_NS;
+}
+
 /* Relationship between s_mode and the DT_xxx types */
 static inline unsigned char dt_type(struct sysfs_dirent *sd)
 {
@@ -1096,15 +1076,15 @@ static int sysfs_readdir(struct file *file, struct dir_context *ctx)
 	struct dentry *dentry = file->f_path.dentry;
 	struct sysfs_dirent *parent_sd = dentry->d_fsdata;
 	struct sysfs_dirent *pos = file->private_data;
-	enum kobj_ns_type type;
-	const void *ns;
-
-	type = sysfs_ns_type(parent_sd);
-	ns = sysfs_info(dentry->d_sb)->ns[type];
+	const void *ns = NULL;
 
 	if (!dir_emit_dots(file, ctx))
 		return 0;
 	mutex_lock(&sysfs_mutex);
+
+	if (parent_sd->s_flags & SYSFS_FLAG_NS)
+		ns = sysfs_info(dentry->d_sb)->ns;
+
 	for (pos = sysfs_dir_pos(ns, parent_sd, ctx->pos, pos);
 	     pos;
 	     pos = sysfs_dir_next_pos(ns, parent_sd, ctx->pos, pos)) {
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 834ec2c..8c24bce 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -36,7 +36,7 @@ static const struct super_operations sysfs_ops = {
 struct sysfs_dirent sysfs_root = {
 	.s_name		= "",
 	.s_count	= ATOMIC_INIT(1),
-	.s_flags	= SYSFS_DIR | (KOBJ_NS_TYPE_NONE << SYSFS_NS_TYPE_SHIFT),
+	.s_flags	= SYSFS_DIR,
 	.s_mode		= S_IFDIR | S_IRUGO | S_IXUGO,
 	.s_ino		= 1,
 };
@@ -77,14 +77,8 @@ static int sysfs_test_super(struct super_block *sb, void *data)
 {
 	struct sysfs_super_info *sb_info = sysfs_info(sb);
 	struct sysfs_super_info *info = data;
-	enum kobj_ns_type type;
-	int found = 1;
 
-	for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) {
-		if (sb_info->ns[type] != info->ns[type])
-			found = 0;
-	}
-	return found;
+	return sb_info->ns == info->ns;
 }
 
 static int sysfs_set_super(struct super_block *sb, void *data)
@@ -98,9 +92,7 @@ static int sysfs_set_super(struct super_block *sb, void *data)
 
 static void free_sysfs_super_info(struct sysfs_super_info *info)
 {
-	int type;
-	for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
-		kobj_ns_drop(type, info->ns[type]);
+	kobj_ns_drop(KOBJ_NS_TYPE_NET, info->ns);
 	kfree(info);
 }
 
@@ -108,7 +100,6 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data)
 {
 	struct sysfs_super_info *info;
-	enum kobj_ns_type type;
 	struct super_block *sb;
 	int error;
 
@@ -116,18 +107,15 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 		if (!capable(CAP_SYS_ADMIN) && !fs_fully_visible(fs_type))
 			return ERR_PTR(-EPERM);
 
-		for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) {
-			if (!kobj_ns_current_may_mount(type))
-				return ERR_PTR(-EPERM);
-		}
+		if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))
+			return ERR_PTR(-EPERM);
 	}
 
 	info = kzalloc(sizeof(*info), GFP_KERNEL);
 	if (!info)
 		return ERR_PTR(-ENOMEM);
 
-	for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
-		info->ns[type] = kobj_ns_grab_current(type);
+	info->ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
 
 	sb = sget(fs_type, sysfs_test_super, sysfs_set_super, flags, info);
 	if (IS_ERR(sb) || sb->s_fs_info != info)
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 3ae3f1b..c660363 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -28,7 +28,6 @@ static int sysfs_do_create_link_sd(struct sysfs_dirent *parent_sd,
 	struct sysfs_dirent *target_sd = NULL;
 	struct sysfs_dirent *sd = NULL;
 	struct sysfs_addrm_cxt acxt;
-	enum kobj_ns_type ns_type;
 	int error;
 
 	BUG_ON(!name || !parent_sd);
@@ -52,29 +51,16 @@ static int sysfs_do_create_link_sd(struct sysfs_dirent *parent_sd,
 	if (!sd)
 		goto out_put;
 
-	ns_type = sysfs_ns_type(parent_sd);
-	if (ns_type)
+	if (parent_sd->s_flags & SYSFS_FLAG_NS)
 		sd->s_ns = target_sd->s_ns;
 	sd->s_symlink.target_sd = target_sd;
 	target_sd = NULL;	/* reference is now owned by the symlink */
 
 	sysfs_addrm_start(&acxt);
-	/* Symlinks must be between directories with the same ns_type */
-	if (!ns_type ||
-	    (ns_type == sysfs_ns_type(sd->s_symlink.target_sd->s_parent))) {
-		if (warn)
-			error = sysfs_add_one(&acxt, sd, parent_sd);
-		else
-			error = __sysfs_add_one(&acxt, sd, parent_sd);
-	} else {
-		error = -EINVAL;
-		WARN(1, KERN_WARNING
-			"sysfs: symlink across ns_types %s/%s -> %s/%s\n",
-			parent_sd->s_name,
-			sd->s_name,
-			sd->s_symlink.target_sd->s_parent->s_name,
-			sd->s_symlink.target_sd->s_name);
-	}
+	if (warn)
+		error = sysfs_add_one(&acxt, sd, parent_sd);
+	else
+		error = __sysfs_add_one(&acxt, sd, parent_sd);
 	sysfs_addrm_finish(&acxt);
 
 	if (error)
@@ -164,7 +150,7 @@ void sysfs_delete_link(struct kobject *kobj, struct kobject *targ,
 	 * sysfs_remove_dir() for details.
 	 */
 	spin_lock(&sysfs_symlink_target_lock);
-	if (targ->sd && sysfs_ns_type(kobj->sd))
+	if (targ->sd && (kobj->sd->s_flags & SYSFS_FLAG_NS))
 		ns = targ->sd->s_ns;
 	spin_unlock(&sysfs_symlink_target_lock);
 	sysfs_hash_and_remove(kobj->sd, name, ns);
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 0af09fb..e116c21 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -90,11 +90,8 @@ struct sysfs_dirent {
 #define SYSFS_COPY_NAME			(SYSFS_DIR | SYSFS_KOBJ_LINK)
 #define SYSFS_ACTIVE_REF		(SYSFS_KOBJ_ATTR | SYSFS_KOBJ_BIN_ATTR)
 
-/* identify any namespace tag on sysfs_dirents */
-#define SYSFS_NS_TYPE_MASK		0xf00
-#define SYSFS_NS_TYPE_SHIFT		8
-
-#define SYSFS_FLAG_MASK			~(SYSFS_NS_TYPE_MASK|SYSFS_TYPE_MASK)
+#define SYSFS_FLAG_MASK			~SYSFS_TYPE_MASK
+#define SYSFS_FLAG_NS			0x01000
 #define SYSFS_FLAG_REMOVED		0x02000
 
 static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
@@ -102,15 +99,6 @@ static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
 	return sd->s_flags & SYSFS_TYPE_MASK;
 }
 
-/*
- * Return any namespace tags on this dirent.
- * enum kobj_ns_type is defined in linux/kobject.h
- */
-static inline enum kobj_ns_type sysfs_ns_type(struct sysfs_dirent *sd)
-{
-	return (sd->s_flags & SYSFS_NS_TYPE_MASK) >> SYSFS_NS_TYPE_SHIFT;
-}
-
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 
 #define sysfs_dirent_init_lockdep(sd)				\
@@ -155,12 +143,13 @@ struct sysfs_addrm_cxt {
  */
 
 /*
- * Each sb is associated with a set of namespace tags (i.e.
- * the network namespace of the task which mounted this sysfs
- * instance).
+ * Each sb is associated with one namespace tag, currently the network
+ * namespace of the task which mounted this sysfs instance.  If multiple
+ * tags become necessary, make the following an array and compare
+ * sysfs_dirent tag against every entry.
  */
 struct sysfs_super_info {
-	void *ns[KOBJ_NS_TYPES];
+	void *ns;
 };
 #define sysfs_info(SB) ((struct sysfs_super_info *)(SB->s_fs_info))
 extern struct sysfs_dirent sysfs_root;
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 6695040..6c85be6 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -220,6 +220,8 @@ int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *target,
 void sysfs_delete_link(struct kobject *dir, struct kobject *targ,
 			const char *name);
 
+void sysfs_enable_ns(struct sysfs_dirent *sd);
+
 int __must_check sysfs_create_group(struct kobject *kobj,
 				    const struct attribute_group *grp);
 int __must_check sysfs_create_groups(struct kobject *kobj,
diff --git a/lib/kobject.c b/lib/kobject.c
index 5b4b888..16e9335 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -65,13 +65,17 @@ static int populate_dir(struct kobject *kobj)
 
 static int create_dir(struct kobject *kobj)
 {
+	const struct kobj_ns_type_operations *ops;
 	int error;
 
 	error = sysfs_create_dir_ns(kobj, kobject_namespace(kobj));
-	if (!error) {
-		error = populate_dir(kobj);
-		if (error)
-			sysfs_remove_dir(kobj);
+	if (error)
+		return error;
+
+	error = populate_dir(kobj);
+	if (error) {
+		sysfs_remove_dir(kobj);
+		return error;
 	}
 
 	/*
@@ -80,7 +84,20 @@ static int create_dir(struct kobject *kobj)
 	 */
 	sysfs_get(kobj->sd);
 
-	return error;
+	/*
+	 * If @kobj has ns_ops, its children need to be filtered based on
+	 * their namespace tags.  Enable namespace support on @kobj->sd.
+	 */
+	ops = kobj_child_ns_ops(kobj);
+	if (ops) {
+		BUG_ON(ops->type <= KOBJ_NS_TYPE_NONE);
+		BUG_ON(ops->type >= KOBJ_NS_TYPES);
+		BUG_ON(!kobj_ns_type_registered(ops->type));
+
+		sysfs_enable_ns(kobj->sd);
+	}
+
+	return 0;
 }
 
 static int get_kobj_path_length(struct kobject *kobj)
-- 
1.8.4.2

[PATCH 02/41] sysfs: make __sysfs_add_one() fail if the parent isn't a directory

[Tejun Heo]

Currently the kobject based interface guarantees that a parent
sysfs_dirent is always a directory; however, the planned kernfs
interface will be directly based on sysfs_dirents and the caller may
specify non-directory node as the parent.  Add an explicit check in
__sysfs_add_one() so that such attempts fail with -EINVAL.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/dir.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index b3cf61d..98701c0 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -429,6 +429,9 @@ int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
 		return -EINVAL;
 	}
 
+	if (sysfs_type(parent_sd) != SYSFS_DIR)
+		return -EINVAL;
+
 	sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
 	sd->s_parent = sysfs_get(parent_sd);
 
-- 
1.8.4.2

[PATCH 03/41] sysfs, kernfs: add skeletons for kernfs

[Tejun Heo]

Core sysfs implementation will be separated into kernfs so that it can
be used by other non-kobject users.

This patch creates fs/kernfs/ directory and makes boilerplate changes.
kernfs interface will be directly based on sysfs_dirent and its
forward declaration is moved to include/linux/kernfs.h which is
included from include/linux/sysfs.h.  sysfs core implementation will
be gradually separated out and moved to kernfs.

This patch doesn't introduce any functional changes.

v2: mount.c added.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/Makefile            |  2 +-
 fs/kernfs/Makefile     |  5 +++++
 fs/kernfs/dir.c        |  9 +++++++++
 fs/kernfs/file.c       |  9 +++++++++
 fs/kernfs/inode.c      |  9 +++++++++
 fs/kernfs/mount.c      |  9 +++++++++
 fs/kernfs/symlink.c    |  9 +++++++++
 include/linux/kernfs.h | 12 ++++++++++++
 include/linux/sysfs.h  |  3 +--
 9 files changed, 64 insertions(+), 3 deletions(-)
 create mode 100644 fs/kernfs/Makefile
 create mode 100644 fs/kernfs/dir.c
 create mode 100644 fs/kernfs/file.c
 create mode 100644 fs/kernfs/inode.c
 create mode 100644 fs/kernfs/mount.c
 create mode 100644 fs/kernfs/symlink.c
 create mode 100644 include/linux/kernfs.h

diff --git a/fs/Makefile b/fs/Makefile
index 4fe6df3..39a824f 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -53,7 +53,7 @@ obj-$(CONFIG_FHANDLE)		+= fhandle.o
 obj-y				+= quota/
 
 obj-$(CONFIG_PROC_FS)		+= proc/
-obj-$(CONFIG_SYSFS)		+= sysfs/
+obj-$(CONFIG_SYSFS)		+= sysfs/ kernfs/
 obj-$(CONFIG_CONFIGFS_FS)	+= configfs/
 obj-y				+= devpts/
 
diff --git a/fs/kernfs/Makefile b/fs/kernfs/Makefile
new file mode 100644
index 0000000..674337c
--- /dev/null
+++ b/fs/kernfs/Makefile
@@ -0,0 +1,5 @@
+#
+# Makefile for the kernfs pseudo filesystem
+#
+
+obj-y		:= mount.o inode.o dir.o file.o symlink.o
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
new file mode 100644
index 0000000..1061602
--- /dev/null
+++ b/fs/kernfs/dir.c
@@ -0,0 +1,9 @@
+/*
+ * fs/kernfs/dir.c - kernfs directory implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
+ *
+ * This file is released under the GPLv2.
+ */
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
new file mode 100644
index 0000000..90b1e88
--- /dev/null
+++ b/fs/kernfs/file.c
@@ -0,0 +1,9 @@
+/*
+ * fs/kernfs/file.c - kernfs file implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
+ *
+ * This file is released under the GPLv2.
+ */
diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
new file mode 100644
index 0000000..86bfeea
--- /dev/null
+++ b/fs/kernfs/inode.c
@@ -0,0 +1,9 @@
+/*
+ * fs/kernfs/inode.c - kernfs inode implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
+ *
+ * This file is released under the GPLv2.
+ */
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
new file mode 100644
index 0000000..872e262
--- /dev/null
+++ b/fs/kernfs/mount.c
@@ -0,0 +1,9 @@
+/*
+ * fs/kernfs/mount.c - kernfs mount implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
+ *
+ * This file is released under the GPLv2.
+ */
diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c
new file mode 100644
index 0000000..2578715
--- /dev/null
+++ b/fs/kernfs/symlink.c
@@ -0,0 +1,9 @@
+/*
+ * fs/kernfs/symlink.c - kernfs symlink implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
+ *
+ * This file is released under the GPLv2.
+ */
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
new file mode 100644
index 0000000..254b9e8
--- /dev/null
+++ b/include/linux/kernfs.h
@@ -0,0 +1,12 @@
+/*
+ * kernfs.h - pseudo filesystem decoupled from vfs locking
+ *
+ * This file is released under the GPLv2.
+ */
+
+#ifndef __LINUX_KERNFS_H
+#define __LINUX_KERNFS_H
+
+struct sysfs_dirent;
+
+#endif	/* __LINUX_KERNFS_H */
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 6c85be6..f82ec46 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -12,6 +12,7 @@
 #ifndef _SYSFS_H_
 #define _SYSFS_H_
 
+#include <linux/kernfs.h>
 #include <linux/compiler.h>
 #include <linux/errno.h>
 #include <linux/list.h>
@@ -175,8 +176,6 @@ struct sysfs_ops {
 	ssize_t	(*store)(struct kobject *, struct attribute *, const char *, size_t);
 };
 
-struct sysfs_dirent;
-
 #ifdef CONFIG_SYSFS
 
 int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
-- 
1.8.4.2

[PATCH 04/41] sysfs, kernfs: introduce kernfs_remove[_by_name[_ns]]()

[Tejun Heo]

Introduce kernfs removal interfaces - kernfs_remove() and
kernfs_remove_by_name[_ns]().

These are just renames of sysfs_remove() and sysfs_hash_and_remove().
No functional changes.

v2: Dummy kernfs_remove_by_name_ns() for !CONFIG_SYSFS updated to
    return -ENOSYS instead of 0.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/dir.c         | 20 ++++++++++----------
 fs/sysfs/file.c        |  6 +++---
 fs/sysfs/group.c       | 15 +++++++--------
 fs/sysfs/symlink.c     |  4 ++--
 fs/sysfs/sysfs.h       |  3 ---
 include/linux/kernfs.h | 24 ++++++++++++++++++++++++
 6 files changed, 46 insertions(+), 26 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 98701c0..edbde4e 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -829,8 +829,8 @@ static struct sysfs_dirent *sysfs_next_descendant_post(struct sysfs_dirent *pos,
 	return pos->s_parent;
 }
 
-static void __sysfs_remove(struct sysfs_addrm_cxt *acxt,
-			   struct sysfs_dirent *sd)
+static void __kernfs_remove(struct sysfs_addrm_cxt *acxt,
+			    struct sysfs_dirent *sd)
 {
 	struct sysfs_dirent *pos, *next;
 
@@ -849,22 +849,22 @@ static void __sysfs_remove(struct sysfs_addrm_cxt *acxt,
 }
 
 /**
- * sysfs_remove - remove a sysfs_dirent recursively
+ * kernfs_remove - remove a sysfs_dirent recursively
  * @sd: the sysfs_dirent to remove
  *
  * Remove @sd along with all its subdirectories and files.
  */
-void sysfs_remove(struct sysfs_dirent *sd)
+void kernfs_remove(struct sysfs_dirent *sd)
 {
 	struct sysfs_addrm_cxt acxt;
 
 	sysfs_addrm_start(&acxt);
-	__sysfs_remove(&acxt, sd);
+	__kernfs_remove(&acxt, sd);
 	sysfs_addrm_finish(&acxt);
 }
 
 /**
- * sysfs_hash_and_remove - find a sysfs_dirent by name and remove it
+ * kernfs_remove_by_name_ns - find a sysfs_dirent by name and remove it
  * @dir_sd: parent of the target
  * @name: name of the sysfs_dirent to remove
  * @ns: namespace tag of the sysfs_dirent to remove
@@ -872,8 +872,8 @@ void sysfs_remove(struct sysfs_dirent *sd)
  * Look for the sysfs_dirent with @name and @ns under @dir_sd and remove
  * it.  Returns 0 on success, -ENOENT if such entry doesn't exist.
  */
-int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name,
-			  const void *ns)
+int kernfs_remove_by_name_ns(struct sysfs_dirent *dir_sd, const char *name,
+			     const void *ns)
 {
 	struct sysfs_addrm_cxt acxt;
 	struct sysfs_dirent *sd;
@@ -888,7 +888,7 @@ int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name,
 
 	sd = sysfs_find_dirent(dir_sd, name, ns);
 	if (sd)
-		__sysfs_remove(&acxt, sd);
+		__kernfs_remove(&acxt, sd);
 
 	sysfs_addrm_finish(&acxt);
 
@@ -928,7 +928,7 @@ void sysfs_remove_dir(struct kobject *kobj)
 
 	if (sd) {
 		WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
-		sysfs_remove(sd);
+		kernfs_remove(sd);
 	}
 }
 
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index b94f936..6e2ee22 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -970,7 +970,7 @@ void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr,
 {
 	struct sysfs_dirent *dir_sd = kobj->sd;
 
-	sysfs_hash_and_remove(dir_sd, attr->name, ns);
+	kernfs_remove_by_name_ns(dir_sd, attr->name, ns);
 }
 EXPORT_SYMBOL_GPL(sysfs_remove_file_ns);
 
@@ -998,7 +998,7 @@ void sysfs_remove_file_from_group(struct kobject *kobj,
 	else
 		dir_sd = sysfs_get(kobj->sd);
 	if (dir_sd) {
-		sysfs_hash_and_remove(dir_sd, attr->name, NULL);
+		kernfs_remove_by_name(dir_sd, attr->name);
 		sysfs_put(dir_sd);
 	}
 }
@@ -1026,7 +1026,7 @@ EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
 void sysfs_remove_bin_file(struct kobject *kobj,
 			   const struct bin_attribute *attr)
 {
-	sysfs_hash_and_remove(kobj->sd, attr->attr.name, NULL);
+	kernfs_remove_by_name(kobj->sd, attr->attr.name);
 }
 EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);
 
diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index 3796afd..01657c5 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -26,7 +26,7 @@ static void remove_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,
 
 	if (grp->attrs)
 		for (attr = grp->attrs; *attr; attr++)
-			sysfs_hash_and_remove(dir_sd, (*attr)->name, NULL);
+			kernfs_remove_by_name(dir_sd, (*attr)->name);
 	if (grp->bin_attrs)
 		for (bin_attr = grp->bin_attrs; *bin_attr; bin_attr++)
 			sysfs_remove_bin_file(kobj, *bin_attr);
@@ -49,8 +49,7 @@ static int create_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,
 			 * re-adding (if required) the file.
 			 */
 			if (update)
-				sysfs_hash_and_remove(dir_sd, (*attr)->name,
-						      NULL);
+				kernfs_remove_by_name(dir_sd, (*attr)->name);
 			if (grp->is_visible) {
 				mode = grp->is_visible(kobj, *attr, i);
 				if (!mode)
@@ -111,7 +110,7 @@ static int internal_create_group(struct kobject *kobj, int update,
 	error = create_files(sd, kobj, grp, update);
 	if (error) {
 		if (grp->name)
-			sysfs_remove(sd);
+			kernfs_remove(sd);
 	}
 	sysfs_put(sd);
 	return error;
@@ -228,7 +227,7 @@ void sysfs_remove_group(struct kobject *kobj,
 
 	remove_files(sd, kobj, grp);
 	if (grp->name)
-		sysfs_remove(sd);
+		kernfs_remove(sd);
 
 	sysfs_put(sd);
 }
@@ -279,7 +278,7 @@ int sysfs_merge_group(struct kobject *kobj,
 		error = sysfs_add_file(dir_sd, *attr, SYSFS_KOBJ_ATTR);
 	if (error) {
 		while (--i >= 0)
-			sysfs_hash_and_remove(dir_sd, (*--attr)->name, NULL);
+			kernfs_remove_by_name(dir_sd, (*--attr)->name);
 	}
 	sysfs_put(dir_sd);
 
@@ -301,7 +300,7 @@ void sysfs_unmerge_group(struct kobject *kobj,
 	dir_sd = sysfs_get_dirent(kobj->sd, grp->name);
 	if (dir_sd) {
 		for (attr = grp->attrs; *attr; ++attr)
-			sysfs_hash_and_remove(dir_sd, (*attr)->name, NULL);
+			kernfs_remove_by_name(dir_sd, (*attr)->name);
 		sysfs_put(dir_sd);
 	}
 }
@@ -344,7 +343,7 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
 
 	dir_sd = sysfs_get_dirent(kobj->sd, group_name);
 	if (dir_sd) {
-		sysfs_hash_and_remove(dir_sd, link_name, NULL);
+		kernfs_remove_by_name(dir_sd, link_name);
 		sysfs_put(dir_sd);
 	}
 }
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index c660363..71583fc 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -153,7 +153,7 @@ void sysfs_delete_link(struct kobject *kobj, struct kobject *targ,
 	if (targ->sd && (kobj->sd->s_flags & SYSFS_FLAG_NS))
 		ns = targ->sd->s_ns;
 	spin_unlock(&sysfs_symlink_target_lock);
-	sysfs_hash_and_remove(kobj->sd, name, ns);
+	kernfs_remove_by_name_ns(kobj->sd, name, ns);
 }
 
 /**
@@ -170,7 +170,7 @@ void sysfs_remove_link(struct kobject *kobj, const char *name)
 	else
 		parent_sd = kobj->sd;
 
-	sysfs_hash_and_remove(parent_sd, name, NULL);
+	kernfs_remove_by_name(parent_sd, name);
 }
 EXPORT_SYMBOL_GPL(sysfs_remove_link);
 
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index e116c21..97625b1 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -173,9 +173,6 @@ int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
 		    struct sysfs_dirent *parent_sd);
 int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
 		  struct sysfs_dirent *parent_sd);
-void sysfs_remove(struct sysfs_dirent *sd);
-int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name,
-			  const void *ns);
 void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
 
 struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 254b9e8..83e151a 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -7,6 +7,30 @@
 #ifndef __LINUX_KERNFS_H
 #define __LINUX_KERNFS_H
 
+#include <linux/kernel.h>
+
 struct sysfs_dirent;
 
+#ifdef CONFIG_SYSFS
+
+void kernfs_remove(struct sysfs_dirent *sd);
+int kernfs_remove_by_name_ns(struct sysfs_dirent *parent, const char *name,
+			     const void *ns);
+
+#else	/* CONFIG_SYSFS */
+
+static inline void kernfs_remove(struct sysfs_dirent *sd) { }
+
+static inline int kernfs_remove_by_name_ns(struct sysfs_dirent *parent,
+					   const char *name, const void *ns)
+{ return -ENOSYS; }
+
+#endif	/* CONFIG_SYSFS */
+
+static inline int kernfs_remove_by_name(struct sysfs_dirent *parent,
+					const char *name)
+{
+	return kernfs_remove_by_name_ns(parent, name, NULL);
+}
+
 #endif	/* __LINUX_KERNFS_H */
-- 
1.8.4.2

[PATCH 05/41] sysfs, kernfs: introduce kernfs_create_link()

[Tejun Heo]

Separate out kernfs symlink interface - kernfs_create_link() - which
takes and returns sysfs_dirents, from sysfs_do_create_link_sd().
sysfs_do_create_link_sd() now just determines the parent and target
sysfs_dirents and invokes the new interface and handles dup warning.

This patch doesn't introduce behavior changes.

v2: Dummy implementation for !CONFIG_SYSFS updated to return -ENOSYS.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/symlink.c     | 76 ++++++++++++++++++++++++++++++--------------------
 include/linux/kernfs.h |  9 ++++++
 2 files changed, 55 insertions(+), 30 deletions(-)

diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 71583fc..41138e9 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -21,14 +21,48 @@
 
 #include "sysfs.h"
 
+/**
+ * kernfs_create_link - create a symlink
+ * @parent: directory to create the symlink in
+ * @name: name of the symlink
+ * @target: target node for the symlink to point to
+ *
+ * Returns the created node on success, ERR_PTR() value on error.
+ */
+struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
+					const char *name,
+					struct sysfs_dirent *target)
+{
+	struct sysfs_dirent *sd;
+	struct sysfs_addrm_cxt acxt;
+	int error;
+
+	sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
+	if (!sd)
+		return ERR_PTR(-ENOMEM);
+
+	if (parent->s_flags & SYSFS_FLAG_NS)
+		sd->s_ns = target->s_ns;
+	sd->s_symlink.target_sd = target;
+	sysfs_get(target);	/* ref owned by symlink */
+
+	sysfs_addrm_start(&acxt);
+	error = __sysfs_add_one(&acxt, sd, parent);
+	sysfs_addrm_finish(&acxt);
+
+	if (!error)
+		return sd;
+
+	sysfs_put(sd);
+	return ERR_PTR(error);
+}
+
+
 static int sysfs_do_create_link_sd(struct sysfs_dirent *parent_sd,
 				   struct kobject *target,
 				   const char *name, int warn)
 {
-	struct sysfs_dirent *target_sd = NULL;
-	struct sysfs_dirent *sd = NULL;
-	struct sysfs_addrm_cxt acxt;
-	int error;
+	struct sysfs_dirent *sd, *target_sd = NULL;
 
 	BUG_ON(!name || !parent_sd);
 
@@ -42,36 +76,18 @@ static int sysfs_do_create_link_sd(struct sysfs_dirent *parent_sd,
 		target_sd = sysfs_get(target->sd);
 	spin_unlock(&sysfs_symlink_target_lock);
 
-	error = -ENOENT;
 	if (!target_sd)
-		goto out_put;
+		return -ENOENT;
 
-	error = -ENOMEM;
-	sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
-	if (!sd)
-		goto out_put;
-
-	if (parent_sd->s_flags & SYSFS_FLAG_NS)
-		sd->s_ns = target_sd->s_ns;
-	sd->s_symlink.target_sd = target_sd;
-	target_sd = NULL;	/* reference is now owned by the symlink */
-
-	sysfs_addrm_start(&acxt);
-	if (warn)
-		error = sysfs_add_one(&acxt, sd, parent_sd);
-	else
-		error = __sysfs_add_one(&acxt, sd, parent_sd);
-	sysfs_addrm_finish(&acxt);
-
-	if (error)
-		goto out_put;
+	sd = kernfs_create_link(parent_sd, name, target_sd);
+	sysfs_put(target_sd);
 
-	return 0;
+	if (!IS_ERR(sd))
+		return 0;
 
- out_put:
-	sysfs_put(target_sd);
-	sysfs_put(sd);
-	return error;
+	if (warn && PTR_ERR(sd) == -EEXIST)
+		sysfs_warn_dup(parent_sd, name);
+	return PTR_ERR(sd);
 }
 
 /**
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 83e151a..fe6290d 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -8,17 +8,26 @@
 #define __LINUX_KERNFS_H
 
 #include <linux/kernel.h>
+#include <linux/err.h>
 
 struct sysfs_dirent;
 
 #ifdef CONFIG_SYSFS
 
+struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
+					const char *name,
+					struct sysfs_dirent *target);
 void kernfs_remove(struct sysfs_dirent *sd);
 int kernfs_remove_by_name_ns(struct sysfs_dirent *parent, const char *name,
 			     const void *ns);
 
 #else	/* CONFIG_SYSFS */
 
+static inline struct sysfs_dirent *
+kernfs_create_link(struct sysfs_dirent *parent, const char *name,
+		   struct sysfs_dirent *target)
+{ return ERR_PTR(-ENOSYS); }
+
 static inline void kernfs_remove(struct sysfs_dirent *sd) { }
 
 static inline int kernfs_remove_by_name_ns(struct sysfs_dirent *parent,
-- 
1.8.4.2

[PATCH 06/41] sysfs, kernfs: introduce kernfs_rename[_ns]()

[Tejun Heo]

Introduce kernfs rename interface, krenfs_rename[_ns]().

This is just rename of sysfs_rename().  No functional changes.
Function comment is added to kernfs_rename_ns() and @new_parent_sd is
renamed to @new_parent for consistency with other kernfs interfaces.

v2: Dummy implementation for !CONFIG_SYSFS updated to return -ENOSYS.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/dir.c         | 23 +++++++++++++++--------
 fs/sysfs/symlink.c     |  2 +-
 fs/sysfs/sysfs.h       |  3 ---
 include/linux/kernfs.h |  7 +++++++
 4 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index edbde4e..5ba8966 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -932,20 +932,27 @@ void sysfs_remove_dir(struct kobject *kobj)
 	}
 }
 
-int sysfs_rename(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent_sd,
-		 const char *new_name, const void *new_ns)
+/**
+ * kernfs_rename_ns - move and rename a kernfs_node
+ * @sd: target node
+ * @new_parent: new parent to put @sd under
+ * @new_name: new name
+ * @new_ns: new namespace tag
+ */
+int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
+		     const char *new_name, const void *new_ns)
 {
 	int error;
 
 	mutex_lock(&sysfs_mutex);
 
 	error = 0;
-	if ((sd->s_parent == new_parent_sd) && (sd->s_ns == new_ns) &&
+	if ((sd->s_parent == new_parent) && (sd->s_ns == new_ns) &&
 	    (strcmp(sd->s_name, new_name) == 0))
 		goto out;	/* nothing to rename */
 
 	error = -EEXIST;
-	if (sysfs_find_dirent(new_parent_sd, new_name, new_ns))
+	if (sysfs_find_dirent(new_parent, new_name, new_ns))
 		goto out;
 
 	/* rename sysfs_dirent */
@@ -963,11 +970,11 @@ int sysfs_rename(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent_sd,
 	 * Move to the appropriate place in the appropriate directories rbtree.
 	 */
 	sysfs_unlink_sibling(sd);
-	sysfs_get(new_parent_sd);
+	sysfs_get(new_parent);
 	sysfs_put(sd->s_parent);
 	sd->s_ns = new_ns;
 	sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
-	sd->s_parent = new_parent_sd;
+	sd->s_parent = new_parent;
 	sysfs_link_sibling(sd);
 
 	error = 0;
@@ -981,7 +988,7 @@ int sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name,
 {
 	struct sysfs_dirent *parent_sd = kobj->sd->s_parent;
 
-	return sysfs_rename(kobj->sd, parent_sd, new_name, new_ns);
+	return kernfs_rename_ns(kobj->sd, parent_sd, new_name, new_ns);
 }
 
 int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
@@ -994,7 +1001,7 @@ int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
 	new_parent_sd = new_parent_kobj && new_parent_kobj->sd ?
 		new_parent_kobj->sd : &sysfs_root;
 
-	return sysfs_rename(sd, new_parent_sd, sd->s_name, new_ns);
+	return kernfs_rename_ns(sd, new_parent_sd, sd->s_name, new_ns);
 }
 
 /**
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 41138e9..0922c53 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -226,7 +226,7 @@ int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *targ,
 	if (sd->s_symlink.target_sd->s_dir.kobj != targ)
 		goto out;
 
-	result = sysfs_rename(sd, parent_sd, new, new_ns);
+	result = kernfs_rename_ns(sd, parent_sd, new, new_ns);
 
 out:
 	sysfs_put(sd);
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 97625b1..8b3fc21 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -185,9 +185,6 @@ void release_sysfs_dirent(struct sysfs_dirent *sd);
 int sysfs_create_subdir(struct kobject *kobj, const char *name,
 			struct sysfs_dirent **p_sd);
 
-int sysfs_rename(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent_sd,
-		 const char *new_name, const void *new_ns);
-
 static inline struct sysfs_dirent *__sysfs_get(struct sysfs_dirent *sd)
 {
 	if (sd) {
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index fe6290d..803d960 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -20,6 +20,8 @@ struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
 void kernfs_remove(struct sysfs_dirent *sd);
 int kernfs_remove_by_name_ns(struct sysfs_dirent *parent, const char *name,
 			     const void *ns);
+int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
+		     const char *new_name, const void *new_ns);
 
 #else	/* CONFIG_SYSFS */
 
@@ -34,6 +36,11 @@ static inline int kernfs_remove_by_name_ns(struct sysfs_dirent *parent,
 					   const char *name, const void *ns)
 { return -ENOSYS; }
 
+static inline int kernfs_rename_ns(struct sysfs_dirent *sd,
+				   struct sysfs_dirent *new_parent,
+				   const char *new_name, const void *new_ns)
+{ return -ENOSYS; }
+
 #endif	/* CONFIG_SYSFS */
 
 static inline int kernfs_remove_by_name(struct sysfs_dirent *parent,
-- 
1.8.4.2

[PATCH 07/41] sysfs, kernfs: introduce kernfs_setattr()

[Tejun Heo]

Introduce kernfs setattr interface - kernfs_setattr().

sysfs_sd_setattr() is renamed to __kernfs_setattr() and
kernfs_setattr() is a simple wrapper around it with sysfs_mutex
locking.  sysfs_chmod_file() is updated to get an explicit ref on
kobj->sd and then invoke kernfs_setattr() so that it doesn't have to
use internal interface.

This patch doesn't introduce any behavior differences.

v2: Dummy implementation for !CONFIG_SYSFS updated to return -ENOSYS.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c        | 13 +++++--------
 fs/sysfs/inode.c       | 21 +++++++++++++++++++--
 fs/sysfs/sysfs.h       |  1 -
 include/linux/kernfs.h |  8 ++++++++
 4 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 6e2ee22..0f3f0a2 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -940,19 +940,16 @@ int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
 	struct iattr newattrs;
 	int rc;
 
-	mutex_lock(&sysfs_mutex);
-
-	rc = -ENOENT;
-	sd = sysfs_find_dirent(kobj->sd, attr->name, NULL);
+	sd = sysfs_get_dirent(kobj->sd, attr->name);
 	if (!sd)
-		goto out;
+		return -ENOENT;
 
 	newattrs.ia_mode = (mode & S_IALLUGO) | (sd->s_mode & ~S_IALLUGO);
 	newattrs.ia_valid = ATTR_MODE;
-	rc = sysfs_sd_setattr(sd, &newattrs);
 
- out:
-	mutex_unlock(&sysfs_mutex);
+	rc = kernfs_setattr(sd, &newattrs);
+
+	sysfs_put(sd);
 	return rc;
 }
 EXPORT_SYMBOL_GPL(sysfs_chmod_file);
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index 1750f79..5f7e2af 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -67,7 +67,7 @@ static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
 	return attrs;
 }
 
-int sysfs_sd_setattr(struct sysfs_dirent *sd, struct iattr *iattr)
+static int __kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
 {
 	struct sysfs_inode_attrs *sd_attrs;
 	struct iattr *iattrs;
@@ -102,6 +102,23 @@ int sysfs_sd_setattr(struct sysfs_dirent *sd, struct iattr *iattr)
 	return 0;
 }
 
+/**
+ * kernfs_setattr - set iattr on a node
+ * @sd: target node
+ * @iattr: iattr to set
+ *
+ * Returns 0 on success, -errno on failure.
+ */
+int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
+{
+	int ret;
+
+	mutex_lock(&sysfs_mutex);
+	ret = __kernfs_setattr(sd, iattr);
+	mutex_unlock(&sysfs_mutex);
+	return ret;
+}
+
 int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
 {
 	struct inode *inode = dentry->d_inode;
@@ -116,7 +133,7 @@ int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
 	if (error)
 		goto out;
 
-	error = sysfs_sd_setattr(sd, iattr);
+	error = __kernfs_setattr(sd, iattr);
 	if (error)
 		goto out;
 
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 8b3fc21..2abccfd 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -207,7 +207,6 @@ static inline void __sysfs_put(struct sysfs_dirent *sd)
  */
 struct inode *sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd);
 void sysfs_evict_inode(struct inode *inode);
-int sysfs_sd_setattr(struct sysfs_dirent *sd, struct iattr *iattr);
 int sysfs_permission(struct inode *inode, int mask);
 int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
 int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 803d960..8cb6738 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -10,6 +10,9 @@
 #include <linux/kernel.h>
 #include <linux/err.h>
 
+struct file;
+struct iattr;
+
 struct sysfs_dirent;
 
 #ifdef CONFIG_SYSFS
@@ -22,6 +25,7 @@ int kernfs_remove_by_name_ns(struct sysfs_dirent *parent, const char *name,
 			     const void *ns);
 int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
 		     const char *new_name, const void *new_ns);
+int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr);
 
 #else	/* CONFIG_SYSFS */
 
@@ -41,6 +45,10 @@ static inline int kernfs_rename_ns(struct sysfs_dirent *sd,
 				   const char *new_name, const void *new_ns)
 { return -ENOSYS; }
 
+static inline int kernfs_setattr(struct sysfs_dirent *sd,
+				 const struct iattr *iattr)
+{ return -ENOSYS; }
+
 #endif	/* CONFIG_SYSFS */
 
 static inline int kernfs_remove_by_name(struct sysfs_dirent *parent,
-- 
1.8.4.2

[PATCH 08/41] sysfs, kernfs: replace sysfs_dirent->s_dir.kobj and ->s_attr.[bin_]attr with ->priv

[Tejun Heo]

A directory sysfs_dirent points to the associated kobj.  A regular or
bin file points to the associated [bin_]attribute.  This patch
replaces sysfs_dirent->s_dir.kobj and ->s_attr.[bin_]attr with void *
->priv.

This is to prepare for kernfs interface so that sysfs can specify the
private data in the same way for directories and files.  This lower
debuggability but not by much - the whole thing was overlaid in a
union anyway.  If debuggability becomes an issue, we can later add
->priv accessors which explicitly check for the sysfs_dirent type and
performs casting.

This patch doesn't introduce any behavior difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/dir.c     |  2 +-
 fs/sysfs/file.c    | 26 +++++++++++++-------------
 fs/sysfs/inode.c   |  2 +-
 fs/sysfs/symlink.c |  2 +-
 fs/sysfs/sysfs.h   | 13 +++++--------
 5 files changed, 21 insertions(+), 24 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 5ba8966..aeb08bd 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -681,7 +681,7 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
 		return -ENOMEM;
 
 	sd->s_ns = ns;
-	sd->s_dir.kobj = kobj;
+	sd->priv = kobj;
 
 	/* link in */
 	sysfs_addrm_start(&acxt);
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 0f3f0a2..9b58d87 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -74,7 +74,7 @@ static struct sysfs_open_file *sysfs_of(struct file *file)
  */
 static const struct sysfs_ops *sysfs_file_ops(struct sysfs_dirent *sd)
 {
-	struct kobject *kobj = sd->s_parent->s_dir.kobj;
+	struct kobject *kobj = sd->s_parent->priv;
 
 	if (!sysfs_ignore_lockdep(sd))
 		lockdep_assert_held(sd);
@@ -89,7 +89,7 @@ static const struct sysfs_ops *sysfs_file_ops(struct sysfs_dirent *sd)
 static int sysfs_seq_show(struct seq_file *sf, void *v)
 {
 	struct sysfs_open_file *of = sf->private;
-	struct kobject *kobj = of->sd->s_parent->s_dir.kobj;
+	struct kobject *kobj = of->sd->s_parent->priv;
 	const struct sysfs_ops *ops;
 	char *buf;
 	ssize_t count;
@@ -120,7 +120,7 @@ static int sysfs_seq_show(struct seq_file *sf, void *v)
 	 */
 	ops = sysfs_file_ops(of->sd);
 	if (ops->show)
-		count = ops->show(kobj, of->sd->s_attr.attr, buf);
+		count = ops->show(kobj, of->sd->priv, buf);
 	else
 		count = 0;
 
@@ -154,8 +154,8 @@ static ssize_t sysfs_bin_read(struct file *file, char __user *userbuf,
 			      size_t bytes, loff_t *off)
 {
 	struct sysfs_open_file *of = sysfs_of(file);
-	struct bin_attribute *battr = of->sd->s_attr.bin_attr;
-	struct kobject *kobj = of->sd->s_parent->s_dir.kobj;
+	struct bin_attribute *battr = of->sd->priv;
+	struct kobject *kobj = of->sd->s_parent->priv;
 	loff_t size = file_inode(file)->i_size;
 	int count = min_t(size_t, bytes, PAGE_SIZE);
 	loff_t offs = *off;
@@ -221,7 +221,7 @@ static ssize_t sysfs_bin_read(struct file *file, char __user *userbuf,
 static int flush_write_buffer(struct sysfs_open_file *of, char *buf, loff_t off,
 			      size_t count)
 {
-	struct kobject *kobj = of->sd->s_parent->s_dir.kobj;
+	struct kobject *kobj = of->sd->s_parent->priv;
 	int rc = 0;
 
 	/*
@@ -236,7 +236,7 @@ static int flush_write_buffer(struct sysfs_open_file *of, char *buf, loff_t off,
 	}
 
 	if (sysfs_is_bin(of->sd)) {
-		struct bin_attribute *battr = of->sd->s_attr.bin_attr;
+		struct bin_attribute *battr = of->sd->priv;
 
 		rc = -EIO;
 		if (battr->write)
@@ -245,7 +245,7 @@ static int flush_write_buffer(struct sysfs_open_file *of, char *buf, loff_t off,
 	} else {
 		const struct sysfs_ops *ops = sysfs_file_ops(of->sd);
 
-		rc = ops->store(kobj, of->sd->s_attr.attr, buf, count);
+		rc = ops->store(kobj, of->sd->priv, buf, count);
 	}
 
 	sysfs_put_active(of->sd);
@@ -466,8 +466,8 @@ static const struct vm_operations_struct sysfs_bin_vm_ops = {
 static int sysfs_bin_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	struct sysfs_open_file *of = sysfs_of(file);
-	struct bin_attribute *battr = of->sd->s_attr.bin_attr;
-	struct kobject *kobj = of->sd->s_parent->s_dir.kobj;
+	struct bin_attribute *battr = of->sd->priv;
+	struct kobject *kobj = of->sd->s_parent->priv;
 	int rc;
 
 	mutex_lock(&of->mutex);
@@ -607,7 +607,7 @@ static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
 static int sysfs_open_file(struct inode *inode, struct file *file)
 {
 	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
-	struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
+	struct kobject *kobj = attr_sd->s_parent->priv;
 	struct sysfs_open_file *of;
 	bool has_read, has_write, has_mmap;
 	int error = -EACCES;
@@ -617,7 +617,7 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
 		return -ENODEV;
 
 	if (sysfs_is_bin(attr_sd)) {
-		struct bin_attribute *battr = attr_sd->s_attr.bin_attr;
+		struct bin_attribute *battr = attr_sd->priv;
 
 		has_read = battr->read || battr->mmap;
 		has_write = battr->write || battr->mmap;
@@ -848,7 +848,7 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 		return -ENOMEM;
 
 	sd->s_ns = ns;
-	sd->s_attr.attr = (void *)attr;
+	sd->priv = (void *)attr;
 	sysfs_dirent_init_lockdep(sd);
 
 	sysfs_addrm_start(&acxt);
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index 5f7e2af..81cc858 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -275,7 +275,7 @@ static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
 		inode->i_fop = &sysfs_file_operations;
 		break;
 	case SYSFS_KOBJ_BIN_ATTR:
-		bin_attr = sd->s_attr.bin_attr;
+		bin_attr = sd->priv;
 		inode->i_size = bin_attr->size;
 		inode->i_fop = &sysfs_bin_operations;
 		break;
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 0922c53..352fbbb 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -223,7 +223,7 @@ int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *targ,
 	result = -EINVAL;
 	if (sysfs_type(sd) != SYSFS_KOBJ_LINK)
 		goto out;
-	if (sd->s_symlink.target_sd->s_dir.kobj != targ)
+	if (sd->s_symlink.target_sd->priv != targ)
 		goto out;
 
 	result = kernfs_rename_ns(sd, parent_sd, new, new_ns);
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 2abccfd..a6f3fa3 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -17,8 +17,6 @@ struct sysfs_open_dirent;
 
 /* type-specific structures for sysfs_dirent->s_* union members */
 struct sysfs_elem_dir {
-	struct kobject		*kobj;
-
 	unsigned long		subdirs;
 	/* children rbtree starts here and goes through sd->s_rb */
 	struct rb_root		children;
@@ -29,10 +27,6 @@ struct sysfs_elem_symlink {
 };
 
 struct sysfs_elem_attr {
-	union {
-		struct attribute	*attr;
-		struct bin_attribute	*bin_attr;
-	};
 	struct sysfs_open_dirent *open;
 };
 
@@ -74,6 +68,8 @@ struct sysfs_dirent {
 		struct sysfs_elem_attr		s_attr;
 	};
 
+	void			*priv;
+
 	unsigned short		s_flags;
 	umode_t			s_mode;
 	unsigned int		s_ino;
@@ -103,7 +99,7 @@ static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
 
 #define sysfs_dirent_init_lockdep(sd)				\
 do {								\
-	struct attribute *attr = sd->s_attr.attr;		\
+	struct attribute *attr = sd->priv;			\
 	struct lock_class_key *key = attr->key;			\
 	if (!key)						\
 		key = &attr->skey;				\
@@ -114,10 +110,11 @@ do {								\
 /* Test for attributes that want to ignore lockdep for read-locking */
 static inline bool sysfs_ignore_lockdep(struct sysfs_dirent *sd)
 {
+	struct attribute *attr = sd->priv;
 	int type = sysfs_type(sd);
 
 	return (type == SYSFS_KOBJ_ATTR || type == SYSFS_KOBJ_BIN_ATTR) &&
-		sd->s_attr.attr->ignore_lockdep;
+		attr->ignore_lockdep;
 }
 
 #else
-- 
1.8.4.2

[PATCH 09/41] sysfs, kernfs: introduce kernfs_create_dir[_ns]()

[Tejun Heo]

Introduce kernfs interface to manipulate a directory which takes and
returns sysfs_dirents.

create_dir() is renamed to kernfs_create_dir_ns() and its argumantes
and return value are updated.  create_dir() usages are replaced with
kernfs_create_dir_ns() and sysfs_create_subdir() usages are replaced
with kernfs_create_dir().  Dup warnings are handled explicitly by
sysfs users of the kernfs interface.

sysfs_enable_ns() is renamed to kernfs_enable_ns().

This patch doesn't introduce any behavior changes.

v2: Dummy implementation for !CONFIG_SYSFS updated to return -ENOSYS.

v3: kernfs_enable_ns() added.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/dir.c         | 54 ++++++++++++++++++++++++++++----------------------
 fs/sysfs/group.c       |  9 ++++++---
 fs/sysfs/sysfs.h       |  3 ---
 include/linux/kernfs.h | 17 ++++++++++++++++
 include/linux/sysfs.h  |  2 --
 lib/kobject.c          |  2 +-
 6 files changed, 54 insertions(+), 33 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index aeb08bd..cfbf409 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -666,9 +666,18 @@ struct sysfs_dirent *sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd,
 }
 EXPORT_SYMBOL_GPL(sysfs_get_dirent_ns);
 
-static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
-		      const char *name, const void *ns,
-		      struct sysfs_dirent **p_sd)
+/**
+ * kernfs_create_dir_ns - create a directory
+ * @parent: parent in which to create a new directory
+ * @name: name of the new directory
+ * @priv: opaque data associated with the new directory
+ * @ns: optional namespace tag of the directory
+ *
+ * Returns the created node on success, ERR_PTR() value on failure.
+ */
+struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
+					  const char *name, void *priv,
+					  const void *ns)
 {
 	umode_t mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
 	struct sysfs_addrm_cxt acxt;
@@ -678,28 +687,21 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
 	/* allocate */
 	sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
 	if (!sd)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
 	sd->s_ns = ns;
-	sd->priv = kobj;
+	sd->priv = priv;
 
 	/* link in */
 	sysfs_addrm_start(&acxt);
-	rc = sysfs_add_one(&acxt, sd, parent_sd);
+	rc = __sysfs_add_one(&acxt, sd, parent);
 	sysfs_addrm_finish(&acxt);
 
-	if (rc == 0)
-		*p_sd = sd;
-	else
-		sysfs_put(sd);
+	if (!rc)
+		return sd;
 
-	return rc;
-}
-
-int sysfs_create_subdir(struct kobject *kobj, const char *name,
-			struct sysfs_dirent **p_sd)
-{
-	return create_dir(kobj, kobj->sd, name, NULL, p_sd);
+	sysfs_put(sd);
+	return ERR_PTR(rc);
 }
 
 /**
@@ -710,7 +712,6 @@ int sysfs_create_subdir(struct kobject *kobj, const char *name,
 int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
 {
 	struct sysfs_dirent *parent_sd, *sd;
-	int error = 0;
 
 	BUG_ON(!kobj);
 
@@ -722,10 +723,15 @@ int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
 	if (!parent_sd)
 		return -ENOENT;
 
-	error = create_dir(kobj, parent_sd, kobject_name(kobj), ns, &sd);
-	if (!error)
-		kobj->sd = sd;
-	return error;
+	sd = kernfs_create_dir_ns(parent_sd, kobject_name(kobj), kobj, ns);
+	if (IS_ERR(sd)) {
+		if (PTR_ERR(sd) == -EEXIST)
+			sysfs_warn_dup(parent_sd, kobject_name(kobj));
+		return PTR_ERR(sd);
+	}
+
+	kobj->sd = sd;
+	return 0;
 }
 
 static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry,
@@ -1005,14 +1011,14 @@ int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
 }
 
 /**
- * sysfs_enable_ns - enable namespace under a directory
+ * kernfs_enable_ns - enable namespace under a directory
  * @sd: directory of interest, should be empty
  *
  * This is to be called right after @sd is created to enable namespace
  * under it.  All children of @sd must have non-NULL namespace tags and
  * only the ones which match the super_block's tag will be visible.
  */
-void sysfs_enable_ns(struct sysfs_dirent *sd)
+void kernfs_enable_ns(struct sysfs_dirent *sd)
 {
 	WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
 	WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));
diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index 01657c5..11be6de 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -101,9 +101,12 @@ static int internal_create_group(struct kobject *kobj, int update,
 		return -EINVAL;
 	}
 	if (grp->name) {
-		error = sysfs_create_subdir(kobj, grp->name, &sd);
-		if (error)
-			return error;
+		sd = kernfs_create_dir(kobj->sd, grp->name, kobj);
+		if (IS_ERR(sd)) {
+			if (PTR_ERR(sd) == -EEXIST)
+				sysfs_warn_dup(kobj->sd, grp->name);
+			return PTR_ERR(sd);
+		}
 	} else
 		sd = kobj->sd;
 	sysfs_get(sd);
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index a6f3fa3..9ac234e 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -179,9 +179,6 @@ struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);
 
 void release_sysfs_dirent(struct sysfs_dirent *sd);
 
-int sysfs_create_subdir(struct kobject *kobj, const char *name,
-			struct sysfs_dirent **p_sd);
-
 static inline struct sysfs_dirent *__sysfs_get(struct sysfs_dirent *sd)
 {
 	if (sd) {
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 8cb6738..e8b73d4 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -17,6 +17,9 @@ struct sysfs_dirent;
 
 #ifdef CONFIG_SYSFS
 
+struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
+					  const char *name, void *priv,
+					  const void *ns);
 struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
 					const char *name,
 					struct sysfs_dirent *target);
@@ -25,11 +28,17 @@ int kernfs_remove_by_name_ns(struct sysfs_dirent *parent, const char *name,
 			     const void *ns);
 int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
 		     const char *new_name, const void *new_ns);
+void kernfs_enable_ns(struct sysfs_dirent *sd);
 int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr);
 
 #else	/* CONFIG_SYSFS */
 
 static inline struct sysfs_dirent *
+kernfs_create_dir_ns(struct sysfs_dirent *parent, const char *name, void *priv,
+		     const void *ns)
+{ return ERR_PTR(-ENOSYS); }
+
+static inline struct sysfs_dirent *
 kernfs_create_link(struct sysfs_dirent *parent, const char *name,
 		   struct sysfs_dirent *target)
 { return ERR_PTR(-ENOSYS); }
@@ -45,12 +54,20 @@ static inline int kernfs_rename_ns(struct sysfs_dirent *sd,
 				   const char *new_name, const void *new_ns)
 { return -ENOSYS; }
 
+static inline void kernfs_enable_ns(struct sysfs_dirent *sd) { }
+
 static inline int kernfs_setattr(struct sysfs_dirent *sd,
 				 const struct iattr *iattr)
 { return -ENOSYS; }
 
 #endif	/* CONFIG_SYSFS */
 
+static inline struct sysfs_dirent *
+kernfs_create_dir(struct sysfs_dirent *parent, const char *name, void *priv)
+{
+	return kernfs_create_dir_ns(parent, name, priv, NULL);
+}
+
 static inline int kernfs_remove_by_name(struct sysfs_dirent *parent,
 					const char *name)
 {
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index f82ec46..2bc735d 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -219,8 +219,6 @@ int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *target,
 void sysfs_delete_link(struct kobject *dir, struct kobject *targ,
 			const char *name);
 
-void sysfs_enable_ns(struct sysfs_dirent *sd);
-
 int __must_check sysfs_create_group(struct kobject *kobj,
 				    const struct attribute_group *grp);
 int __must_check sysfs_create_groups(struct kobject *kobj,
diff --git a/lib/kobject.c b/lib/kobject.c
index 16e9335..b8d848f 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -94,7 +94,7 @@ static int create_dir(struct kobject *kobj)
 		BUG_ON(ops->type >= KOBJ_NS_TYPES);
 		BUG_ON(!kobj_ns_type_registered(ops->type));
 
-		sysfs_enable_ns(kobj->sd);
+		kernfs_enable_ns(kobj->sd);
 	}
 
 	return 0;
-- 
1.8.4.2

[PATCH 10/41] sysfs, kernfs: prepare read path for kernfs

[Tejun Heo]

We're in the process of separating out core sysfs functionality into
kernfs which will deal with sysfs_dirents directly.  This patch
rearranges read path so that the kernfs and sysfs parts are separate.

* Regular file read path is refactored such that
  kernfs_seq_start/next/stop/show() handle all the boilerplate work
  including locking and updating event count for poll, while
  sysfs_kf_seq_show() deals with interaction with kobj show method.

* Bin file read path is refactored such that kernfs_file_direct_read()
  handles all the boilerplate work including buffer management and
  locking, while sysfs_kf_bin_read() deals with interaction with
  bin_attribute read method.

kernfs_file_read() is added.  It invokes either the seq_file or direct
read path depending on the file type.  This will eventually allow
using the same file_operations for both file types, which is necessary
to separate out kernfs.

While this patch changes the order of some operations, it shouldn't
change any visible behavior.

v2: Dropped unnecessary zeroing of @count from sysfs_kf_seq_show().
    Add comments explaining single_open() behavior.  Both suggested by
    Pavel.

v3: seq_stop() is called even after seq_start() failed.
    kernfs_seq_start() updated so that it doesn't unlock
    sysfs_open_file->mutex on failure so that kernfs_seq_stop()
    doesn't try to unlock an already unlocked mutex.  Reported by
    Fengguang.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Fengguang Wu <fengguang.wu@intel.com>
---
 fs/sysfs/file.c | 191 +++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 126 insertions(+), 65 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 9b58d87..b695b8b 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -86,13 +86,13 @@ static const struct sysfs_ops *sysfs_file_ops(struct sysfs_dirent *sd)
  * details like buffering and seeking.  The following function pipes
  * sysfs_ops->show() result through seq_file.
  */
-static int sysfs_seq_show(struct seq_file *sf, void *v)
+static int sysfs_kf_seq_show(struct seq_file *sf, void *v)
 {
 	struct sysfs_open_file *of = sf->private;
 	struct kobject *kobj = of->sd->s_parent->priv;
-	const struct sysfs_ops *ops;
-	char *buf;
+	const struct sysfs_ops *ops = sysfs_file_ops(of->sd);
 	ssize_t count;
+	char *buf;
 
 	/* acquire buffer and ensure that it's >= PAGE_SIZE */
 	count = seq_get_buf(sf, &buf);
@@ -102,33 +102,14 @@ static int sysfs_seq_show(struct seq_file *sf, void *v)
 	}
 
 	/*
-	 * Need @of->sd for attr and ops, its parent for kobj.  @of->mutex
-	 * nests outside active ref and is just to ensure that the ops
-	 * aren't called concurrently for the same open file.
+	 * Invoke show().  Control may reach here via seq file lseek even
+	 * if @ops->show() isn't implemented.
 	 */
-	mutex_lock(&of->mutex);
-	if (!sysfs_get_active(of->sd)) {
-		mutex_unlock(&of->mutex);
-		return -ENODEV;
-	}
-
-	of->event = atomic_read(&of->sd->s_attr.open->event);
-
-	/*
-	 * Lookup @ops and invoke show().  Control may reach here via seq
-	 * file lseek even if @ops->show() isn't implemented.
-	 */
-	ops = sysfs_file_ops(of->sd);
-	if (ops->show)
+	if (ops->show) {
 		count = ops->show(kobj, of->sd->priv, buf);
-	else
-		count = 0;
-
-	sysfs_put_active(of->sd);
-	mutex_unlock(&of->mutex);
-
-	if (count < 0)
-		return count;
+		if (count < 0)
+			return count;
+	}
 
 	/*
 	 * The code works fine with PAGE_SIZE return but it's likely to
@@ -144,68 +125,146 @@ static int sysfs_seq_show(struct seq_file *sf, void *v)
 	return 0;
 }
 
-/*
- * Read method for bin files.  As reading a bin file can have side-effects,
- * the exact offset and bytes specified in read(2) call should be passed to
- * the read callback making it difficult to use seq_file.  Implement
- * simplistic custom buffering for bin files.
- */
-static ssize_t sysfs_bin_read(struct file *file, char __user *userbuf,
-			      size_t bytes, loff_t *off)
+static ssize_t sysfs_kf_bin_read(struct sysfs_open_file *of, char *buf,
+				 size_t count, loff_t pos)
 {
-	struct sysfs_open_file *of = sysfs_of(file);
 	struct bin_attribute *battr = of->sd->priv;
 	struct kobject *kobj = of->sd->s_parent->priv;
-	loff_t size = file_inode(file)->i_size;
-	int count = min_t(size_t, bytes, PAGE_SIZE);
-	loff_t offs = *off;
-	char *buf;
+	loff_t size = file_inode(of->file)->i_size;
 
-	if (!bytes)
+	if (!count)
 		return 0;
 
 	if (size) {
-		if (offs > size)
+		if (pos > size)
 			return 0;
-		if (offs + count > size)
-			count = size - offs;
+		if (pos + count > size)
+			count = size - pos;
 	}
 
-	buf = kmalloc(count, GFP_KERNEL);
+	if (!battr->read)
+		return -EIO;
+
+	return battr->read(of->file, kobj, battr, buf, pos, count);
+}
+
+static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos)
+{
+	struct sysfs_open_file *of = sf->private;
+
+	/*
+	 * @of->mutex nests outside active ref and is just to ensure that
+	 * the ops aren't called concurrently for the same open file.
+	 */
+	mutex_lock(&of->mutex);
+	if (!sysfs_get_active(of->sd))
+		return ERR_PTR(-ENODEV);
+
+	/*
+	 * The same behavior and code as single_open().  Returns !NULL if
+	 * pos is at the beginning; otherwise, NULL.
+	 */
+	return NULL + !*ppos;
+}
+
+static void *kernfs_seq_next(struct seq_file *sf, void *v, loff_t *ppos)
+{
+	/*
+	 * The same behavior and code as single_open(), always terminate
+	 * after the initial read.
+	 */
+	++*ppos;
+	return NULL;
+}
+
+static void kernfs_seq_stop(struct seq_file *sf, void *v)
+{
+	struct sysfs_open_file *of = sf->private;
+
+	sysfs_put_active(of->sd);
+	mutex_unlock(&of->mutex);
+}
+
+static int kernfs_seq_show(struct seq_file *sf, void *v)
+{
+	struct sysfs_open_file *of = sf->private;
+
+	of->event = atomic_read(&of->sd->s_attr.open->event);
+
+	return sysfs_kf_seq_show(sf, v);
+}
+
+static const struct seq_operations kernfs_seq_ops = {
+	.start = kernfs_seq_start,
+	.next = kernfs_seq_next,
+	.stop = kernfs_seq_stop,
+	.show = kernfs_seq_show,
+};
+
+/*
+ * As reading a bin file can have side-effects, the exact offset and bytes
+ * specified in read(2) call should be passed to the read callback making
+ * it difficult to use seq_file.  Implement simplistic custom buffering for
+ * bin files.
+ */
+static ssize_t kernfs_file_direct_read(struct sysfs_open_file *of,
+				       char __user *user_buf, size_t count,
+				       loff_t *ppos)
+{
+	ssize_t len = min_t(size_t, count, PAGE_SIZE);
+	char *buf;
+
+	buf = kmalloc(len, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
-	/* need of->sd for battr, its parent for kobj */
+	/*
+	 * @of->mutex nests outside active ref and is just to ensure that
+	 * the ops aren't called concurrently for the same open file.
+	 */
 	mutex_lock(&of->mutex);
 	if (!sysfs_get_active(of->sd)) {
-		count = -ENODEV;
+		len = -ENODEV;
 		mutex_unlock(&of->mutex);
 		goto out_free;
 	}
 
-	if (battr->read)
-		count = battr->read(file, kobj, battr, buf, offs, count);
-	else
-		count = -EIO;
+	len = sysfs_kf_bin_read(of, buf, len, *ppos);
 
 	sysfs_put_active(of->sd);
 	mutex_unlock(&of->mutex);
 
-	if (count < 0)
+	if (len < 0)
 		goto out_free;
 
-	if (copy_to_user(userbuf, buf, count)) {
-		count = -EFAULT;
+	if (copy_to_user(user_buf, buf, len)) {
+		len = -EFAULT;
 		goto out_free;
 	}
 
-	pr_debug("offs = %lld, *off = %lld, count = %d\n", offs, *off, count);
-
-	*off = offs + count;
+	*ppos += len;
 
  out_free:
 	kfree(buf);
-	return count;
+	return len;
+}
+
+/**
+ * kernfs_file_read - kernfs vfs read callback
+ * @file: file pointer
+ * @user_buf: data to write
+ * @count: number of bytes
+ * @ppos: starting offset
+ */
+static ssize_t kernfs_file_read(struct file *file, char __user *user_buf,
+				size_t count, loff_t *ppos)
+{
+	struct sysfs_open_file *of = sysfs_of(file);
+
+	if (sysfs_is_bin(of->sd))
+		return kernfs_file_direct_read(of, user_buf, count, ppos);
+	else
+		return seq_read(file, user_buf, count, ppos);
 }
 
 /**
@@ -677,12 +736,14 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
 	 * and readable regular files are the vast majority anyway.
 	 */
 	if (sysfs_is_bin(attr_sd))
-		error = single_open(file, NULL, of);
+		error = seq_open(file, NULL);
 	else
-		error = single_open(file, sysfs_seq_show, of);
+		error = seq_open(file, &kernfs_seq_ops);
 	if (error)
 		goto err_free;
 
+	((struct seq_file *)file->private_data)->private = of;
+
 	/* seq_file clears PWRITE unconditionally, restore it if WRITE */
 	if (file->f_mode & FMODE_WRITE)
 		file->f_mode |= FMODE_PWRITE;
@@ -697,7 +758,7 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
 	return 0;
 
 err_close:
-	single_release(inode, file);
+	seq_release(inode, file);
 err_free:
 	kfree(of);
 err_out:
@@ -711,7 +772,7 @@ static int sysfs_release(struct inode *inode, struct file *filp)
 	struct sysfs_open_file *of = sysfs_of(filp);
 
 	sysfs_put_open_dirent(sd, of);
-	single_release(inode, filp);
+	seq_release(inode, filp);
 	kfree(of);
 
 	return 0;
@@ -816,7 +877,7 @@ void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
 EXPORT_SYMBOL_GPL(sysfs_notify);
 
 const struct file_operations sysfs_file_operations = {
-	.read		= seq_read,
+	.read		= kernfs_file_read,
 	.write		= sysfs_write_file,
 	.llseek		= generic_file_llseek,
 	.open		= sysfs_open_file,
@@ -825,7 +886,7 @@ const struct file_operations sysfs_file_operations = {
 };
 
 const struct file_operations sysfs_bin_operations = {
-	.read		= sysfs_bin_read,
+	.read		= kernfs_file_read,
 	.write		= sysfs_write_file,
 	.llseek		= generic_file_llseek,
 	.mmap		= sysfs_bin_mmap,
-- 
1.8.4.2

[PATCH 11/41] sysfs, kernfs: prepare write path for kernfs

[Tejun Heo]

We're in the process of separating out core sysfs functionality into
kernfs which will deal with sysfs_dirents directly.  This patch
rearranges write path so that the kernfs and sysfs parts are separate.

kernfs_file_write() handles all boilerplate work including buffer
management and locking and invokes sysfs_kf_write() or
sysfs_kf_bin_write() depending on the file type which deals with the
interaction with kobj store or bin_attribute write method.

While this patch changes the order of some operations, it shouldn't
change any visible behavior.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c | 103 +++++++++++++++++++++++++++-----------------------------
 1 file changed, 50 insertions(+), 53 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index b695b8b..2f849e8 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -267,61 +267,50 @@ static ssize_t kernfs_file_read(struct file *file, char __user *user_buf,
 		return seq_read(file, user_buf, count, ppos);
 }
 
-/**
- * flush_write_buffer - push buffer to kobject
- * @of: open file
- * @buf: data buffer for file
- * @off: file offset to write to
- * @count: number of bytes
- *
- * Get the correct pointers for the kobject and the attribute we're dealing
- * with, then call the store() method for it with @buf.
- */
-static int flush_write_buffer(struct sysfs_open_file *of, char *buf, loff_t off,
-			      size_t count)
+/* kernfs write callback for regular sysfs files */
+static ssize_t sysfs_kf_write(struct sysfs_open_file *of, char *buf,
+			      size_t count, loff_t pos)
 {
+	const struct sysfs_ops *ops = sysfs_file_ops(of->sd);
 	struct kobject *kobj = of->sd->s_parent->priv;
-	int rc = 0;
 
-	/*
-	 * Need @of->sd for attr and ops, its parent for kobj.  @of->mutex
-	 * nests outside active ref and is just to ensure that the ops
-	 * aren't called concurrently for the same open file.
-	 */
-	mutex_lock(&of->mutex);
-	if (!sysfs_get_active(of->sd)) {
-		mutex_unlock(&of->mutex);
-		return -ENODEV;
-	}
+	if (!count)
+		return 0;
 
-	if (sysfs_is_bin(of->sd)) {
-		struct bin_attribute *battr = of->sd->priv;
+	return ops->store(kobj, of->sd->priv, buf, count);
+}
 
-		rc = -EIO;
-		if (battr->write)
-			rc = battr->write(of->file, kobj, battr, buf, off,
-					  count);
-	} else {
-		const struct sysfs_ops *ops = sysfs_file_ops(of->sd);
+/* kernfs write callback for bin sysfs files */
+static ssize_t sysfs_kf_bin_write(struct sysfs_open_file *of, char *buf,
+				  size_t count, loff_t pos)
+{
+	struct bin_attribute *battr = of->sd->priv;
+	struct kobject *kobj = of->sd->s_parent->priv;
+	loff_t size = file_inode(of->file)->i_size;
 
-		rc = ops->store(kobj, of->sd->priv, buf, count);
+	if (size) {
+		if (size <= pos)
+			return 0;
+		count = min_t(ssize_t, count, size - pos);
 	}
+	if (!count)
+		return 0;
 
-	sysfs_put_active(of->sd);
-	mutex_unlock(&of->mutex);
+	if (!battr->write)
+		return -EIO;
 
-	return rc;
+	return battr->write(of->file, kobj, battr, buf, pos, count);
 }
 
 /**
- * sysfs_write_file - write an attribute
+ * kernfs_file_write - kernfs vfs write callback
  * @file: file pointer
  * @user_buf: data to write
  * @count: number of bytes
  * @ppos: starting offset
  *
- * Copy data in from userland and pass it to the matching
- * sysfs_ops->store() by invoking flush_write_buffer().
+ * Copy data in from userland and pass it to the matching kernfs write
+ * operation.
  *
  * There is no easy way for us to know if userspace is only doing a partial
  * write, so we don't support them. We expect the entire buffer to come on
@@ -329,23 +318,13 @@ static int flush_write_buffer(struct sysfs_open_file *of, char *buf, loff_t off,
  * modify only the the value you're changing, then write entire buffer
  * back.
  */
-static ssize_t sysfs_write_file(struct file *file, const char __user *user_buf,
-				size_t count, loff_t *ppos)
+static ssize_t kernfs_file_write(struct file *file, const char __user *user_buf,
+				 size_t count, loff_t *ppos)
 {
 	struct sysfs_open_file *of = sysfs_of(file);
 	ssize_t len = min_t(size_t, count, PAGE_SIZE);
-	loff_t size = file_inode(file)->i_size;
 	char *buf;
 
-	if (sysfs_is_bin(of->sd) && size) {
-		if (size <= *ppos)
-			return 0;
-		len = min_t(ssize_t, len, size - *ppos);
-	}
-
-	if (!len)
-		return 0;
-
 	buf = kmalloc(len + 1, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
@@ -356,7 +335,25 @@ static ssize_t sysfs_write_file(struct file *file, const char __user *user_buf,
 	}
 	buf[len] = '\0';	/* guarantee string termination */
 
-	len = flush_write_buffer(of, buf, *ppos, len);
+	/*
+	 * @of->mutex nests outside active ref and is just to ensure that
+	 * the ops aren't called concurrently for the same open file.
+	 */
+	mutex_lock(&of->mutex);
+	if (!sysfs_get_active(of->sd)) {
+		mutex_unlock(&of->mutex);
+		len = -ENODEV;
+		goto out_free;
+	}
+
+	if (sysfs_is_bin(of->sd))
+		len = sysfs_kf_bin_write(of, buf, len, *ppos);
+	else
+		len = sysfs_kf_write(of, buf, len, *ppos);
+
+	sysfs_put_active(of->sd);
+	mutex_unlock(&of->mutex);
+
 	if (len > 0)
 		*ppos += len;
 out_free:
@@ -878,7 +875,7 @@ EXPORT_SYMBOL_GPL(sysfs_notify);
 
 const struct file_operations sysfs_file_operations = {
 	.read		= kernfs_file_read,
-	.write		= sysfs_write_file,
+	.write		= kernfs_file_write,
 	.llseek		= generic_file_llseek,
 	.open		= sysfs_open_file,
 	.release	= sysfs_release,
@@ -887,7 +884,7 @@ const struct file_operations sysfs_file_operations = {
 
 const struct file_operations sysfs_bin_operations = {
 	.read		= kernfs_file_read,
-	.write		= sysfs_write_file,
+	.write		= kernfs_file_write,
 	.llseek		= generic_file_llseek,
 	.mmap		= sysfs_bin_mmap,
 	.open		= sysfs_open_file,
-- 
1.8.4.2

[PATCH 12/41] sysfs, kernfs: prepare mmap path for kernfs

[Tejun Heo]

We're in the process of separating out core sysfs functionality into
kernfs which will deal with sysfs_dirents directly.  This patch
rearranges mmap path so that the kernfs and sysfs parts are separate.

sysfs_kf_bin_mmap() which handles the interaction with bin_attribute
mmap method is factored out of sysfs_bin_mmap(), which is renamed to
kernfs_file_mmap().  All vma ops are renamed accordingly.

sysfs_bin_mmap() is updated such that it can be used for both file
types.  This will eventually allow using the same file_operations for
both file types, which is necessary to separate out kernfs.

This patch doesn't introduce any behavior changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c | 69 ++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 39 insertions(+), 30 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 2f849e8..2e24e89 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -361,7 +361,19 @@ out_free:
 	return len;
 }
 
-static void sysfs_bin_vma_open(struct vm_area_struct *vma)
+static int sysfs_kf_bin_mmap(struct sysfs_open_file *of,
+			     struct vm_area_struct *vma)
+{
+	struct bin_attribute *battr = of->sd->priv;
+	struct kobject *kobj = of->sd->s_parent->priv;
+
+	if (!battr->mmap)
+		return -ENODEV;
+
+	return battr->mmap(of->file, kobj, battr, vma);
+}
+
+static void kernfs_vma_open(struct vm_area_struct *vma)
 {
 	struct file *file = vma->vm_file;
 	struct sysfs_open_file *of = sysfs_of(file);
@@ -378,7 +390,7 @@ static void sysfs_bin_vma_open(struct vm_area_struct *vma)
 	sysfs_put_active(of->sd);
 }
 
-static int sysfs_bin_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+static int kernfs_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	struct file *file = vma->vm_file;
 	struct sysfs_open_file *of = sysfs_of(file);
@@ -398,8 +410,8 @@ static int sysfs_bin_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 	return ret;
 }
 
-static int sysfs_bin_page_mkwrite(struct vm_area_struct *vma,
-				  struct vm_fault *vmf)
+static int kernfs_vma_page_mkwrite(struct vm_area_struct *vma,
+				   struct vm_fault *vmf)
 {
 	struct file *file = vma->vm_file;
 	struct sysfs_open_file *of = sysfs_of(file);
@@ -421,8 +433,8 @@ static int sysfs_bin_page_mkwrite(struct vm_area_struct *vma,
 	return ret;
 }
 
-static int sysfs_bin_access(struct vm_area_struct *vma, unsigned long addr,
-			    void *buf, int len, int write)
+static int kernfs_vma_access(struct vm_area_struct *vma, unsigned long addr,
+			     void *buf, int len, int write)
 {
 	struct file *file = vma->vm_file;
 	struct sysfs_open_file *of = sysfs_of(file);
@@ -443,8 +455,8 @@ static int sysfs_bin_access(struct vm_area_struct *vma, unsigned long addr,
 }
 
 #ifdef CONFIG_NUMA
-static int sysfs_bin_set_policy(struct vm_area_struct *vma,
-				struct mempolicy *new)
+static int kernfs_vma_set_policy(struct vm_area_struct *vma,
+				 struct mempolicy *new)
 {
 	struct file *file = vma->vm_file;
 	struct sysfs_open_file *of = sysfs_of(file);
@@ -464,8 +476,8 @@ static int sysfs_bin_set_policy(struct vm_area_struct *vma,
 	return ret;
 }
 
-static struct mempolicy *sysfs_bin_get_policy(struct vm_area_struct *vma,
-					      unsigned long addr)
+static struct mempolicy *kernfs_vma_get_policy(struct vm_area_struct *vma,
+					       unsigned long addr)
 {
 	struct file *file = vma->vm_file;
 	struct sysfs_open_file *of = sysfs_of(file);
@@ -485,8 +497,9 @@ static struct mempolicy *sysfs_bin_get_policy(struct vm_area_struct *vma,
 	return pol;
 }
 
-static int sysfs_bin_migrate(struct vm_area_struct *vma, const nodemask_t *from,
-			     const nodemask_t *to, unsigned long flags)
+static int kernfs_vma_migrate(struct vm_area_struct *vma,
+			      const nodemask_t *from, const nodemask_t *to,
+			      unsigned long flags)
 {
 	struct file *file = vma->vm_file;
 	struct sysfs_open_file *of = sysfs_of(file);
@@ -507,36 +520,31 @@ static int sysfs_bin_migrate(struct vm_area_struct *vma, const nodemask_t *from,
 }
 #endif
 
-static const struct vm_operations_struct sysfs_bin_vm_ops = {
-	.open		= sysfs_bin_vma_open,
-	.fault		= sysfs_bin_fault,
-	.page_mkwrite	= sysfs_bin_page_mkwrite,
-	.access		= sysfs_bin_access,
+static const struct vm_operations_struct kernfs_vm_ops = {
+	.open		= kernfs_vma_open,
+	.fault		= kernfs_vma_fault,
+	.page_mkwrite	= kernfs_vma_page_mkwrite,
+	.access		= kernfs_vma_access,
 #ifdef CONFIG_NUMA
-	.set_policy	= sysfs_bin_set_policy,
-	.get_policy	= sysfs_bin_get_policy,
-	.migrate	= sysfs_bin_migrate,
+	.set_policy	= kernfs_vma_set_policy,
+	.get_policy	= kernfs_vma_get_policy,
+	.migrate	= kernfs_vma_migrate,
 #endif
 };
 
-static int sysfs_bin_mmap(struct file *file, struct vm_area_struct *vma)
+static int kernfs_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	struct sysfs_open_file *of = sysfs_of(file);
-	struct bin_attribute *battr = of->sd->priv;
-	struct kobject *kobj = of->sd->s_parent->priv;
 	int rc;
 
 	mutex_lock(&of->mutex);
 
-	/* need of->sd for battr, its parent for kobj */
 	rc = -ENODEV;
 	if (!sysfs_get_active(of->sd))
 		goto out_unlock;
 
-	if (!battr->mmap)
-		goto out_put;
-
-	rc = battr->mmap(file, kobj, battr, vma);
+	if (sysfs_is_bin(of->sd))
+		rc = sysfs_kf_bin_mmap(of, vma);
 	if (rc)
 		goto out_put;
 
@@ -563,7 +571,7 @@ static int sysfs_bin_mmap(struct file *file, struct vm_area_struct *vma)
 	rc = 0;
 	of->mmapped = 1;
 	of->vm_ops = vma->vm_ops;
-	vma->vm_ops = &sysfs_bin_vm_ops;
+	vma->vm_ops = &kernfs_vm_ops;
 out_put:
 	sysfs_put_active(of->sd);
 out_unlock:
@@ -877,6 +885,7 @@ const struct file_operations sysfs_file_operations = {
 	.read		= kernfs_file_read,
 	.write		= kernfs_file_write,
 	.llseek		= generic_file_llseek,
+	.mmap		= kernfs_file_mmap,
 	.open		= sysfs_open_file,
 	.release	= sysfs_release,
 	.poll		= sysfs_poll,
@@ -886,7 +895,7 @@ const struct file_operations sysfs_bin_operations = {
 	.read		= kernfs_file_read,
 	.write		= kernfs_file_write,
 	.llseek		= generic_file_llseek,
-	.mmap		= sysfs_bin_mmap,
+	.mmap		= kernfs_file_mmap,
 	.open		= sysfs_open_file,
 	.release	= sysfs_release,
 	.poll		= sysfs_poll,
-- 
1.8.4.2

[PATCH 13/41] sysfs, kernfs: prepare open, release, poll paths for kernfs

[Tejun Heo]

We're in the process of separating out core sysfs functionality into
kernfs which will deal with sysfs_dirents directly.  This patch
prepares the rest - open, release and poll.  There isn't much to do.
Just renaming is enough.  As sysfs_file_operations and
sysfs_bin_operations are identical now, use the same file_operations
for both - kernfs_file_operations.

This patch doesn't introduce any behavior changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c  | 24 +++++++-----------------
 fs/sysfs/inode.c |  4 ++--
 fs/sysfs/sysfs.h |  3 +--
 3 files changed, 10 insertions(+), 21 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 2e24e89..a43df04 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -668,7 +668,7 @@ static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
 	kfree(od);
 }
 
-static int sysfs_open_file(struct inode *inode, struct file *file)
+static int kernfs_file_open(struct inode *inode, struct file *file)
 {
 	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 	struct kobject *kobj = attr_sd->s_parent->priv;
@@ -771,7 +771,7 @@ err_out:
 	return error;
 }
 
-static int sysfs_release(struct inode *inode, struct file *filp)
+static int kernfs_file_release(struct inode *inode, struct file *filp)
 {
 	struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata;
 	struct sysfs_open_file *of = sysfs_of(filp);
@@ -822,7 +822,7 @@ void sysfs_unmap_bin_file(struct sysfs_dirent *sd)
  * to see if it supports poll (Neither 'poll' nor 'select' return
  * an appropriate error code).  When in doubt, set a suitable timeout value.
  */
-static unsigned int sysfs_poll(struct file *filp, poll_table *wait)
+static unsigned int kernfs_file_poll(struct file *filp, poll_table *wait)
 {
 	struct sysfs_open_file *of = sysfs_of(filp);
 	struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
@@ -881,24 +881,14 @@ void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
 }
 EXPORT_SYMBOL_GPL(sysfs_notify);
 
-const struct file_operations sysfs_file_operations = {
+const struct file_operations kernfs_file_operations = {
 	.read		= kernfs_file_read,
 	.write		= kernfs_file_write,
 	.llseek		= generic_file_llseek,
 	.mmap		= kernfs_file_mmap,
-	.open		= sysfs_open_file,
-	.release	= sysfs_release,
-	.poll		= sysfs_poll,
-};
-
-const struct file_operations sysfs_bin_operations = {
-	.read		= kernfs_file_read,
-	.write		= kernfs_file_write,
-	.llseek		= generic_file_llseek,
-	.mmap		= kernfs_file_mmap,
-	.open		= sysfs_open_file,
-	.release	= sysfs_release,
-	.poll		= sysfs_poll,
+	.open		= kernfs_file_open,
+	.release	= kernfs_file_release,
+	.poll		= kernfs_file_poll,
 };
 
 int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index 81cc858..4c463da 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -272,12 +272,12 @@ static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
 		break;
 	case SYSFS_KOBJ_ATTR:
 		inode->i_size = PAGE_SIZE;
-		inode->i_fop = &sysfs_file_operations;
+		inode->i_fop = &kernfs_file_operations;
 		break;
 	case SYSFS_KOBJ_BIN_ATTR:
 		bin_attr = sd->priv;
 		inode->i_size = bin_attr->size;
-		inode->i_fop = &sysfs_bin_operations;
+		inode->i_fop = &kernfs_file_operations;
 		break;
 	case SYSFS_KOBJ_LINK:
 		inode->i_op = &sysfs_symlink_inode_operations;
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 9ac234e..619250d 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -212,8 +212,7 @@ int sysfs_inode_init(void);
 /*
  * file.c
  */
-extern const struct file_operations sysfs_file_operations;
-extern const struct file_operations sysfs_bin_operations;
+extern const struct file_operations kernfs_file_operations;
 
 int sysfs_add_file(struct sysfs_dirent *dir_sd,
 		   const struct attribute *attr, int type);
-- 
1.8.4.2

[PATCH 14/41] sysfs, kernfs: move sysfs_open_file to include/linux/kernfs.h

[Tejun Heo]

sysfs_open_file will be used as the primary handle for kernfs methods.
Move its definition from fs/sysfs/file.c to include/linux/kernfs.h and
mark the public and private fields.

This is pure relocation.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c        | 11 -----------
 include/linux/kernfs.h | 18 ++++++++++++++++++
 2 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index a43df04..acba583 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -47,17 +47,6 @@ struct sysfs_open_dirent {
 	struct list_head	files; /* goes through sysfs_open_file.list */
 };
 
-struct sysfs_open_file {
-	struct sysfs_dirent	*sd;
-	struct file		*file;
-	struct mutex		mutex;
-	int			event;
-	struct list_head	list;
-
-	bool			mmapped;
-	const struct vm_operations_struct *vm_ops;
-};
-
 static bool sysfs_is_bin(struct sysfs_dirent *sd)
 {
 	return sysfs_type(sd) == SYSFS_KOBJ_BIN_ATTR;
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index e8b73d4..b923052 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -9,12 +9,30 @@
 
 #include <linux/kernel.h>
 #include <linux/err.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
 
 struct file;
 struct iattr;
+struct seq_file;
+struct vm_area_struct;
 
 struct sysfs_dirent;
 
+struct sysfs_open_file {
+	/* published fields */
+	struct sysfs_dirent	*sd;
+	struct file		*file;
+
+	/* private fields, do not use outside kernfs proper */
+	struct mutex		mutex;
+	int			event;
+	struct list_head	list;
+
+	bool			mmapped;
+	const struct vm_operations_struct *vm_ops;
+};
+
 #ifdef CONFIG_SYSFS
 
 struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
-- 
1.8.4.2

[PATCH 15/41] sysfs, kernfs: introduce kernfs_ops

[Tejun Heo]

We're in the process of separating out core sysfs functionality into
kernfs which will deal with sysfs_dirents directly.  This patch
introduces kernfs_ops which hosts methods kernfs users implement and
updates fs/sysfs/file.c such that sysfs_kf_*() functions populate
kernfs_ops and kernfs_file_*() functions call the matching entries
from kernfs_ops.

kernfs_ops contains the following groups of methods.

* seq_show() - for kernfs files which use seq_file for reads.

* read() - for direct read implementations.  Used iff seq_show() is
  not implemented.

* write() - for writes.

* mmap() - for mmaps.

Notes:

* sysfs_elem_attr->ops is added so that kernfs_ops can be accessed
  from sysfs_dirent.  kernfs_ops() helper is added to verify locking
  and access the field.

* SYSFS_FLAG_HAS_(SEQ_SHOW|MMAP) added.  sd->s_attr->ops is accessible
  only while holding active_ref and there are cases where we want to
  take different actions depending on which ops are implemented.
  These two flags cache whether the two ops are implemented for those.

* kernfs_file_*() no longer test sysfs type but chooses different
  behaviors depending on which methods in kernfs_ops are implemented.
  The conversions are trivial except for the open path.  As
  kernfs_file_open() now decides whether to allow read/write accesses
  depending on the kernfs_ops implemented, the presence of methods in
  kobjs and attribute_bin should be propagated to kernfs_ops.
  sysfs_add_file_mode_ns() is updated so that it propagates presence /
  absence of the callbacks through _empty, _ro, _wo, _rw kernfs_ops.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c        | 146 +++++++++++++++++++++++++++++++++++++------------
 fs/sysfs/sysfs.h       |   3 +
 include/linux/kernfs.h |  26 +++++++++
 3 files changed, 141 insertions(+), 34 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index acba583..cbebc33 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -58,6 +58,17 @@ static struct sysfs_open_file *sysfs_of(struct file *file)
 }
 
 /*
+ * Determine the kernfs_ops for the given sysfs_dirent.  This function must
+ * be called while holding an active reference.
+ */
+static const struct kernfs_ops *kernfs_ops(struct sysfs_dirent *sd)
+{
+	if (!sysfs_ignore_lockdep(sd))
+		lockdep_assert_held(sd);
+	return sd->s_attr.ops;
+}
+
+/*
  * Determine ktype->sysfs_ops for the given sysfs_dirent.  This function
  * must be called while holding an active reference.
  */
@@ -180,7 +191,7 @@ static int kernfs_seq_show(struct seq_file *sf, void *v)
 
 	of->event = atomic_read(&of->sd->s_attr.open->event);
 
-	return sysfs_kf_seq_show(sf, v);
+	return of->sd->s_attr.ops->seq_show(sf, v);
 }
 
 static const struct seq_operations kernfs_seq_ops = {
@@ -201,6 +212,7 @@ static ssize_t kernfs_file_direct_read(struct sysfs_open_file *of,
 				       loff_t *ppos)
 {
 	ssize_t len = min_t(size_t, count, PAGE_SIZE);
+	const struct kernfs_ops *ops;
 	char *buf;
 
 	buf = kmalloc(len, GFP_KERNEL);
@@ -218,7 +230,11 @@ static ssize_t kernfs_file_direct_read(struct sysfs_open_file *of,
 		goto out_free;
 	}
 
-	len = sysfs_kf_bin_read(of, buf, len, *ppos);
+	ops = kernfs_ops(of->sd);
+	if (ops->read)
+		len = ops->read(of, buf, len, *ppos);
+	else
+		len = -EINVAL;
 
 	sysfs_put_active(of->sd);
 	mutex_unlock(&of->mutex);
@@ -250,10 +266,10 @@ static ssize_t kernfs_file_read(struct file *file, char __user *user_buf,
 {
 	struct sysfs_open_file *of = sysfs_of(file);
 
-	if (sysfs_is_bin(of->sd))
-		return kernfs_file_direct_read(of, user_buf, count, ppos);
-	else
+	if (of->sd->s_flags & SYSFS_FLAG_HAS_SEQ_SHOW)
 		return seq_read(file, user_buf, count, ppos);
+	else
+		return kernfs_file_direct_read(of, user_buf, count, ppos);
 }
 
 /* kernfs write callback for regular sysfs files */
@@ -312,6 +328,7 @@ static ssize_t kernfs_file_write(struct file *file, const char __user *user_buf,
 {
 	struct sysfs_open_file *of = sysfs_of(file);
 	ssize_t len = min_t(size_t, count, PAGE_SIZE);
+	const struct kernfs_ops *ops;
 	char *buf;
 
 	buf = kmalloc(len + 1, GFP_KERNEL);
@@ -335,10 +352,11 @@ static ssize_t kernfs_file_write(struct file *file, const char __user *user_buf,
 		goto out_free;
 	}
 
-	if (sysfs_is_bin(of->sd))
-		len = sysfs_kf_bin_write(of, buf, len, *ppos);
+	ops = kernfs_ops(of->sd);
+	if (ops->write)
+		len = ops->write(of, buf, len, *ppos);
 	else
-		len = sysfs_kf_write(of, buf, len, *ppos);
+		len = -EINVAL;
 
 	sysfs_put_active(of->sd);
 	mutex_unlock(&of->mutex);
@@ -524,6 +542,7 @@ static const struct vm_operations_struct kernfs_vm_ops = {
 static int kernfs_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	struct sysfs_open_file *of = sysfs_of(file);
+	const struct kernfs_ops *ops;
 	int rc;
 
 	mutex_lock(&of->mutex);
@@ -532,8 +551,9 @@ static int kernfs_file_mmap(struct file *file, struct vm_area_struct *vma)
 	if (!sysfs_get_active(of->sd))
 		goto out_unlock;
 
-	if (sysfs_is_bin(of->sd))
-		rc = sysfs_kf_bin_mmap(of, vma);
+	ops = kernfs_ops(of->sd);
+	if (ops->mmap)
+		rc = ops->mmap(of, vma);
 	if (rc)
 		goto out_put;
 
@@ -660,34 +680,19 @@ static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
 static int kernfs_file_open(struct inode *inode, struct file *file)
 {
 	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
-	struct kobject *kobj = attr_sd->s_parent->priv;
+	const struct kernfs_ops *ops;
 	struct sysfs_open_file *of;
 	bool has_read, has_write, has_mmap;
 	int error = -EACCES;
 
-	/* need attr_sd for attr and ops, its parent for kobj */
 	if (!sysfs_get_active(attr_sd))
 		return -ENODEV;
 
-	if (sysfs_is_bin(attr_sd)) {
-		struct bin_attribute *battr = attr_sd->priv;
+	ops = kernfs_ops(attr_sd);
 
-		has_read = battr->read || battr->mmap;
-		has_write = battr->write || battr->mmap;
-		has_mmap = battr->mmap;
-	} else {
-		const struct sysfs_ops *ops = sysfs_file_ops(attr_sd);
-
-		/* every kobject with an attribute needs a ktype assigned */
-		if (WARN(!ops, KERN_ERR
-			 "missing sysfs attribute operations for kobject: %s\n",
-			 kobject_name(kobj)))
-			goto err_out;
-
-		has_read = ops->show;
-		has_write = ops->store;
-		has_mmap = false;
-	}
+	has_read = ops->seq_show || ops->read || ops->mmap;
+	has_write = ops->write || ops->mmap;
+	has_mmap = ops->mmap;
 
 	/* check perms and supported operations */
 	if ((file->f_mode & FMODE_WRITE) &&
@@ -729,10 +734,10 @@ static int kernfs_file_open(struct inode *inode, struct file *file)
 	 * seq_file or is not requested.  This unifies private data access
 	 * and readable regular files are the vast majority anyway.
 	 */
-	if (sysfs_is_bin(attr_sd))
-		error = seq_open(file, NULL);
-	else
+	if (ops->seq_show)
 		error = seq_open(file, &kernfs_seq_ops);
+	else
+		error = seq_open(file, NULL);
 	if (error)
 		goto err_free;
 
@@ -777,7 +782,7 @@ void sysfs_unmap_bin_file(struct sysfs_dirent *sd)
 	struct sysfs_open_dirent *od;
 	struct sysfs_open_file *of;
 
-	if (!sysfs_is_bin(sd))
+	if (!(sd->s_flags & SYSFS_FLAG_HAS_MMAP))
 		return;
 
 	spin_lock_irq(&sysfs_open_dirent_lock);
@@ -880,23 +885,96 @@ const struct file_operations kernfs_file_operations = {
 	.poll		= kernfs_file_poll,
 };
 
+static const struct kernfs_ops sysfs_file_kfops_empty = {
+};
+
+static const struct kernfs_ops sysfs_file_kfops_ro = {
+	.seq_show	= sysfs_kf_seq_show,
+};
+
+static const struct kernfs_ops sysfs_file_kfops_wo = {
+	.write		= sysfs_kf_write,
+};
+
+static const struct kernfs_ops sysfs_file_kfops_rw = {
+	.seq_show	= sysfs_kf_seq_show,
+	.write		= sysfs_kf_write,
+};
+
+static const struct kernfs_ops sysfs_bin_kfops_ro = {
+	.read		= sysfs_kf_bin_read,
+};
+
+static const struct kernfs_ops sysfs_bin_kfops_wo = {
+	.write		= sysfs_kf_bin_write,
+};
+
+static const struct kernfs_ops sysfs_bin_kfops_rw = {
+	.read		= sysfs_kf_bin_read,
+	.write		= sysfs_kf_bin_write,
+	.mmap		= sysfs_kf_bin_mmap,
+};
+
 int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 			   const struct attribute *attr, int type,
 			   umode_t amode, const void *ns)
 {
 	umode_t mode = (amode & S_IALLUGO) | S_IFREG;
+	const struct kernfs_ops *ops;
 	struct sysfs_addrm_cxt acxt;
 	struct sysfs_dirent *sd;
 	int rc;
 
+	if (type == SYSFS_KOBJ_ATTR) {
+		struct kobject *kobj = dir_sd->priv;
+		const struct sysfs_ops *sysfs_ops = kobj->ktype->sysfs_ops;
+
+		/* every kobject with an attribute needs a ktype assigned */
+		if (WARN(!sysfs_ops, KERN_ERR
+			 "missing sysfs attribute operations for kobject: %s\n",
+			 kobject_name(kobj)))
+			return -EINVAL;
+
+		if (sysfs_ops->show && sysfs_ops->store)
+			ops = &sysfs_file_kfops_rw;
+		else if (sysfs_ops->show)
+			ops = &sysfs_file_kfops_ro;
+		else if (sysfs_ops->store)
+			ops = &sysfs_file_kfops_wo;
+		else
+			ops = &sysfs_file_kfops_empty;
+	} else {
+		struct bin_attribute *battr = (void *)attr;
+
+		if ((battr->read && battr->write) || battr->mmap)
+			ops = &sysfs_bin_kfops_rw;
+		else if (battr->read)
+			ops = &sysfs_bin_kfops_ro;
+		else if (battr->write)
+			ops = &sysfs_bin_kfops_wo;
+		else
+			ops = &sysfs_file_kfops_empty;
+	}
+
 	sd = sysfs_new_dirent(attr->name, mode, type);
 	if (!sd)
 		return -ENOMEM;
 
+	sd->s_attr.ops = ops;
 	sd->s_ns = ns;
 	sd->priv = (void *)attr;
 	sysfs_dirent_init_lockdep(sd);
 
+	/*
+	 * sd->s_attr.ops is accesible only while holding active ref.  We
+	 * need to know whether some ops are implemented outside active
+	 * ref.  Cache their existence in flags.
+	 */
+	if (ops->seq_show)
+		sd->s_flags |= SYSFS_FLAG_HAS_SEQ_SHOW;
+	if (ops->mmap)
+		sd->s_flags |= SYSFS_FLAG_HAS_MMAP;
+
 	sysfs_addrm_start(&acxt);
 	rc = sysfs_add_one(&acxt, sd, dir_sd);
 	sysfs_addrm_finish(&acxt);
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 619250d..c05e0dd 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -27,6 +27,7 @@ struct sysfs_elem_symlink {
 };
 
 struct sysfs_elem_attr {
+	const struct kernfs_ops	*ops;
 	struct sysfs_open_dirent *open;
 };
 
@@ -89,6 +90,8 @@ struct sysfs_dirent {
 #define SYSFS_FLAG_MASK			~SYSFS_TYPE_MASK
 #define SYSFS_FLAG_NS			0x01000
 #define SYSFS_FLAG_REMOVED		0x02000
+#define SYSFS_FLAG_HAS_SEQ_SHOW		0x04000
+#define SYSFS_FLAG_HAS_MMAP		0x08000
 
 static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
 {
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index b923052..97c6c0f 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -33,6 +33,32 @@ struct sysfs_open_file {
 	const struct vm_operations_struct *vm_ops;
 };
 
+struct kernfs_ops {
+	/*
+	 * Read is handled by either seq_file or raw_read().
+	 *
+	 * If seq_show() is present, seq_file path is active.  The behavior
+	 * is equivalent to single_open().  @sf->private points to the
+	 * associated sysfs_open_file.
+	 *
+	 * read() is bounced through kernel buffer and a read larger than
+	 * PAGE_SIZE results in partial operation of PAGE_SIZE.
+	 */
+	int (*seq_show)(struct seq_file *sf, void *v);
+
+	ssize_t (*read)(struct sysfs_open_file *of, char *buf, size_t bytes,
+			loff_t off);
+
+	/*
+	 * write() is bounced through kernel buffer and a write larger than
+	 * PAGE_SIZE results in partial operation of PAGE_SIZE.
+	 */
+	ssize_t (*write)(struct sysfs_open_file *of, char *buf, size_t bytes,
+			 loff_t off);
+
+	int (*mmap)(struct sysfs_open_file *of, struct vm_area_struct *vma);
+};
+
 #ifdef CONFIG_SYSFS
 
 struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
-- 
1.8.4.2

[PATCH 16/41] sysfs, kernfs: add sysfs_dirent->s_attr.size

[Tejun Heo]

sysfs sets the size of regular files unconditionally at PAGE_SIZE and
takes the size of bin files from bin_attribute.  The latter is a
pretty bad interface which forces bin_attribute users to create a
separate copy of bin_attribute for each instance of the file -
e.g. pci resource files.

Add sysfs_dirent->s_attr.size so that the size can be specified
separately.  This unifies inode init paths of ATTR and BIN_ATTR
identical and allows for generic size handling for kernfs.

Unfortunately, this grows the size of sysfs_dirent by sizeof(loff_t).

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c  | 6 ++++++
 fs/sysfs/inode.c | 8 +-------
 fs/sysfs/sysfs.h | 1 +
 3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index cbebc33..0b0cec8 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -923,6 +923,7 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 	const struct kernfs_ops *ops;
 	struct sysfs_addrm_cxt acxt;
 	struct sysfs_dirent *sd;
+	loff_t size;
 	int rc;
 
 	if (type == SYSFS_KOBJ_ATTR) {
@@ -943,6 +944,8 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 			ops = &sysfs_file_kfops_wo;
 		else
 			ops = &sysfs_file_kfops_empty;
+
+		size = PAGE_SIZE;
 	} else {
 		struct bin_attribute *battr = (void *)attr;
 
@@ -954,6 +957,8 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 			ops = &sysfs_bin_kfops_wo;
 		else
 			ops = &sysfs_file_kfops_empty;
+
+		size = battr->size;
 	}
 
 	sd = sysfs_new_dirent(attr->name, mode, type);
@@ -961,6 +966,7 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 		return -ENOMEM;
 
 	sd->s_attr.ops = ops;
+	sd->s_attr.size = size;
 	sd->s_ns = ns;
 	sd->priv = (void *)attr;
 	sysfs_dirent_init_lockdep(sd);
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index 4c463da..037a892 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -254,8 +254,6 @@ int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
 
 static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
 {
-	struct bin_attribute *bin_attr;
-
 	inode->i_private = sysfs_get(sd);
 	inode->i_mapping->a_ops = &sysfs_aops;
 	inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
@@ -271,12 +269,8 @@ static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
 		inode->i_fop = &sysfs_dir_operations;
 		break;
 	case SYSFS_KOBJ_ATTR:
-		inode->i_size = PAGE_SIZE;
-		inode->i_fop = &kernfs_file_operations;
-		break;
 	case SYSFS_KOBJ_BIN_ATTR:
-		bin_attr = sd->priv;
-		inode->i_size = bin_attr->size;
+		inode->i_size = sd->s_attr.size;
 		inode->i_fop = &kernfs_file_operations;
 		break;
 	case SYSFS_KOBJ_LINK:
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index c05e0dd..d40e85e 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -29,6 +29,7 @@ struct sysfs_elem_symlink {
 struct sysfs_elem_attr {
 	const struct kernfs_ops	*ops;
 	struct sysfs_open_dirent *open;
+	loff_t			size;
 };
 
 struct sysfs_inode_attrs {
-- 
1.8.4.2

[PATCH 17/41] sysfs, kernfs: remove SYSFS_KOBJ_BIN_ATTR

[Tejun Heo]

After kernfs_ops and sysfs_dirent->s_attr.size addition, the
distinction between SYSFS_KOBJ_BIN_ATTR and SYSFS_KOBJ_ATTR is only
necessary while creating files to decide which kernfs_ops to use.
Afterwards, they behave exactly the same.

This patch removes SYSFS_KOBJ_BIN_ATTR along with sysfs_is_bin().
sysfs_add_file[_mode_ns]() are updated to take bool @is_bin instead of
@type.

This patch doesn't introduce any behavior changes.  This completely
isolates the distinction between the two sysfs file types in the sysfs
layer proper.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c  | 23 ++++++++---------------
 fs/sysfs/group.c |  5 ++---
 fs/sysfs/inode.c |  1 -
 fs/sysfs/sysfs.h | 11 ++++-------
 4 files changed, 14 insertions(+), 26 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 0b0cec8..e2ce674 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -47,11 +47,6 @@ struct sysfs_open_dirent {
 	struct list_head	files; /* goes through sysfs_open_file.list */
 };
 
-static bool sysfs_is_bin(struct sysfs_dirent *sd)
-{
-	return sysfs_type(sd) == SYSFS_KOBJ_BIN_ATTR;
-}
-
 static struct sysfs_open_file *sysfs_of(struct file *file)
 {
 	return ((struct seq_file *)file->private_data)->private;
@@ -916,7 +911,7 @@ static const struct kernfs_ops sysfs_bin_kfops_rw = {
 };
 
 int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
-			   const struct attribute *attr, int type,
+			   const struct attribute *attr, bool is_bin,
 			   umode_t amode, const void *ns)
 {
 	umode_t mode = (amode & S_IALLUGO) | S_IFREG;
@@ -926,7 +921,7 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 	loff_t size;
 	int rc;
 
-	if (type == SYSFS_KOBJ_ATTR) {
+	if (!is_bin) {
 		struct kobject *kobj = dir_sd->priv;
 		const struct sysfs_ops *sysfs_ops = kobj->ktype->sysfs_ops;
 
@@ -961,7 +956,7 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 		size = battr->size;
 	}
 
-	sd = sysfs_new_dirent(attr->name, mode, type);
+	sd = sysfs_new_dirent(attr->name, mode, SYSFS_KOBJ_ATTR);
 	if (!sd)
 		return -ENOMEM;
 
@@ -991,11 +986,10 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 	return rc;
 }
 
-
 int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
-		   int type)
+		   bool is_bin)
 {
-	return sysfs_add_file_mode_ns(dir_sd, attr, type, attr->mode, NULL);
+	return sysfs_add_file_mode_ns(dir_sd, attr, is_bin, attr->mode, NULL);
 }
 
 /**
@@ -1009,8 +1003,7 @@ int sysfs_create_file_ns(struct kobject *kobj, const struct attribute *attr,
 {
 	BUG_ON(!kobj || !kobj->sd || !attr);
 
-	return sysfs_add_file_mode_ns(kobj->sd, attr, SYSFS_KOBJ_ATTR,
-				      attr->mode, ns);
+	return sysfs_add_file_mode_ns(kobj->sd, attr, false, attr->mode, ns);
 
 }
 EXPORT_SYMBOL_GPL(sysfs_create_file_ns);
@@ -1049,7 +1042,7 @@ int sysfs_add_file_to_group(struct kobject *kobj,
 	if (!dir_sd)
 		return -ENOENT;
 
-	error = sysfs_add_file(dir_sd, attr, SYSFS_KOBJ_ATTR);
+	error = sysfs_add_file(dir_sd, attr, false);
 	sysfs_put(dir_sd);
 
 	return error;
@@ -1141,7 +1134,7 @@ int sysfs_create_bin_file(struct kobject *kobj,
 {
 	BUG_ON(!kobj || !kobj->sd || !attr);
 
-	return sysfs_add_file(kobj->sd, &attr->attr, SYSFS_KOBJ_BIN_ATTR);
+	return sysfs_add_file(kobj->sd, &attr->attr, true);
 }
 EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
 
diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index 11be6de..d7f4f6e 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -55,8 +55,7 @@ static int create_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,
 				if (!mode)
 					continue;
 			}
-			error = sysfs_add_file_mode_ns(dir_sd, *attr,
-						       SYSFS_KOBJ_ATTR,
+			error = sysfs_add_file_mode_ns(dir_sd, *attr, false,
 						       (*attr)->mode | mode,
 						       NULL);
 			if (unlikely(error))
@@ -278,7 +277,7 @@ int sysfs_merge_group(struct kobject *kobj,
 		return -ENOENT;
 
 	for ((i = 0, attr = grp->attrs); *attr && !error; (++i, ++attr))
-		error = sysfs_add_file(dir_sd, *attr, SYSFS_KOBJ_ATTR);
+		error = sysfs_add_file(dir_sd, *attr, false);
 	if (error) {
 		while (--i >= 0)
 			kernfs_remove_by_name(dir_sd, (*--attr)->name);
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index 037a892..b3c717a 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -269,7 +269,6 @@ static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
 		inode->i_fop = &sysfs_dir_operations;
 		break;
 	case SYSFS_KOBJ_ATTR:
-	case SYSFS_KOBJ_BIN_ATTR:
 		inode->i_size = sd->s_attr.size;
 		inode->i_fop = &kernfs_file_operations;
 		break;
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index d40e85e..28898fa 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -83,10 +83,9 @@ struct sysfs_dirent {
 #define SYSFS_TYPE_MASK			0x00ff
 #define SYSFS_DIR			0x0001
 #define SYSFS_KOBJ_ATTR			0x0002
-#define SYSFS_KOBJ_BIN_ATTR		0x0004
 #define SYSFS_KOBJ_LINK			0x0008
 #define SYSFS_COPY_NAME			(SYSFS_DIR | SYSFS_KOBJ_LINK)
-#define SYSFS_ACTIVE_REF		(SYSFS_KOBJ_ATTR | SYSFS_KOBJ_BIN_ATTR)
+#define SYSFS_ACTIVE_REF		SYSFS_KOBJ_ATTR
 
 #define SYSFS_FLAG_MASK			~SYSFS_TYPE_MASK
 #define SYSFS_FLAG_NS			0x01000
@@ -115,10 +114,8 @@ do {								\
 static inline bool sysfs_ignore_lockdep(struct sysfs_dirent *sd)
 {
 	struct attribute *attr = sd->priv;
-	int type = sysfs_type(sd);
 
-	return (type == SYSFS_KOBJ_ATTR || type == SYSFS_KOBJ_BIN_ATTR) &&
-		attr->ignore_lockdep;
+	return sysfs_type(sd) == SYSFS_KOBJ_ATTR && attr->ignore_lockdep;
 }
 
 #else
@@ -219,10 +216,10 @@ int sysfs_inode_init(void);
 extern const struct file_operations kernfs_file_operations;
 
 int sysfs_add_file(struct sysfs_dirent *dir_sd,
-		   const struct attribute *attr, int type);
+		   const struct attribute *attr, bool is_bin);
 
 int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
-			   const struct attribute *attr, int type,
+			   const struct attribute *attr, bool is_bin,
 			   umode_t amode, const void *ns);
 void sysfs_unmap_bin_file(struct sysfs_dirent *sd);
 
-- 
1.8.4.2

[PATCH 18/41] sysfs, kernfs: introduce kernfs_create_file[_ns]()

[Tejun Heo]

Introduce kernfs interface to create a file which takes and returns
sysfs_dirents.

The actual file creation part is separated out from
sysfs_add_file_mode_ns() into kernfs_create_file_ns().  The former now
only decides the kernfs_ops to use and the file's size and invokes the
latter.

This patch doesn't introduce behavior changes.

v2: Dummy implementation for !CONFIG_SYSFS updated to return -ENOSYS.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c        | 53 +++++++++++++++++++++++++++++++++++++++-----------
 include/linux/kernfs.h | 18 +++++++++++++++++
 2 files changed, 60 insertions(+), 11 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index e2ce674..69cca0f 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -912,14 +912,11 @@ static const struct kernfs_ops sysfs_bin_kfops_rw = {
 
 int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 			   const struct attribute *attr, bool is_bin,
-			   umode_t amode, const void *ns)
+			   umode_t mode, const void *ns)
 {
-	umode_t mode = (amode & S_IALLUGO) | S_IFREG;
 	const struct kernfs_ops *ops;
-	struct sysfs_addrm_cxt acxt;
 	struct sysfs_dirent *sd;
 	loff_t size;
-	int rc;
 
 	if (!is_bin) {
 		struct kobject *kobj = dir_sd->priv;
@@ -956,14 +953,47 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 		size = battr->size;
 	}
 
-	sd = sysfs_new_dirent(attr->name, mode, SYSFS_KOBJ_ATTR);
+	sd = kernfs_create_file_ns(dir_sd, attr->name, mode, size,
+				   ops, (void *)attr, ns);
+	if (IS_ERR(sd)) {
+		if (PTR_ERR(sd) == -EEXIST)
+			sysfs_warn_dup(dir_sd, attr->name);
+		return PTR_ERR(sd);
+	}
+	return 0;
+}
+
+/**
+ * kernfs_create_file_ns - create a file
+ * @parent: directory to create the file in
+ * @name: name of the file
+ * @mode: mode of the file
+ * @size: size of the file
+ * @ops: kernfs operations for the file
+ * @priv: private data for the file
+ * @ns: optional namespace tag of the file
+ *
+ * Returns the created node on success, ERR_PTR() value on error.
+ */
+struct sysfs_dirent *kernfs_create_file_ns(struct sysfs_dirent *parent,
+					   const char *name,
+					   umode_t mode, loff_t size,
+					   const struct kernfs_ops *ops,
+					   void *priv, const void *ns)
+{
+	struct sysfs_addrm_cxt acxt;
+	struct sysfs_dirent *sd;
+	int rc;
+
+	sd = sysfs_new_dirent(name, (mode & S_IALLUGO) | S_IFREG,
+			      SYSFS_KOBJ_ATTR);
 	if (!sd)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
 	sd->s_attr.ops = ops;
 	sd->s_attr.size = size;
 	sd->s_ns = ns;
-	sd->priv = (void *)attr;
+	sd->priv = priv;
 	sysfs_dirent_init_lockdep(sd);
 
 	/*
@@ -977,13 +1007,14 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 		sd->s_flags |= SYSFS_FLAG_HAS_MMAP;
 
 	sysfs_addrm_start(&acxt);
-	rc = sysfs_add_one(&acxt, sd, dir_sd);
+	rc = __sysfs_add_one(&acxt, sd, parent);
 	sysfs_addrm_finish(&acxt);
 
-	if (rc)
+	if (rc) {
 		sysfs_put(sd);
-
-	return rc;
+		return ERR_PTR(rc);
+	}
+	return sd;
 }
 
 int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 97c6c0f..d0912cf 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -64,6 +64,11 @@ struct kernfs_ops {
 struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
 					  const char *name, void *priv,
 					  const void *ns);
+struct sysfs_dirent *kernfs_create_file_ns(struct sysfs_dirent *parent,
+					   const char *name,
+					   umode_t mode, loff_t size,
+					   const struct kernfs_ops *ops,
+					   void *priv, const void *ns);
 struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
 					const char *name,
 					struct sysfs_dirent *target);
@@ -83,6 +88,12 @@ kernfs_create_dir_ns(struct sysfs_dirent *parent, const char *name, void *priv,
 { return ERR_PTR(-ENOSYS); }
 
 static inline struct sysfs_dirent *
+kernfs_create_file_ns(struct sysfs_dirent *parent, const char *name,
+		      umode_t mode, loff_t size, const struct kernfs_ops *ops,
+		      void *priv, const void *ns)
+{ return ERR_PTR(-ENOSYS); }
+
+static inline struct sysfs_dirent *
 kernfs_create_link(struct sysfs_dirent *parent, const char *name,
 		   struct sysfs_dirent *target)
 { return ERR_PTR(-ENOSYS); }
@@ -112,6 +123,13 @@ kernfs_create_dir(struct sysfs_dirent *parent, const char *name, void *priv)
 	return kernfs_create_dir_ns(parent, name, priv, NULL);
 }
 
+static inline struct sysfs_dirent *
+kernfs_create_file(struct sysfs_dirent *parent, const char *name, umode_t mode,
+		   loff_t size, const struct kernfs_ops *ops, void *priv)
+{
+	return kernfs_create_file_ns(parent, name, mode, size, ops, priv, NULL);
+}
+
 static inline int kernfs_remove_by_name(struct sysfs_dirent *parent,
 					const char *name)
 {
-- 
1.8.4.2

[PATCH 19/41] sysfs, kernfs: remove sysfs_add_one()

[Tejun Heo]

sysfs_add_one() is a wrapper around __sysfs_add_one() which prints out
duplicate name warning if __sysfs_add_one() fails with -EEXIST.  The
previous kernfs conversions moved all dup warnings to sysfs interface
functions and sysfs_add_one() doesn't have any user left.

Remove sysfs_add_one() and update __sysfs_add_one() to take its name.

This patch doesn't make any functional changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/dir.c     | 41 ++++-------------------------------------
 fs/sysfs/file.c    |  2 +-
 fs/sysfs/symlink.c |  2 +-
 fs/sysfs/sysfs.h   |  2 --
 4 files changed, 6 insertions(+), 41 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index cfbf409..e88e9a9 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -395,7 +395,7 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt)
 }
 
 /**
- *	__sysfs_add_one - add sysfs_dirent to parent without warning
+ *	sysfs_add_one - add sysfs_dirent to parent without warning
  *	@acxt: addrm context to use
  *	@sd: sysfs_dirent to be added
  *	@parent_sd: the parent sysfs_dirent to add @sd to
@@ -415,8 +415,8 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt)
  *	0 on success, -EEXIST if entry with the given name already
  *	exists.
  */
-int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
-		    struct sysfs_dirent *parent_sd)
+int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
+		  struct sysfs_dirent *parent_sd)
 {
 	bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS;
 	struct sysfs_inode_attrs *ps_iattr;
@@ -488,39 +488,6 @@ void sysfs_warn_dup(struct sysfs_dirent *parent, const char *name)
 }
 
 /**
- *	sysfs_add_one - add sysfs_dirent to parent
- *	@acxt: addrm context to use
- *	@sd: sysfs_dirent to be added
- *	@parent_sd: the parent sysfs_dirent to add @sd to
- *
- *	Get @parent_sd and set @sd->s_parent to it and increment nlink of
- *	the parent inode if @sd is a directory and link into the children
- *	list of the parent.
- *
- *	This function should be called between calls to
- *	sysfs_addrm_start() and sysfs_addrm_finish() and should be
- *	passed the same @acxt as passed to sysfs_addrm_start().
- *
- *	LOCKING:
- *	Determined by sysfs_addrm_start().
- *
- *	RETURNS:
- *	0 on success, -EEXIST if entry with the given name already
- *	exists.
- */
-int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
-		  struct sysfs_dirent *parent_sd)
-{
-	int ret;
-
-	ret = __sysfs_add_one(acxt, sd, parent_sd);
-
-	if (ret == -EEXIST)
-		sysfs_warn_dup(parent_sd, sd->s_name);
-	return ret;
-}
-
-/**
  *	sysfs_remove_one - remove sysfs_dirent from parent
  *	@acxt: addrm context to use
  *	@sd: sysfs_dirent to be removed
@@ -694,7 +661,7 @@ struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
 
 	/* link in */
 	sysfs_addrm_start(&acxt);
-	rc = __sysfs_add_one(&acxt, sd, parent);
+	rc = sysfs_add_one(&acxt, sd, parent);
 	sysfs_addrm_finish(&acxt);
 
 	if (!rc)
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 69cca0f..9852450 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -1007,7 +1007,7 @@ struct sysfs_dirent *kernfs_create_file_ns(struct sysfs_dirent *parent,
 		sd->s_flags |= SYSFS_FLAG_HAS_MMAP;
 
 	sysfs_addrm_start(&acxt);
-	rc = __sysfs_add_one(&acxt, sd, parent);
+	rc = sysfs_add_one(&acxt, sd, parent);
 	sysfs_addrm_finish(&acxt);
 
 	if (rc) {
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 352fbbb..76efeab 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -47,7 +47,7 @@ struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
 	sysfs_get(target);	/* ref owned by symlink */
 
 	sysfs_addrm_start(&acxt);
-	error = __sysfs_add_one(&acxt, sd, parent);
+	error = sysfs_add_one(&acxt, sd, parent);
 	sysfs_addrm_finish(&acxt);
 
 	if (!error)
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 28898fa..a6542d2 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -167,8 +167,6 @@ struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd);
 void sysfs_put_active(struct sysfs_dirent *sd);
 void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt);
 void sysfs_warn_dup(struct sysfs_dirent *parent, const char *name);
-int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
-		    struct sysfs_dirent *parent_sd);
 int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
 		  struct sysfs_dirent *parent_sd);
 void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
-- 
1.8.4.2

[PATCH 20/41] sysfs, kernfs: add kernfs_ops->seq_{start|next|stop}()

[Tejun Heo]

kernfs_ops currently only supports single_open() behavior which is
pretty restrictive.  Add optional callbacks ->seq_{start|next|stop}()
which, when implemented, are invoked for seq_file traversal.  This
allows full seq_file functionality for kernfs users.  This currently
doesn't have any user and doesn't change any behavior.

v2: Refreshed on top of the updated "sysfs, kernfs: prepare read path
    for kernfs".

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c        | 39 ++++++++++++++++++++++++++++-----------
 include/linux/kernfs.h |  9 +++++++--
 2 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 9852450..74e3478 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -146,6 +146,7 @@ static ssize_t sysfs_kf_bin_read(struct sysfs_open_file *of, char *buf,
 static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos)
 {
 	struct sysfs_open_file *of = sf->private;
+	const struct kernfs_ops *ops;
 
 	/*
 	 * @of->mutex nests outside active ref and is just to ensure that
@@ -155,26 +156,42 @@ static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos)
 	if (!sysfs_get_active(of->sd))
 		return ERR_PTR(-ENODEV);
 
-	/*
-	 * The same behavior and code as single_open().  Returns !NULL if
-	 * pos is at the beginning; otherwise, NULL.
-	 */
-	return NULL + !*ppos;
+	ops = kernfs_ops(of->sd);
+	if (ops->seq_start) {
+		return ops->seq_start(sf, ppos);
+	} else {
+		/*
+		 * The same behavior and code as single_open().  Returns
+		 * !NULL if pos is at the beginning; otherwise, NULL.
+		 */
+		return NULL + !*ppos;
+	}
 }
 
 static void *kernfs_seq_next(struct seq_file *sf, void *v, loff_t *ppos)
 {
-	/*
-	 * The same behavior and code as single_open(), always terminate
-	 * after the initial read.
-	 */
-	++*ppos;
-	return NULL;
+	struct sysfs_open_file *of = sf->private;
+	const struct kernfs_ops *ops = kernfs_ops(of->sd);
+
+	if (ops->seq_next) {
+		return ops->seq_next(sf, v, ppos);
+	} else {
+		/*
+		 * The same behavior and code as single_open(), always
+		 * terminate after the initial read.
+		 */
+		++*ppos;
+		return NULL;
+	}
 }
 
 static void kernfs_seq_stop(struct seq_file *sf, void *v)
 {
 	struct sysfs_open_file *of = sf->private;
+	const struct kernfs_ops *ops = kernfs_ops(of->sd);
+
+	if (ops->seq_stop)
+		ops->seq_stop(sf, v);
 
 	sysfs_put_active(of->sd);
 	mutex_unlock(&of->mutex);
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index d0912cf..ba993eb 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -37,8 +37,9 @@ struct kernfs_ops {
 	/*
 	 * Read is handled by either seq_file or raw_read().
 	 *
-	 * If seq_show() is present, seq_file path is active.  The behavior
-	 * is equivalent to single_open().  @sf->private points to the
+	 * If seq_show() is present, seq_file path is active.  Other seq
+	 * operations are optional and if not implemented, the behavior is
+	 * equivalent to single_open().  @sf->private points to the
 	 * associated sysfs_open_file.
 	 *
 	 * read() is bounced through kernel buffer and a read larger than
@@ -46,6 +47,10 @@ struct kernfs_ops {
 	 */
 	int (*seq_show)(struct seq_file *sf, void *v);
 
+	void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
+	void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
+	void (*seq_stop)(struct seq_file *sf, void *v);
+
 	ssize_t (*read)(struct sysfs_open_file *of, char *buf, size_t bytes,
 			loff_t off);
 
-- 
1.8.4.2

[PATCH 21/41] sysfs, kernfs: introduce kernfs_notify()

[Tejun Heo]

Introduce kernfs interface to wake up poll(2) which takes and returns
sysfs_dirents.

sysfs_notify_dirent() is renamed to kernfs_notify() and sysfs_notify()
is updated so that it doesn't directly grab sysfs_mutex but acquires
the target sysfs_dirents using sysfs_get_dirent().
sysfs_notify_dirent() is reimplemented as a dumb inline wrapper around
kernfs_notify().

This patch doesn't introduce any behavior changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c        | 33 ++++++++++++++++++++++-----------
 include/linux/kernfs.h |  3 +++
 include/linux/sysfs.h  |  9 +++++----
 3 files changed, 30 insertions(+), 15 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 74e3478..a68cbef 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -851,7 +851,13 @@ static unsigned int kernfs_file_poll(struct file *filp, poll_table *wait)
 	return DEFAULT_POLLMASK|POLLERR|POLLPRI;
 }
 
-void sysfs_notify_dirent(struct sysfs_dirent *sd)
+/**
+ * kernfs_notify - notify a kernfs file
+ * @sd: file to notify
+ *
+ * Notify @sd such that poll(2) on @sd wakes up.
+ */
+void kernfs_notify(struct sysfs_dirent *sd)
 {
 	struct sysfs_open_dirent *od;
 	unsigned long flags;
@@ -868,22 +874,27 @@ void sysfs_notify_dirent(struct sysfs_dirent *sd)
 
 	spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
 }
-EXPORT_SYMBOL_GPL(sysfs_notify_dirent);
+EXPORT_SYMBOL_GPL(kernfs_notify);
 
 void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
 {
-	struct sysfs_dirent *sd = k->sd;
-
-	mutex_lock(&sysfs_mutex);
+	struct sysfs_dirent *sd = k->sd, *tmp;
 
 	if (sd && dir)
-		sd = sysfs_find_dirent(sd, dir, NULL);
-	if (sd && attr)
-		sd = sysfs_find_dirent(sd, attr, NULL);
-	if (sd)
-		sysfs_notify_dirent(sd);
+		sd = sysfs_get_dirent(sd, dir);
+	else
+		sysfs_get(sd);
 
-	mutex_unlock(&sysfs_mutex);
+	if (sd && attr) {
+		tmp = sysfs_get_dirent(sd, attr);
+		sysfs_put(sd);
+		sd = tmp;
+	}
+
+	if (sd) {
+		kernfs_notify(sd);
+		sysfs_put(sd);
+	}
 }
 EXPORT_SYMBOL_GPL(sysfs_notify);
 
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index ba993eb..f20796e 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -84,6 +84,7 @@ int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
 		     const char *new_name, const void *new_ns);
 void kernfs_enable_ns(struct sysfs_dirent *sd);
 int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr);
+void kernfs_notify(struct sysfs_dirent *sd);
 
 #else	/* CONFIG_SYSFS */
 
@@ -120,6 +121,8 @@ static inline int kernfs_setattr(struct sysfs_dirent *sd,
 				 const struct iattr *iattr)
 { return -ENOSYS; }
 
+static inline void kernfs_notify(struct sysfs_dirent *sd) { }
+
 #endif	/* CONFIG_SYSFS */
 
 static inline struct sysfs_dirent *
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 2bc735d..0ab2b02 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -243,7 +243,6 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
 				  const char *link_name);
 
 void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr);
-void sysfs_notify_dirent(struct sysfs_dirent *sd);
 struct sysfs_dirent *sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd,
 					 const unsigned char *name,
 					 const void *ns);
@@ -418,9 +417,6 @@ static inline void sysfs_notify(struct kobject *kobj, const char *dir,
 				const char *attr)
 {
 }
-static inline void sysfs_notify_dirent(struct sysfs_dirent *sd)
-{
-}
 static inline struct sysfs_dirent *
 sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd, const unsigned char *name,
 		    const void *ns)
@@ -466,4 +462,9 @@ sysfs_get_dirent(struct sysfs_dirent *parent_sd, const unsigned char *name)
 	return sysfs_get_dirent_ns(parent_sd, name, NULL);
 }
 
+static inline void sysfs_notify_dirent(struct sysfs_dirent *sd)
+{
+	kernfs_notify(sd);
+}
+
 #endif /* _SYSFS_H_ */
-- 
1.8.4.2

[PATCH 22/41] sysfs, kernfs: reorganize SYSFS_* constants

[Tejun Heo]

We want to add one more SYSFS_FLAG_* but we can't use the next higher
bit, 0x10000, as the flag field is 16bits wide.  The flags are
currently arranged weirdly - 8 bits are set aside for the type flags
when there are only three three used, the first flag starts at 0x1000
instead of 0x0100 and flag literals have 5 digits (20 bits) when only
4 digits can be used.

Rearrange them so that type bits are only the lowest four, flags start
at 0x0010 and similar flags are grouped.

This patch doesn't cause any behavior difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/sysfs.h | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index a6542d2..c86456c 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -80,18 +80,18 @@ struct sysfs_dirent {
 
 #define SD_DEACTIVATED_BIAS		INT_MIN
 
-#define SYSFS_TYPE_MASK			0x00ff
+#define SYSFS_TYPE_MASK			0x000f
 #define SYSFS_DIR			0x0001
 #define SYSFS_KOBJ_ATTR			0x0002
-#define SYSFS_KOBJ_LINK			0x0008
+#define SYSFS_KOBJ_LINK			0x0004
 #define SYSFS_COPY_NAME			(SYSFS_DIR | SYSFS_KOBJ_LINK)
 #define SYSFS_ACTIVE_REF		SYSFS_KOBJ_ATTR
 
 #define SYSFS_FLAG_MASK			~SYSFS_TYPE_MASK
-#define SYSFS_FLAG_NS			0x01000
-#define SYSFS_FLAG_REMOVED		0x02000
-#define SYSFS_FLAG_HAS_SEQ_SHOW		0x04000
-#define SYSFS_FLAG_HAS_MMAP		0x08000
+#define SYSFS_FLAG_REMOVED		0x0010
+#define SYSFS_FLAG_NS			0x0020
+#define SYSFS_FLAG_HAS_SEQ_SHOW		0x0040
+#define SYSFS_FLAG_HAS_MMAP		0x0080
 
 static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
 {
-- 
1.8.4.2

[PATCH 23/41] sysfs, kernfs: revamp sysfs_dirent active_ref lockdep annotation

[Tejun Heo]

Currently, sysfs_dirent active_ref lockdep annotation uses
attribute->[s]key as the lockdep key, which forces
kernfs_create_file_ns() to assume that sysfs_dirent->priv is pointing
to a struct attribute which may not be true for non-sysfs users.  This
patch restructures the lockdep annotation such that

* kernfs_ops contains lockdep_key which is used by default for files
  created kernfs_create_file_ns().

* kernfs_create_file_ns_key() is introduced which takes an extra @key
  argument.  The created file will use the specified key for
  active_ref lockdep annotation.  If NULL is specified, lockdep for
  the file is disabled.

* sysfs_add_file_mode_ns() is updated to use
  kernfs_create_file_ns_key() with the appropriate key from the
  attribute or NULL if ignore_lockdep is set.

This makes the lockdep annotation properly contained in kernfs while
allowing sysfs to cleanly keep its current behavior.  This patch
doesn't introduce any behavior differences.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/dir.c         |  4 ++--
 fs/sysfs/file.c        | 35 ++++++++++++++++++++++++-----------
 fs/sysfs/sysfs.h       | 32 +-------------------------------
 include/linux/kernfs.h | 37 +++++++++++++++++++++++++++++--------
 4 files changed, 56 insertions(+), 52 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index e88e9a9..8f2d577 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -150,7 +150,7 @@ struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
 	if (!atomic_inc_unless_negative(&sd->s_active))
 		return NULL;
 
-	if (likely(!sysfs_ignore_lockdep(sd)))
+	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
 		rwsem_acquire_read(&sd->dep_map, 0, 1, _RET_IP_);
 	return sd;
 }
@@ -169,7 +169,7 @@ void sysfs_put_active(struct sysfs_dirent *sd)
 	if (unlikely(!sd))
 		return;
 
-	if (likely(!sysfs_ignore_lockdep(sd)))
+	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
 		rwsem_release(&sd->dep_map, 1, _RET_IP_);
 	v = atomic_dec_return(&sd->s_active);
 	if (likely(v != SD_DEACTIVATED_BIAS))
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index a68cbef..e4eca28 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -58,7 +58,7 @@ static struct sysfs_open_file *sysfs_of(struct file *file)
  */
 static const struct kernfs_ops *kernfs_ops(struct sysfs_dirent *sd)
 {
-	if (!sysfs_ignore_lockdep(sd))
+	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
 		lockdep_assert_held(sd);
 	return sd->s_attr.ops;
 }
@@ -71,7 +71,7 @@ static const struct sysfs_ops *sysfs_file_ops(struct sysfs_dirent *sd)
 {
 	struct kobject *kobj = sd->s_parent->priv;
 
-	if (!sysfs_ignore_lockdep(sd))
+	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
 		lockdep_assert_held(sd);
 	return kobj->ktype ? kobj->ktype->sysfs_ops : NULL;
 }
@@ -942,6 +942,7 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 			   const struct attribute *attr, bool is_bin,
 			   umode_t mode, const void *ns)
 {
+	struct lock_class_key *key = NULL;
 	const struct kernfs_ops *ops;
 	struct sysfs_dirent *sd;
 	loff_t size;
@@ -981,8 +982,12 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 		size = battr->size;
 	}
 
-	sd = kernfs_create_file_ns(dir_sd, attr->name, mode, size,
-				   ops, (void *)attr, ns);
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	if (!attr->ignore_lockdep)
+		key = attr->key ?: (struct lock_class_key *)&attr->skey;
+#endif
+	sd = kernfs_create_file_ns_key(dir_sd, attr->name, mode, size,
+				       ops, (void *)attr, ns, key);
 	if (IS_ERR(sd)) {
 		if (PTR_ERR(sd) == -EEXIST)
 			sysfs_warn_dup(dir_sd, attr->name);
@@ -992,7 +997,7 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 }
 
 /**
- * kernfs_create_file_ns - create a file
+ * kernfs_create_file_ns_key - create a file
  * @parent: directory to create the file in
  * @name: name of the file
  * @mode: mode of the file
@@ -1000,14 +1005,16 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
  * @ops: kernfs operations for the file
  * @priv: private data for the file
  * @ns: optional namespace tag of the file
+ * @key: lockdep key for the file's active_ref, %NULL to disable lockdep
  *
  * Returns the created node on success, ERR_PTR() value on error.
  */
-struct sysfs_dirent *kernfs_create_file_ns(struct sysfs_dirent *parent,
-					   const char *name,
-					   umode_t mode, loff_t size,
-					   const struct kernfs_ops *ops,
-					   void *priv, const void *ns)
+struct sysfs_dirent *kernfs_create_file_ns_key(struct sysfs_dirent *parent,
+					       const char *name,
+					       umode_t mode, loff_t size,
+					       const struct kernfs_ops *ops,
+					       void *priv, const void *ns,
+					       struct lock_class_key *key)
 {
 	struct sysfs_addrm_cxt acxt;
 	struct sysfs_dirent *sd;
@@ -1022,7 +1029,13 @@ struct sysfs_dirent *kernfs_create_file_ns(struct sysfs_dirent *parent,
 	sd->s_attr.size = size;
 	sd->s_ns = ns;
 	sd->priv = priv;
-	sysfs_dirent_init_lockdep(sd);
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	if (key) {
+		lockdep_init_map(&sd->dep_map, "s_active", key, 0);
+		sd->s_flags |= SYSFS_FLAG_LOCKDEP;
+	}
+#endif
 
 	/*
 	 * sd->s_attr.ops is accesible only while holding active ref.  We
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index c86456c..e93f8b8 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -92,43 +92,13 @@ struct sysfs_dirent {
 #define SYSFS_FLAG_NS			0x0020
 #define SYSFS_FLAG_HAS_SEQ_SHOW		0x0040
 #define SYSFS_FLAG_HAS_MMAP		0x0080
+#define SYSFS_FLAG_LOCKDEP		0x0100
 
 static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
 {
 	return sd->s_flags & SYSFS_TYPE_MASK;
 }
 
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-
-#define sysfs_dirent_init_lockdep(sd)				\
-do {								\
-	struct attribute *attr = sd->priv;			\
-	struct lock_class_key *key = attr->key;			\
-	if (!key)						\
-		key = &attr->skey;				\
-								\
-	lockdep_init_map(&sd->dep_map, "s_active", key, 0);	\
-} while (0)
-
-/* Test for attributes that want to ignore lockdep for read-locking */
-static inline bool sysfs_ignore_lockdep(struct sysfs_dirent *sd)
-{
-	struct attribute *attr = sd->priv;
-
-	return sysfs_type(sd) == SYSFS_KOBJ_ATTR && attr->ignore_lockdep;
-}
-
-#else
-
-#define sysfs_dirent_init_lockdep(sd) do {} while (0)
-
-static inline bool sysfs_ignore_lockdep(struct sysfs_dirent *sd)
-{
-	return true;
-}
-
-#endif
-
 /*
  * Context structure to be used while adding/removing nodes.
  */
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index f20796e..105d09d 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -11,6 +11,7 @@
 #include <linux/err.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
+#include <linux/lockdep.h>
 
 struct file;
 struct iattr;
@@ -62,6 +63,10 @@ struct kernfs_ops {
 			 loff_t off);
 
 	int (*mmap)(struct sysfs_open_file *of, struct vm_area_struct *vma);
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lock_class_key	lockdep_key;
+#endif
 };
 
 #ifdef CONFIG_SYSFS
@@ -69,11 +74,12 @@ struct kernfs_ops {
 struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
 					  const char *name, void *priv,
 					  const void *ns);
-struct sysfs_dirent *kernfs_create_file_ns(struct sysfs_dirent *parent,
-					   const char *name,
-					   umode_t mode, loff_t size,
-					   const struct kernfs_ops *ops,
-					   void *priv, const void *ns);
+struct sysfs_dirent *kernfs_create_file_ns_key(struct sysfs_dirent *parent,
+					       const char *name,
+					       umode_t mode, loff_t size,
+					       const struct kernfs_ops *ops,
+					       void *priv, const void *ns,
+					       struct lock_class_key *key);
 struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
 					const char *name,
 					struct sysfs_dirent *target);
@@ -94,9 +100,10 @@ kernfs_create_dir_ns(struct sysfs_dirent *parent, const char *name, void *priv,
 { return ERR_PTR(-ENOSYS); }
 
 static inline struct sysfs_dirent *
-kernfs_create_file_ns(struct sysfs_dirent *parent, const char *name,
-		      umode_t mode, loff_t size, const struct kernfs_ops *ops,
-		      void *priv, const void *ns)
+kernfs_create_file_ns_key(struct sysfs_dirent *parent, const char *name,
+			  umode_t mode, loff_t size,
+			  const struct kernfs_ops *ops, void *priv,
+			  const void *ns, struct lock_class_key *key)
 { return ERR_PTR(-ENOSYS); }
 
 static inline struct sysfs_dirent *
@@ -132,6 +139,20 @@ kernfs_create_dir(struct sysfs_dirent *parent, const char *name, void *priv)
 }
 
 static inline struct sysfs_dirent *
+kernfs_create_file_ns(struct sysfs_dirent *parent, const char *name,
+		      umode_t mode, loff_t size, const struct kernfs_ops *ops,
+		      void *priv, const void *ns)
+{
+	struct lock_class_key *key = NULL;
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	key = (struct lock_class_key *)&ops->lockdep_key;
+#endif
+	return kernfs_create_file_ns_key(parent, name, mode, size, ops, priv,
+					 ns, key);
+}
+
+static inline struct sysfs_dirent *
 kernfs_create_file(struct sysfs_dirent *parent, const char *name, umode_t mode,
 		   loff_t size, const struct kernfs_ops *ops, void *priv)
 {
-- 
1.8.4.2

[PATCH 24/41] sysfs, kernfs: introduce kernfs[_find_and]_get() and kernfs_put()

[Tejun Heo]

Introduce kernfs interface for finding, getting and putting
sysfs_dirents.

* sysfs_find_dirent() is renamed to kernfs_find_ns() and lockdep
  assertion for sysfs_mutex is added.

* sysfs_get_dirent_ns() is renamed to kernfs_find_and_get().

* Macro inline dancing around __sysfs_get/put() are removed and
  kernfs_get/put() are made proper functions implemented in
  fs/sysfs/dir.c.

While the conversions are mostly equivalent, there's one difference -
kernfs_get() doesn't return the input param as its return value.  This
change is intentional.  While passing through the input increases
writability in some areas, it is unnecessary and has been shown to
cause confusion regarding how the last ref is handled.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/dir.c         | 117 ++++++++++++++++++++++++++++---------------------
 fs/sysfs/file.c        |  41 +++++++++--------
 fs/sysfs/group.c       |  30 +++++++------
 fs/sysfs/inode.c       |   5 ++-
 fs/sysfs/mount.c       |  14 ------
 fs/sysfs/symlink.c     |  16 ++++---
 fs/sysfs/sysfs.h       |  22 ----------
 include/linux/kernfs.h |  19 ++++++++
 include/linux/sysfs.h  |  35 ++++++---------
 9 files changed, 151 insertions(+), 148 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 8f2d577..0d806ef 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -240,10 +240,31 @@ static void sysfs_free_ino(unsigned int ino)
 	spin_unlock(&sysfs_ino_lock);
 }
 
-void release_sysfs_dirent(struct sysfs_dirent *sd)
+/**
+ * kernfs_get - get a reference count on a sysfs_dirent
+ * @sd: the target sysfs_dirent
+ */
+void kernfs_get(struct sysfs_dirent *sd)
+{
+	if (sd) {
+		WARN_ON(!atomic_read(&sd->s_count));
+		atomic_inc(&sd->s_count);
+	}
+}
+EXPORT_SYMBOL_GPL(kernfs_get);
+
+/**
+ * kernfs_put - put a reference count on a sysfs_dirent
+ * @sd: the target sysfs_dirent
+ *
+ * Put a reference count of @sd and destroy it if it reached zero.
+ */
+void kernfs_put(struct sysfs_dirent *sd)
 {
 	struct sysfs_dirent *parent_sd;
 
+	if (!sd || !atomic_dec_and_test(&sd->s_count))
+		return;
  repeat:
 	/* Moving/renaming is always done while holding reference.
 	 * sd->s_parent won't change beneath us.
@@ -255,7 +276,7 @@ void release_sysfs_dirent(struct sysfs_dirent *sd)
 		parent_sd ? parent_sd->s_name : "", sd->s_name);
 
 	if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
-		sysfs_put(sd->s_symlink.target_sd);
+		kernfs_put(sd->s_symlink.target_sd);
 	if (sysfs_type(sd) & SYSFS_COPY_NAME)
 		kfree(sd->s_name);
 	if (sd->s_iattr && sd->s_iattr->ia_secdata)
@@ -269,6 +290,7 @@ void release_sysfs_dirent(struct sysfs_dirent *sd)
 	if (sd && atomic_dec_and_test(&sd->s_count))
 		goto repeat;
 }
+EXPORT_SYMBOL_GPL(kernfs_put);
 
 static int sysfs_dentry_delete(const struct dentry *dentry)
 {
@@ -331,7 +353,7 @@ out_bad:
 
 static void sysfs_dentry_release(struct dentry *dentry)
 {
-	sysfs_put(dentry->d_fsdata);
+	kernfs_put(dentry->d_fsdata);
 }
 
 const struct dentry_operations sysfs_dentry_ops = {
@@ -433,7 +455,8 @@ int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
 		return -EINVAL;
 
 	sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
-	sd->s_parent = sysfs_get(parent_sd);
+	sd->s_parent = parent_sd;
+	kernfs_get(parent_sd);
 
 	ret = sysfs_link_sibling(sd);
 	if (ret)
@@ -553,36 +576,33 @@ void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
 
 		sysfs_deactivate(sd);
 		sysfs_unmap_bin_file(sd);
-		sysfs_put(sd);
+		kernfs_put(sd);
 	}
 }
 
 /**
- *	sysfs_find_dirent - find sysfs_dirent with the given name
- *	@parent_sd: sysfs_dirent to search under
- *	@name: name to look for
- *	@ns: the namespace tag to use
- *
- *	Look for sysfs_dirent with name @name under @parent_sd.
- *
- *	LOCKING:
- *	mutex_lock(sysfs_mutex)
+ * kernfs_find_ns - find sysfs_dirent with the given name
+ * @parent: sysfs_dirent to search under
+ * @name: name to look for
+ * @ns: the namespace tag to use
  *
- *	RETURNS:
- *	Pointer to sysfs_dirent if found, NULL if not.
+ * Look for sysfs_dirent with name @name under @parent.  Returns pointer to
+ * the found sysfs_dirent on success, %NULL on failure.
  */
-struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
-				       const unsigned char *name,
-				       const void *ns)
+static struct sysfs_dirent *kernfs_find_ns(struct sysfs_dirent *parent,
+					   const unsigned char *name,
+					   const void *ns)
 {
-	struct rb_node *node = parent_sd->s_dir.children.rb_node;
-	bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS;
+	struct rb_node *node = parent->s_dir.children.rb_node;
+	bool has_ns = parent->s_flags & SYSFS_FLAG_NS;
 	unsigned int hash;
 
+	lockdep_assert_held(&sysfs_mutex);
+
 	if (has_ns != (bool)ns) {
 		WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
 		     has_ns ? "required" : "invalid",
-		     parent_sd->s_name, name);
+		     parent->s_name, name);
 		return NULL;
 	}
 
@@ -604,34 +624,28 @@ struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
 }
 
 /**
- *	sysfs_get_dirent_ns - find and get sysfs_dirent with the given name
- *	@parent_sd: sysfs_dirent to search under
- *	@name: name to look for
- *	@ns: the namespace tag to use
- *
- *	Look for sysfs_dirent with name @name under @parent_sd and get
- *	it if found.
- *
- *	LOCKING:
- *	Kernel thread context (may sleep).  Grabs sysfs_mutex.
+ * kernfs_find_and_get_ns - find and get sysfs_dirent with the given name
+ * @parent: sysfs_dirent to search under
+ * @name: name to look for
+ * @ns: the namespace tag to use
  *
- *	RETURNS:
- *	Pointer to sysfs_dirent if found, NULL if not.
+ * Look for sysfs_dirent with name @name under @parent and get a reference
+ * if found.  This function may sleep and returns pointer to the found
+ * sysfs_dirent on success, %NULL on failure.
  */
-struct sysfs_dirent *sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd,
-					 const unsigned char *name,
-					 const void *ns)
+struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
+					    const char *name, const void *ns)
 {
 	struct sysfs_dirent *sd;
 
 	mutex_lock(&sysfs_mutex);
-	sd = sysfs_find_dirent(parent_sd, name, ns);
-	sysfs_get(sd);
+	sd = kernfs_find_ns(parent, name, ns);
+	kernfs_get(sd);
 	mutex_unlock(&sysfs_mutex);
 
 	return sd;
 }
-EXPORT_SYMBOL_GPL(sysfs_get_dirent_ns);
+EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns);
 
 /**
  * kernfs_create_dir_ns - create a directory
@@ -667,7 +681,7 @@ struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
 	if (!rc)
 		return sd;
 
-	sysfs_put(sd);
+	kernfs_put(sd);
 	return ERR_PTR(rc);
 }
 
@@ -716,14 +730,15 @@ static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry,
 	if (parent_sd->s_flags & SYSFS_FLAG_NS)
 		ns = sysfs_info(dir->i_sb)->ns;
 
-	sd = sysfs_find_dirent(parent_sd, dentry->d_name.name, ns);
+	sd = kernfs_find_ns(parent_sd, dentry->d_name.name, ns);
 
 	/* no such entry */
 	if (!sd) {
 		ret = ERR_PTR(-ENOENT);
 		goto out_unlock;
 	}
-	dentry->d_fsdata = sysfs_get(sd);
+	kernfs_get(sd);
+	dentry->d_fsdata = sd;
 
 	/* attach dentry and inode */
 	inode = sysfs_get_inode(dir->i_sb, sd);
@@ -859,7 +874,7 @@ int kernfs_remove_by_name_ns(struct sysfs_dirent *dir_sd, const char *name,
 
 	sysfs_addrm_start(&acxt);
 
-	sd = sysfs_find_dirent(dir_sd, name, ns);
+	sd = kernfs_find_ns(dir_sd, name, ns);
 	if (sd)
 		__kernfs_remove(&acxt, sd);
 
@@ -925,7 +940,7 @@ int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
 		goto out;	/* nothing to rename */
 
 	error = -EEXIST;
-	if (sysfs_find_dirent(new_parent, new_name, new_ns))
+	if (kernfs_find_ns(new_parent, new_name, new_ns))
 		goto out;
 
 	/* rename sysfs_dirent */
@@ -943,8 +958,8 @@ int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
 	 * Move to the appropriate place in the appropriate directories rbtree.
 	 */
 	sysfs_unlink_sibling(sd);
-	sysfs_get(new_parent);
-	sysfs_put(sd->s_parent);
+	kernfs_get(new_parent);
+	kernfs_put(sd->s_parent);
 	sd->s_ns = new_ns;
 	sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
 	sd->s_parent = new_parent;
@@ -1000,7 +1015,7 @@ static inline unsigned char dt_type(struct sysfs_dirent *sd)
 
 static int sysfs_dir_release(struct inode *inode, struct file *filp)
 {
-	sysfs_put(filp->private_data);
+	kernfs_put(filp->private_data);
 	return 0;
 }
 
@@ -1011,7 +1026,7 @@ static struct sysfs_dirent *sysfs_dir_pos(const void *ns,
 		int valid = !(pos->s_flags & SYSFS_FLAG_REMOVED) &&
 			pos->s_parent == parent_sd &&
 			hash == pos->s_hash;
-		sysfs_put(pos);
+		kernfs_put(pos);
 		if (!valid)
 			pos = NULL;
 	}
@@ -1075,8 +1090,10 @@ static int sysfs_readdir(struct file *file, struct dir_context *ctx)
 		unsigned int type = dt_type(pos);
 		int len = strlen(name);
 		ino_t ino = pos->s_ino;
+
 		ctx->pos = pos->s_hash;
-		file->private_data = sysfs_get(pos);
+		file->private_data = pos;
+		kernfs_get(pos);
 
 		mutex_unlock(&sysfs_mutex);
 		if (!dir_emit(ctx, name, len, ino, type))
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index e4eca28..7f0a79f 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -881,19 +881,19 @@ void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
 	struct sysfs_dirent *sd = k->sd, *tmp;
 
 	if (sd && dir)
-		sd = sysfs_get_dirent(sd, dir);
+		sd = kernfs_find_and_get(sd, dir);
 	else
-		sysfs_get(sd);
+		kernfs_get(sd);
 
 	if (sd && attr) {
-		tmp = sysfs_get_dirent(sd, attr);
-		sysfs_put(sd);
+		tmp = kernfs_find_and_get(sd, attr);
+		kernfs_put(sd);
 		sd = tmp;
 	}
 
 	if (sd) {
 		kernfs_notify(sd);
-		sysfs_put(sd);
+		kernfs_put(sd);
 	}
 }
 EXPORT_SYMBOL_GPL(sysfs_notify);
@@ -1052,7 +1052,7 @@ struct sysfs_dirent *kernfs_create_file_ns_key(struct sysfs_dirent *parent,
 	sysfs_addrm_finish(&acxt);
 
 	if (rc) {
-		sysfs_put(sd);
+		kernfs_put(sd);
 		return ERR_PTR(rc);
 	}
 	return sd;
@@ -1106,16 +1106,18 @@ int sysfs_add_file_to_group(struct kobject *kobj,
 	struct sysfs_dirent *dir_sd;
 	int error;
 
-	if (group)
-		dir_sd = sysfs_get_dirent(kobj->sd, group);
-	else
-		dir_sd = sysfs_get(kobj->sd);
+	if (group) {
+		dir_sd = kernfs_find_and_get(kobj->sd, group);
+	} else {
+		dir_sd = kobj->sd;
+		kernfs_get(dir_sd);
+	}
 
 	if (!dir_sd)
 		return -ENOENT;
 
 	error = sysfs_add_file(dir_sd, attr, false);
-	sysfs_put(dir_sd);
+	kernfs_put(dir_sd);
 
 	return error;
 }
@@ -1135,7 +1137,7 @@ int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
 	struct iattr newattrs;
 	int rc;
 
-	sd = sysfs_get_dirent(kobj->sd, attr->name);
+	sd = kernfs_find_and_get(kobj->sd, attr->name);
 	if (!sd)
 		return -ENOENT;
 
@@ -1144,7 +1146,7 @@ int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
 
 	rc = kernfs_setattr(sd, &newattrs);
 
-	sysfs_put(sd);
+	kernfs_put(sd);
 	return rc;
 }
 EXPORT_SYMBOL_GPL(sysfs_chmod_file);
@@ -1185,13 +1187,16 @@ void sysfs_remove_file_from_group(struct kobject *kobj,
 {
 	struct sysfs_dirent *dir_sd;
 
-	if (group)
-		dir_sd = sysfs_get_dirent(kobj->sd, group);
-	else
-		dir_sd = sysfs_get(kobj->sd);
+	if (group) {
+		dir_sd = kernfs_find_and_get(kobj->sd, group);
+	} else {
+		dir_sd = kobj->sd;
+		kernfs_get(dir_sd);
+	}
+
 	if (dir_sd) {
 		kernfs_remove_by_name(dir_sd, attr->name);
-		sysfs_put(dir_sd);
+		kernfs_put(dir_sd);
 	}
 }
 EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index d7f4f6e..d538031 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -108,13 +108,13 @@ static int internal_create_group(struct kobject *kobj, int update,
 		}
 	} else
 		sd = kobj->sd;
-	sysfs_get(sd);
+	kernfs_get(sd);
 	error = create_files(sd, kobj, grp, update);
 	if (error) {
 		if (grp->name)
 			kernfs_remove(sd);
 	}
-	sysfs_put(sd);
+	kernfs_put(sd);
 	return error;
 }
 
@@ -217,21 +217,23 @@ void sysfs_remove_group(struct kobject *kobj,
 		return;
 
 	if (grp->name) {
-		sd = sysfs_get_dirent(dir_sd, grp->name);
+		sd = kernfs_find_and_get(dir_sd, grp->name);
 		if (!sd) {
 			WARN(!sd, KERN_WARNING
 			     "sysfs group %p not found for kobject '%s'\n",
 			     grp, kobject_name(kobj));
 			return;
 		}
-	} else
-		sd = sysfs_get(dir_sd);
+	} else {
+		sd = dir_sd;
+		kernfs_get(sd);
+	}
 
 	remove_files(sd, kobj, grp);
 	if (grp->name)
 		kernfs_remove(sd);
 
-	sysfs_put(sd);
+	kernfs_put(sd);
 }
 EXPORT_SYMBOL_GPL(sysfs_remove_group);
 
@@ -272,7 +274,7 @@ int sysfs_merge_group(struct kobject *kobj,
 	struct attribute *const *attr;
 	int i;
 
-	dir_sd = sysfs_get_dirent(kobj->sd, grp->name);
+	dir_sd = kernfs_find_and_get(kobj->sd, grp->name);
 	if (!dir_sd)
 		return -ENOENT;
 
@@ -282,7 +284,7 @@ int sysfs_merge_group(struct kobject *kobj,
 		while (--i >= 0)
 			kernfs_remove_by_name(dir_sd, (*--attr)->name);
 	}
-	sysfs_put(dir_sd);
+	kernfs_put(dir_sd);
 
 	return error;
 }
@@ -299,11 +301,11 @@ void sysfs_unmerge_group(struct kobject *kobj,
 	struct sysfs_dirent *dir_sd;
 	struct attribute *const *attr;
 
-	dir_sd = sysfs_get_dirent(kobj->sd, grp->name);
+	dir_sd = kernfs_find_and_get(kobj->sd, grp->name);
 	if (dir_sd) {
 		for (attr = grp->attrs; *attr; ++attr)
 			kernfs_remove_by_name(dir_sd, (*attr)->name);
-		sysfs_put(dir_sd);
+		kernfs_put(dir_sd);
 	}
 }
 EXPORT_SYMBOL_GPL(sysfs_unmerge_group);
@@ -321,12 +323,12 @@ int sysfs_add_link_to_group(struct kobject *kobj, const char *group_name,
 	struct sysfs_dirent *dir_sd;
 	int error = 0;
 
-	dir_sd = sysfs_get_dirent(kobj->sd, group_name);
+	dir_sd = kernfs_find_and_get(kobj->sd, group_name);
 	if (!dir_sd)
 		return -ENOENT;
 
 	error = sysfs_create_link_sd(dir_sd, target, link_name);
-	sysfs_put(dir_sd);
+	kernfs_put(dir_sd);
 
 	return error;
 }
@@ -343,10 +345,10 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
 {
 	struct sysfs_dirent *dir_sd;
 
-	dir_sd = sysfs_get_dirent(kobj->sd, group_name);
+	dir_sd = kernfs_find_and_get(kobj->sd, group_name);
 	if (dir_sd) {
 		kernfs_remove_by_name(dir_sd, link_name);
-		sysfs_put(dir_sd);
+		kernfs_put(dir_sd);
 	}
 }
 EXPORT_SYMBOL_GPL(sysfs_remove_link_from_group);
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index b3c717a..bfe4478 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -254,7 +254,8 @@ int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
 
 static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
 {
-	inode->i_private = sysfs_get(sd);
+	kernfs_get(sd);
+	inode->i_private = sd;
 	inode->i_mapping->a_ops = &sysfs_aops;
 	inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
 	inode->i_op = &sysfs_inode_operations;
@@ -321,7 +322,7 @@ void sysfs_evict_inode(struct inode *inode)
 
 	truncate_inode_pages(&inode->i_data, 0);
 	clear_inode(inode);
-	sysfs_put(sd);
+	kernfs_put(sd);
 }
 
 int sysfs_permission(struct inode *inode, int mask)
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 8c24bce..852d115 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -184,17 +184,3 @@ out_err:
 	sysfs_dir_cachep = NULL;
 	goto out;
 }
-
-#undef sysfs_get
-struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
-{
-	return __sysfs_get(sd);
-}
-EXPORT_SYMBOL_GPL(sysfs_get);
-
-#undef sysfs_put
-void sysfs_put(struct sysfs_dirent *sd)
-{
-	__sysfs_put(sd);
-}
-EXPORT_SYMBOL_GPL(sysfs_put);
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 76efeab..b137aa3 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -44,7 +44,7 @@ struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
 	if (parent->s_flags & SYSFS_FLAG_NS)
 		sd->s_ns = target->s_ns;
 	sd->s_symlink.target_sd = target;
-	sysfs_get(target);	/* ref owned by symlink */
+	kernfs_get(target);	/* ref owned by symlink */
 
 	sysfs_addrm_start(&acxt);
 	error = sysfs_add_one(&acxt, sd, parent);
@@ -53,7 +53,7 @@ struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
 	if (!error)
 		return sd;
 
-	sysfs_put(sd);
+	kernfs_put(sd);
 	return ERR_PTR(error);
 }
 
@@ -72,15 +72,17 @@ static int sysfs_do_create_link_sd(struct sysfs_dirent *parent_sd,
 	 * sysfs_remove_dir() for details.
 	 */
 	spin_lock(&sysfs_symlink_target_lock);
-	if (target->sd)
-		target_sd = sysfs_get(target->sd);
+	if (target->sd) {
+		target_sd = target->sd;
+		kernfs_get(target_sd);
+	}
 	spin_unlock(&sysfs_symlink_target_lock);
 
 	if (!target_sd)
 		return -ENOENT;
 
 	sd = kernfs_create_link(parent_sd, name, target_sd);
-	sysfs_put(target_sd);
+	kernfs_put(target_sd);
 
 	if (!IS_ERR(sd))
 		return 0;
@@ -216,7 +218,7 @@ int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *targ,
 		old_ns = targ->sd->s_ns;
 
 	result = -ENOENT;
-	sd = sysfs_get_dirent_ns(parent_sd, old, old_ns);
+	sd = kernfs_find_and_get_ns(parent_sd, old, old_ns);
 	if (!sd)
 		goto out;
 
@@ -229,7 +231,7 @@ int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *targ,
 	result = kernfs_rename_ns(sd, parent_sd, new, new_ns);
 
 out:
-	sysfs_put(sd);
+	kernfs_put(sd);
 	return result;
 }
 EXPORT_SYMBOL_GPL(sysfs_rename_link_ns);
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index e93f8b8..85315e2 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -141,30 +141,8 @@ int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
 		  struct sysfs_dirent *parent_sd);
 void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
 
-struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
-				       const unsigned char *name,
-				       const void *ns);
 struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);
 
-void release_sysfs_dirent(struct sysfs_dirent *sd);
-
-static inline struct sysfs_dirent *__sysfs_get(struct sysfs_dirent *sd)
-{
-	if (sd) {
-		WARN_ON(!atomic_read(&sd->s_count));
-		atomic_inc(&sd->s_count);
-	}
-	return sd;
-}
-#define sysfs_get(sd) __sysfs_get(sd)
-
-static inline void __sysfs_put(struct sysfs_dirent *sd)
-{
-	if (sd && atomic_dec_and_test(&sd->s_count))
-		release_sysfs_dirent(sd);
-}
-#define sysfs_put(sd) __sysfs_put(sd)
-
 /*
  * inode.c
  */
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 105d09d..fd8f574 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -71,6 +71,11 @@ struct kernfs_ops {
 
 #ifdef CONFIG_SYSFS
 
+struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
+					    const char *name, const void *ns);
+void kernfs_get(struct sysfs_dirent *sd);
+void kernfs_put(struct sysfs_dirent *sd);
+
 struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
 					  const char *name, void *priv,
 					  const void *ns);
@@ -95,6 +100,14 @@ void kernfs_notify(struct sysfs_dirent *sd);
 #else	/* CONFIG_SYSFS */
 
 static inline struct sysfs_dirent *
+kernfs_find_and_get_ns(struct sysfs_dirent *parent, const char *name,
+		       const void *ns)
+{ return NULL; }
+
+static inline void kernfs_get(struct sysfs_dirent *sd) { }
+static inline void kernfs_put(struct sysfs_dirent *sd) { }
+
+static inline struct sysfs_dirent *
 kernfs_create_dir_ns(struct sysfs_dirent *parent, const char *name, void *priv,
 		     const void *ns)
 { return ERR_PTR(-ENOSYS); }
@@ -133,6 +146,12 @@ static inline void kernfs_notify(struct sysfs_dirent *sd) { }
 #endif	/* CONFIG_SYSFS */
 
 static inline struct sysfs_dirent *
+kernfs_find_and_get(struct sysfs_dirent *sd, const char *name)
+{
+	return kernfs_find_and_get_ns(sd, name, NULL);
+}
+
+static inline struct sysfs_dirent *
 kernfs_create_dir(struct sysfs_dirent *parent, const char *name, void *priv)
 {
 	return kernfs_create_dir_ns(parent, name, priv, NULL);
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 0ab2b02..cd8f90b 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -243,11 +243,6 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
 				  const char *link_name);
 
 void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr);
-struct sysfs_dirent *sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd,
-					 const unsigned char *name,
-					 const void *ns);
-struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd);
-void sysfs_put(struct sysfs_dirent *sd);
 
 int __must_check sysfs_init(void);
 
@@ -417,19 +412,6 @@ static inline void sysfs_notify(struct kobject *kobj, const char *dir,
 				const char *attr)
 {
 }
-static inline struct sysfs_dirent *
-sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd, const unsigned char *name,
-		    const void *ns)
-{
-	return NULL;
-}
-static inline struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
-{
-	return NULL;
-}
-static inline void sysfs_put(struct sysfs_dirent *sd)
-{
-}
 
 static inline int __must_check sysfs_init(void)
 {
@@ -456,15 +438,26 @@ static inline int sysfs_rename_link(struct kobject *kobj, struct kobject *target
 	return sysfs_rename_link_ns(kobj, target, old_name, new_name, NULL);
 }
 
+static inline void sysfs_notify_dirent(struct sysfs_dirent *sd)
+{
+	kernfs_notify(sd);
+}
+
 static inline struct sysfs_dirent *
 sysfs_get_dirent(struct sysfs_dirent *parent_sd, const unsigned char *name)
 {
-	return sysfs_get_dirent_ns(parent_sd, name, NULL);
+	return kernfs_find_and_get(parent_sd, name);
 }
 
-static inline void sysfs_notify_dirent(struct sysfs_dirent *sd)
+static inline struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
 {
-	kernfs_notify(sd);
+	kernfs_get(sd);
+	return sd;
+}
+
+static inline void sysfs_put(struct sysfs_dirent *sd)
+{
+	kernfs_put(sd);
 }
 
 #endif /* _SYSFS_H_ */
-- 
1.8.4.2

[PATCH 25/41] sysfs, kernfs: move internal decls to fs/kernfs/kernfs-internal.h

[Tejun Heo]

Move data structure, constant and basic accessor declarations from
fs/sysfs/sysfs.h to fs/kernfs/kernfs-internal.h.  The two files
currently include each other.  Once kernfs / sysfs separation is
complete, the cross inclusions will be removed.  Inclusion protectors
are added to fs/sysfs/sysfs.h to allow cross-inclusion.

This patch doesn't introduce any functional changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/kernfs-internal.h | 115 ++++++++++++++++++++++++++++++++++++++++++++
 fs/sysfs/sysfs.h            | 102 +++------------------------------------
 2 files changed, 121 insertions(+), 96 deletions(-)
 create mode 100644 fs/kernfs/kernfs-internal.h

diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
new file mode 100644
index 0000000..5a2c3a1
--- /dev/null
+++ b/fs/kernfs/kernfs-internal.h
@@ -0,0 +1,115 @@
+/*
+ * fs/kernfs/kernfs-internal.h - kernfs internal header file
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007, 2013 Tejun Heo <teheo@suse.de>
+ *
+ * This file is released under the GPLv2.
+ */
+
+#ifndef __KERNFS_INTERNAL_H
+#define __KERNFS_INTERNAL_H
+
+#include <linux/lockdep.h>
+#include <linux/fs.h>
+#include <linux/rbtree.h>
+
+#include <linux/kernfs.h>
+
+struct sysfs_open_dirent;
+
+/* type-specific structures for sysfs_dirent->s_* union members */
+struct sysfs_elem_dir {
+	unsigned long		subdirs;
+	/* children rbtree starts here and goes through sd->s_rb */
+	struct rb_root		children;
+};
+
+struct sysfs_elem_symlink {
+	struct sysfs_dirent	*target_sd;
+};
+
+struct sysfs_elem_attr {
+	const struct kernfs_ops	*ops;
+	struct sysfs_open_dirent *open;
+	loff_t			size;
+};
+
+struct sysfs_inode_attrs {
+	struct iattr	ia_iattr;
+	void		*ia_secdata;
+	u32		ia_secdata_len;
+};
+
+/*
+ * sysfs_dirent - the building block of sysfs hierarchy.  Each and
+ * every sysfs node is represented by single sysfs_dirent.
+ *
+ * As long as s_count reference is held, the sysfs_dirent itself is
+ * accessible.  Dereferencing s_elem or any other outer entity
+ * requires s_active reference.
+ */
+struct sysfs_dirent {
+	atomic_t		s_count;
+	atomic_t		s_active;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lockdep_map	dep_map;
+#endif
+	struct sysfs_dirent	*s_parent;
+	const char		*s_name;
+
+	struct rb_node		s_rb;
+
+	union {
+		struct completion	*completion;
+		struct sysfs_dirent	*removed_list;
+	} u;
+
+	const void		*s_ns; /* namespace tag */
+	unsigned int		s_hash; /* ns + name hash */
+	union {
+		struct sysfs_elem_dir		s_dir;
+		struct sysfs_elem_symlink	s_symlink;
+		struct sysfs_elem_attr		s_attr;
+	};
+
+	void			*priv;
+
+	unsigned short		s_flags;
+	umode_t			s_mode;
+	unsigned int		s_ino;
+	struct sysfs_inode_attrs *s_iattr;
+};
+
+#define SD_DEACTIVATED_BIAS		INT_MIN
+
+#define SYSFS_TYPE_MASK			0x000f
+#define SYSFS_DIR			0x0001
+#define SYSFS_KOBJ_ATTR			0x0002
+#define SYSFS_KOBJ_LINK			0x0004
+#define SYSFS_COPY_NAME			(SYSFS_DIR | SYSFS_KOBJ_LINK)
+#define SYSFS_ACTIVE_REF		SYSFS_KOBJ_ATTR
+
+#define SYSFS_FLAG_MASK			~SYSFS_TYPE_MASK
+#define SYSFS_FLAG_REMOVED		0x0010
+#define SYSFS_FLAG_NS			0x0020
+#define SYSFS_FLAG_HAS_SEQ_SHOW		0x0040
+#define SYSFS_FLAG_HAS_MMAP		0x0080
+#define SYSFS_FLAG_LOCKDEP		0x0100
+
+static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
+{
+	return sd->s_flags & SYSFS_TYPE_MASK;
+}
+
+/*
+ * Context structure to be used while adding/removing nodes.
+ */
+struct sysfs_addrm_cxt {
+	struct sysfs_dirent	*removed;
+};
+
+#include "../sysfs/sysfs.h"
+
+#endif	/* __KERNFS_INTERNAL_H */
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 85315e2..f8c936f 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -8,103 +8,11 @@
  * This file is released under the GPLv2.
  */
 
-#include <linux/lockdep.h>
-#include <linux/kobject_ns.h>
-#include <linux/fs.h>
-#include <linux/rbtree.h>
+#ifndef __SYSFS_INTERNAL_H
+#define __SYSFS_INTERNAL_H
 
-struct sysfs_open_dirent;
-
-/* type-specific structures for sysfs_dirent->s_* union members */
-struct sysfs_elem_dir {
-	unsigned long		subdirs;
-	/* children rbtree starts here and goes through sd->s_rb */
-	struct rb_root		children;
-};
-
-struct sysfs_elem_symlink {
-	struct sysfs_dirent	*target_sd;
-};
-
-struct sysfs_elem_attr {
-	const struct kernfs_ops	*ops;
-	struct sysfs_open_dirent *open;
-	loff_t			size;
-};
-
-struct sysfs_inode_attrs {
-	struct iattr	ia_iattr;
-	void		*ia_secdata;
-	u32		ia_secdata_len;
-};
-
-/*
- * sysfs_dirent - the building block of sysfs hierarchy.  Each and
- * every sysfs node is represented by single sysfs_dirent.
- *
- * As long as s_count reference is held, the sysfs_dirent itself is
- * accessible.  Dereferencing s_elem or any other outer entity
- * requires s_active reference.
- */
-struct sysfs_dirent {
-	atomic_t		s_count;
-	atomic_t		s_active;
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-	struct lockdep_map	dep_map;
-#endif
-	struct sysfs_dirent	*s_parent;
-	const char		*s_name;
-
-	struct rb_node		s_rb;
-
-	union {
-		struct completion	*completion;
-		struct sysfs_dirent	*removed_list;
-	} u;
-
-	const void		*s_ns; /* namespace tag */
-	unsigned int		s_hash; /* ns + name hash */
-	union {
-		struct sysfs_elem_dir		s_dir;
-		struct sysfs_elem_symlink	s_symlink;
-		struct sysfs_elem_attr		s_attr;
-	};
-
-	void			*priv;
-
-	unsigned short		s_flags;
-	umode_t			s_mode;
-	unsigned int		s_ino;
-	struct sysfs_inode_attrs *s_iattr;
-};
-
-#define SD_DEACTIVATED_BIAS		INT_MIN
-
-#define SYSFS_TYPE_MASK			0x000f
-#define SYSFS_DIR			0x0001
-#define SYSFS_KOBJ_ATTR			0x0002
-#define SYSFS_KOBJ_LINK			0x0004
-#define SYSFS_COPY_NAME			(SYSFS_DIR | SYSFS_KOBJ_LINK)
-#define SYSFS_ACTIVE_REF		SYSFS_KOBJ_ATTR
-
-#define SYSFS_FLAG_MASK			~SYSFS_TYPE_MASK
-#define SYSFS_FLAG_REMOVED		0x0010
-#define SYSFS_FLAG_NS			0x0020
-#define SYSFS_FLAG_HAS_SEQ_SHOW		0x0040
-#define SYSFS_FLAG_HAS_MMAP		0x0080
-#define SYSFS_FLAG_LOCKDEP		0x0100
-
-static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
-{
-	return sd->s_flags & SYSFS_TYPE_MASK;
-}
-
-/*
- * Context structure to be used while adding/removing nodes.
- */
-struct sysfs_addrm_cxt {
-	struct sysfs_dirent	*removed;
-};
+#include "../kernfs/kernfs-internal.h"
+#include <linux/sysfs.h>
 
 /*
  * mount.c
@@ -175,3 +83,5 @@ void sysfs_unmap_bin_file(struct sysfs_dirent *sd);
 extern const struct inode_operations sysfs_symlink_inode_operations;
 int sysfs_create_link_sd(struct sysfs_dirent *sd, struct kobject *target,
 			 const char *name);
+
+#endif	/* __SYSFS_INTERNAL_H */
-- 
1.8.4.2

[PATCH 26/41] sysfs, kernfs: move inode code to fs/kernfs/inode.c

[Tejun Heo]

There's nothing sysfs-specific in fs/sysfs/inode.c.  Move everything
in it to fs/kernfs/inode.c.  The respective declarations in
fs/sysfs/sysfs.h are moved to fs/kernfs/kernfs-internal.h.

This is pure relocation.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/inode.c           | 327 ++++++++++++++++++++++++++++++++++++++++++
 fs/kernfs/kernfs-internal.h |  13 ++
 fs/sysfs/Makefile           |   2 +-
 fs/sysfs/inode.c            | 342 --------------------------------------------
 fs/sysfs/sysfs.h            |  13 --
 5 files changed, 341 insertions(+), 356 deletions(-)
 delete mode 100644 fs/sysfs/inode.c

diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 86bfeea..9d4fab4 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -7,3 +7,330 @@
  *
  * This file is released under the GPLv2.
  */
+
+#include <linux/pagemap.h>
+#include <linux/backing-dev.h>
+#include <linux/capability.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/xattr.h>
+#include <linux/security.h>
+
+#include "kernfs-internal.h"
+
+static const struct address_space_operations sysfs_aops = {
+	.readpage	= simple_readpage,
+	.write_begin	= simple_write_begin,
+	.write_end	= simple_write_end,
+};
+
+static struct backing_dev_info sysfs_backing_dev_info = {
+	.name		= "sysfs",
+	.ra_pages	= 0,	/* No readahead */
+	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK,
+};
+
+static const struct inode_operations sysfs_inode_operations = {
+	.permission	= sysfs_permission,
+	.setattr	= sysfs_setattr,
+	.getattr	= sysfs_getattr,
+	.setxattr	= sysfs_setxattr,
+};
+
+int __init sysfs_inode_init(void)
+{
+	return bdi_init(&sysfs_backing_dev_info);
+}
+
+static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
+{
+	struct sysfs_inode_attrs *attrs;
+	struct iattr *iattrs;
+
+	attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
+	if (!attrs)
+		return NULL;
+	iattrs = &attrs->ia_iattr;
+
+	/* assign default attributes */
+	iattrs->ia_mode = sd->s_mode;
+	iattrs->ia_uid = GLOBAL_ROOT_UID;
+	iattrs->ia_gid = GLOBAL_ROOT_GID;
+	iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
+
+	return attrs;
+}
+
+static int __kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
+{
+	struct sysfs_inode_attrs *sd_attrs;
+	struct iattr *iattrs;
+	unsigned int ia_valid = iattr->ia_valid;
+
+	sd_attrs = sd->s_iattr;
+
+	if (!sd_attrs) {
+		/* setting attributes for the first time, allocate now */
+		sd_attrs = sysfs_init_inode_attrs(sd);
+		if (!sd_attrs)
+			return -ENOMEM;
+		sd->s_iattr = sd_attrs;
+	}
+	/* attributes were changed at least once in past */
+	iattrs = &sd_attrs->ia_iattr;
+
+	if (ia_valid & ATTR_UID)
+		iattrs->ia_uid = iattr->ia_uid;
+	if (ia_valid & ATTR_GID)
+		iattrs->ia_gid = iattr->ia_gid;
+	if (ia_valid & ATTR_ATIME)
+		iattrs->ia_atime = iattr->ia_atime;
+	if (ia_valid & ATTR_MTIME)
+		iattrs->ia_mtime = iattr->ia_mtime;
+	if (ia_valid & ATTR_CTIME)
+		iattrs->ia_ctime = iattr->ia_ctime;
+	if (ia_valid & ATTR_MODE) {
+		umode_t mode = iattr->ia_mode;
+		iattrs->ia_mode = sd->s_mode = mode;
+	}
+	return 0;
+}
+
+/**
+ * kernfs_setattr - set iattr on a node
+ * @sd: target node
+ * @iattr: iattr to set
+ *
+ * Returns 0 on success, -errno on failure.
+ */
+int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
+{
+	int ret;
+
+	mutex_lock(&sysfs_mutex);
+	ret = __kernfs_setattr(sd, iattr);
+	mutex_unlock(&sysfs_mutex);
+	return ret;
+}
+
+int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
+{
+	struct inode *inode = dentry->d_inode;
+	struct sysfs_dirent *sd = dentry->d_fsdata;
+	int error;
+
+	if (!sd)
+		return -EINVAL;
+
+	mutex_lock(&sysfs_mutex);
+	error = inode_change_ok(inode, iattr);
+	if (error)
+		goto out;
+
+	error = __kernfs_setattr(sd, iattr);
+	if (error)
+		goto out;
+
+	/* this ignores size changes */
+	setattr_copy(inode, iattr);
+
+out:
+	mutex_unlock(&sysfs_mutex);
+	return error;
+}
+
+static int sysfs_sd_setsecdata(struct sysfs_dirent *sd, void **secdata,
+			       u32 *secdata_len)
+{
+	struct sysfs_inode_attrs *iattrs;
+	void *old_secdata;
+	size_t old_secdata_len;
+
+	if (!sd->s_iattr) {
+		sd->s_iattr = sysfs_init_inode_attrs(sd);
+		if (!sd->s_iattr)
+			return -ENOMEM;
+	}
+
+	iattrs = sd->s_iattr;
+	old_secdata = iattrs->ia_secdata;
+	old_secdata_len = iattrs->ia_secdata_len;
+
+	iattrs->ia_secdata = *secdata;
+	iattrs->ia_secdata_len = *secdata_len;
+
+	*secdata = old_secdata;
+	*secdata_len = old_secdata_len;
+	return 0;
+}
+
+int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
+		size_t size, int flags)
+{
+	struct sysfs_dirent *sd = dentry->d_fsdata;
+	void *secdata;
+	int error;
+	u32 secdata_len = 0;
+
+	if (!sd)
+		return -EINVAL;
+
+	if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
+		const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
+		error = security_inode_setsecurity(dentry->d_inode, suffix,
+						value, size, flags);
+		if (error)
+			goto out;
+		error = security_inode_getsecctx(dentry->d_inode,
+						&secdata, &secdata_len);
+		if (error)
+			goto out;
+
+		mutex_lock(&sysfs_mutex);
+		error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
+		mutex_unlock(&sysfs_mutex);
+
+		if (secdata)
+			security_release_secctx(secdata, secdata_len);
+	} else
+		return -EINVAL;
+out:
+	return error;
+}
+
+static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
+{
+	inode->i_mode = mode;
+	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+}
+
+static inline void set_inode_attr(struct inode *inode, struct iattr *iattr)
+{
+	inode->i_uid = iattr->ia_uid;
+	inode->i_gid = iattr->ia_gid;
+	inode->i_atime = iattr->ia_atime;
+	inode->i_mtime = iattr->ia_mtime;
+	inode->i_ctime = iattr->ia_ctime;
+}
+
+static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
+{
+	struct sysfs_inode_attrs *iattrs = sd->s_iattr;
+
+	inode->i_mode = sd->s_mode;
+	if (iattrs) {
+		/* sysfs_dirent has non-default attributes
+		 * get them from persistent copy in sysfs_dirent
+		 */
+		set_inode_attr(inode, &iattrs->ia_iattr);
+		security_inode_notifysecctx(inode,
+					    iattrs->ia_secdata,
+					    iattrs->ia_secdata_len);
+	}
+
+	if (sysfs_type(sd) == SYSFS_DIR)
+		set_nlink(inode, sd->s_dir.subdirs + 2);
+}
+
+int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
+		  struct kstat *stat)
+{
+	struct sysfs_dirent *sd = dentry->d_fsdata;
+	struct inode *inode = dentry->d_inode;
+
+	mutex_lock(&sysfs_mutex);
+	sysfs_refresh_inode(sd, inode);
+	mutex_unlock(&sysfs_mutex);
+
+	generic_fillattr(inode, stat);
+	return 0;
+}
+
+static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
+{
+	kernfs_get(sd);
+	inode->i_private = sd;
+	inode->i_mapping->a_ops = &sysfs_aops;
+	inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
+	inode->i_op = &sysfs_inode_operations;
+
+	set_default_inode_attr(inode, sd->s_mode);
+	sysfs_refresh_inode(sd, inode);
+
+	/* initialize inode according to type */
+	switch (sysfs_type(sd)) {
+	case SYSFS_DIR:
+		inode->i_op = &sysfs_dir_inode_operations;
+		inode->i_fop = &sysfs_dir_operations;
+		break;
+	case SYSFS_KOBJ_ATTR:
+		inode->i_size = sd->s_attr.size;
+		inode->i_fop = &kernfs_file_operations;
+		break;
+	case SYSFS_KOBJ_LINK:
+		inode->i_op = &sysfs_symlink_inode_operations;
+		break;
+	default:
+		BUG();
+	}
+
+	unlock_new_inode(inode);
+}
+
+/**
+ *	sysfs_get_inode - get inode for sysfs_dirent
+ *	@sb: super block
+ *	@sd: sysfs_dirent to allocate inode for
+ *
+ *	Get inode for @sd.  If such inode doesn't exist, a new inode
+ *	is allocated and basics are initialized.  New inode is
+ *	returned locked.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	Pointer to allocated inode on success, NULL on failure.
+ */
+struct inode *sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd)
+{
+	struct inode *inode;
+
+	inode = iget_locked(sb, sd->s_ino);
+	if (inode && (inode->i_state & I_NEW))
+		sysfs_init_inode(sd, inode);
+
+	return inode;
+}
+
+/*
+ * The sysfs_dirent serves as both an inode and a directory entry for sysfs.
+ * To prevent the sysfs inode numbers from being freed prematurely we take a
+ * reference to sysfs_dirent from the sysfs inode.  A
+ * super_operations.evict_inode() implementation is needed to drop that
+ * reference upon inode destruction.
+ */
+void sysfs_evict_inode(struct inode *inode)
+{
+	struct sysfs_dirent *sd  = inode->i_private;
+
+	truncate_inode_pages(&inode->i_data, 0);
+	clear_inode(inode);
+	kernfs_put(sd);
+}
+
+int sysfs_permission(struct inode *inode, int mask)
+{
+	struct sysfs_dirent *sd;
+
+	if (mask & MAY_NOT_BLOCK)
+		return -ECHILD;
+
+	sd = inode->i_private;
+
+	mutex_lock(&sysfs_mutex);
+	sysfs_refresh_inode(sd, inode);
+	mutex_unlock(&sysfs_mutex);
+
+	return generic_permission(inode, mask);
+}
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 5a2c3a1..933ac8d 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -112,4 +112,17 @@ struct sysfs_addrm_cxt {
 
 #include "../sysfs/sysfs.h"
 
+/*
+ * inode.c
+ */
+struct inode *sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd);
+void sysfs_evict_inode(struct inode *inode);
+int sysfs_permission(struct inode *inode, int mask);
+int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
+int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
+		  struct kstat *stat);
+int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
+		   size_t size, int flags);
+int sysfs_inode_init(void);
+
 #endif	/* __KERNFS_INTERNAL_H */
diff --git a/fs/sysfs/Makefile b/fs/sysfs/Makefile
index 8876ac1..6eff6e1 100644
--- a/fs/sysfs/Makefile
+++ b/fs/sysfs/Makefile
@@ -2,4 +2,4 @@
 # Makefile for the sysfs virtual filesystem
 #
 
-obj-y		:= inode.o file.o dir.o symlink.o mount.o group.o
+obj-y		:= file.o dir.o symlink.o mount.o group.o
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
deleted file mode 100644
index bfe4478..0000000
--- a/fs/sysfs/inode.c
+++ /dev/null
@@ -1,342 +0,0 @@
-/*
- * fs/sysfs/inode.c - basic sysfs inode and dentry operations
- *
- * Copyright (c) 2001-3 Patrick Mochel
- * Copyright (c) 2007 SUSE Linux Products GmbH
- * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
- *
- * This file is released under the GPLv2.
- *
- * Please see Documentation/filesystems/sysfs.txt for more information.
- */
-
-#undef DEBUG
-
-#include <linux/pagemap.h>
-#include <linux/namei.h>
-#include <linux/backing-dev.h>
-#include <linux/capability.h>
-#include <linux/errno.h>
-#include <linux/sched.h>
-#include <linux/slab.h>
-#include <linux/sysfs.h>
-#include <linux/xattr.h>
-#include <linux/security.h>
-#include "sysfs.h"
-
-static const struct address_space_operations sysfs_aops = {
-	.readpage	= simple_readpage,
-	.write_begin	= simple_write_begin,
-	.write_end	= simple_write_end,
-};
-
-static struct backing_dev_info sysfs_backing_dev_info = {
-	.name		= "sysfs",
-	.ra_pages	= 0,	/* No readahead */
-	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK,
-};
-
-static const struct inode_operations sysfs_inode_operations = {
-	.permission	= sysfs_permission,
-	.setattr	= sysfs_setattr,
-	.getattr	= sysfs_getattr,
-	.setxattr	= sysfs_setxattr,
-};
-
-int __init sysfs_inode_init(void)
-{
-	return bdi_init(&sysfs_backing_dev_info);
-}
-
-static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
-{
-	struct sysfs_inode_attrs *attrs;
-	struct iattr *iattrs;
-
-	attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
-	if (!attrs)
-		return NULL;
-	iattrs = &attrs->ia_iattr;
-
-	/* assign default attributes */
-	iattrs->ia_mode = sd->s_mode;
-	iattrs->ia_uid = GLOBAL_ROOT_UID;
-	iattrs->ia_gid = GLOBAL_ROOT_GID;
-	iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
-
-	return attrs;
-}
-
-static int __kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
-{
-	struct sysfs_inode_attrs *sd_attrs;
-	struct iattr *iattrs;
-	unsigned int ia_valid = iattr->ia_valid;
-
-	sd_attrs = sd->s_iattr;
-
-	if (!sd_attrs) {
-		/* setting attributes for the first time, allocate now */
-		sd_attrs = sysfs_init_inode_attrs(sd);
-		if (!sd_attrs)
-			return -ENOMEM;
-		sd->s_iattr = sd_attrs;
-	}
-	/* attributes were changed at least once in past */
-	iattrs = &sd_attrs->ia_iattr;
-
-	if (ia_valid & ATTR_UID)
-		iattrs->ia_uid = iattr->ia_uid;
-	if (ia_valid & ATTR_GID)
-		iattrs->ia_gid = iattr->ia_gid;
-	if (ia_valid & ATTR_ATIME)
-		iattrs->ia_atime = iattr->ia_atime;
-	if (ia_valid & ATTR_MTIME)
-		iattrs->ia_mtime = iattr->ia_mtime;
-	if (ia_valid & ATTR_CTIME)
-		iattrs->ia_ctime = iattr->ia_ctime;
-	if (ia_valid & ATTR_MODE) {
-		umode_t mode = iattr->ia_mode;
-		iattrs->ia_mode = sd->s_mode = mode;
-	}
-	return 0;
-}
-
-/**
- * kernfs_setattr - set iattr on a node
- * @sd: target node
- * @iattr: iattr to set
- *
- * Returns 0 on success, -errno on failure.
- */
-int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
-{
-	int ret;
-
-	mutex_lock(&sysfs_mutex);
-	ret = __kernfs_setattr(sd, iattr);
-	mutex_unlock(&sysfs_mutex);
-	return ret;
-}
-
-int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
-{
-	struct inode *inode = dentry->d_inode;
-	struct sysfs_dirent *sd = dentry->d_fsdata;
-	int error;
-
-	if (!sd)
-		return -EINVAL;
-
-	mutex_lock(&sysfs_mutex);
-	error = inode_change_ok(inode, iattr);
-	if (error)
-		goto out;
-
-	error = __kernfs_setattr(sd, iattr);
-	if (error)
-		goto out;
-
-	/* this ignores size changes */
-	setattr_copy(inode, iattr);
-
-out:
-	mutex_unlock(&sysfs_mutex);
-	return error;
-}
-
-static int sysfs_sd_setsecdata(struct sysfs_dirent *sd, void **secdata,
-			       u32 *secdata_len)
-{
-	struct sysfs_inode_attrs *iattrs;
-	void *old_secdata;
-	size_t old_secdata_len;
-
-	if (!sd->s_iattr) {
-		sd->s_iattr = sysfs_init_inode_attrs(sd);
-		if (!sd->s_iattr)
-			return -ENOMEM;
-	}
-
-	iattrs = sd->s_iattr;
-	old_secdata = iattrs->ia_secdata;
-	old_secdata_len = iattrs->ia_secdata_len;
-
-	iattrs->ia_secdata = *secdata;
-	iattrs->ia_secdata_len = *secdata_len;
-
-	*secdata = old_secdata;
-	*secdata_len = old_secdata_len;
-	return 0;
-}
-
-int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
-		size_t size, int flags)
-{
-	struct sysfs_dirent *sd = dentry->d_fsdata;
-	void *secdata;
-	int error;
-	u32 secdata_len = 0;
-
-	if (!sd)
-		return -EINVAL;
-
-	if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
-		const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
-		error = security_inode_setsecurity(dentry->d_inode, suffix,
-						value, size, flags);
-		if (error)
-			goto out;
-		error = security_inode_getsecctx(dentry->d_inode,
-						&secdata, &secdata_len);
-		if (error)
-			goto out;
-
-		mutex_lock(&sysfs_mutex);
-		error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
-		mutex_unlock(&sysfs_mutex);
-
-		if (secdata)
-			security_release_secctx(secdata, secdata_len);
-	} else
-		return -EINVAL;
-out:
-	return error;
-}
-
-static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
-{
-	inode->i_mode = mode;
-	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
-}
-
-static inline void set_inode_attr(struct inode *inode, struct iattr *iattr)
-{
-	inode->i_uid = iattr->ia_uid;
-	inode->i_gid = iattr->ia_gid;
-	inode->i_atime = iattr->ia_atime;
-	inode->i_mtime = iattr->ia_mtime;
-	inode->i_ctime = iattr->ia_ctime;
-}
-
-static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
-{
-	struct sysfs_inode_attrs *iattrs = sd->s_iattr;
-
-	inode->i_mode = sd->s_mode;
-	if (iattrs) {
-		/* sysfs_dirent has non-default attributes
-		 * get them from persistent copy in sysfs_dirent
-		 */
-		set_inode_attr(inode, &iattrs->ia_iattr);
-		security_inode_notifysecctx(inode,
-					    iattrs->ia_secdata,
-					    iattrs->ia_secdata_len);
-	}
-
-	if (sysfs_type(sd) == SYSFS_DIR)
-		set_nlink(inode, sd->s_dir.subdirs + 2);
-}
-
-int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
-		  struct kstat *stat)
-{
-	struct sysfs_dirent *sd = dentry->d_fsdata;
-	struct inode *inode = dentry->d_inode;
-
-	mutex_lock(&sysfs_mutex);
-	sysfs_refresh_inode(sd, inode);
-	mutex_unlock(&sysfs_mutex);
-
-	generic_fillattr(inode, stat);
-	return 0;
-}
-
-static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
-{
-	kernfs_get(sd);
-	inode->i_private = sd;
-	inode->i_mapping->a_ops = &sysfs_aops;
-	inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
-	inode->i_op = &sysfs_inode_operations;
-
-	set_default_inode_attr(inode, sd->s_mode);
-	sysfs_refresh_inode(sd, inode);
-
-	/* initialize inode according to type */
-	switch (sysfs_type(sd)) {
-	case SYSFS_DIR:
-		inode->i_op = &sysfs_dir_inode_operations;
-		inode->i_fop = &sysfs_dir_operations;
-		break;
-	case SYSFS_KOBJ_ATTR:
-		inode->i_size = sd->s_attr.size;
-		inode->i_fop = &kernfs_file_operations;
-		break;
-	case SYSFS_KOBJ_LINK:
-		inode->i_op = &sysfs_symlink_inode_operations;
-		break;
-	default:
-		BUG();
-	}
-
-	unlock_new_inode(inode);
-}
-
-/**
- *	sysfs_get_inode - get inode for sysfs_dirent
- *	@sb: super block
- *	@sd: sysfs_dirent to allocate inode for
- *
- *	Get inode for @sd.  If such inode doesn't exist, a new inode
- *	is allocated and basics are initialized.  New inode is
- *	returned locked.
- *
- *	LOCKING:
- *	Kernel thread context (may sleep).
- *
- *	RETURNS:
- *	Pointer to allocated inode on success, NULL on failure.
- */
-struct inode *sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd)
-{
-	struct inode *inode;
-
-	inode = iget_locked(sb, sd->s_ino);
-	if (inode && (inode->i_state & I_NEW))
-		sysfs_init_inode(sd, inode);
-
-	return inode;
-}
-
-/*
- * The sysfs_dirent serves as both an inode and a directory entry for sysfs.
- * To prevent the sysfs inode numbers from being freed prematurely we take a
- * reference to sysfs_dirent from the sysfs inode.  A
- * super_operations.evict_inode() implementation is needed to drop that
- * reference upon inode destruction.
- */
-void sysfs_evict_inode(struct inode *inode)
-{
-	struct sysfs_dirent *sd  = inode->i_private;
-
-	truncate_inode_pages(&inode->i_data, 0);
-	clear_inode(inode);
-	kernfs_put(sd);
-}
-
-int sysfs_permission(struct inode *inode, int mask)
-{
-	struct sysfs_dirent *sd;
-
-	if (mask & MAY_NOT_BLOCK)
-		return -ECHILD;
-
-	sd = inode->i_private;
-
-	mutex_lock(&sysfs_mutex);
-	sysfs_refresh_inode(sd, inode);
-	mutex_unlock(&sysfs_mutex);
-
-	return generic_permission(inode, mask);
-}
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index f8c936f..93c1910 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -52,19 +52,6 @@ void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
 struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);
 
 /*
- * inode.c
- */
-struct inode *sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd);
-void sysfs_evict_inode(struct inode *inode);
-int sysfs_permission(struct inode *inode, int mask);
-int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
-int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
-		  struct kstat *stat);
-int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
-		   size_t size, int flags);
-int sysfs_inode_init(void);
-
-/*
  * file.c
  */
 extern const struct file_operations kernfs_file_operations;
-- 
1.8.4.2

[PATCH 27/41] sysfs, kernfs: move dir core code to fs/kernfs/dir.c

[Tejun Heo]

Move core dir code to fs/kernfs/dir.c.  fs/sysfs/dir.c now only
contains sysfs_warn_dup() and sysfs wrappers around kernfs interfaces.
The respective declarations in fs/sysfs/sysfs.h are moved to
fs/kernfs/kernfs-internal.h.

This is pure relocation.

v2: sysfs_symlink_target_lock was mistakenly relocated to kernfs.  It
    should remain with sysfs.  Fixed.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/dir.c             | 988 ++++++++++++++++++++++++++++++++++++++++++++
 fs/kernfs/kernfs-internal.h |  17 +
 fs/sysfs/dir.c              | 986 -------------------------------------------
 fs/sysfs/sysfs.h            |  13 -
 4 files changed, 1005 insertions(+), 999 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 1061602..a4ca4de 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -7,3 +7,991 @@
  *
  * This file is released under the GPLv2.
  */
+
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/idr.h>
+#include <linux/slab.h>
+#include <linux/security.h>
+#include <linux/hash.h>
+
+#include "kernfs-internal.h"
+
+DEFINE_MUTEX(sysfs_mutex);
+
+#define to_sysfs_dirent(X) rb_entry((X), struct sysfs_dirent, s_rb)
+
+static DEFINE_SPINLOCK(sysfs_ino_lock);
+static DEFINE_IDA(sysfs_ino_ida);
+
+/**
+ *	sysfs_name_hash
+ *	@name: Null terminated string to hash
+ *	@ns:   Namespace tag to hash
+ *
+ *	Returns 31 bit hash of ns + name (so it fits in an off_t )
+ */
+static unsigned int sysfs_name_hash(const char *name, const void *ns)
+{
+	unsigned long hash = init_name_hash();
+	unsigned int len = strlen(name);
+	while (len--)
+		hash = partial_name_hash(*name++, hash);
+	hash = (end_name_hash(hash) ^ hash_ptr((void *)ns, 31));
+	hash &= 0x7fffffffU;
+	/* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */
+	if (hash < 1)
+		hash += 2;
+	if (hash >= INT_MAX)
+		hash = INT_MAX - 1;
+	return hash;
+}
+
+static int sysfs_name_compare(unsigned int hash, const char *name,
+			      const void *ns, const struct sysfs_dirent *sd)
+{
+	if (hash != sd->s_hash)
+		return hash - sd->s_hash;
+	if (ns != sd->s_ns)
+		return ns - sd->s_ns;
+	return strcmp(name, sd->s_name);
+}
+
+static int sysfs_sd_compare(const struct sysfs_dirent *left,
+			    const struct sysfs_dirent *right)
+{
+	return sysfs_name_compare(left->s_hash, left->s_name, left->s_ns,
+				  right);
+}
+
+/**
+ *	sysfs_link_sibling - link sysfs_dirent into sibling rbtree
+ *	@sd: sysfs_dirent of interest
+ *
+ *	Link @sd into its sibling rbtree which starts from
+ *	sd->s_parent->s_dir.children.
+ *
+ *	Locking:
+ *	mutex_lock(sysfs_mutex)
+ *
+ *	RETURNS:
+ *	0 on susccess -EEXIST on failure.
+ */
+static int sysfs_link_sibling(struct sysfs_dirent *sd)
+{
+	struct rb_node **node = &sd->s_parent->s_dir.children.rb_node;
+	struct rb_node *parent = NULL;
+
+	if (sysfs_type(sd) == SYSFS_DIR)
+		sd->s_parent->s_dir.subdirs++;
+
+	while (*node) {
+		struct sysfs_dirent *pos;
+		int result;
+
+		pos = to_sysfs_dirent(*node);
+		parent = *node;
+		result = sysfs_sd_compare(sd, pos);
+		if (result < 0)
+			node = &pos->s_rb.rb_left;
+		else if (result > 0)
+			node = &pos->s_rb.rb_right;
+		else
+			return -EEXIST;
+	}
+	/* add new node and rebalance the tree */
+	rb_link_node(&sd->s_rb, parent, node);
+	rb_insert_color(&sd->s_rb, &sd->s_parent->s_dir.children);
+	return 0;
+}
+
+/**
+ *	sysfs_unlink_sibling - unlink sysfs_dirent from sibling rbtree
+ *	@sd: sysfs_dirent of interest
+ *
+ *	Unlink @sd from its sibling rbtree which starts from
+ *	sd->s_parent->s_dir.children.
+ *
+ *	Locking:
+ *	mutex_lock(sysfs_mutex)
+ */
+static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
+{
+	if (sysfs_type(sd) == SYSFS_DIR)
+		sd->s_parent->s_dir.subdirs--;
+
+	rb_erase(&sd->s_rb, &sd->s_parent->s_dir.children);
+}
+
+/**
+ *	sysfs_get_active - get an active reference to sysfs_dirent
+ *	@sd: sysfs_dirent to get an active reference to
+ *
+ *	Get an active reference of @sd.  This function is noop if @sd
+ *	is NULL.
+ *
+ *	RETURNS:
+ *	Pointer to @sd on success, NULL on failure.
+ */
+struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
+{
+	if (unlikely(!sd))
+		return NULL;
+
+	if (!atomic_inc_unless_negative(&sd->s_active))
+		return NULL;
+
+	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
+		rwsem_acquire_read(&sd->dep_map, 0, 1, _RET_IP_);
+	return sd;
+}
+
+/**
+ *	sysfs_put_active - put an active reference to sysfs_dirent
+ *	@sd: sysfs_dirent to put an active reference to
+ *
+ *	Put an active reference to @sd.  This function is noop if @sd
+ *	is NULL.
+ */
+void sysfs_put_active(struct sysfs_dirent *sd)
+{
+	int v;
+
+	if (unlikely(!sd))
+		return;
+
+	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
+		rwsem_release(&sd->dep_map, 1, _RET_IP_);
+	v = atomic_dec_return(&sd->s_active);
+	if (likely(v != SD_DEACTIVATED_BIAS))
+		return;
+
+	/* atomic_dec_return() is a mb(), we'll always see the updated
+	 * sd->u.completion.
+	 */
+	complete(sd->u.completion);
+}
+
+/**
+ *	sysfs_deactivate - deactivate sysfs_dirent
+ *	@sd: sysfs_dirent to deactivate
+ *
+ *	Deny new active references and drain existing ones.
+ */
+static void sysfs_deactivate(struct sysfs_dirent *sd)
+{
+	DECLARE_COMPLETION_ONSTACK(wait);
+	int v;
+
+	BUG_ON(!(sd->s_flags & SYSFS_FLAG_REMOVED));
+
+	if (!(sysfs_type(sd) & SYSFS_ACTIVE_REF))
+		return;
+
+	sd->u.completion = (void *)&wait;
+
+	rwsem_acquire(&sd->dep_map, 0, 0, _RET_IP_);
+	/* atomic_add_return() is a mb(), put_active() will always see
+	 * the updated sd->u.completion.
+	 */
+	v = atomic_add_return(SD_DEACTIVATED_BIAS, &sd->s_active);
+
+	if (v != SD_DEACTIVATED_BIAS) {
+		lock_contended(&sd->dep_map, _RET_IP_);
+		wait_for_completion(&wait);
+	}
+
+	lock_acquired(&sd->dep_map, _RET_IP_);
+	rwsem_release(&sd->dep_map, 1, _RET_IP_);
+}
+
+static int sysfs_alloc_ino(unsigned int *pino)
+{
+	int ino, rc;
+
+ retry:
+	spin_lock(&sysfs_ino_lock);
+	rc = ida_get_new_above(&sysfs_ino_ida, 2, &ino);
+	spin_unlock(&sysfs_ino_lock);
+
+	if (rc == -EAGAIN) {
+		if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL))
+			goto retry;
+		rc = -ENOMEM;
+	}
+
+	*pino = ino;
+	return rc;
+}
+
+static void sysfs_free_ino(unsigned int ino)
+{
+	spin_lock(&sysfs_ino_lock);
+	ida_remove(&sysfs_ino_ida, ino);
+	spin_unlock(&sysfs_ino_lock);
+}
+
+/**
+ * kernfs_get - get a reference count on a sysfs_dirent
+ * @sd: the target sysfs_dirent
+ */
+void kernfs_get(struct sysfs_dirent *sd)
+{
+	if (sd) {
+		WARN_ON(!atomic_read(&sd->s_count));
+		atomic_inc(&sd->s_count);
+	}
+}
+EXPORT_SYMBOL_GPL(kernfs_get);
+
+/**
+ * kernfs_put - put a reference count on a sysfs_dirent
+ * @sd: the target sysfs_dirent
+ *
+ * Put a reference count of @sd and destroy it if it reached zero.
+ */
+void kernfs_put(struct sysfs_dirent *sd)
+{
+	struct sysfs_dirent *parent_sd;
+
+	if (!sd || !atomic_dec_and_test(&sd->s_count))
+		return;
+ repeat:
+	/* Moving/renaming is always done while holding reference.
+	 * sd->s_parent won't change beneath us.
+	 */
+	parent_sd = sd->s_parent;
+
+	WARN(!(sd->s_flags & SYSFS_FLAG_REMOVED),
+		"sysfs: free using entry: %s/%s\n",
+		parent_sd ? parent_sd->s_name : "", sd->s_name);
+
+	if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
+		kernfs_put(sd->s_symlink.target_sd);
+	if (sysfs_type(sd) & SYSFS_COPY_NAME)
+		kfree(sd->s_name);
+	if (sd->s_iattr && sd->s_iattr->ia_secdata)
+		security_release_secctx(sd->s_iattr->ia_secdata,
+					sd->s_iattr->ia_secdata_len);
+	kfree(sd->s_iattr);
+	sysfs_free_ino(sd->s_ino);
+	kmem_cache_free(sysfs_dir_cachep, sd);
+
+	sd = parent_sd;
+	if (sd && atomic_dec_and_test(&sd->s_count))
+		goto repeat;
+}
+EXPORT_SYMBOL_GPL(kernfs_put);
+
+static int sysfs_dentry_delete(const struct dentry *dentry)
+{
+	struct sysfs_dirent *sd = dentry->d_fsdata;
+	return !(sd && !(sd->s_flags & SYSFS_FLAG_REMOVED));
+}
+
+static int sysfs_dentry_revalidate(struct dentry *dentry, unsigned int flags)
+{
+	struct sysfs_dirent *sd;
+
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
+
+	sd = dentry->d_fsdata;
+	mutex_lock(&sysfs_mutex);
+
+	/* The sysfs dirent has been deleted */
+	if (sd->s_flags & SYSFS_FLAG_REMOVED)
+		goto out_bad;
+
+	/* The sysfs dirent has been moved? */
+	if (dentry->d_parent->d_fsdata != sd->s_parent)
+		goto out_bad;
+
+	/* The sysfs dirent has been renamed */
+	if (strcmp(dentry->d_name.name, sd->s_name) != 0)
+		goto out_bad;
+
+	/* The sysfs dirent has been moved to a different namespace */
+	if (sd->s_parent && (sd->s_parent->s_flags & SYSFS_FLAG_NS) &&
+	    sysfs_info(dentry->d_sb)->ns != sd->s_ns)
+		goto out_bad;
+
+	mutex_unlock(&sysfs_mutex);
+out_valid:
+	return 1;
+out_bad:
+	/* Remove the dentry from the dcache hashes.
+	 * If this is a deleted dentry we use d_drop instead of d_delete
+	 * so sysfs doesn't need to cope with negative dentries.
+	 *
+	 * If this is a dentry that has simply been renamed we
+	 * use d_drop to remove it from the dcache lookup on its
+	 * old parent.  If this dentry persists later when a lookup
+	 * is performed at its new name the dentry will be readded
+	 * to the dcache hashes.
+	 */
+	mutex_unlock(&sysfs_mutex);
+
+	/* If we have submounts we must allow the vfs caches
+	 * to lie about the state of the filesystem to prevent
+	 * leaks and other nasty things.
+	 */
+	if (check_submounts_and_drop(dentry) != 0)
+		goto out_valid;
+
+	return 0;
+}
+
+static void sysfs_dentry_release(struct dentry *dentry)
+{
+	kernfs_put(dentry->d_fsdata);
+}
+
+const struct dentry_operations sysfs_dentry_ops = {
+	.d_revalidate	= sysfs_dentry_revalidate,
+	.d_delete	= sysfs_dentry_delete,
+	.d_release	= sysfs_dentry_release,
+};
+
+struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
+{
+	char *dup_name = NULL;
+	struct sysfs_dirent *sd;
+
+	if (type & SYSFS_COPY_NAME) {
+		name = dup_name = kstrdup(name, GFP_KERNEL);
+		if (!name)
+			return NULL;
+	}
+
+	sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL);
+	if (!sd)
+		goto err_out1;
+
+	if (sysfs_alloc_ino(&sd->s_ino))
+		goto err_out2;
+
+	atomic_set(&sd->s_count, 1);
+	atomic_set(&sd->s_active, 0);
+
+	sd->s_name = name;
+	sd->s_mode = mode;
+	sd->s_flags = type | SYSFS_FLAG_REMOVED;
+
+	return sd;
+
+ err_out2:
+	kmem_cache_free(sysfs_dir_cachep, sd);
+ err_out1:
+	kfree(dup_name);
+	return NULL;
+}
+
+/**
+ *	sysfs_addrm_start - prepare for sysfs_dirent add/remove
+ *	@acxt: pointer to sysfs_addrm_cxt to be used
+ *
+ *	This function is called when the caller is about to add or remove
+ *	sysfs_dirent.  This function acquires sysfs_mutex.  @acxt is used
+ *	to keep and pass context to other addrm functions.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).  sysfs_mutex is locked on
+ *	return.
+ */
+void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt)
+	__acquires(sysfs_mutex)
+{
+	memset(acxt, 0, sizeof(*acxt));
+
+	mutex_lock(&sysfs_mutex);
+}
+
+/**
+ *	sysfs_add_one - add sysfs_dirent to parent without warning
+ *	@acxt: addrm context to use
+ *	@sd: sysfs_dirent to be added
+ *	@parent_sd: the parent sysfs_dirent to add @sd to
+ *
+ *	Get @parent_sd and set @sd->s_parent to it and increment nlink of
+ *	the parent inode if @sd is a directory and link into the children
+ *	list of the parent.
+ *
+ *	This function should be called between calls to
+ *	sysfs_addrm_start() and sysfs_addrm_finish() and should be
+ *	passed the same @acxt as passed to sysfs_addrm_start().
+ *
+ *	LOCKING:
+ *	Determined by sysfs_addrm_start().
+ *
+ *	RETURNS:
+ *	0 on success, -EEXIST if entry with the given name already
+ *	exists.
+ */
+int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
+		  struct sysfs_dirent *parent_sd)
+{
+	bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS;
+	struct sysfs_inode_attrs *ps_iattr;
+	int ret;
+
+	if (has_ns != (bool)sd->s_ns) {
+		WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
+		     has_ns ? "required" : "invalid",
+		     parent_sd->s_name, sd->s_name);
+		return -EINVAL;
+	}
+
+	if (sysfs_type(parent_sd) != SYSFS_DIR)
+		return -EINVAL;
+
+	sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
+	sd->s_parent = parent_sd;
+	kernfs_get(parent_sd);
+
+	ret = sysfs_link_sibling(sd);
+	if (ret)
+		return ret;
+
+	/* Update timestamps on the parent */
+	ps_iattr = parent_sd->s_iattr;
+	if (ps_iattr) {
+		struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
+		ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
+	}
+
+	/* Mark the entry added into directory tree */
+	sd->s_flags &= ~SYSFS_FLAG_REMOVED;
+
+	return 0;
+}
+
+/**
+ *	sysfs_remove_one - remove sysfs_dirent from parent
+ *	@acxt: addrm context to use
+ *	@sd: sysfs_dirent to be removed
+ *
+ *	Mark @sd removed and drop nlink of parent inode if @sd is a
+ *	directory.  @sd is unlinked from the children list.
+ *
+ *	This function should be called between calls to
+ *	sysfs_addrm_start() and sysfs_addrm_finish() and should be
+ *	passed the same @acxt as passed to sysfs_addrm_start().
+ *
+ *	LOCKING:
+ *	Determined by sysfs_addrm_start().
+ */
+static void sysfs_remove_one(struct sysfs_addrm_cxt *acxt,
+			     struct sysfs_dirent *sd)
+{
+	struct sysfs_inode_attrs *ps_iattr;
+
+	/*
+	 * Removal can be called multiple times on the same node.  Only the
+	 * first invocation is effective and puts the base ref.
+	 */
+	if (sd->s_flags & SYSFS_FLAG_REMOVED)
+		return;
+
+	sysfs_unlink_sibling(sd);
+
+	/* Update timestamps on the parent */
+	ps_iattr = sd->s_parent->s_iattr;
+	if (ps_iattr) {
+		struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
+		ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
+	}
+
+	sd->s_flags |= SYSFS_FLAG_REMOVED;
+	sd->u.removed_list = acxt->removed;
+	acxt->removed = sd;
+}
+
+/**
+ *	sysfs_addrm_finish - finish up sysfs_dirent add/remove
+ *	@acxt: addrm context to finish up
+ *
+ *	Finish up sysfs_dirent add/remove.  Resources acquired by
+ *	sysfs_addrm_start() are released and removed sysfs_dirents are
+ *	cleaned up.
+ *
+ *	LOCKING:
+ *	sysfs_mutex is released.
+ */
+void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
+	__releases(sysfs_mutex)
+{
+	/* release resources acquired by sysfs_addrm_start() */
+	mutex_unlock(&sysfs_mutex);
+
+	/* kill removed sysfs_dirents */
+	while (acxt->removed) {
+		struct sysfs_dirent *sd = acxt->removed;
+
+		acxt->removed = sd->u.removed_list;
+
+		sysfs_deactivate(sd);
+		sysfs_unmap_bin_file(sd);
+		kernfs_put(sd);
+	}
+}
+
+/**
+ * kernfs_find_ns - find sysfs_dirent with the given name
+ * @parent: sysfs_dirent to search under
+ * @name: name to look for
+ * @ns: the namespace tag to use
+ *
+ * Look for sysfs_dirent with name @name under @parent.  Returns pointer to
+ * the found sysfs_dirent on success, %NULL on failure.
+ */
+static struct sysfs_dirent *kernfs_find_ns(struct sysfs_dirent *parent,
+					   const unsigned char *name,
+					   const void *ns)
+{
+	struct rb_node *node = parent->s_dir.children.rb_node;
+	bool has_ns = parent->s_flags & SYSFS_FLAG_NS;
+	unsigned int hash;
+
+	lockdep_assert_held(&sysfs_mutex);
+
+	if (has_ns != (bool)ns) {
+		WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
+		     has_ns ? "required" : "invalid",
+		     parent->s_name, name);
+		return NULL;
+	}
+
+	hash = sysfs_name_hash(name, ns);
+	while (node) {
+		struct sysfs_dirent *sd;
+		int result;
+
+		sd = to_sysfs_dirent(node);
+		result = sysfs_name_compare(hash, name, ns, sd);
+		if (result < 0)
+			node = node->rb_left;
+		else if (result > 0)
+			node = node->rb_right;
+		else
+			return sd;
+	}
+	return NULL;
+}
+
+/**
+ * kernfs_find_and_get_ns - find and get sysfs_dirent with the given name
+ * @parent: sysfs_dirent to search under
+ * @name: name to look for
+ * @ns: the namespace tag to use
+ *
+ * Look for sysfs_dirent with name @name under @parent and get a reference
+ * if found.  This function may sleep and returns pointer to the found
+ * sysfs_dirent on success, %NULL on failure.
+ */
+struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
+					    const char *name, const void *ns)
+{
+	struct sysfs_dirent *sd;
+
+	mutex_lock(&sysfs_mutex);
+	sd = kernfs_find_ns(parent, name, ns);
+	kernfs_get(sd);
+	mutex_unlock(&sysfs_mutex);
+
+	return sd;
+}
+EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns);
+
+/**
+ * kernfs_create_dir_ns - create a directory
+ * @parent: parent in which to create a new directory
+ * @name: name of the new directory
+ * @priv: opaque data associated with the new directory
+ * @ns: optional namespace tag of the directory
+ *
+ * Returns the created node on success, ERR_PTR() value on failure.
+ */
+struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
+					  const char *name, void *priv,
+					  const void *ns)
+{
+	umode_t mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
+	struct sysfs_addrm_cxt acxt;
+	struct sysfs_dirent *sd;
+	int rc;
+
+	/* allocate */
+	sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
+	if (!sd)
+		return ERR_PTR(-ENOMEM);
+
+	sd->s_ns = ns;
+	sd->priv = priv;
+
+	/* link in */
+	sysfs_addrm_start(&acxt);
+	rc = sysfs_add_one(&acxt, sd, parent);
+	sysfs_addrm_finish(&acxt);
+
+	if (!rc)
+		return sd;
+
+	kernfs_put(sd);
+	return ERR_PTR(rc);
+}
+
+static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry,
+				   unsigned int flags)
+{
+	struct dentry *ret = NULL;
+	struct dentry *parent = dentry->d_parent;
+	struct sysfs_dirent *parent_sd = parent->d_fsdata;
+	struct sysfs_dirent *sd;
+	struct inode *inode;
+	const void *ns = NULL;
+
+	mutex_lock(&sysfs_mutex);
+
+	if (parent_sd->s_flags & SYSFS_FLAG_NS)
+		ns = sysfs_info(dir->i_sb)->ns;
+
+	sd = kernfs_find_ns(parent_sd, dentry->d_name.name, ns);
+
+	/* no such entry */
+	if (!sd) {
+		ret = ERR_PTR(-ENOENT);
+		goto out_unlock;
+	}
+	kernfs_get(sd);
+	dentry->d_fsdata = sd;
+
+	/* attach dentry and inode */
+	inode = sysfs_get_inode(dir->i_sb, sd);
+	if (!inode) {
+		ret = ERR_PTR(-ENOMEM);
+		goto out_unlock;
+	}
+
+	/* instantiate and hash dentry */
+	ret = d_materialise_unique(dentry, inode);
+ out_unlock:
+	mutex_unlock(&sysfs_mutex);
+	return ret;
+}
+
+const struct inode_operations sysfs_dir_inode_operations = {
+	.lookup		= sysfs_lookup,
+	.permission	= sysfs_permission,
+	.setattr	= sysfs_setattr,
+	.getattr	= sysfs_getattr,
+	.setxattr	= sysfs_setxattr,
+};
+
+static struct sysfs_dirent *sysfs_leftmost_descendant(struct sysfs_dirent *pos)
+{
+	struct sysfs_dirent *last;
+
+	while (true) {
+		struct rb_node *rbn;
+
+		last = pos;
+
+		if (sysfs_type(pos) != SYSFS_DIR)
+			break;
+
+		rbn = rb_first(&pos->s_dir.children);
+		if (!rbn)
+			break;
+
+		pos = to_sysfs_dirent(rbn);
+	}
+
+	return last;
+}
+
+/**
+ * sysfs_next_descendant_post - find the next descendant for post-order walk
+ * @pos: the current position (%NULL to initiate traversal)
+ * @root: sysfs_dirent whose descendants to walk
+ *
+ * Find the next descendant to visit for post-order traversal of @root's
+ * descendants.  @root is included in the iteration and the last node to be
+ * visited.
+ */
+static struct sysfs_dirent *sysfs_next_descendant_post(struct sysfs_dirent *pos,
+						       struct sysfs_dirent *root)
+{
+	struct rb_node *rbn;
+
+	lockdep_assert_held(&sysfs_mutex);
+
+	/* if first iteration, visit leftmost descendant which may be root */
+	if (!pos)
+		return sysfs_leftmost_descendant(root);
+
+	/* if we visited @root, we're done */
+	if (pos == root)
+		return NULL;
+
+	/* if there's an unvisited sibling, visit its leftmost descendant */
+	rbn = rb_next(&pos->s_rb);
+	if (rbn)
+		return sysfs_leftmost_descendant(to_sysfs_dirent(rbn));
+
+	/* no sibling left, visit parent */
+	return pos->s_parent;
+}
+
+static void __kernfs_remove(struct sysfs_addrm_cxt *acxt,
+			    struct sysfs_dirent *sd)
+{
+	struct sysfs_dirent *pos, *next;
+
+	if (!sd)
+		return;
+
+	pr_debug("sysfs %s: removing\n", sd->s_name);
+
+	next = NULL;
+	do {
+		pos = next;
+		next = sysfs_next_descendant_post(pos, sd);
+		if (pos)
+			sysfs_remove_one(acxt, pos);
+	} while (next);
+}
+
+/**
+ * kernfs_remove - remove a sysfs_dirent recursively
+ * @sd: the sysfs_dirent to remove
+ *
+ * Remove @sd along with all its subdirectories and files.
+ */
+void kernfs_remove(struct sysfs_dirent *sd)
+{
+	struct sysfs_addrm_cxt acxt;
+
+	sysfs_addrm_start(&acxt);
+	__kernfs_remove(&acxt, sd);
+	sysfs_addrm_finish(&acxt);
+}
+
+/**
+ * kernfs_remove_by_name_ns - find a sysfs_dirent by name and remove it
+ * @dir_sd: parent of the target
+ * @name: name of the sysfs_dirent to remove
+ * @ns: namespace tag of the sysfs_dirent to remove
+ *
+ * Look for the sysfs_dirent with @name and @ns under @dir_sd and remove
+ * it.  Returns 0 on success, -ENOENT if such entry doesn't exist.
+ */
+int kernfs_remove_by_name_ns(struct sysfs_dirent *dir_sd, const char *name,
+			     const void *ns)
+{
+	struct sysfs_addrm_cxt acxt;
+	struct sysfs_dirent *sd;
+
+	if (!dir_sd) {
+		WARN(1, KERN_WARNING "sysfs: can not remove '%s', no directory\n",
+			name);
+		return -ENOENT;
+	}
+
+	sysfs_addrm_start(&acxt);
+
+	sd = kernfs_find_ns(dir_sd, name, ns);
+	if (sd)
+		__kernfs_remove(&acxt, sd);
+
+	sysfs_addrm_finish(&acxt);
+
+	if (sd)
+		return 0;
+	else
+		return -ENOENT;
+}
+
+/**
+ * kernfs_rename_ns - move and rename a kernfs_node
+ * @sd: target node
+ * @new_parent: new parent to put @sd under
+ * @new_name: new name
+ * @new_ns: new namespace tag
+ */
+int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
+		     const char *new_name, const void *new_ns)
+{
+	int error;
+
+	mutex_lock(&sysfs_mutex);
+
+	error = 0;
+	if ((sd->s_parent == new_parent) && (sd->s_ns == new_ns) &&
+	    (strcmp(sd->s_name, new_name) == 0))
+		goto out;	/* nothing to rename */
+
+	error = -EEXIST;
+	if (kernfs_find_ns(new_parent, new_name, new_ns))
+		goto out;
+
+	/* rename sysfs_dirent */
+	if (strcmp(sd->s_name, new_name) != 0) {
+		error = -ENOMEM;
+		new_name = kstrdup(new_name, GFP_KERNEL);
+		if (!new_name)
+			goto out;
+
+		kfree(sd->s_name);
+		sd->s_name = new_name;
+	}
+
+	/*
+	 * Move to the appropriate place in the appropriate directories rbtree.
+	 */
+	sysfs_unlink_sibling(sd);
+	kernfs_get(new_parent);
+	kernfs_put(sd->s_parent);
+	sd->s_ns = new_ns;
+	sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
+	sd->s_parent = new_parent;
+	sysfs_link_sibling(sd);
+
+	error = 0;
+ out:
+	mutex_unlock(&sysfs_mutex);
+	return error;
+}
+
+/**
+ * kernfs_enable_ns - enable namespace under a directory
+ * @sd: directory of interest, should be empty
+ *
+ * This is to be called right after @sd is created to enable namespace
+ * under it.  All children of @sd must have non-NULL namespace tags and
+ * only the ones which match the super_block's tag will be visible.
+ */
+void kernfs_enable_ns(struct sysfs_dirent *sd)
+{
+	WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
+	WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));
+	sd->s_flags |= SYSFS_FLAG_NS;
+}
+
+/* Relationship between s_mode and the DT_xxx types */
+static inline unsigned char dt_type(struct sysfs_dirent *sd)
+{
+	return (sd->s_mode >> 12) & 15;
+}
+
+static int sysfs_dir_release(struct inode *inode, struct file *filp)
+{
+	kernfs_put(filp->private_data);
+	return 0;
+}
+
+static struct sysfs_dirent *sysfs_dir_pos(const void *ns,
+	struct sysfs_dirent *parent_sd,	loff_t hash, struct sysfs_dirent *pos)
+{
+	if (pos) {
+		int valid = !(pos->s_flags & SYSFS_FLAG_REMOVED) &&
+			pos->s_parent == parent_sd &&
+			hash == pos->s_hash;
+		kernfs_put(pos);
+		if (!valid)
+			pos = NULL;
+	}
+	if (!pos && (hash > 1) && (hash < INT_MAX)) {
+		struct rb_node *node = parent_sd->s_dir.children.rb_node;
+		while (node) {
+			pos = to_sysfs_dirent(node);
+
+			if (hash < pos->s_hash)
+				node = node->rb_left;
+			else if (hash > pos->s_hash)
+				node = node->rb_right;
+			else
+				break;
+		}
+	}
+	/* Skip over entries in the wrong namespace */
+	while (pos && pos->s_ns != ns) {
+		struct rb_node *node = rb_next(&pos->s_rb);
+		if (!node)
+			pos = NULL;
+		else
+			pos = to_sysfs_dirent(node);
+	}
+	return pos;
+}
+
+static struct sysfs_dirent *sysfs_dir_next_pos(const void *ns,
+	struct sysfs_dirent *parent_sd,	ino_t ino, struct sysfs_dirent *pos)
+{
+	pos = sysfs_dir_pos(ns, parent_sd, ino, pos);
+	if (pos)
+		do {
+			struct rb_node *node = rb_next(&pos->s_rb);
+			if (!node)
+				pos = NULL;
+			else
+				pos = to_sysfs_dirent(node);
+		} while (pos && pos->s_ns != ns);
+	return pos;
+}
+
+static int sysfs_readdir(struct file *file, struct dir_context *ctx)
+{
+	struct dentry *dentry = file->f_path.dentry;
+	struct sysfs_dirent *parent_sd = dentry->d_fsdata;
+	struct sysfs_dirent *pos = file->private_data;
+	const void *ns = NULL;
+
+	if (!dir_emit_dots(file, ctx))
+		return 0;
+	mutex_lock(&sysfs_mutex);
+
+	if (parent_sd->s_flags & SYSFS_FLAG_NS)
+		ns = sysfs_info(dentry->d_sb)->ns;
+
+	for (pos = sysfs_dir_pos(ns, parent_sd, ctx->pos, pos);
+	     pos;
+	     pos = sysfs_dir_next_pos(ns, parent_sd, ctx->pos, pos)) {
+		const char *name = pos->s_name;
+		unsigned int type = dt_type(pos);
+		int len = strlen(name);
+		ino_t ino = pos->s_ino;
+
+		ctx->pos = pos->s_hash;
+		file->private_data = pos;
+		kernfs_get(pos);
+
+		mutex_unlock(&sysfs_mutex);
+		if (!dir_emit(ctx, name, len, ino, type))
+			return 0;
+		mutex_lock(&sysfs_mutex);
+	}
+	mutex_unlock(&sysfs_mutex);
+	file->private_data = NULL;
+	ctx->pos = INT_MAX;
+	return 0;
+}
+
+static loff_t sysfs_dir_llseek(struct file *file, loff_t offset, int whence)
+{
+	struct inode *inode = file_inode(file);
+	loff_t ret;
+
+	mutex_lock(&inode->i_mutex);
+	ret = generic_file_llseek(file, offset, whence);
+	mutex_unlock(&inode->i_mutex);
+
+	return ret;
+}
+
+const struct file_operations sysfs_dir_operations = {
+	.read		= generic_read_dir,
+	.iterate	= sysfs_readdir,
+	.release	= sysfs_dir_release,
+	.llseek		= sysfs_dir_llseek,
+};
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 933ac8d..31f0dbe 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -14,6 +14,7 @@
 #include <linux/lockdep.h>
 #include <linux/fs.h>
 #include <linux/rbtree.h>
+#include <linux/mutex.h>
 
 #include <linux/kernfs.h>
 
@@ -125,4 +126,20 @@ int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
 		   size_t size, int flags);
 int sysfs_inode_init(void);
 
+/*
+ * dir.c
+ */
+extern struct mutex sysfs_mutex;
+extern const struct dentry_operations sysfs_dentry_ops;
+extern const struct file_operations sysfs_dir_operations;
+extern const struct inode_operations sysfs_dir_inode_operations;
+
+struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd);
+void sysfs_put_active(struct sysfs_dirent *sd);
+void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt);
+int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
+		  struct sysfs_dirent *parent_sd);
+void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
+struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);
+
 #endif	/* __KERNFS_INTERNAL_H */
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 0d806ef..e5c4e71 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -13,468 +13,12 @@
 #undef DEBUG
 
 #include <linux/fs.h>
-#include <linux/mount.h>
-#include <linux/module.h>
 #include <linux/kobject.h>
-#include <linux/namei.h>
-#include <linux/idr.h>
-#include <linux/completion.h>
-#include <linux/mutex.h>
 #include <linux/slab.h>
-#include <linux/security.h>
-#include <linux/hash.h>
 #include "sysfs.h"
 
-DEFINE_MUTEX(sysfs_mutex);
 DEFINE_SPINLOCK(sysfs_symlink_target_lock);
 
-#define to_sysfs_dirent(X) rb_entry((X), struct sysfs_dirent, s_rb)
-
-static DEFINE_SPINLOCK(sysfs_ino_lock);
-static DEFINE_IDA(sysfs_ino_ida);
-
-/**
- *	sysfs_name_hash
- *	@name: Null terminated string to hash
- *	@ns:   Namespace tag to hash
- *
- *	Returns 31 bit hash of ns + name (so it fits in an off_t )
- */
-static unsigned int sysfs_name_hash(const char *name, const void *ns)
-{
-	unsigned long hash = init_name_hash();
-	unsigned int len = strlen(name);
-	while (len--)
-		hash = partial_name_hash(*name++, hash);
-	hash = (end_name_hash(hash) ^ hash_ptr((void *)ns, 31));
-	hash &= 0x7fffffffU;
-	/* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */
-	if (hash < 1)
-		hash += 2;
-	if (hash >= INT_MAX)
-		hash = INT_MAX - 1;
-	return hash;
-}
-
-static int sysfs_name_compare(unsigned int hash, const char *name,
-			      const void *ns, const struct sysfs_dirent *sd)
-{
-	if (hash != sd->s_hash)
-		return hash - sd->s_hash;
-	if (ns != sd->s_ns)
-		return ns - sd->s_ns;
-	return strcmp(name, sd->s_name);
-}
-
-static int sysfs_sd_compare(const struct sysfs_dirent *left,
-			    const struct sysfs_dirent *right)
-{
-	return sysfs_name_compare(left->s_hash, left->s_name, left->s_ns,
-				  right);
-}
-
-/**
- *	sysfs_link_sibling - link sysfs_dirent into sibling rbtree
- *	@sd: sysfs_dirent of interest
- *
- *	Link @sd into its sibling rbtree which starts from
- *	sd->s_parent->s_dir.children.
- *
- *	Locking:
- *	mutex_lock(sysfs_mutex)
- *
- *	RETURNS:
- *	0 on susccess -EEXIST on failure.
- */
-static int sysfs_link_sibling(struct sysfs_dirent *sd)
-{
-	struct rb_node **node = &sd->s_parent->s_dir.children.rb_node;
-	struct rb_node *parent = NULL;
-
-	if (sysfs_type(sd) == SYSFS_DIR)
-		sd->s_parent->s_dir.subdirs++;
-
-	while (*node) {
-		struct sysfs_dirent *pos;
-		int result;
-
-		pos = to_sysfs_dirent(*node);
-		parent = *node;
-		result = sysfs_sd_compare(sd, pos);
-		if (result < 0)
-			node = &pos->s_rb.rb_left;
-		else if (result > 0)
-			node = &pos->s_rb.rb_right;
-		else
-			return -EEXIST;
-	}
-	/* add new node and rebalance the tree */
-	rb_link_node(&sd->s_rb, parent, node);
-	rb_insert_color(&sd->s_rb, &sd->s_parent->s_dir.children);
-	return 0;
-}
-
-/**
- *	sysfs_unlink_sibling - unlink sysfs_dirent from sibling rbtree
- *	@sd: sysfs_dirent of interest
- *
- *	Unlink @sd from its sibling rbtree which starts from
- *	sd->s_parent->s_dir.children.
- *
- *	Locking:
- *	mutex_lock(sysfs_mutex)
- */
-static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
-{
-	if (sysfs_type(sd) == SYSFS_DIR)
-		sd->s_parent->s_dir.subdirs--;
-
-	rb_erase(&sd->s_rb, &sd->s_parent->s_dir.children);
-}
-
-/**
- *	sysfs_get_active - get an active reference to sysfs_dirent
- *	@sd: sysfs_dirent to get an active reference to
- *
- *	Get an active reference of @sd.  This function is noop if @sd
- *	is NULL.
- *
- *	RETURNS:
- *	Pointer to @sd on success, NULL on failure.
- */
-struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
-{
-	if (unlikely(!sd))
-		return NULL;
-
-	if (!atomic_inc_unless_negative(&sd->s_active))
-		return NULL;
-
-	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
-		rwsem_acquire_read(&sd->dep_map, 0, 1, _RET_IP_);
-	return sd;
-}
-
-/**
- *	sysfs_put_active - put an active reference to sysfs_dirent
- *	@sd: sysfs_dirent to put an active reference to
- *
- *	Put an active reference to @sd.  This function is noop if @sd
- *	is NULL.
- */
-void sysfs_put_active(struct sysfs_dirent *sd)
-{
-	int v;
-
-	if (unlikely(!sd))
-		return;
-
-	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
-		rwsem_release(&sd->dep_map, 1, _RET_IP_);
-	v = atomic_dec_return(&sd->s_active);
-	if (likely(v != SD_DEACTIVATED_BIAS))
-		return;
-
-	/* atomic_dec_return() is a mb(), we'll always see the updated
-	 * sd->u.completion.
-	 */
-	complete(sd->u.completion);
-}
-
-/**
- *	sysfs_deactivate - deactivate sysfs_dirent
- *	@sd: sysfs_dirent to deactivate
- *
- *	Deny new active references and drain existing ones.
- */
-static void sysfs_deactivate(struct sysfs_dirent *sd)
-{
-	DECLARE_COMPLETION_ONSTACK(wait);
-	int v;
-
-	BUG_ON(!(sd->s_flags & SYSFS_FLAG_REMOVED));
-
-	if (!(sysfs_type(sd) & SYSFS_ACTIVE_REF))
-		return;
-
-	sd->u.completion = (void *)&wait;
-
-	rwsem_acquire(&sd->dep_map, 0, 0, _RET_IP_);
-	/* atomic_add_return() is a mb(), put_active() will always see
-	 * the updated sd->u.completion.
-	 */
-	v = atomic_add_return(SD_DEACTIVATED_BIAS, &sd->s_active);
-
-	if (v != SD_DEACTIVATED_BIAS) {
-		lock_contended(&sd->dep_map, _RET_IP_);
-		wait_for_completion(&wait);
-	}
-
-	lock_acquired(&sd->dep_map, _RET_IP_);
-	rwsem_release(&sd->dep_map, 1, _RET_IP_);
-}
-
-static int sysfs_alloc_ino(unsigned int *pino)
-{
-	int ino, rc;
-
- retry:
-	spin_lock(&sysfs_ino_lock);
-	rc = ida_get_new_above(&sysfs_ino_ida, 2, &ino);
-	spin_unlock(&sysfs_ino_lock);
-
-	if (rc == -EAGAIN) {
-		if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL))
-			goto retry;
-		rc = -ENOMEM;
-	}
-
-	*pino = ino;
-	return rc;
-}
-
-static void sysfs_free_ino(unsigned int ino)
-{
-	spin_lock(&sysfs_ino_lock);
-	ida_remove(&sysfs_ino_ida, ino);
-	spin_unlock(&sysfs_ino_lock);
-}
-
-/**
- * kernfs_get - get a reference count on a sysfs_dirent
- * @sd: the target sysfs_dirent
- */
-void kernfs_get(struct sysfs_dirent *sd)
-{
-	if (sd) {
-		WARN_ON(!atomic_read(&sd->s_count));
-		atomic_inc(&sd->s_count);
-	}
-}
-EXPORT_SYMBOL_GPL(kernfs_get);
-
-/**
- * kernfs_put - put a reference count on a sysfs_dirent
- * @sd: the target sysfs_dirent
- *
- * Put a reference count of @sd and destroy it if it reached zero.
- */
-void kernfs_put(struct sysfs_dirent *sd)
-{
-	struct sysfs_dirent *parent_sd;
-
-	if (!sd || !atomic_dec_and_test(&sd->s_count))
-		return;
- repeat:
-	/* Moving/renaming is always done while holding reference.
-	 * sd->s_parent won't change beneath us.
-	 */
-	parent_sd = sd->s_parent;
-
-	WARN(!(sd->s_flags & SYSFS_FLAG_REMOVED),
-		"sysfs: free using entry: %s/%s\n",
-		parent_sd ? parent_sd->s_name : "", sd->s_name);
-
-	if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
-		kernfs_put(sd->s_symlink.target_sd);
-	if (sysfs_type(sd) & SYSFS_COPY_NAME)
-		kfree(sd->s_name);
-	if (sd->s_iattr && sd->s_iattr->ia_secdata)
-		security_release_secctx(sd->s_iattr->ia_secdata,
-					sd->s_iattr->ia_secdata_len);
-	kfree(sd->s_iattr);
-	sysfs_free_ino(sd->s_ino);
-	kmem_cache_free(sysfs_dir_cachep, sd);
-
-	sd = parent_sd;
-	if (sd && atomic_dec_and_test(&sd->s_count))
-		goto repeat;
-}
-EXPORT_SYMBOL_GPL(kernfs_put);
-
-static int sysfs_dentry_delete(const struct dentry *dentry)
-{
-	struct sysfs_dirent *sd = dentry->d_fsdata;
-	return !(sd && !(sd->s_flags & SYSFS_FLAG_REMOVED));
-}
-
-static int sysfs_dentry_revalidate(struct dentry *dentry, unsigned int flags)
-{
-	struct sysfs_dirent *sd;
-
-	if (flags & LOOKUP_RCU)
-		return -ECHILD;
-
-	sd = dentry->d_fsdata;
-	mutex_lock(&sysfs_mutex);
-
-	/* The sysfs dirent has been deleted */
-	if (sd->s_flags & SYSFS_FLAG_REMOVED)
-		goto out_bad;
-
-	/* The sysfs dirent has been moved? */
-	if (dentry->d_parent->d_fsdata != sd->s_parent)
-		goto out_bad;
-
-	/* The sysfs dirent has been renamed */
-	if (strcmp(dentry->d_name.name, sd->s_name) != 0)
-		goto out_bad;
-
-	/* The sysfs dirent has been moved to a different namespace */
-	if (sd->s_parent && (sd->s_parent->s_flags & SYSFS_FLAG_NS) &&
-	    sysfs_info(dentry->d_sb)->ns != sd->s_ns)
-		goto out_bad;
-
-	mutex_unlock(&sysfs_mutex);
-out_valid:
-	return 1;
-out_bad:
-	/* Remove the dentry from the dcache hashes.
-	 * If this is a deleted dentry we use d_drop instead of d_delete
-	 * so sysfs doesn't need to cope with negative dentries.
-	 *
-	 * If this is a dentry that has simply been renamed we
-	 * use d_drop to remove it from the dcache lookup on its
-	 * old parent.  If this dentry persists later when a lookup
-	 * is performed at its new name the dentry will be readded
-	 * to the dcache hashes.
-	 */
-	mutex_unlock(&sysfs_mutex);
-
-	/* If we have submounts we must allow the vfs caches
-	 * to lie about the state of the filesystem to prevent
-	 * leaks and other nasty things.
-	 */
-	if (check_submounts_and_drop(dentry) != 0)
-		goto out_valid;
-
-	return 0;
-}
-
-static void sysfs_dentry_release(struct dentry *dentry)
-{
-	kernfs_put(dentry->d_fsdata);
-}
-
-const struct dentry_operations sysfs_dentry_ops = {
-	.d_revalidate	= sysfs_dentry_revalidate,
-	.d_delete	= sysfs_dentry_delete,
-	.d_release	= sysfs_dentry_release,
-};
-
-struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
-{
-	char *dup_name = NULL;
-	struct sysfs_dirent *sd;
-
-	if (type & SYSFS_COPY_NAME) {
-		name = dup_name = kstrdup(name, GFP_KERNEL);
-		if (!name)
-			return NULL;
-	}
-
-	sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL);
-	if (!sd)
-		goto err_out1;
-
-	if (sysfs_alloc_ino(&sd->s_ino))
-		goto err_out2;
-
-	atomic_set(&sd->s_count, 1);
-	atomic_set(&sd->s_active, 0);
-
-	sd->s_name = name;
-	sd->s_mode = mode;
-	sd->s_flags = type | SYSFS_FLAG_REMOVED;
-
-	return sd;
-
- err_out2:
-	kmem_cache_free(sysfs_dir_cachep, sd);
- err_out1:
-	kfree(dup_name);
-	return NULL;
-}
-
-/**
- *	sysfs_addrm_start - prepare for sysfs_dirent add/remove
- *	@acxt: pointer to sysfs_addrm_cxt to be used
- *
- *	This function is called when the caller is about to add or remove
- *	sysfs_dirent.  This function acquires sysfs_mutex.  @acxt is used
- *	to keep and pass context to other addrm functions.
- *
- *	LOCKING:
- *	Kernel thread context (may sleep).  sysfs_mutex is locked on
- *	return.
- */
-void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt)
-	__acquires(sysfs_mutex)
-{
-	memset(acxt, 0, sizeof(*acxt));
-
-	mutex_lock(&sysfs_mutex);
-}
-
-/**
- *	sysfs_add_one - add sysfs_dirent to parent without warning
- *	@acxt: addrm context to use
- *	@sd: sysfs_dirent to be added
- *	@parent_sd: the parent sysfs_dirent to add @sd to
- *
- *	Get @parent_sd and set @sd->s_parent to it and increment nlink of
- *	the parent inode if @sd is a directory and link into the children
- *	list of the parent.
- *
- *	This function should be called between calls to
- *	sysfs_addrm_start() and sysfs_addrm_finish() and should be
- *	passed the same @acxt as passed to sysfs_addrm_start().
- *
- *	LOCKING:
- *	Determined by sysfs_addrm_start().
- *
- *	RETURNS:
- *	0 on success, -EEXIST if entry with the given name already
- *	exists.
- */
-int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
-		  struct sysfs_dirent *parent_sd)
-{
-	bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS;
-	struct sysfs_inode_attrs *ps_iattr;
-	int ret;
-
-	if (has_ns != (bool)sd->s_ns) {
-		WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
-		     has_ns ? "required" : "invalid",
-		     parent_sd->s_name, sd->s_name);
-		return -EINVAL;
-	}
-
-	if (sysfs_type(parent_sd) != SYSFS_DIR)
-		return -EINVAL;
-
-	sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
-	sd->s_parent = parent_sd;
-	kernfs_get(parent_sd);
-
-	ret = sysfs_link_sibling(sd);
-	if (ret)
-		return ret;
-
-	/* Update timestamps on the parent */
-	ps_iattr = parent_sd->s_iattr;
-	if (ps_iattr) {
-		struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
-		ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
-	}
-
-	/* Mark the entry added into directory tree */
-	sd->s_flags &= ~SYSFS_FLAG_REMOVED;
-
-	return 0;
-}
-
 /**
  *	sysfs_pathname - return full path to sysfs dirent
  *	@sd: sysfs_dirent whose path we want
@@ -511,181 +55,6 @@ void sysfs_warn_dup(struct sysfs_dirent *parent, const char *name)
 }
 
 /**
- *	sysfs_remove_one - remove sysfs_dirent from parent
- *	@acxt: addrm context to use
- *	@sd: sysfs_dirent to be removed
- *
- *	Mark @sd removed and drop nlink of parent inode if @sd is a
- *	directory.  @sd is unlinked from the children list.
- *
- *	This function should be called between calls to
- *	sysfs_addrm_start() and sysfs_addrm_finish() and should be
- *	passed the same @acxt as passed to sysfs_addrm_start().
- *
- *	LOCKING:
- *	Determined by sysfs_addrm_start().
- */
-static void sysfs_remove_one(struct sysfs_addrm_cxt *acxt,
-			     struct sysfs_dirent *sd)
-{
-	struct sysfs_inode_attrs *ps_iattr;
-
-	/*
-	 * Removal can be called multiple times on the same node.  Only the
-	 * first invocation is effective and puts the base ref.
-	 */
-	if (sd->s_flags & SYSFS_FLAG_REMOVED)
-		return;
-
-	sysfs_unlink_sibling(sd);
-
-	/* Update timestamps on the parent */
-	ps_iattr = sd->s_parent->s_iattr;
-	if (ps_iattr) {
-		struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
-		ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
-	}
-
-	sd->s_flags |= SYSFS_FLAG_REMOVED;
-	sd->u.removed_list = acxt->removed;
-	acxt->removed = sd;
-}
-
-/**
- *	sysfs_addrm_finish - finish up sysfs_dirent add/remove
- *	@acxt: addrm context to finish up
- *
- *	Finish up sysfs_dirent add/remove.  Resources acquired by
- *	sysfs_addrm_start() are released and removed sysfs_dirents are
- *	cleaned up.
- *
- *	LOCKING:
- *	sysfs_mutex is released.
- */
-void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
-	__releases(sysfs_mutex)
-{
-	/* release resources acquired by sysfs_addrm_start() */
-	mutex_unlock(&sysfs_mutex);
-
-	/* kill removed sysfs_dirents */
-	while (acxt->removed) {
-		struct sysfs_dirent *sd = acxt->removed;
-
-		acxt->removed = sd->u.removed_list;
-
-		sysfs_deactivate(sd);
-		sysfs_unmap_bin_file(sd);
-		kernfs_put(sd);
-	}
-}
-
-/**
- * kernfs_find_ns - find sysfs_dirent with the given name
- * @parent: sysfs_dirent to search under
- * @name: name to look for
- * @ns: the namespace tag to use
- *
- * Look for sysfs_dirent with name @name under @parent.  Returns pointer to
- * the found sysfs_dirent on success, %NULL on failure.
- */
-static struct sysfs_dirent *kernfs_find_ns(struct sysfs_dirent *parent,
-					   const unsigned char *name,
-					   const void *ns)
-{
-	struct rb_node *node = parent->s_dir.children.rb_node;
-	bool has_ns = parent->s_flags & SYSFS_FLAG_NS;
-	unsigned int hash;
-
-	lockdep_assert_held(&sysfs_mutex);
-
-	if (has_ns != (bool)ns) {
-		WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
-		     has_ns ? "required" : "invalid",
-		     parent->s_name, name);
-		return NULL;
-	}
-
-	hash = sysfs_name_hash(name, ns);
-	while (node) {
-		struct sysfs_dirent *sd;
-		int result;
-
-		sd = to_sysfs_dirent(node);
-		result = sysfs_name_compare(hash, name, ns, sd);
-		if (result < 0)
-			node = node->rb_left;
-		else if (result > 0)
-			node = node->rb_right;
-		else
-			return sd;
-	}
-	return NULL;
-}
-
-/**
- * kernfs_find_and_get_ns - find and get sysfs_dirent with the given name
- * @parent: sysfs_dirent to search under
- * @name: name to look for
- * @ns: the namespace tag to use
- *
- * Look for sysfs_dirent with name @name under @parent and get a reference
- * if found.  This function may sleep and returns pointer to the found
- * sysfs_dirent on success, %NULL on failure.
- */
-struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
-					    const char *name, const void *ns)
-{
-	struct sysfs_dirent *sd;
-
-	mutex_lock(&sysfs_mutex);
-	sd = kernfs_find_ns(parent, name, ns);
-	kernfs_get(sd);
-	mutex_unlock(&sysfs_mutex);
-
-	return sd;
-}
-EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns);
-
-/**
- * kernfs_create_dir_ns - create a directory
- * @parent: parent in which to create a new directory
- * @name: name of the new directory
- * @priv: opaque data associated with the new directory
- * @ns: optional namespace tag of the directory
- *
- * Returns the created node on success, ERR_PTR() value on failure.
- */
-struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
-					  const char *name, void *priv,
-					  const void *ns)
-{
-	umode_t mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
-	struct sysfs_addrm_cxt acxt;
-	struct sysfs_dirent *sd;
-	int rc;
-
-	/* allocate */
-	sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
-	if (!sd)
-		return ERR_PTR(-ENOMEM);
-
-	sd->s_ns = ns;
-	sd->priv = priv;
-
-	/* link in */
-	sysfs_addrm_start(&acxt);
-	rc = sysfs_add_one(&acxt, sd, parent);
-	sysfs_addrm_finish(&acxt);
-
-	if (!rc)
-		return sd;
-
-	kernfs_put(sd);
-	return ERR_PTR(rc);
-}
-
-/**
  * sysfs_create_dir_ns - create a directory for an object with a namespace tag
  * @kobj: object we're creating directory for
  * @ns: the namespace tag to use
@@ -715,177 +84,6 @@ int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
 	return 0;
 }
 
-static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry,
-				   unsigned int flags)
-{
-	struct dentry *ret = NULL;
-	struct dentry *parent = dentry->d_parent;
-	struct sysfs_dirent *parent_sd = parent->d_fsdata;
-	struct sysfs_dirent *sd;
-	struct inode *inode;
-	const void *ns = NULL;
-
-	mutex_lock(&sysfs_mutex);
-
-	if (parent_sd->s_flags & SYSFS_FLAG_NS)
-		ns = sysfs_info(dir->i_sb)->ns;
-
-	sd = kernfs_find_ns(parent_sd, dentry->d_name.name, ns);
-
-	/* no such entry */
-	if (!sd) {
-		ret = ERR_PTR(-ENOENT);
-		goto out_unlock;
-	}
-	kernfs_get(sd);
-	dentry->d_fsdata = sd;
-
-	/* attach dentry and inode */
-	inode = sysfs_get_inode(dir->i_sb, sd);
-	if (!inode) {
-		ret = ERR_PTR(-ENOMEM);
-		goto out_unlock;
-	}
-
-	/* instantiate and hash dentry */
-	ret = d_materialise_unique(dentry, inode);
- out_unlock:
-	mutex_unlock(&sysfs_mutex);
-	return ret;
-}
-
-const struct inode_operations sysfs_dir_inode_operations = {
-	.lookup		= sysfs_lookup,
-	.permission	= sysfs_permission,
-	.setattr	= sysfs_setattr,
-	.getattr	= sysfs_getattr,
-	.setxattr	= sysfs_setxattr,
-};
-
-static struct sysfs_dirent *sysfs_leftmost_descendant(struct sysfs_dirent *pos)
-{
-	struct sysfs_dirent *last;
-
-	while (true) {
-		struct rb_node *rbn;
-
-		last = pos;
-
-		if (sysfs_type(pos) != SYSFS_DIR)
-			break;
-
-		rbn = rb_first(&pos->s_dir.children);
-		if (!rbn)
-			break;
-
-		pos = to_sysfs_dirent(rbn);
-	}
-
-	return last;
-}
-
-/**
- * sysfs_next_descendant_post - find the next descendant for post-order walk
- * @pos: the current position (%NULL to initiate traversal)
- * @root: sysfs_dirent whose descendants to walk
- *
- * Find the next descendant to visit for post-order traversal of @root's
- * descendants.  @root is included in the iteration and the last node to be
- * visited.
- */
-static struct sysfs_dirent *sysfs_next_descendant_post(struct sysfs_dirent *pos,
-						       struct sysfs_dirent *root)
-{
-	struct rb_node *rbn;
-
-	lockdep_assert_held(&sysfs_mutex);
-
-	/* if first iteration, visit leftmost descendant which may be root */
-	if (!pos)
-		return sysfs_leftmost_descendant(root);
-
-	/* if we visited @root, we're done */
-	if (pos == root)
-		return NULL;
-
-	/* if there's an unvisited sibling, visit its leftmost descendant */
-	rbn = rb_next(&pos->s_rb);
-	if (rbn)
-		return sysfs_leftmost_descendant(to_sysfs_dirent(rbn));
-
-	/* no sibling left, visit parent */
-	return pos->s_parent;
-}
-
-static void __kernfs_remove(struct sysfs_addrm_cxt *acxt,
-			    struct sysfs_dirent *sd)
-{
-	struct sysfs_dirent *pos, *next;
-
-	if (!sd)
-		return;
-
-	pr_debug("sysfs %s: removing\n", sd->s_name);
-
-	next = NULL;
-	do {
-		pos = next;
-		next = sysfs_next_descendant_post(pos, sd);
-		if (pos)
-			sysfs_remove_one(acxt, pos);
-	} while (next);
-}
-
-/**
- * kernfs_remove - remove a sysfs_dirent recursively
- * @sd: the sysfs_dirent to remove
- *
- * Remove @sd along with all its subdirectories and files.
- */
-void kernfs_remove(struct sysfs_dirent *sd)
-{
-	struct sysfs_addrm_cxt acxt;
-
-	sysfs_addrm_start(&acxt);
-	__kernfs_remove(&acxt, sd);
-	sysfs_addrm_finish(&acxt);
-}
-
-/**
- * kernfs_remove_by_name_ns - find a sysfs_dirent by name and remove it
- * @dir_sd: parent of the target
- * @name: name of the sysfs_dirent to remove
- * @ns: namespace tag of the sysfs_dirent to remove
- *
- * Look for the sysfs_dirent with @name and @ns under @dir_sd and remove
- * it.  Returns 0 on success, -ENOENT if such entry doesn't exist.
- */
-int kernfs_remove_by_name_ns(struct sysfs_dirent *dir_sd, const char *name,
-			     const void *ns)
-{
-	struct sysfs_addrm_cxt acxt;
-	struct sysfs_dirent *sd;
-
-	if (!dir_sd) {
-		WARN(1, KERN_WARNING "sysfs: can not remove '%s', no directory\n",
-			name);
-		return -ENOENT;
-	}
-
-	sysfs_addrm_start(&acxt);
-
-	sd = kernfs_find_ns(dir_sd, name, ns);
-	if (sd)
-		__kernfs_remove(&acxt, sd);
-
-	sysfs_addrm_finish(&acxt);
-
-	if (sd)
-		return 0;
-	else
-		return -ENOENT;
-}
-
 /**
  *	sysfs_remove_dir - remove an object's directory.
  *	@kobj:	object.
@@ -920,57 +118,6 @@ void sysfs_remove_dir(struct kobject *kobj)
 	}
 }
 
-/**
- * kernfs_rename_ns - move and rename a kernfs_node
- * @sd: target node
- * @new_parent: new parent to put @sd under
- * @new_name: new name
- * @new_ns: new namespace tag
- */
-int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
-		     const char *new_name, const void *new_ns)
-{
-	int error;
-
-	mutex_lock(&sysfs_mutex);
-
-	error = 0;
-	if ((sd->s_parent == new_parent) && (sd->s_ns == new_ns) &&
-	    (strcmp(sd->s_name, new_name) == 0))
-		goto out;	/* nothing to rename */
-
-	error = -EEXIST;
-	if (kernfs_find_ns(new_parent, new_name, new_ns))
-		goto out;
-
-	/* rename sysfs_dirent */
-	if (strcmp(sd->s_name, new_name) != 0) {
-		error = -ENOMEM;
-		new_name = kstrdup(new_name, GFP_KERNEL);
-		if (!new_name)
-			goto out;
-
-		kfree(sd->s_name);
-		sd->s_name = new_name;
-	}
-
-	/*
-	 * Move to the appropriate place in the appropriate directories rbtree.
-	 */
-	sysfs_unlink_sibling(sd);
-	kernfs_get(new_parent);
-	kernfs_put(sd->s_parent);
-	sd->s_ns = new_ns;
-	sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
-	sd->s_parent = new_parent;
-	sysfs_link_sibling(sd);
-
-	error = 0;
- out:
-	mutex_unlock(&sysfs_mutex);
-	return error;
-}
-
 int sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name,
 			const void *new_ns)
 {
@@ -991,136 +138,3 @@ int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
 
 	return kernfs_rename_ns(sd, new_parent_sd, sd->s_name, new_ns);
 }
-
-/**
- * kernfs_enable_ns - enable namespace under a directory
- * @sd: directory of interest, should be empty
- *
- * This is to be called right after @sd is created to enable namespace
- * under it.  All children of @sd must have non-NULL namespace tags and
- * only the ones which match the super_block's tag will be visible.
- */
-void kernfs_enable_ns(struct sysfs_dirent *sd)
-{
-	WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
-	WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));
-	sd->s_flags |= SYSFS_FLAG_NS;
-}
-
-/* Relationship between s_mode and the DT_xxx types */
-static inline unsigned char dt_type(struct sysfs_dirent *sd)
-{
-	return (sd->s_mode >> 12) & 15;
-}
-
-static int sysfs_dir_release(struct inode *inode, struct file *filp)
-{
-	kernfs_put(filp->private_data);
-	return 0;
-}
-
-static struct sysfs_dirent *sysfs_dir_pos(const void *ns,
-	struct sysfs_dirent *parent_sd,	loff_t hash, struct sysfs_dirent *pos)
-{
-	if (pos) {
-		int valid = !(pos->s_flags & SYSFS_FLAG_REMOVED) &&
-			pos->s_parent == parent_sd &&
-			hash == pos->s_hash;
-		kernfs_put(pos);
-		if (!valid)
-			pos = NULL;
-	}
-	if (!pos && (hash > 1) && (hash < INT_MAX)) {
-		struct rb_node *node = parent_sd->s_dir.children.rb_node;
-		while (node) {
-			pos = to_sysfs_dirent(node);
-
-			if (hash < pos->s_hash)
-				node = node->rb_left;
-			else if (hash > pos->s_hash)
-				node = node->rb_right;
-			else
-				break;
-		}
-	}
-	/* Skip over entries in the wrong namespace */
-	while (pos && pos->s_ns != ns) {
-		struct rb_node *node = rb_next(&pos->s_rb);
-		if (!node)
-			pos = NULL;
-		else
-			pos = to_sysfs_dirent(node);
-	}
-	return pos;
-}
-
-static struct sysfs_dirent *sysfs_dir_next_pos(const void *ns,
-	struct sysfs_dirent *parent_sd,	ino_t ino, struct sysfs_dirent *pos)
-{
-	pos = sysfs_dir_pos(ns, parent_sd, ino, pos);
-	if (pos)
-		do {
-			struct rb_node *node = rb_next(&pos->s_rb);
-			if (!node)
-				pos = NULL;
-			else
-				pos = to_sysfs_dirent(node);
-		} while (pos && pos->s_ns != ns);
-	return pos;
-}
-
-static int sysfs_readdir(struct file *file, struct dir_context *ctx)
-{
-	struct dentry *dentry = file->f_path.dentry;
-	struct sysfs_dirent *parent_sd = dentry->d_fsdata;
-	struct sysfs_dirent *pos = file->private_data;
-	const void *ns = NULL;
-
-	if (!dir_emit_dots(file, ctx))
-		return 0;
-	mutex_lock(&sysfs_mutex);
-
-	if (parent_sd->s_flags & SYSFS_FLAG_NS)
-		ns = sysfs_info(dentry->d_sb)->ns;
-
-	for (pos = sysfs_dir_pos(ns, parent_sd, ctx->pos, pos);
-	     pos;
-	     pos = sysfs_dir_next_pos(ns, parent_sd, ctx->pos, pos)) {
-		const char *name = pos->s_name;
-		unsigned int type = dt_type(pos);
-		int len = strlen(name);
-		ino_t ino = pos->s_ino;
-
-		ctx->pos = pos->s_hash;
-		file->private_data = pos;
-		kernfs_get(pos);
-
-		mutex_unlock(&sysfs_mutex);
-		if (!dir_emit(ctx, name, len, ino, type))
-			return 0;
-		mutex_lock(&sysfs_mutex);
-	}
-	mutex_unlock(&sysfs_mutex);
-	file->private_data = NULL;
-	ctx->pos = INT_MAX;
-	return 0;
-}
-
-static loff_t sysfs_dir_llseek(struct file *file, loff_t offset, int whence)
-{
-	struct inode *inode = file_inode(file);
-	loff_t ret;
-
-	mutex_lock(&inode->i_mutex);
-	ret = generic_file_llseek(file, offset, whence);
-	mutex_unlock(&inode->i_mutex);
-
-	return ret;
-}
-
-const struct file_operations sysfs_dir_operations = {
-	.read		= generic_read_dir,
-	.iterate	= sysfs_readdir,
-	.release	= sysfs_dir_release,
-	.llseek		= sysfs_dir_llseek,
-};
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 93c1910..972b4a4 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -34,22 +34,9 @@ extern struct kmem_cache *sysfs_dir_cachep;
 /*
  * dir.c
  */
-extern struct mutex sysfs_mutex;
 extern spinlock_t sysfs_symlink_target_lock;
-extern const struct dentry_operations sysfs_dentry_ops;
 
-extern const struct file_operations sysfs_dir_operations;
-extern const struct inode_operations sysfs_dir_inode_operations;
-
-struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd);
-void sysfs_put_active(struct sysfs_dirent *sd);
-void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt);
 void sysfs_warn_dup(struct sysfs_dirent *parent, const char *name);
-int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
-		  struct sysfs_dirent *parent_sd);
-void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
-
-struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);
 
 /*
  * file.c
-- 
1.8.4.2

[PATCH 28/41] sysfs, kernfs: move file core code to fs/kernfs/file.c

[Tejun Heo]

Move core file code to fs/kernfs/file.c.  fs/sysfs/file.c now contains
sysfs kernfs_ops callbacks, sysfs wrappers around kernfs interfaces,
and sysfs_schedule_callback().  The respective declarations in
fs/sysfs/sysfs.h are moved to fs/kernfs/kernfs-internal.h.

This is pure relocation.

v2: Refreshed on top of the v2 of "sysfs, kernfs: prepare read path
    for kernfs".

v3: Refreshed on top of the v3 of "sysfs, kernfs: prepare read path
    for kernfs".

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/file.c            | 805 ++++++++++++++++++++++++++++++++++++++++++++
 fs/kernfs/kernfs-internal.h |   7 +
 fs/sysfs/file.c             | 802 +------------------------------------------
 fs/sysfs/sysfs.h            |   4 -
 4 files changed, 813 insertions(+), 805 deletions(-)

diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index 90b1e88..fa172e8 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -7,3 +7,808 @@
  *
  * This file is released under the GPLv2.
  */
+
+#include <linux/fs.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include <linux/poll.h>
+#include <linux/pagemap.h>
+#include <linux/poll.h>
+#include <linux/sched.h>
+
+#include "kernfs-internal.h"
+
+/*
+ * There's one sysfs_open_file for each open file and one sysfs_open_dirent
+ * for each sysfs_dirent with one or more open files.
+ *
+ * sysfs_dirent->s_attr.open points to sysfs_open_dirent.  s_attr.open is
+ * protected by sysfs_open_dirent_lock.
+ *
+ * filp->private_data points to seq_file whose ->private points to
+ * sysfs_open_file.  sysfs_open_files are chained at
+ * sysfs_open_dirent->files, which is protected by sysfs_open_file_mutex.
+ */
+static DEFINE_SPINLOCK(sysfs_open_dirent_lock);
+static DEFINE_MUTEX(sysfs_open_file_mutex);
+
+struct sysfs_open_dirent {
+	atomic_t		refcnt;
+	atomic_t		event;
+	wait_queue_head_t	poll;
+	struct list_head	files; /* goes through sysfs_open_file.list */
+};
+
+static struct sysfs_open_file *sysfs_of(struct file *file)
+{
+	return ((struct seq_file *)file->private_data)->private;
+}
+
+/*
+ * Determine the kernfs_ops for the given sysfs_dirent.  This function must
+ * be called while holding an active reference.
+ */
+static const struct kernfs_ops *kernfs_ops(struct sysfs_dirent *sd)
+{
+	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
+		lockdep_assert_held(sd);
+	return sd->s_attr.ops;
+}
+
+static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos)
+{
+	struct sysfs_open_file *of = sf->private;
+	const struct kernfs_ops *ops;
+
+	/*
+	 * @of->mutex nests outside active ref and is just to ensure that
+	 * the ops aren't called concurrently for the same open file.
+	 */
+	mutex_lock(&of->mutex);
+	if (!sysfs_get_active(of->sd))
+		return ERR_PTR(-ENODEV);
+
+	ops = kernfs_ops(of->sd);
+	if (ops->seq_start) {
+		return ops->seq_start(sf, ppos);
+	} else {
+		/*
+		 * The same behavior and code as single_open().  Returns
+		 * !NULL if pos is at the beginning; otherwise, NULL.
+		 */
+		return NULL + !*ppos;
+	}
+}
+
+static void *kernfs_seq_next(struct seq_file *sf, void *v, loff_t *ppos)
+{
+	struct sysfs_open_file *of = sf->private;
+	const struct kernfs_ops *ops = kernfs_ops(of->sd);
+
+	if (ops->seq_next) {
+		return ops->seq_next(sf, v, ppos);
+	} else {
+		/*
+		 * The same behavior and code as single_open(), always
+		 * terminate after the initial read.
+		 */
+		++*ppos;
+		return NULL;
+	}
+}
+
+static void kernfs_seq_stop(struct seq_file *sf, void *v)
+{
+	struct sysfs_open_file *of = sf->private;
+	const struct kernfs_ops *ops = kernfs_ops(of->sd);
+
+	if (ops->seq_stop)
+		ops->seq_stop(sf, v);
+
+	sysfs_put_active(of->sd);
+	mutex_unlock(&of->mutex);
+}
+
+static int kernfs_seq_show(struct seq_file *sf, void *v)
+{
+	struct sysfs_open_file *of = sf->private;
+
+	of->event = atomic_read(&of->sd->s_attr.open->event);
+
+	return of->sd->s_attr.ops->seq_show(sf, v);
+}
+
+static const struct seq_operations kernfs_seq_ops = {
+	.start = kernfs_seq_start,
+	.next = kernfs_seq_next,
+	.stop = kernfs_seq_stop,
+	.show = kernfs_seq_show,
+};
+
+/*
+ * As reading a bin file can have side-effects, the exact offset and bytes
+ * specified in read(2) call should be passed to the read callback making
+ * it difficult to use seq_file.  Implement simplistic custom buffering for
+ * bin files.
+ */
+static ssize_t kernfs_file_direct_read(struct sysfs_open_file *of,
+				       char __user *user_buf, size_t count,
+				       loff_t *ppos)
+{
+	ssize_t len = min_t(size_t, count, PAGE_SIZE);
+	const struct kernfs_ops *ops;
+	char *buf;
+
+	buf = kmalloc(len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	/*
+	 * @of->mutex nests outside active ref and is just to ensure that
+	 * the ops aren't called concurrently for the same open file.
+	 */
+	mutex_lock(&of->mutex);
+	if (!sysfs_get_active(of->sd)) {
+		len = -ENODEV;
+		mutex_unlock(&of->mutex);
+		goto out_free;
+	}
+
+	ops = kernfs_ops(of->sd);
+	if (ops->read)
+		len = ops->read(of, buf, len, *ppos);
+	else
+		len = -EINVAL;
+
+	sysfs_put_active(of->sd);
+	mutex_unlock(&of->mutex);
+
+	if (len < 0)
+		goto out_free;
+
+	if (copy_to_user(user_buf, buf, len)) {
+		len = -EFAULT;
+		goto out_free;
+	}
+
+	*ppos += len;
+
+ out_free:
+	kfree(buf);
+	return len;
+}
+
+/**
+ * kernfs_file_read - kernfs vfs read callback
+ * @file: file pointer
+ * @user_buf: data to write
+ * @count: number of bytes
+ * @ppos: starting offset
+ */
+static ssize_t kernfs_file_read(struct file *file, char __user *user_buf,
+				size_t count, loff_t *ppos)
+{
+	struct sysfs_open_file *of = sysfs_of(file);
+
+	if (of->sd->s_flags & SYSFS_FLAG_HAS_SEQ_SHOW)
+		return seq_read(file, user_buf, count, ppos);
+	else
+		return kernfs_file_direct_read(of, user_buf, count, ppos);
+}
+
+/**
+ * kernfs_file_write - kernfs vfs write callback
+ * @file: file pointer
+ * @user_buf: data to write
+ * @count: number of bytes
+ * @ppos: starting offset
+ *
+ * Copy data in from userland and pass it to the matching kernfs write
+ * operation.
+ *
+ * There is no easy way for us to know if userspace is only doing a partial
+ * write, so we don't support them. We expect the entire buffer to come on
+ * the first write.  Hint: if you're writing a value, first read the file,
+ * modify only the the value you're changing, then write entire buffer
+ * back.
+ */
+static ssize_t kernfs_file_write(struct file *file, const char __user *user_buf,
+				 size_t count, loff_t *ppos)
+{
+	struct sysfs_open_file *of = sysfs_of(file);
+	ssize_t len = min_t(size_t, count, PAGE_SIZE);
+	const struct kernfs_ops *ops;
+	char *buf;
+
+	buf = kmalloc(len + 1, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	if (copy_from_user(buf, user_buf, len)) {
+		len = -EFAULT;
+		goto out_free;
+	}
+	buf[len] = '\0';	/* guarantee string termination */
+
+	/*
+	 * @of->mutex nests outside active ref and is just to ensure that
+	 * the ops aren't called concurrently for the same open file.
+	 */
+	mutex_lock(&of->mutex);
+	if (!sysfs_get_active(of->sd)) {
+		mutex_unlock(&of->mutex);
+		len = -ENODEV;
+		goto out_free;
+	}
+
+	ops = kernfs_ops(of->sd);
+	if (ops->write)
+		len = ops->write(of, buf, len, *ppos);
+	else
+		len = -EINVAL;
+
+	sysfs_put_active(of->sd);
+	mutex_unlock(&of->mutex);
+
+	if (len > 0)
+		*ppos += len;
+out_free:
+	kfree(buf);
+	return len;
+}
+
+static void kernfs_vma_open(struct vm_area_struct *vma)
+{
+	struct file *file = vma->vm_file;
+	struct sysfs_open_file *of = sysfs_of(file);
+
+	if (!of->vm_ops)
+		return;
+
+	if (!sysfs_get_active(of->sd))
+		return;
+
+	if (of->vm_ops->open)
+		of->vm_ops->open(vma);
+
+	sysfs_put_active(of->sd);
+}
+
+static int kernfs_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	struct file *file = vma->vm_file;
+	struct sysfs_open_file *of = sysfs_of(file);
+	int ret;
+
+	if (!of->vm_ops)
+		return VM_FAULT_SIGBUS;
+
+	if (!sysfs_get_active(of->sd))
+		return VM_FAULT_SIGBUS;
+
+	ret = VM_FAULT_SIGBUS;
+	if (of->vm_ops->fault)
+		ret = of->vm_ops->fault(vma, vmf);
+
+	sysfs_put_active(of->sd);
+	return ret;
+}
+
+static int kernfs_vma_page_mkwrite(struct vm_area_struct *vma,
+				   struct vm_fault *vmf)
+{
+	struct file *file = vma->vm_file;
+	struct sysfs_open_file *of = sysfs_of(file);
+	int ret;
+
+	if (!of->vm_ops)
+		return VM_FAULT_SIGBUS;
+
+	if (!sysfs_get_active(of->sd))
+		return VM_FAULT_SIGBUS;
+
+	ret = 0;
+	if (of->vm_ops->page_mkwrite)
+		ret = of->vm_ops->page_mkwrite(vma, vmf);
+	else
+		file_update_time(file);
+
+	sysfs_put_active(of->sd);
+	return ret;
+}
+
+static int kernfs_vma_access(struct vm_area_struct *vma, unsigned long addr,
+			     void *buf, int len, int write)
+{
+	struct file *file = vma->vm_file;
+	struct sysfs_open_file *of = sysfs_of(file);
+	int ret;
+
+	if (!of->vm_ops)
+		return -EINVAL;
+
+	if (!sysfs_get_active(of->sd))
+		return -EINVAL;
+
+	ret = -EINVAL;
+	if (of->vm_ops->access)
+		ret = of->vm_ops->access(vma, addr, buf, len, write);
+
+	sysfs_put_active(of->sd);
+	return ret;
+}
+
+#ifdef CONFIG_NUMA
+static int kernfs_vma_set_policy(struct vm_area_struct *vma,
+				 struct mempolicy *new)
+{
+	struct file *file = vma->vm_file;
+	struct sysfs_open_file *of = sysfs_of(file);
+	int ret;
+
+	if (!of->vm_ops)
+		return 0;
+
+	if (!sysfs_get_active(of->sd))
+		return -EINVAL;
+
+	ret = 0;
+	if (of->vm_ops->set_policy)
+		ret = of->vm_ops->set_policy(vma, new);
+
+	sysfs_put_active(of->sd);
+	return ret;
+}
+
+static struct mempolicy *kernfs_vma_get_policy(struct vm_area_struct *vma,
+					       unsigned long addr)
+{
+	struct file *file = vma->vm_file;
+	struct sysfs_open_file *of = sysfs_of(file);
+	struct mempolicy *pol;
+
+	if (!of->vm_ops)
+		return vma->vm_policy;
+
+	if (!sysfs_get_active(of->sd))
+		return vma->vm_policy;
+
+	pol = vma->vm_policy;
+	if (of->vm_ops->get_policy)
+		pol = of->vm_ops->get_policy(vma, addr);
+
+	sysfs_put_active(of->sd);
+	return pol;
+}
+
+static int kernfs_vma_migrate(struct vm_area_struct *vma,
+			      const nodemask_t *from, const nodemask_t *to,
+			      unsigned long flags)
+{
+	struct file *file = vma->vm_file;
+	struct sysfs_open_file *of = sysfs_of(file);
+	int ret;
+
+	if (!of->vm_ops)
+		return 0;
+
+	if (!sysfs_get_active(of->sd))
+		return 0;
+
+	ret = 0;
+	if (of->vm_ops->migrate)
+		ret = of->vm_ops->migrate(vma, from, to, flags);
+
+	sysfs_put_active(of->sd);
+	return ret;
+}
+#endif
+
+static const struct vm_operations_struct kernfs_vm_ops = {
+	.open		= kernfs_vma_open,
+	.fault		= kernfs_vma_fault,
+	.page_mkwrite	= kernfs_vma_page_mkwrite,
+	.access		= kernfs_vma_access,
+#ifdef CONFIG_NUMA
+	.set_policy	= kernfs_vma_set_policy,
+	.get_policy	= kernfs_vma_get_policy,
+	.migrate	= kernfs_vma_migrate,
+#endif
+};
+
+static int kernfs_file_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct sysfs_open_file *of = sysfs_of(file);
+	const struct kernfs_ops *ops;
+	int rc;
+
+	mutex_lock(&of->mutex);
+
+	rc = -ENODEV;
+	if (!sysfs_get_active(of->sd))
+		goto out_unlock;
+
+	ops = kernfs_ops(of->sd);
+	if (ops->mmap)
+		rc = ops->mmap(of, vma);
+	if (rc)
+		goto out_put;
+
+	/*
+	 * PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup()
+	 * to satisfy versions of X which crash if the mmap fails: that
+	 * substitutes a new vm_file, and we don't then want bin_vm_ops.
+	 */
+	if (vma->vm_file != file)
+		goto out_put;
+
+	rc = -EINVAL;
+	if (of->mmapped && of->vm_ops != vma->vm_ops)
+		goto out_put;
+
+	/*
+	 * It is not possible to successfully wrap close.
+	 * So error if someone is trying to use close.
+	 */
+	rc = -EINVAL;
+	if (vma->vm_ops && vma->vm_ops->close)
+		goto out_put;
+
+	rc = 0;
+	of->mmapped = 1;
+	of->vm_ops = vma->vm_ops;
+	vma->vm_ops = &kernfs_vm_ops;
+out_put:
+	sysfs_put_active(of->sd);
+out_unlock:
+	mutex_unlock(&of->mutex);
+
+	return rc;
+}
+
+/**
+ *	sysfs_get_open_dirent - get or create sysfs_open_dirent
+ *	@sd: target sysfs_dirent
+ *	@of: sysfs_open_file for this instance of open
+ *
+ *	If @sd->s_attr.open exists, increment its reference count;
+ *	otherwise, create one.  @of is chained to the files list.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+static int sysfs_get_open_dirent(struct sysfs_dirent *sd,
+				 struct sysfs_open_file *of)
+{
+	struct sysfs_open_dirent *od, *new_od = NULL;
+
+ retry:
+	mutex_lock(&sysfs_open_file_mutex);
+	spin_lock_irq(&sysfs_open_dirent_lock);
+
+	if (!sd->s_attr.open && new_od) {
+		sd->s_attr.open = new_od;
+		new_od = NULL;
+	}
+
+	od = sd->s_attr.open;
+	if (od) {
+		atomic_inc(&od->refcnt);
+		list_add_tail(&of->list, &od->files);
+	}
+
+	spin_unlock_irq(&sysfs_open_dirent_lock);
+	mutex_unlock(&sysfs_open_file_mutex);
+
+	if (od) {
+		kfree(new_od);
+		return 0;
+	}
+
+	/* not there, initialize a new one and retry */
+	new_od = kmalloc(sizeof(*new_od), GFP_KERNEL);
+	if (!new_od)
+		return -ENOMEM;
+
+	atomic_set(&new_od->refcnt, 0);
+	atomic_set(&new_od->event, 1);
+	init_waitqueue_head(&new_od->poll);
+	INIT_LIST_HEAD(&new_od->files);
+	goto retry;
+}
+
+/**
+ *	sysfs_put_open_dirent - put sysfs_open_dirent
+ *	@sd: target sysfs_dirent
+ *	@of: associated sysfs_open_file
+ *
+ *	Put @sd->s_attr.open and unlink @of from the files list.  If
+ *	reference count reaches zero, disassociate and free it.
+ *
+ *	LOCKING:
+ *	None.
+ */
+static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
+				  struct sysfs_open_file *of)
+{
+	struct sysfs_open_dirent *od = sd->s_attr.open;
+	unsigned long flags;
+
+	mutex_lock(&sysfs_open_file_mutex);
+	spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
+
+	if (of)
+		list_del(&of->list);
+
+	if (atomic_dec_and_test(&od->refcnt))
+		sd->s_attr.open = NULL;
+	else
+		od = NULL;
+
+	spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
+	mutex_unlock(&sysfs_open_file_mutex);
+
+	kfree(od);
+}
+
+static int kernfs_file_open(struct inode *inode, struct file *file)
+{
+	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
+	const struct kernfs_ops *ops;
+	struct sysfs_open_file *of;
+	bool has_read, has_write, has_mmap;
+	int error = -EACCES;
+
+	if (!sysfs_get_active(attr_sd))
+		return -ENODEV;
+
+	ops = kernfs_ops(attr_sd);
+
+	has_read = ops->seq_show || ops->read || ops->mmap;
+	has_write = ops->write || ops->mmap;
+	has_mmap = ops->mmap;
+
+	/* check perms and supported operations */
+	if ((file->f_mode & FMODE_WRITE) &&
+	    (!(inode->i_mode & S_IWUGO) || !has_write))
+		goto err_out;
+
+	if ((file->f_mode & FMODE_READ) &&
+	    (!(inode->i_mode & S_IRUGO) || !has_read))
+		goto err_out;
+
+	/* allocate a sysfs_open_file for the file */
+	error = -ENOMEM;
+	of = kzalloc(sizeof(struct sysfs_open_file), GFP_KERNEL);
+	if (!of)
+		goto err_out;
+
+	/*
+	 * The following is done to give a different lockdep key to
+	 * @of->mutex for files which implement mmap.  This is a rather
+	 * crude way to avoid false positive lockdep warning around
+	 * mm->mmap_sem - mmap nests @of->mutex under mm->mmap_sem and
+	 * reading /sys/block/sda/trace/act_mask grabs sr_mutex, under
+	 * which mm->mmap_sem nests, while holding @of->mutex.  As each
+	 * open file has a separate mutex, it's okay as long as those don't
+	 * happen on the same file.  At this point, we can't easily give
+	 * each file a separate locking class.  Let's differentiate on
+	 * whether the file has mmap or not for now.
+	 */
+	if (has_mmap)
+		mutex_init(&of->mutex);
+	else
+		mutex_init(&of->mutex);
+
+	of->sd = attr_sd;
+	of->file = file;
+
+	/*
+	 * Always instantiate seq_file even if read access doesn't use
+	 * seq_file or is not requested.  This unifies private data access
+	 * and readable regular files are the vast majority anyway.
+	 */
+	if (ops->seq_show)
+		error = seq_open(file, &kernfs_seq_ops);
+	else
+		error = seq_open(file, NULL);
+	if (error)
+		goto err_free;
+
+	((struct seq_file *)file->private_data)->private = of;
+
+	/* seq_file clears PWRITE unconditionally, restore it if WRITE */
+	if (file->f_mode & FMODE_WRITE)
+		file->f_mode |= FMODE_PWRITE;
+
+	/* make sure we have open dirent struct */
+	error = sysfs_get_open_dirent(attr_sd, of);
+	if (error)
+		goto err_close;
+
+	/* open succeeded, put active references */
+	sysfs_put_active(attr_sd);
+	return 0;
+
+err_close:
+	seq_release(inode, file);
+err_free:
+	kfree(of);
+err_out:
+	sysfs_put_active(attr_sd);
+	return error;
+}
+
+static int kernfs_file_release(struct inode *inode, struct file *filp)
+{
+	struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata;
+	struct sysfs_open_file *of = sysfs_of(filp);
+
+	sysfs_put_open_dirent(sd, of);
+	seq_release(inode, filp);
+	kfree(of);
+
+	return 0;
+}
+
+void sysfs_unmap_bin_file(struct sysfs_dirent *sd)
+{
+	struct sysfs_open_dirent *od;
+	struct sysfs_open_file *of;
+
+	if (!(sd->s_flags & SYSFS_FLAG_HAS_MMAP))
+		return;
+
+	spin_lock_irq(&sysfs_open_dirent_lock);
+	od = sd->s_attr.open;
+	if (od)
+		atomic_inc(&od->refcnt);
+	spin_unlock_irq(&sysfs_open_dirent_lock);
+	if (!od)
+		return;
+
+	mutex_lock(&sysfs_open_file_mutex);
+	list_for_each_entry(of, &od->files, list) {
+		struct inode *inode = file_inode(of->file);
+		unmap_mapping_range(inode->i_mapping, 0, 0, 1);
+	}
+	mutex_unlock(&sysfs_open_file_mutex);
+
+	sysfs_put_open_dirent(sd, NULL);
+}
+
+/* Sysfs attribute files are pollable.  The idea is that you read
+ * the content and then you use 'poll' or 'select' to wait for
+ * the content to change.  When the content changes (assuming the
+ * manager for the kobject supports notification), poll will
+ * return POLLERR|POLLPRI, and select will return the fd whether
+ * it is waiting for read, write, or exceptions.
+ * Once poll/select indicates that the value has changed, you
+ * need to close and re-open the file, or seek to 0 and read again.
+ * Reminder: this only works for attributes which actively support
+ * it, and it is not possible to test an attribute from userspace
+ * to see if it supports poll (Neither 'poll' nor 'select' return
+ * an appropriate error code).  When in doubt, set a suitable timeout value.
+ */
+static unsigned int kernfs_file_poll(struct file *filp, poll_table *wait)
+{
+	struct sysfs_open_file *of = sysfs_of(filp);
+	struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
+	struct sysfs_open_dirent *od = attr_sd->s_attr.open;
+
+	/* need parent for the kobj, grab both */
+	if (!sysfs_get_active(attr_sd))
+		goto trigger;
+
+	poll_wait(filp, &od->poll, wait);
+
+	sysfs_put_active(attr_sd);
+
+	if (of->event != atomic_read(&od->event))
+		goto trigger;
+
+	return DEFAULT_POLLMASK;
+
+ trigger:
+	return DEFAULT_POLLMASK|POLLERR|POLLPRI;
+}
+
+/**
+ * kernfs_notify - notify a kernfs file
+ * @sd: file to notify
+ *
+ * Notify @sd such that poll(2) on @sd wakes up.
+ */
+void kernfs_notify(struct sysfs_dirent *sd)
+{
+	struct sysfs_open_dirent *od;
+	unsigned long flags;
+
+	spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
+
+	if (!WARN_ON(sysfs_type(sd) != SYSFS_KOBJ_ATTR)) {
+		od = sd->s_attr.open;
+		if (od) {
+			atomic_inc(&od->event);
+			wake_up_interruptible(&od->poll);
+		}
+	}
+
+	spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
+}
+EXPORT_SYMBOL_GPL(kernfs_notify);
+
+const struct file_operations kernfs_file_operations = {
+	.read		= kernfs_file_read,
+	.write		= kernfs_file_write,
+	.llseek		= generic_file_llseek,
+	.mmap		= kernfs_file_mmap,
+	.open		= kernfs_file_open,
+	.release	= kernfs_file_release,
+	.poll		= kernfs_file_poll,
+};
+
+/**
+ * kernfs_create_file_ns_key - create a file
+ * @parent: directory to create the file in
+ * @name: name of the file
+ * @mode: mode of the file
+ * @size: size of the file
+ * @ops: kernfs operations for the file
+ * @priv: private data for the file
+ * @ns: optional namespace tag of the file
+ * @key: lockdep key for the file's active_ref, %NULL to disable lockdep
+ *
+ * Returns the created node on success, ERR_PTR() value on error.
+ */
+struct sysfs_dirent *kernfs_create_file_ns_key(struct sysfs_dirent *parent,
+					       const char *name,
+					       umode_t mode, loff_t size,
+					       const struct kernfs_ops *ops,
+					       void *priv, const void *ns,
+					       struct lock_class_key *key)
+{
+	struct sysfs_addrm_cxt acxt;
+	struct sysfs_dirent *sd;
+	int rc;
+
+	sd = sysfs_new_dirent(name, (mode & S_IALLUGO) | S_IFREG,
+			      SYSFS_KOBJ_ATTR);
+	if (!sd)
+		return ERR_PTR(-ENOMEM);
+
+	sd->s_attr.ops = ops;
+	sd->s_attr.size = size;
+	sd->s_ns = ns;
+	sd->priv = priv;
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	if (key) {
+		lockdep_init_map(&sd->dep_map, "s_active", key, 0);
+		sd->s_flags |= SYSFS_FLAG_LOCKDEP;
+	}
+#endif
+
+	/*
+	 * sd->s_attr.ops is accesible only while holding active ref.  We
+	 * need to know whether some ops are implemented outside active
+	 * ref.  Cache their existence in flags.
+	 */
+	if (ops->seq_show)
+		sd->s_flags |= SYSFS_FLAG_HAS_SEQ_SHOW;
+	if (ops->mmap)
+		sd->s_flags |= SYSFS_FLAG_HAS_MMAP;
+
+	sysfs_addrm_start(&acxt);
+	rc = sysfs_add_one(&acxt, sd, parent);
+	sysfs_addrm_finish(&acxt);
+
+	if (rc) {
+		kernfs_put(sd);
+		return ERR_PTR(rc);
+	}
+	return sd;
+}
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 31f0dbe..38e3a16 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -142,4 +142,11 @@ int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
 void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
 struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);
 
+/*
+ * file.c
+ */
+extern const struct file_operations kernfs_file_operations;
+
+void sysfs_unmap_bin_file(struct sysfs_dirent *sd);
+
 #endif	/* __KERNFS_INTERNAL_H */
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 7f0a79f..ac77d2b 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -14,54 +14,12 @@
 #include <linux/kobject.h>
 #include <linux/kallsyms.h>
 #include <linux/slab.h>
-#include <linux/fsnotify.h>
-#include <linux/namei.h>
-#include <linux/poll.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
-#include <linux/limits.h>
-#include <linux/uaccess.h>
 #include <linux/seq_file.h>
-#include <linux/mm.h>
 
 #include "sysfs.h"
-
-/*
- * There's one sysfs_open_file for each open file and one sysfs_open_dirent
- * for each sysfs_dirent with one or more open files.
- *
- * sysfs_dirent->s_attr.open points to sysfs_open_dirent.  s_attr.open is
- * protected by sysfs_open_dirent_lock.
- *
- * filp->private_data points to seq_file whose ->private points to
- * sysfs_open_file.  sysfs_open_files are chained at
- * sysfs_open_dirent->files, which is protected by sysfs_open_file_mutex.
- */
-static DEFINE_SPINLOCK(sysfs_open_dirent_lock);
-static DEFINE_MUTEX(sysfs_open_file_mutex);
-
-struct sysfs_open_dirent {
-	atomic_t		refcnt;
-	atomic_t		event;
-	wait_queue_head_t	poll;
-	struct list_head	files; /* goes through sysfs_open_file.list */
-};
-
-static struct sysfs_open_file *sysfs_of(struct file *file)
-{
-	return ((struct seq_file *)file->private_data)->private;
-}
-
-/*
- * Determine the kernfs_ops for the given sysfs_dirent.  This function must
- * be called while holding an active reference.
- */
-static const struct kernfs_ops *kernfs_ops(struct sysfs_dirent *sd)
-{
-	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
-		lockdep_assert_held(sd);
-	return sd->s_attr.ops;
-}
+#include "../kernfs/kernfs-internal.h"
 
 /*
  * Determine ktype->sysfs_ops for the given sysfs_dirent.  This function
@@ -143,147 +101,6 @@ static ssize_t sysfs_kf_bin_read(struct sysfs_open_file *of, char *buf,
 	return battr->read(of->file, kobj, battr, buf, pos, count);
 }
 
-static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos)
-{
-	struct sysfs_open_file *of = sf->private;
-	const struct kernfs_ops *ops;
-
-	/*
-	 * @of->mutex nests outside active ref and is just to ensure that
-	 * the ops aren't called concurrently for the same open file.
-	 */
-	mutex_lock(&of->mutex);
-	if (!sysfs_get_active(of->sd))
-		return ERR_PTR(-ENODEV);
-
-	ops = kernfs_ops(of->sd);
-	if (ops->seq_start) {
-		return ops->seq_start(sf, ppos);
-	} else {
-		/*
-		 * The same behavior and code as single_open().  Returns
-		 * !NULL if pos is at the beginning; otherwise, NULL.
-		 */
-		return NULL + !*ppos;
-	}
-}
-
-static void *kernfs_seq_next(struct seq_file *sf, void *v, loff_t *ppos)
-{
-	struct sysfs_open_file *of = sf->private;
-	const struct kernfs_ops *ops = kernfs_ops(of->sd);
-
-	if (ops->seq_next) {
-		return ops->seq_next(sf, v, ppos);
-	} else {
-		/*
-		 * The same behavior and code as single_open(), always
-		 * terminate after the initial read.
-		 */
-		++*ppos;
-		return NULL;
-	}
-}
-
-static void kernfs_seq_stop(struct seq_file *sf, void *v)
-{
-	struct sysfs_open_file *of = sf->private;
-	const struct kernfs_ops *ops = kernfs_ops(of->sd);
-
-	if (ops->seq_stop)
-		ops->seq_stop(sf, v);
-
-	sysfs_put_active(of->sd);
-	mutex_unlock(&of->mutex);
-}
-
-static int kernfs_seq_show(struct seq_file *sf, void *v)
-{
-	struct sysfs_open_file *of = sf->private;
-
-	of->event = atomic_read(&of->sd->s_attr.open->event);
-
-	return of->sd->s_attr.ops->seq_show(sf, v);
-}
-
-static const struct seq_operations kernfs_seq_ops = {
-	.start = kernfs_seq_start,
-	.next = kernfs_seq_next,
-	.stop = kernfs_seq_stop,
-	.show = kernfs_seq_show,
-};
-
-/*
- * As reading a bin file can have side-effects, the exact offset and bytes
- * specified in read(2) call should be passed to the read callback making
- * it difficult to use seq_file.  Implement simplistic custom buffering for
- * bin files.
- */
-static ssize_t kernfs_file_direct_read(struct sysfs_open_file *of,
-				       char __user *user_buf, size_t count,
-				       loff_t *ppos)
-{
-	ssize_t len = min_t(size_t, count, PAGE_SIZE);
-	const struct kernfs_ops *ops;
-	char *buf;
-
-	buf = kmalloc(len, GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
-
-	/*
-	 * @of->mutex nests outside active ref and is just to ensure that
-	 * the ops aren't called concurrently for the same open file.
-	 */
-	mutex_lock(&of->mutex);
-	if (!sysfs_get_active(of->sd)) {
-		len = -ENODEV;
-		mutex_unlock(&of->mutex);
-		goto out_free;
-	}
-
-	ops = kernfs_ops(of->sd);
-	if (ops->read)
-		len = ops->read(of, buf, len, *ppos);
-	else
-		len = -EINVAL;
-
-	sysfs_put_active(of->sd);
-	mutex_unlock(&of->mutex);
-
-	if (len < 0)
-		goto out_free;
-
-	if (copy_to_user(user_buf, buf, len)) {
-		len = -EFAULT;
-		goto out_free;
-	}
-
-	*ppos += len;
-
- out_free:
-	kfree(buf);
-	return len;
-}
-
-/**
- * kernfs_file_read - kernfs vfs read callback
- * @file: file pointer
- * @user_buf: data to write
- * @count: number of bytes
- * @ppos: starting offset
- */
-static ssize_t kernfs_file_read(struct file *file, char __user *user_buf,
-				size_t count, loff_t *ppos)
-{
-	struct sysfs_open_file *of = sysfs_of(file);
-
-	if (of->sd->s_flags & SYSFS_FLAG_HAS_SEQ_SHOW)
-		return seq_read(file, user_buf, count, ppos);
-	else
-		return kernfs_file_direct_read(of, user_buf, count, ppos);
-}
-
 /* kernfs write callback for regular sysfs files */
 static ssize_t sysfs_kf_write(struct sysfs_open_file *of, char *buf,
 			      size_t count, loff_t pos)
@@ -319,67 +136,6 @@ static ssize_t sysfs_kf_bin_write(struct sysfs_open_file *of, char *buf,
 	return battr->write(of->file, kobj, battr, buf, pos, count);
 }
 
-/**
- * kernfs_file_write - kernfs vfs write callback
- * @file: file pointer
- * @user_buf: data to write
- * @count: number of bytes
- * @ppos: starting offset
- *
- * Copy data in from userland and pass it to the matching kernfs write
- * operation.
- *
- * There is no easy way for us to know if userspace is only doing a partial
- * write, so we don't support them. We expect the entire buffer to come on
- * the first write.  Hint: if you're writing a value, first read the file,
- * modify only the the value you're changing, then write entire buffer
- * back.
- */
-static ssize_t kernfs_file_write(struct file *file, const char __user *user_buf,
-				 size_t count, loff_t *ppos)
-{
-	struct sysfs_open_file *of = sysfs_of(file);
-	ssize_t len = min_t(size_t, count, PAGE_SIZE);
-	const struct kernfs_ops *ops;
-	char *buf;
-
-	buf = kmalloc(len + 1, GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
-
-	if (copy_from_user(buf, user_buf, len)) {
-		len = -EFAULT;
-		goto out_free;
-	}
-	buf[len] = '\0';	/* guarantee string termination */
-
-	/*
-	 * @of->mutex nests outside active ref and is just to ensure that
-	 * the ops aren't called concurrently for the same open file.
-	 */
-	mutex_lock(&of->mutex);
-	if (!sysfs_get_active(of->sd)) {
-		mutex_unlock(&of->mutex);
-		len = -ENODEV;
-		goto out_free;
-	}
-
-	ops = kernfs_ops(of->sd);
-	if (ops->write)
-		len = ops->write(of, buf, len, *ppos);
-	else
-		len = -EINVAL;
-
-	sysfs_put_active(of->sd);
-	mutex_unlock(&of->mutex);
-
-	if (len > 0)
-		*ppos += len;
-out_free:
-	kfree(buf);
-	return len;
-}
-
 static int sysfs_kf_bin_mmap(struct sysfs_open_file *of,
 			     struct vm_area_struct *vma)
 {
@@ -392,490 +148,6 @@ static int sysfs_kf_bin_mmap(struct sysfs_open_file *of,
 	return battr->mmap(of->file, kobj, battr, vma);
 }
 
-static void kernfs_vma_open(struct vm_area_struct *vma)
-{
-	struct file *file = vma->vm_file;
-	struct sysfs_open_file *of = sysfs_of(file);
-
-	if (!of->vm_ops)
-		return;
-
-	if (!sysfs_get_active(of->sd))
-		return;
-
-	if (of->vm_ops->open)
-		of->vm_ops->open(vma);
-
-	sysfs_put_active(of->sd);
-}
-
-static int kernfs_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
-{
-	struct file *file = vma->vm_file;
-	struct sysfs_open_file *of = sysfs_of(file);
-	int ret;
-
-	if (!of->vm_ops)
-		return VM_FAULT_SIGBUS;
-
-	if (!sysfs_get_active(of->sd))
-		return VM_FAULT_SIGBUS;
-
-	ret = VM_FAULT_SIGBUS;
-	if (of->vm_ops->fault)
-		ret = of->vm_ops->fault(vma, vmf);
-
-	sysfs_put_active(of->sd);
-	return ret;
-}
-
-static int kernfs_vma_page_mkwrite(struct vm_area_struct *vma,
-				   struct vm_fault *vmf)
-{
-	struct file *file = vma->vm_file;
-	struct sysfs_open_file *of = sysfs_of(file);
-	int ret;
-
-	if (!of->vm_ops)
-		return VM_FAULT_SIGBUS;
-
-	if (!sysfs_get_active(of->sd))
-		return VM_FAULT_SIGBUS;
-
-	ret = 0;
-	if (of->vm_ops->page_mkwrite)
-		ret = of->vm_ops->page_mkwrite(vma, vmf);
-	else
-		file_update_time(file);
-
-	sysfs_put_active(of->sd);
-	return ret;
-}
-
-static int kernfs_vma_access(struct vm_area_struct *vma, unsigned long addr,
-			     void *buf, int len, int write)
-{
-	struct file *file = vma->vm_file;
-	struct sysfs_open_file *of = sysfs_of(file);
-	int ret;
-
-	if (!of->vm_ops)
-		return -EINVAL;
-
-	if (!sysfs_get_active(of->sd))
-		return -EINVAL;
-
-	ret = -EINVAL;
-	if (of->vm_ops->access)
-		ret = of->vm_ops->access(vma, addr, buf, len, write);
-
-	sysfs_put_active(of->sd);
-	return ret;
-}
-
-#ifdef CONFIG_NUMA
-static int kernfs_vma_set_policy(struct vm_area_struct *vma,
-				 struct mempolicy *new)
-{
-	struct file *file = vma->vm_file;
-	struct sysfs_open_file *of = sysfs_of(file);
-	int ret;
-
-	if (!of->vm_ops)
-		return 0;
-
-	if (!sysfs_get_active(of->sd))
-		return -EINVAL;
-
-	ret = 0;
-	if (of->vm_ops->set_policy)
-		ret = of->vm_ops->set_policy(vma, new);
-
-	sysfs_put_active(of->sd);
-	return ret;
-}
-
-static struct mempolicy *kernfs_vma_get_policy(struct vm_area_struct *vma,
-					       unsigned long addr)
-{
-	struct file *file = vma->vm_file;
-	struct sysfs_open_file *of = sysfs_of(file);
-	struct mempolicy *pol;
-
-	if (!of->vm_ops)
-		return vma->vm_policy;
-
-	if (!sysfs_get_active(of->sd))
-		return vma->vm_policy;
-
-	pol = vma->vm_policy;
-	if (of->vm_ops->get_policy)
-		pol = of->vm_ops->get_policy(vma, addr);
-
-	sysfs_put_active(of->sd);
-	return pol;
-}
-
-static int kernfs_vma_migrate(struct vm_area_struct *vma,
-			      const nodemask_t *from, const nodemask_t *to,
-			      unsigned long flags)
-{
-	struct file *file = vma->vm_file;
-	struct sysfs_open_file *of = sysfs_of(file);
-	int ret;
-
-	if (!of->vm_ops)
-		return 0;
-
-	if (!sysfs_get_active(of->sd))
-		return 0;
-
-	ret = 0;
-	if (of->vm_ops->migrate)
-		ret = of->vm_ops->migrate(vma, from, to, flags);
-
-	sysfs_put_active(of->sd);
-	return ret;
-}
-#endif
-
-static const struct vm_operations_struct kernfs_vm_ops = {
-	.open		= kernfs_vma_open,
-	.fault		= kernfs_vma_fault,
-	.page_mkwrite	= kernfs_vma_page_mkwrite,
-	.access		= kernfs_vma_access,
-#ifdef CONFIG_NUMA
-	.set_policy	= kernfs_vma_set_policy,
-	.get_policy	= kernfs_vma_get_policy,
-	.migrate	= kernfs_vma_migrate,
-#endif
-};
-
-static int kernfs_file_mmap(struct file *file, struct vm_area_struct *vma)
-{
-	struct sysfs_open_file *of = sysfs_of(file);
-	const struct kernfs_ops *ops;
-	int rc;
-
-	mutex_lock(&of->mutex);
-
-	rc = -ENODEV;
-	if (!sysfs_get_active(of->sd))
-		goto out_unlock;
-
-	ops = kernfs_ops(of->sd);
-	if (ops->mmap)
-		rc = ops->mmap(of, vma);
-	if (rc)
-		goto out_put;
-
-	/*
-	 * PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup()
-	 * to satisfy versions of X which crash if the mmap fails: that
-	 * substitutes a new vm_file, and we don't then want bin_vm_ops.
-	 */
-	if (vma->vm_file != file)
-		goto out_put;
-
-	rc = -EINVAL;
-	if (of->mmapped && of->vm_ops != vma->vm_ops)
-		goto out_put;
-
-	/*
-	 * It is not possible to successfully wrap close.
-	 * So error if someone is trying to use close.
-	 */
-	rc = -EINVAL;
-	if (vma->vm_ops && vma->vm_ops->close)
-		goto out_put;
-
-	rc = 0;
-	of->mmapped = 1;
-	of->vm_ops = vma->vm_ops;
-	vma->vm_ops = &kernfs_vm_ops;
-out_put:
-	sysfs_put_active(of->sd);
-out_unlock:
-	mutex_unlock(&of->mutex);
-
-	return rc;
-}
-
-/**
- *	sysfs_get_open_dirent - get or create sysfs_open_dirent
- *	@sd: target sysfs_dirent
- *	@of: sysfs_open_file for this instance of open
- *
- *	If @sd->s_attr.open exists, increment its reference count;
- *	otherwise, create one.  @of is chained to the files list.
- *
- *	LOCKING:
- *	Kernel thread context (may sleep).
- *
- *	RETURNS:
- *	0 on success, -errno on failure.
- */
-static int sysfs_get_open_dirent(struct sysfs_dirent *sd,
-				 struct sysfs_open_file *of)
-{
-	struct sysfs_open_dirent *od, *new_od = NULL;
-
- retry:
-	mutex_lock(&sysfs_open_file_mutex);
-	spin_lock_irq(&sysfs_open_dirent_lock);
-
-	if (!sd->s_attr.open && new_od) {
-		sd->s_attr.open = new_od;
-		new_od = NULL;
-	}
-
-	od = sd->s_attr.open;
-	if (od) {
-		atomic_inc(&od->refcnt);
-		list_add_tail(&of->list, &od->files);
-	}
-
-	spin_unlock_irq(&sysfs_open_dirent_lock);
-	mutex_unlock(&sysfs_open_file_mutex);
-
-	if (od) {
-		kfree(new_od);
-		return 0;
-	}
-
-	/* not there, initialize a new one and retry */
-	new_od = kmalloc(sizeof(*new_od), GFP_KERNEL);
-	if (!new_od)
-		return -ENOMEM;
-
-	atomic_set(&new_od->refcnt, 0);
-	atomic_set(&new_od->event, 1);
-	init_waitqueue_head(&new_od->poll);
-	INIT_LIST_HEAD(&new_od->files);
-	goto retry;
-}
-
-/**
- *	sysfs_put_open_dirent - put sysfs_open_dirent
- *	@sd: target sysfs_dirent
- *	@of: associated sysfs_open_file
- *
- *	Put @sd->s_attr.open and unlink @of from the files list.  If
- *	reference count reaches zero, disassociate and free it.
- *
- *	LOCKING:
- *	None.
- */
-static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
-				  struct sysfs_open_file *of)
-{
-	struct sysfs_open_dirent *od = sd->s_attr.open;
-	unsigned long flags;
-
-	mutex_lock(&sysfs_open_file_mutex);
-	spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
-
-	if (of)
-		list_del(&of->list);
-
-	if (atomic_dec_and_test(&od->refcnt))
-		sd->s_attr.open = NULL;
-	else
-		od = NULL;
-
-	spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
-	mutex_unlock(&sysfs_open_file_mutex);
-
-	kfree(od);
-}
-
-static int kernfs_file_open(struct inode *inode, struct file *file)
-{
-	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
-	const struct kernfs_ops *ops;
-	struct sysfs_open_file *of;
-	bool has_read, has_write, has_mmap;
-	int error = -EACCES;
-
-	if (!sysfs_get_active(attr_sd))
-		return -ENODEV;
-
-	ops = kernfs_ops(attr_sd);
-
-	has_read = ops->seq_show || ops->read || ops->mmap;
-	has_write = ops->write || ops->mmap;
-	has_mmap = ops->mmap;
-
-	/* check perms and supported operations */
-	if ((file->f_mode & FMODE_WRITE) &&
-	    (!(inode->i_mode & S_IWUGO) || !has_write))
-		goto err_out;
-
-	if ((file->f_mode & FMODE_READ) &&
-	    (!(inode->i_mode & S_IRUGO) || !has_read))
-		goto err_out;
-
-	/* allocate a sysfs_open_file for the file */
-	error = -ENOMEM;
-	of = kzalloc(sizeof(struct sysfs_open_file), GFP_KERNEL);
-	if (!of)
-		goto err_out;
-
-	/*
-	 * The following is done to give a different lockdep key to
-	 * @of->mutex for files which implement mmap.  This is a rather
-	 * crude way to avoid false positive lockdep warning around
-	 * mm->mmap_sem - mmap nests @of->mutex under mm->mmap_sem and
-	 * reading /sys/block/sda/trace/act_mask grabs sr_mutex, under
-	 * which mm->mmap_sem nests, while holding @of->mutex.  As each
-	 * open file has a separate mutex, it's okay as long as those don't
-	 * happen on the same file.  At this point, we can't easily give
-	 * each file a separate locking class.  Let's differentiate on
-	 * whether the file has mmap or not for now.
-	 */
-	if (has_mmap)
-		mutex_init(&of->mutex);
-	else
-		mutex_init(&of->mutex);
-
-	of->sd = attr_sd;
-	of->file = file;
-
-	/*
-	 * Always instantiate seq_file even if read access doesn't use
-	 * seq_file or is not requested.  This unifies private data access
-	 * and readable regular files are the vast majority anyway.
-	 */
-	if (ops->seq_show)
-		error = seq_open(file, &kernfs_seq_ops);
-	else
-		error = seq_open(file, NULL);
-	if (error)
-		goto err_free;
-
-	((struct seq_file *)file->private_data)->private = of;
-
-	/* seq_file clears PWRITE unconditionally, restore it if WRITE */
-	if (file->f_mode & FMODE_WRITE)
-		file->f_mode |= FMODE_PWRITE;
-
-	/* make sure we have open dirent struct */
-	error = sysfs_get_open_dirent(attr_sd, of);
-	if (error)
-		goto err_close;
-
-	/* open succeeded, put active references */
-	sysfs_put_active(attr_sd);
-	return 0;
-
-err_close:
-	seq_release(inode, file);
-err_free:
-	kfree(of);
-err_out:
-	sysfs_put_active(attr_sd);
-	return error;
-}
-
-static int kernfs_file_release(struct inode *inode, struct file *filp)
-{
-	struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata;
-	struct sysfs_open_file *of = sysfs_of(filp);
-
-	sysfs_put_open_dirent(sd, of);
-	seq_release(inode, filp);
-	kfree(of);
-
-	return 0;
-}
-
-void sysfs_unmap_bin_file(struct sysfs_dirent *sd)
-{
-	struct sysfs_open_dirent *od;
-	struct sysfs_open_file *of;
-
-	if (!(sd->s_flags & SYSFS_FLAG_HAS_MMAP))
-		return;
-
-	spin_lock_irq(&sysfs_open_dirent_lock);
-	od = sd->s_attr.open;
-	if (od)
-		atomic_inc(&od->refcnt);
-	spin_unlock_irq(&sysfs_open_dirent_lock);
-	if (!od)
-		return;
-
-	mutex_lock(&sysfs_open_file_mutex);
-	list_for_each_entry(of, &od->files, list) {
-		struct inode *inode = file_inode(of->file);
-		unmap_mapping_range(inode->i_mapping, 0, 0, 1);
-	}
-	mutex_unlock(&sysfs_open_file_mutex);
-
-	sysfs_put_open_dirent(sd, NULL);
-}
-
-/* Sysfs attribute files are pollable.  The idea is that you read
- * the content and then you use 'poll' or 'select' to wait for
- * the content to change.  When the content changes (assuming the
- * manager for the kobject supports notification), poll will
- * return POLLERR|POLLPRI, and select will return the fd whether
- * it is waiting for read, write, or exceptions.
- * Once poll/select indicates that the value has changed, you
- * need to close and re-open the file, or seek to 0 and read again.
- * Reminder: this only works for attributes which actively support
- * it, and it is not possible to test an attribute from userspace
- * to see if it supports poll (Neither 'poll' nor 'select' return
- * an appropriate error code).  When in doubt, set a suitable timeout value.
- */
-static unsigned int kernfs_file_poll(struct file *filp, poll_table *wait)
-{
-	struct sysfs_open_file *of = sysfs_of(filp);
-	struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
-	struct sysfs_open_dirent *od = attr_sd->s_attr.open;
-
-	/* need parent for the kobj, grab both */
-	if (!sysfs_get_active(attr_sd))
-		goto trigger;
-
-	poll_wait(filp, &od->poll, wait);
-
-	sysfs_put_active(attr_sd);
-
-	if (of->event != atomic_read(&od->event))
-		goto trigger;
-
-	return DEFAULT_POLLMASK;
-
- trigger:
-	return DEFAULT_POLLMASK|POLLERR|POLLPRI;
-}
-
-/**
- * kernfs_notify - notify a kernfs file
- * @sd: file to notify
- *
- * Notify @sd such that poll(2) on @sd wakes up.
- */
-void kernfs_notify(struct sysfs_dirent *sd)
-{
-	struct sysfs_open_dirent *od;
-	unsigned long flags;
-
-	spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
-
-	if (!WARN_ON(sysfs_type(sd) != SYSFS_KOBJ_ATTR)) {
-		od = sd->s_attr.open;
-		if (od) {
-			atomic_inc(&od->event);
-			wake_up_interruptible(&od->poll);
-		}
-	}
-
-	spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
-}
-EXPORT_SYMBOL_GPL(kernfs_notify);
-
 void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
 {
 	struct sysfs_dirent *sd = k->sd, *tmp;
@@ -898,16 +170,6 @@ void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
 }
 EXPORT_SYMBOL_GPL(sysfs_notify);
 
-const struct file_operations kernfs_file_operations = {
-	.read		= kernfs_file_read,
-	.write		= kernfs_file_write,
-	.llseek		= generic_file_llseek,
-	.mmap		= kernfs_file_mmap,
-	.open		= kernfs_file_open,
-	.release	= kernfs_file_release,
-	.poll		= kernfs_file_poll,
-};
-
 static const struct kernfs_ops sysfs_file_kfops_empty = {
 };
 
@@ -996,68 +258,6 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 	return 0;
 }
 
-/**
- * kernfs_create_file_ns_key - create a file
- * @parent: directory to create the file in
- * @name: name of the file
- * @mode: mode of the file
- * @size: size of the file
- * @ops: kernfs operations for the file
- * @priv: private data for the file
- * @ns: optional namespace tag of the file
- * @key: lockdep key for the file's active_ref, %NULL to disable lockdep
- *
- * Returns the created node on success, ERR_PTR() value on error.
- */
-struct sysfs_dirent *kernfs_create_file_ns_key(struct sysfs_dirent *parent,
-					       const char *name,
-					       umode_t mode, loff_t size,
-					       const struct kernfs_ops *ops,
-					       void *priv, const void *ns,
-					       struct lock_class_key *key)
-{
-	struct sysfs_addrm_cxt acxt;
-	struct sysfs_dirent *sd;
-	int rc;
-
-	sd = sysfs_new_dirent(name, (mode & S_IALLUGO) | S_IFREG,
-			      SYSFS_KOBJ_ATTR);
-	if (!sd)
-		return ERR_PTR(-ENOMEM);
-
-	sd->s_attr.ops = ops;
-	sd->s_attr.size = size;
-	sd->s_ns = ns;
-	sd->priv = priv;
-
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-	if (key) {
-		lockdep_init_map(&sd->dep_map, "s_active", key, 0);
-		sd->s_flags |= SYSFS_FLAG_LOCKDEP;
-	}
-#endif
-
-	/*
-	 * sd->s_attr.ops is accesible only while holding active ref.  We
-	 * need to know whether some ops are implemented outside active
-	 * ref.  Cache their existence in flags.
-	 */
-	if (ops->seq_show)
-		sd->s_flags |= SYSFS_FLAG_HAS_SEQ_SHOW;
-	if (ops->mmap)
-		sd->s_flags |= SYSFS_FLAG_HAS_MMAP;
-
-	sysfs_addrm_start(&acxt);
-	rc = sysfs_add_one(&acxt, sd, parent);
-	sysfs_addrm_finish(&acxt);
-
-	if (rc) {
-		kernfs_put(sd);
-		return ERR_PTR(rc);
-	}
-	return sd;
-}
-
 int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
 		   bool is_bin)
 {
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 972b4a4..4b8b60d 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -41,15 +41,11 @@ void sysfs_warn_dup(struct sysfs_dirent *parent, const char *name);
 /*
  * file.c
  */
-extern const struct file_operations kernfs_file_operations;
-
 int sysfs_add_file(struct sysfs_dirent *dir_sd,
 		   const struct attribute *attr, bool is_bin);
-
 int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 			   const struct attribute *attr, bool is_bin,
 			   umode_t amode, const void *ns);
-void sysfs_unmap_bin_file(struct sysfs_dirent *sd);
 
 /*
  * symlink.c
-- 
1.8.4.2

[PATCH 29/41] sysfs, kernfs: move symlink core code to fs/kernfs/symlink.c

[Tejun Heo]

Move core symlink code to fs/kernfs/symlink.c.  fs/sysfs/symlink.c now
only contains sysfs wrappers around kernfs interfaces.  The respective
declarations in fs/sysfs/sysfs.h are moved to
fs/kernfs/kernfs-internal.h.

This is pure relocation.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/kernfs-internal.h |   5 ++
 fs/kernfs/symlink.c         | 139 ++++++++++++++++++++++++++++++++++++++++++++
 fs/sysfs/symlink.c          | 137 -------------------------------------------
 fs/sysfs/sysfs.h            |   1 -
 4 files changed, 144 insertions(+), 138 deletions(-)

diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 38e3a16..62ae35f 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -149,4 +149,9 @@ extern const struct file_operations kernfs_file_operations;
 
 void sysfs_unmap_bin_file(struct sysfs_dirent *sd);
 
+/*
+ * symlink.c
+ */
+extern const struct inode_operations sysfs_symlink_inode_operations;
+
 #endif	/* __KERNFS_INTERNAL_H */
diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c
index 2578715..af3570b 100644
--- a/fs/kernfs/symlink.c
+++ b/fs/kernfs/symlink.c
@@ -7,3 +7,142 @@
  *
  * This file is released under the GPLv2.
  */
+
+#include <linux/fs.h>
+#include <linux/gfp.h>
+#include <linux/namei.h>
+
+#include "kernfs-internal.h"
+
+/**
+ * kernfs_create_link - create a symlink
+ * @parent: directory to create the symlink in
+ * @name: name of the symlink
+ * @target: target node for the symlink to point to
+ *
+ * Returns the created node on success, ERR_PTR() value on error.
+ */
+struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
+					const char *name,
+					struct sysfs_dirent *target)
+{
+	struct sysfs_dirent *sd;
+	struct sysfs_addrm_cxt acxt;
+	int error;
+
+	sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
+	if (!sd)
+		return ERR_PTR(-ENOMEM);
+
+	if (parent->s_flags & SYSFS_FLAG_NS)
+		sd->s_ns = target->s_ns;
+	sd->s_symlink.target_sd = target;
+	kernfs_get(target);	/* ref owned by symlink */
+
+	sysfs_addrm_start(&acxt);
+	error = sysfs_add_one(&acxt, sd, parent);
+	sysfs_addrm_finish(&acxt);
+
+	if (!error)
+		return sd;
+
+	kernfs_put(sd);
+	return ERR_PTR(error);
+}
+
+static int sysfs_get_target_path(struct sysfs_dirent *parent_sd,
+				 struct sysfs_dirent *target_sd, char *path)
+{
+	struct sysfs_dirent *base, *sd;
+	char *s = path;
+	int len = 0;
+
+	/* go up to the root, stop at the base */
+	base = parent_sd;
+	while (base->s_parent) {
+		sd = target_sd->s_parent;
+		while (sd->s_parent && base != sd)
+			sd = sd->s_parent;
+
+		if (base == sd)
+			break;
+
+		strcpy(s, "../");
+		s += 3;
+		base = base->s_parent;
+	}
+
+	/* determine end of target string for reverse fillup */
+	sd = target_sd;
+	while (sd->s_parent && sd != base) {
+		len += strlen(sd->s_name) + 1;
+		sd = sd->s_parent;
+	}
+
+	/* check limits */
+	if (len < 2)
+		return -EINVAL;
+	len--;
+	if ((s - path) + len > PATH_MAX)
+		return -ENAMETOOLONG;
+
+	/* reverse fillup of target string from target to base */
+	sd = target_sd;
+	while (sd->s_parent && sd != base) {
+		int slen = strlen(sd->s_name);
+
+		len -= slen;
+		strncpy(s + len, sd->s_name, slen);
+		if (len)
+			s[--len] = '/';
+
+		sd = sd->s_parent;
+	}
+
+	return 0;
+}
+
+static int sysfs_getlink(struct dentry *dentry, char *path)
+{
+	struct sysfs_dirent *sd = dentry->d_fsdata;
+	struct sysfs_dirent *parent_sd = sd->s_parent;
+	struct sysfs_dirent *target_sd = sd->s_symlink.target_sd;
+	int error;
+
+	mutex_lock(&sysfs_mutex);
+	error = sysfs_get_target_path(parent_sd, target_sd, path);
+	mutex_unlock(&sysfs_mutex);
+
+	return error;
+}
+
+static void *sysfs_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+	int error = -ENOMEM;
+	unsigned long page = get_zeroed_page(GFP_KERNEL);
+	if (page) {
+		error = sysfs_getlink(dentry, (char *) page);
+		if (error < 0)
+			free_page((unsigned long)page);
+	}
+	nd_set_link(nd, error ? ERR_PTR(error) : (char *)page);
+	return NULL;
+}
+
+static void sysfs_put_link(struct dentry *dentry, struct nameidata *nd,
+			   void *cookie)
+{
+	char *page = nd_get_link(nd);
+	if (!IS_ERR(page))
+		free_page((unsigned long)page);
+}
+
+const struct inode_operations sysfs_symlink_inode_operations = {
+	.setxattr	= sysfs_setxattr,
+	.readlink	= generic_readlink,
+	.follow_link	= sysfs_follow_link,
+	.put_link	= sysfs_put_link,
+	.setattr	= sysfs_setattr,
+	.getattr	= sysfs_getattr,
+	.permission	= sysfs_permission,
+};
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index b137aa3..6797c9c 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -11,53 +11,13 @@
  */
 
 #include <linux/fs.h>
-#include <linux/gfp.h>
-#include <linux/mount.h>
 #include <linux/module.h>
 #include <linux/kobject.h>
-#include <linux/namei.h>
 #include <linux/mutex.h>
 #include <linux/security.h>
 
 #include "sysfs.h"
 
-/**
- * kernfs_create_link - create a symlink
- * @parent: directory to create the symlink in
- * @name: name of the symlink
- * @target: target node for the symlink to point to
- *
- * Returns the created node on success, ERR_PTR() value on error.
- */
-struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
-					const char *name,
-					struct sysfs_dirent *target)
-{
-	struct sysfs_dirent *sd;
-	struct sysfs_addrm_cxt acxt;
-	int error;
-
-	sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
-	if (!sd)
-		return ERR_PTR(-ENOMEM);
-
-	if (parent->s_flags & SYSFS_FLAG_NS)
-		sd->s_ns = target->s_ns;
-	sd->s_symlink.target_sd = target;
-	kernfs_get(target);	/* ref owned by symlink */
-
-	sysfs_addrm_start(&acxt);
-	error = sysfs_add_one(&acxt, sd, parent);
-	sysfs_addrm_finish(&acxt);
-
-	if (!error)
-		return sd;
-
-	kernfs_put(sd);
-	return ERR_PTR(error);
-}
-
-
 static int sysfs_do_create_link_sd(struct sysfs_dirent *parent_sd,
 				   struct kobject *target,
 				   const char *name, int warn)
@@ -235,100 +195,3 @@ out:
 	return result;
 }
 EXPORT_SYMBOL_GPL(sysfs_rename_link_ns);
-
-static int sysfs_get_target_path(struct sysfs_dirent *parent_sd,
-				 struct sysfs_dirent *target_sd, char *path)
-{
-	struct sysfs_dirent *base, *sd;
-	char *s = path;
-	int len = 0;
-
-	/* go up to the root, stop at the base */
-	base = parent_sd;
-	while (base->s_parent) {
-		sd = target_sd->s_parent;
-		while (sd->s_parent && base != sd)
-			sd = sd->s_parent;
-
-		if (base == sd)
-			break;
-
-		strcpy(s, "../");
-		s += 3;
-		base = base->s_parent;
-	}
-
-	/* determine end of target string for reverse fillup */
-	sd = target_sd;
-	while (sd->s_parent && sd != base) {
-		len += strlen(sd->s_name) + 1;
-		sd = sd->s_parent;
-	}
-
-	/* check limits */
-	if (len < 2)
-		return -EINVAL;
-	len--;
-	if ((s - path) + len > PATH_MAX)
-		return -ENAMETOOLONG;
-
-	/* reverse fillup of target string from target to base */
-	sd = target_sd;
-	while (sd->s_parent && sd != base) {
-		int slen = strlen(sd->s_name);
-
-		len -= slen;
-		strncpy(s + len, sd->s_name, slen);
-		if (len)
-			s[--len] = '/';
-
-		sd = sd->s_parent;
-	}
-
-	return 0;
-}
-
-static int sysfs_getlink(struct dentry *dentry, char *path)
-{
-	struct sysfs_dirent *sd = dentry->d_fsdata;
-	struct sysfs_dirent *parent_sd = sd->s_parent;
-	struct sysfs_dirent *target_sd = sd->s_symlink.target_sd;
-	int error;
-
-	mutex_lock(&sysfs_mutex);
-	error = sysfs_get_target_path(parent_sd, target_sd, path);
-	mutex_unlock(&sysfs_mutex);
-
-	return error;
-}
-
-static void *sysfs_follow_link(struct dentry *dentry, struct nameidata *nd)
-{
-	int error = -ENOMEM;
-	unsigned long page = get_zeroed_page(GFP_KERNEL);
-	if (page) {
-		error = sysfs_getlink(dentry, (char *) page);
-		if (error < 0)
-			free_page((unsigned long)page);
-	}
-	nd_set_link(nd, error ? ERR_PTR(error) : (char *)page);
-	return NULL;
-}
-
-static void sysfs_put_link(struct dentry *dentry, struct nameidata *nd,
-			   void *cookie)
-{
-	char *page = nd_get_link(nd);
-	if (!IS_ERR(page))
-		free_page((unsigned long)page);
-}
-
-const struct inode_operations sysfs_symlink_inode_operations = {
-	.setxattr	= sysfs_setxattr,
-	.readlink	= generic_readlink,
-	.follow_link	= sysfs_follow_link,
-	.put_link	= sysfs_put_link,
-	.setattr	= sysfs_setattr,
-	.getattr	= sysfs_getattr,
-	.permission	= sysfs_permission,
-};
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 4b8b60d..6d0dcea 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -50,7 +50,6 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 /*
  * symlink.c
  */
-extern const struct inode_operations sysfs_symlink_inode_operations;
 int sysfs_create_link_sd(struct sysfs_dirent *sd, struct kobject *target,
 			 const char *name);
 
-- 
1.8.4.2

[PATCH 30/41] sysfs, kernfs: drop unused params from sysfs_fill_super()

[Tejun Heo]

sysfs_fill_super() takes three params - @sb, @data and @silent - but
uses only @sb.  Drop the latter two.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/mount.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 852d115..21070c2 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -41,7 +41,7 @@ struct sysfs_dirent sysfs_root = {
 	.s_ino		= 1,
 };
 
-static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
+static int sysfs_fill_super(struct super_block *sb)
 {
 	struct inode *inode;
 	struct dentry *root;
@@ -123,7 +123,7 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 	if (IS_ERR(sb))
 		return ERR_CAST(sb);
 	if (!sb->s_root) {
-		error = sysfs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
+		error = sysfs_fill_super(sb);
 		if (error) {
 			deactivate_locked_super(sb);
 			return ERR_PTR(error);
-- 
1.8.4.2

[PATCH 31/41] sysfs, kernfs: make sysfs_super_info->ns const

[Tejun Heo]

Add const qualifier to sysfs_super_info->ns so that it's consistent
with other namespace tag usages in sysfs.  Because kobject doesn't use
const qualifier for namespace tags, this ends up requiring an explicit
cast to drop const qualifier in free_sysfs_super_info().

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/mount.c |  2 +-
 fs/sysfs/sysfs.h | 14 +++++++-------
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 21070c2..fcbe5e8 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -92,7 +92,7 @@ static int sysfs_set_super(struct super_block *sb, void *data)
 
 static void free_sysfs_super_info(struct sysfs_super_info *info)
 {
-	kobj_ns_drop(KOBJ_NS_TYPE_NET, info->ns);
+	kobj_ns_drop(KOBJ_NS_TYPE_NET, (void *)info->ns);
 	kfree(info);
 }
 
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 6d0dcea..ce97907 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -18,14 +18,14 @@
  * mount.c
  */
 
-/*
- * Each sb is associated with one namespace tag, currently the network
- * namespace of the task which mounted this sysfs instance.  If multiple
- * tags become necessary, make the following an array and compare
- * sysfs_dirent tag against every entry.
- */
 struct sysfs_super_info {
-	void *ns;
+	/*
+	 * Each sb is associated with one namespace tag, currently the network
+	 * namespace of the task which mounted this sysfs instance.  If multiple
+	 * tags become necessary, make the following an array and compare
+	 * sysfs_dirent tag against every entry.
+	 */
+	const void		*ns;
 };
 #define sysfs_info(SB) ((struct sysfs_super_info *)(SB->s_fs_info))
 extern struct sysfs_dirent sysfs_root;
-- 
1.8.4.2

[PATCH 32/41] sysfs, kernfs: no need to kern_mount() sysfs from sysfs_init()

[Tejun Heo]

It has been very long since sysfs depended on vfs to keep track of
internal states and whether sysfs is mounted or not doesn't make any
difference to sysfs's internal operation.

In addition to init and filesystem type registration, sysfs_init()
invokes kern_mount() to create in-kernel mount of sysfs.  This
internal mounting doesn't server any purpose anymore.  Remove it.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/mount.c | 23 +++++++----------------
 1 file changed, 7 insertions(+), 16 deletions(-)

diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index fcbe5e8..0c80f03 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -24,7 +24,6 @@
 #include "sysfs.h"
 
 
-static struct vfsmount *sysfs_mnt;
 struct kmem_cache *sysfs_dir_cachep;
 
 static const struct super_operations sysfs_ops = {
@@ -153,34 +152,26 @@ static struct file_system_type sysfs_fs_type = {
 
 int __init sysfs_init(void)
 {
-	int err = -ENOMEM;
+	int err;
 
 	sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
 					      sizeof(struct sysfs_dirent),
 					      0, 0, NULL);
 	if (!sysfs_dir_cachep)
-		goto out;
+		return -ENOMEM;
 
 	err = sysfs_inode_init();
 	if (err)
 		goto out_err;
 
 	err = register_filesystem(&sysfs_fs_type);
-	if (!err) {
-		sysfs_mnt = kern_mount(&sysfs_fs_type);
-		if (IS_ERR(sysfs_mnt)) {
-			printk(KERN_ERR "sysfs: could not mount!\n");
-			err = PTR_ERR(sysfs_mnt);
-			sysfs_mnt = NULL;
-			unregister_filesystem(&sysfs_fs_type);
-			goto out_err;
-		}
-	} else
+	if (err)
 		goto out_err;
-out:
-	return err;
+
+	return 0;
+
 out_err:
 	kmem_cache_destroy(sysfs_dir_cachep);
 	sysfs_dir_cachep = NULL;
-	goto out;
+	return err;
 }
-- 
1.8.4.2

[PATCH 33/41] sysfs, kernfs: introduce sysfs_root_sd

[Tejun Heo]

Currently, it's assumed that there's a single kernfs hierarchy in the
system anchored at sysfs_root which is defined as a global struct.  To
allow other users of kernfs, this will be made dynamic.  Introduce a
new global variable sysfs_root_sd which points to &sysfs_root and
convert all &sysfs_root users.

This patch doesn't introduce any behavior difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/dir.c     | 4 ++--
 fs/sysfs/mount.c   | 8 +++++---
 fs/sysfs/symlink.c | 6 +++---
 fs/sysfs/sysfs.h   | 2 +-
 4 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index e5c4e71..2fea501 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -68,7 +68,7 @@ int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
 	if (kobj->parent)
 		parent_sd = kobj->parent->sd;
 	else
-		parent_sd = &sysfs_root;
+		parent_sd = sysfs_root_sd;
 
 	if (!parent_sd)
 		return -ENOENT;
@@ -134,7 +134,7 @@ int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
 
 	BUG_ON(!sd->s_parent);
 	new_parent_sd = new_parent_kobj && new_parent_kobj->sd ?
-		new_parent_kobj->sd : &sysfs_root;
+		new_parent_kobj->sd : sysfs_root_sd;
 
 	return kernfs_rename_ns(sd, new_parent_sd, sd->s_name, new_ns);
 }
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 0c80f03..7cbd1fc 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -32,7 +32,7 @@ static const struct super_operations sysfs_ops = {
 	.evict_inode	= sysfs_evict_inode,
 };
 
-struct sysfs_dirent sysfs_root = {
+static struct sysfs_dirent sysfs_root = {
 	.s_name		= "",
 	.s_count	= ATOMIC_INIT(1),
 	.s_flags	= SYSFS_DIR,
@@ -40,6 +40,8 @@ struct sysfs_dirent sysfs_root = {
 	.s_ino		= 1,
 };
 
+struct sysfs_dirent *sysfs_root_sd = &sysfs_root;
+
 static int sysfs_fill_super(struct super_block *sb)
 {
 	struct inode *inode;
@@ -53,7 +55,7 @@ static int sysfs_fill_super(struct super_block *sb)
 
 	/* get root inode, initialize and unlock it */
 	mutex_lock(&sysfs_mutex);
-	inode = sysfs_get_inode(sb, &sysfs_root);
+	inode = sysfs_get_inode(sb, sysfs_root_sd);
 	mutex_unlock(&sysfs_mutex);
 	if (!inode) {
 		pr_debug("sysfs: could not get root inode\n");
@@ -66,7 +68,7 @@ static int sysfs_fill_super(struct super_block *sb)
 		pr_debug("%s: could not get root dentry!\n", __func__);
 		return -ENOMEM;
 	}
-	root->d_fsdata = &sysfs_root;
+	root->d_fsdata = sysfs_root_sd;
 	sb->s_root = root;
 	sb->s_d_op = &sysfs_dentry_ops;
 	return 0;
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 6797c9c..62f0e01 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -70,7 +70,7 @@ static int sysfs_do_create_link(struct kobject *kobj, struct kobject *target,
 	struct sysfs_dirent *parent_sd = NULL;
 
 	if (!kobj)
-		parent_sd = &sysfs_root;
+		parent_sd = sysfs_root_sd;
 	else
 		parent_sd = kobj->sd;
 
@@ -144,7 +144,7 @@ void sysfs_remove_link(struct kobject *kobj, const char *name)
 	struct sysfs_dirent *parent_sd = NULL;
 
 	if (!kobj)
-		parent_sd = &sysfs_root;
+		parent_sd = sysfs_root_sd;
 	else
 		parent_sd = kobj->sd;
 
@@ -170,7 +170,7 @@ int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *targ,
 	int result;
 
 	if (!kobj)
-		parent_sd = &sysfs_root;
+		parent_sd = sysfs_root_sd;
 	else
 		parent_sd = kobj->sd;
 
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index ce97907..2b217ce 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -28,7 +28,7 @@ struct sysfs_super_info {
 	const void		*ns;
 };
 #define sysfs_info(SB) ((struct sysfs_super_info *)(SB->s_fs_info))
-extern struct sysfs_dirent sysfs_root;
+extern struct sysfs_dirent *sysfs_root_sd;
 extern struct kmem_cache *sysfs_dir_cachep;
 
 /*
-- 
1.8.4.2

[PATCH 34/41] sysfs, kernfs: implement kernfs_create/destroy_root()

[Tejun Heo]

There currently is single kernfs hierarchy in the whole system which
is used for sysfs.  kernfs needs to support multiple hierarchies to
allow other users.  This patch introduces struct kernfs_root which
serves as the root of each kernfs hierarchy and implements
kernfs_create/destroy_root().

* Each kernfs_root is associated with a root sd (sysfs_dentry).  The
  root is freed when the root sd is released and kernfs_destory_root()
  simply invokes kernfs_remove() on the root sd.  sysfs_remove_one()
  is updated to handle release of the root sd.  Note that ps_iattr
  update in sysfs_remove_one() is trivially updated for readability.

* Root sd's are now dynamically allocated using sysfs_new_dirent().
  Update sysfs_alloc_ino() so that it gives out ino from 1 so that the
  root sd still gets ino 1.

* While kernfs currently only points to the root sd, it'll soon grow
  fields which are specific to each hierarchy.  As determining a given
  sd's root will be necessary, sd->s_dir.root is added.  This backlink
  fits better as a separate field in sd; however, sd->s_dir is inside
  union with space to spare, so use it to save space and provide
  kernfs_root() accessor to determine the root sd.

* As hierarchies may be destroyed now, each mount needs to hold onto
  the hierarchy it's attached to.  Update sysfs_fill_super() and
  sysfs_kill_sb() so that they get and put the kernfs_root
  respectively.

* sysfs_root is replaced with kernfs_root which is dynamically created
  by invoking kernfs_create_root() from sysfs_init().

This patch doesn't introduce any visible behavior changes.

v2: kernfs_create_root() forgot to set @sd->priv.  Fixed.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/dir.c             | 71 +++++++++++++++++++++++++++++++++++++++------
 fs/kernfs/kernfs-internal.h | 20 +++++++++++++
 fs/sysfs/mount.c            | 29 +++++++++++-------
 include/linux/kernfs.h      | 13 +++++++++
 4 files changed, 113 insertions(+), 20 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index a4ca4de..246740a 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -211,7 +211,7 @@ static int sysfs_alloc_ino(unsigned int *pino)
 
  retry:
 	spin_lock(&sysfs_ino_lock);
-	rc = ida_get_new_above(&sysfs_ino_ida, 2, &ino);
+	rc = ida_get_new_above(&sysfs_ino_ida, 1, &ino);
 	spin_unlock(&sysfs_ino_lock);
 
 	if (rc == -EAGAIN) {
@@ -253,9 +253,11 @@ EXPORT_SYMBOL_GPL(kernfs_get);
 void kernfs_put(struct sysfs_dirent *sd)
 {
 	struct sysfs_dirent *parent_sd;
+	struct kernfs_root *root;
 
 	if (!sd || !atomic_dec_and_test(&sd->s_count))
 		return;
+	root = kernfs_root(sd);
  repeat:
 	/* Moving/renaming is always done while holding reference.
 	 * sd->s_parent won't change beneath us.
@@ -278,8 +280,13 @@ void kernfs_put(struct sysfs_dirent *sd)
 	kmem_cache_free(sysfs_dir_cachep, sd);
 
 	sd = parent_sd;
-	if (sd && atomic_dec_and_test(&sd->s_count))
-		goto repeat;
+	if (sd) {
+		if (atomic_dec_and_test(&sd->s_count))
+			goto repeat;
+	} else {
+		/* just released the root sd, free @root too */
+		kfree(root);
+	}
 }
 EXPORT_SYMBOL_GPL(kernfs_put);
 
@@ -493,13 +500,15 @@ static void sysfs_remove_one(struct sysfs_addrm_cxt *acxt,
 	if (sd->s_flags & SYSFS_FLAG_REMOVED)
 		return;
 
-	sysfs_unlink_sibling(sd);
+	if (sd->s_parent) {
+		sysfs_unlink_sibling(sd);
 
-	/* Update timestamps on the parent */
-	ps_iattr = sd->s_parent->s_iattr;
-	if (ps_iattr) {
-		struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
-		ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
+		/* Update timestamps on the parent */
+		ps_iattr = sd->s_parent->s_iattr;
+		if (ps_iattr) {
+			ps_iattr->ia_iattr.ia_ctime = CURRENT_TIME;
+			ps_iattr->ia_iattr.ia_mtime = CURRENT_TIME;
+		}
 	}
 
 	sd->s_flags |= SYSFS_FLAG_REMOVED;
@@ -604,6 +613,49 @@ struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
 EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns);
 
 /**
+ * kernfs_create_root - create a new kernfs hierarchy
+ * @priv: opaque data associated with the new directory
+ *
+ * Returns the root of the new hierarchy on success, ERR_PTR() value on
+ * failure.
+ */
+struct kernfs_root *kernfs_create_root(void *priv)
+{
+	struct kernfs_root *root;
+	struct sysfs_dirent *sd;
+
+	root = kzalloc(sizeof(*root), GFP_KERNEL);
+	if (!root)
+		return ERR_PTR(-ENOMEM);
+
+	sd = sysfs_new_dirent("", S_IFDIR | S_IRUGO | S_IXUGO, SYSFS_DIR);
+	if (!sd) {
+		kfree(root);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	sd->s_flags &= ~SYSFS_FLAG_REMOVED;
+	sd->priv = priv;
+	sd->s_dir.root = root;
+
+	root->sd = sd;
+
+	return root;
+}
+
+/**
+ * kernfs_destroy_root - destroy a kernfs hierarchy
+ * @root: root of the hierarchy to destroy
+ *
+ * Destroy the hierarchy anchored at @root by removing all existing
+ * directories and destroying @root.
+ */
+void kernfs_destroy_root(struct kernfs_root *root)
+{
+	kernfs_remove(root->sd);	/* will also free @root */
+}
+
+/**
  * kernfs_create_dir_ns - create a directory
  * @parent: parent in which to create a new directory
  * @name: name of the new directory
@@ -626,6 +678,7 @@ struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
 	if (!sd)
 		return ERR_PTR(-ENOMEM);
 
+	sd->s_dir.root = parent->s_dir.root;
 	sd->s_ns = ns;
 	sd->priv = priv;
 
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 62ae35f..7dfe062 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -25,6 +25,12 @@ struct sysfs_elem_dir {
 	unsigned long		subdirs;
 	/* children rbtree starts here and goes through sd->s_rb */
 	struct rb_root		children;
+
+	/*
+	 * The kernfs hierarchy this directory belongs to.  This fits
+	 * better directly in sysfs_dirent but is here to save space.
+	 */
+	struct kernfs_root	*root;
 };
 
 struct sysfs_elem_symlink {
@@ -104,6 +110,20 @@ static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
 	return sd->s_flags & SYSFS_TYPE_MASK;
 }
 
+/**
+ * kernfs_root - find out the kernfs_root a sysfs_dirent belongs to
+ * @sd: sysfs_dirent of interest
+ *
+ * Return the kernfs_root @sd belongs to.
+ */
+static inline struct kernfs_root *kernfs_root(struct sysfs_dirent *sd)
+{
+	/* if parent exists, it's always a dir; otherwise, @sd is a dir */
+	if (sd->s_parent)
+		sd = sd->s_parent;
+	return sd->s_dir.root;
+}
+
 /*
  * Context structure to be used while adding/removing nodes.
  */
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 7cbd1fc..0b5661b 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -32,15 +32,8 @@ static const struct super_operations sysfs_ops = {
 	.evict_inode	= sysfs_evict_inode,
 };
 
-static struct sysfs_dirent sysfs_root = {
-	.s_name		= "",
-	.s_count	= ATOMIC_INIT(1),
-	.s_flags	= SYSFS_DIR,
-	.s_mode		= S_IFDIR | S_IRUGO | S_IXUGO,
-	.s_ino		= 1,
-};
-
-struct sysfs_dirent *sysfs_root_sd = &sysfs_root;
+static struct kernfs_root *sysfs_root;
+struct sysfs_dirent *sysfs_root_sd;
 
 static int sysfs_fill_super(struct super_block *sb)
 {
@@ -68,6 +61,7 @@ static int sysfs_fill_super(struct super_block *sb)
 		pr_debug("%s: could not get root dentry!\n", __func__);
 		return -ENOMEM;
 	}
+	kernfs_get(sysfs_root_sd);
 	root->d_fsdata = sysfs_root_sd;
 	sb->s_root = root;
 	sb->s_d_op = &sysfs_dentry_ops;
@@ -138,11 +132,15 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 static void sysfs_kill_sb(struct super_block *sb)
 {
 	struct sysfs_super_info *info = sysfs_info(sb);
-	/* Remove the superblock from fs_supers/s_instances
+	struct sysfs_dirent *root_sd = sb->s_root->d_fsdata;
+
+	/*
+	 * Remove the superblock from fs_supers/s_instances
 	 * so we can't find it, before freeing sysfs_super_info.
 	 */
 	kill_anon_super(sb);
 	free_sysfs_super_info(info);
+	kernfs_put(root_sd);
 }
 
 static struct file_system_type sysfs_fs_type = {
@@ -166,12 +164,21 @@ int __init sysfs_init(void)
 	if (err)
 		goto out_err;
 
+	sysfs_root = kernfs_create_root(NULL);
+	if (IS_ERR(sysfs_root)) {
+		err = PTR_ERR(sysfs_root);
+		goto out_err;
+	}
+	sysfs_root_sd = sysfs_root->sd;
+
 	err = register_filesystem(&sysfs_fs_type);
 	if (err)
-		goto out_err;
+		goto out_destroy_root;
 
 	return 0;
 
+out_destroy_root:
+	kernfs_destroy_root(sysfs_root);
 out_err:
 	kmem_cache_destroy(sysfs_dir_cachep);
 	sysfs_dir_cachep = NULL;
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index fd8f574..f75548b 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -20,6 +20,11 @@ struct vm_area_struct;
 
 struct sysfs_dirent;
 
+struct kernfs_root {
+	/* published fields */
+	struct sysfs_dirent	*sd;
+};
+
 struct sysfs_open_file {
 	/* published fields */
 	struct sysfs_dirent	*sd;
@@ -76,6 +81,9 @@ struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
 void kernfs_get(struct sysfs_dirent *sd);
 void kernfs_put(struct sysfs_dirent *sd);
 
+struct kernfs_root *kernfs_create_root(void *priv);
+void kernfs_destroy_root(struct kernfs_root *root);
+
 struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
 					  const char *name, void *priv,
 					  const void *ns);
@@ -107,6 +115,11 @@ kernfs_find_and_get_ns(struct sysfs_dirent *parent, const char *name,
 static inline void kernfs_get(struct sysfs_dirent *sd) { }
 static inline void kernfs_put(struct sysfs_dirent *sd) { }
 
+static inline struct kernfs_root *kernfs_create_root(void *priv)
+{ return ERR_PTR(-ENOSYS); }
+
+static inline void kernfs_destroy_root(struct kernfs_root *root) { }
+
 static inline struct sysfs_dirent *
 kernfs_create_dir_ns(struct sysfs_dirent *parent, const char *name, void *priv,
 		     const void *ns)
-- 
1.8.4.2

[PATCH 35/41] sysfs, kernfs: make inode number ida per kernfs_root

[Tejun Heo]

kernfs is being updated to allow multiple sysfs_dirent hierarchies so
that it can also be used by other users.  Currently, inode number is
allocated using a global ida, sysfs_ino_ida; however, inos for
different hierarchies should be handled separately.

This patch makes ino allocation per kernfs_root.  sysfs_ino_ida is
replaced by kernfs_root->ino_ida and sysfs_new_dirent() is updated to
take @root and allocate ino from it.  ida_simple_get/remove() are used
instead of sysfs_ino_lock and sysfs_alloc/free_ino().

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/dir.c             | 47 +++++++++++++--------------------------------
 fs/kernfs/file.c            |  4 ++--
 fs/kernfs/kernfs-internal.h |  3 ++-
 fs/kernfs/symlink.c         |  3 ++-
 include/linux/kernfs.h      |  4 ++++
 5 files changed, 23 insertions(+), 38 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 246740a..eaffa83 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -21,9 +21,6 @@ DEFINE_MUTEX(sysfs_mutex);
 
 #define to_sysfs_dirent(X) rb_entry((X), struct sysfs_dirent, s_rb)
 
-static DEFINE_SPINLOCK(sysfs_ino_lock);
-static DEFINE_IDA(sysfs_ino_ida);
-
 /**
  *	sysfs_name_hash
  *	@name: Null terminated string to hash
@@ -205,32 +202,6 @@ static void sysfs_deactivate(struct sysfs_dirent *sd)
 	rwsem_release(&sd->dep_map, 1, _RET_IP_);
 }
 
-static int sysfs_alloc_ino(unsigned int *pino)
-{
-	int ino, rc;
-
- retry:
-	spin_lock(&sysfs_ino_lock);
-	rc = ida_get_new_above(&sysfs_ino_ida, 1, &ino);
-	spin_unlock(&sysfs_ino_lock);
-
-	if (rc == -EAGAIN) {
-		if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL))
-			goto retry;
-		rc = -ENOMEM;
-	}
-
-	*pino = ino;
-	return rc;
-}
-
-static void sysfs_free_ino(unsigned int ino)
-{
-	spin_lock(&sysfs_ino_lock);
-	ida_remove(&sysfs_ino_ida, ino);
-	spin_unlock(&sysfs_ino_lock);
-}
-
 /**
  * kernfs_get - get a reference count on a sysfs_dirent
  * @sd: the target sysfs_dirent
@@ -276,7 +247,7 @@ void kernfs_put(struct sysfs_dirent *sd)
 		security_release_secctx(sd->s_iattr->ia_secdata,
 					sd->s_iattr->ia_secdata_len);
 	kfree(sd->s_iattr);
-	sysfs_free_ino(sd->s_ino);
+	ida_simple_remove(&root->ino_ida, sd->s_ino);
 	kmem_cache_free(sysfs_dir_cachep, sd);
 
 	sd = parent_sd;
@@ -285,6 +256,7 @@ void kernfs_put(struct sysfs_dirent *sd)
 			goto repeat;
 	} else {
 		/* just released the root sd, free @root too */
+		ida_destroy(&root->ino_ida);
 		kfree(root);
 	}
 }
@@ -360,10 +332,12 @@ const struct dentry_operations sysfs_dentry_ops = {
 	.d_release	= sysfs_dentry_release,
 };
 
-struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
+struct sysfs_dirent *sysfs_new_dirent(struct kernfs_root *root,
+				      const char *name, umode_t mode, int type)
 {
 	char *dup_name = NULL;
 	struct sysfs_dirent *sd;
+	int ret;
 
 	if (type & SYSFS_COPY_NAME) {
 		name = dup_name = kstrdup(name, GFP_KERNEL);
@@ -375,8 +349,10 @@ struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
 	if (!sd)
 		goto err_out1;
 
-	if (sysfs_alloc_ino(&sd->s_ino))
+	ret = ida_simple_get(&root->ino_ida, 1, 0, GFP_KERNEL);
+	if (ret < 0)
 		goto err_out2;
+	sd->s_ino = ret;
 
 	atomic_set(&sd->s_count, 1);
 	atomic_set(&sd->s_active, 0);
@@ -628,8 +604,11 @@ struct kernfs_root *kernfs_create_root(void *priv)
 	if (!root)
 		return ERR_PTR(-ENOMEM);
 
-	sd = sysfs_new_dirent("", S_IFDIR | S_IRUGO | S_IXUGO, SYSFS_DIR);
+	ida_init(&root->ino_ida);
+
+	sd = sysfs_new_dirent(root, "", S_IFDIR | S_IRUGO | S_IXUGO, SYSFS_DIR);
 	if (!sd) {
+		ida_destroy(&root->ino_ida);
 		kfree(root);
 		return ERR_PTR(-ENOMEM);
 	}
@@ -674,7 +653,7 @@ struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
 	int rc;
 
 	/* allocate */
-	sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
+	sd = sysfs_new_dirent(kernfs_root(parent), name, mode, SYSFS_DIR);
 	if (!sd)
 		return ERR_PTR(-ENOMEM);
 
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index fa172e8..990c97f 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -775,8 +775,8 @@ struct sysfs_dirent *kernfs_create_file_ns_key(struct sysfs_dirent *parent,
 	struct sysfs_dirent *sd;
 	int rc;
 
-	sd = sysfs_new_dirent(name, (mode & S_IALLUGO) | S_IFREG,
-			      SYSFS_KOBJ_ATTR);
+	sd = sysfs_new_dirent(kernfs_root(parent), name,
+			      (mode & S_IALLUGO) | S_IFREG, SYSFS_KOBJ_ATTR);
 	if (!sd)
 		return ERR_PTR(-ENOMEM);
 
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 7dfe062..466943d 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -160,7 +160,8 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt);
 int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
 		  struct sysfs_dirent *parent_sd);
 void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
-struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);
+struct sysfs_dirent *sysfs_new_dirent(struct kernfs_root *root,
+				      const char *name, umode_t mode, int type);
 
 /*
  * file.c
diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c
index af3570b..004c164 100644
--- a/fs/kernfs/symlink.c
+++ b/fs/kernfs/symlink.c
@@ -30,7 +30,8 @@ struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
 	struct sysfs_addrm_cxt acxt;
 	int error;
 
-	sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
+	sd = sysfs_new_dirent(kernfs_root(parent), name, S_IFLNK|S_IRWXUGO,
+			      SYSFS_KOBJ_LINK);
 	if (!sd)
 		return ERR_PTR(-ENOMEM);
 
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index f75548b..fad8b98 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -11,6 +11,7 @@
 #include <linux/err.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
+#include <linux/idr.h>
 #include <linux/lockdep.h>
 
 struct file;
@@ -23,6 +24,9 @@ struct sysfs_dirent;
 struct kernfs_root {
 	/* published fields */
 	struct sysfs_dirent	*sd;
+
+	/* private fields, do not use outside kernfs proper */
+	struct ida		ino_ida;
 };
 
 struct sysfs_open_file {
-- 
1.8.4.2

[PATCH 36/41] sysfs, kernfs: make super_blocks bind to different kernfs_roots

[Tejun Heo]

kernfs is being updated to allow multiple sysfs_dirent hierarchies so
that it can also be used by other users.  Currently, sysfs
super_blocks are always attached to one kernfs_root - sysfs_root - and
distinguished only by their namespace tags.

This patch adds sysfs_super_info->root and update
sysfs_fill/test_super() so that super_blocks are identified by the
combination of both the associated kernfs_root and namespace tag.
This allows mounting different kernfs hierarchies.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/mount.c | 10 ++++++----
 fs/sysfs/sysfs.h |  6 ++++++
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 0b5661b..f143b20 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -37,6 +37,7 @@ struct sysfs_dirent *sysfs_root_sd;
 
 static int sysfs_fill_super(struct super_block *sb)
 {
+	struct sysfs_super_info *info = sysfs_info(sb);
 	struct inode *inode;
 	struct dentry *root;
 
@@ -48,7 +49,7 @@ static int sysfs_fill_super(struct super_block *sb)
 
 	/* get root inode, initialize and unlock it */
 	mutex_lock(&sysfs_mutex);
-	inode = sysfs_get_inode(sb, sysfs_root_sd);
+	inode = sysfs_get_inode(sb, info->root->sd);
 	mutex_unlock(&sysfs_mutex);
 	if (!inode) {
 		pr_debug("sysfs: could not get root inode\n");
@@ -61,8 +62,8 @@ static int sysfs_fill_super(struct super_block *sb)
 		pr_debug("%s: could not get root dentry!\n", __func__);
 		return -ENOMEM;
 	}
-	kernfs_get(sysfs_root_sd);
-	root->d_fsdata = sysfs_root_sd;
+	kernfs_get(info->root->sd);
+	root->d_fsdata = info->root->sd;
 	sb->s_root = root;
 	sb->s_d_op = &sysfs_dentry_ops;
 	return 0;
@@ -73,7 +74,7 @@ static int sysfs_test_super(struct super_block *sb, void *data)
 	struct sysfs_super_info *sb_info = sysfs_info(sb);
 	struct sysfs_super_info *info = data;
 
-	return sb_info->ns == info->ns;
+	return sb_info->root == info->root && sb_info->ns == info->ns;
 }
 
 static int sysfs_set_super(struct super_block *sb, void *data)
@@ -110,6 +111,7 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 	if (!info)
 		return ERR_PTR(-ENOMEM);
 
+	info->root = sysfs_root;
 	info->ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
 
 	sb = sget(fs_type, sysfs_test_super, sysfs_set_super, flags, info);
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 2b217ce..93b4b68 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -20,6 +20,12 @@
 
 struct sysfs_super_info {
 	/*
+	 * The root associated with this super_block.  Each super_block is
+	 * identified by the root and ns it's associated with.
+	 */
+	struct kernfs_root	*root;
+
+	/*
 	 * Each sb is associated with one namespace tag, currently the network
 	 * namespace of the task which mounted this sysfs instance.  If multiple
 	 * tags become necessary, make the following an array and compare
-- 
1.8.4.2

[PATCH 37/41] sysfs, kernfs: prepare mount path for kernfs

[Tejun Heo]

We're in the process of separating out core sysfs functionality into
kernfs which will deal with sysfs_dirents directly.  This patch
rearranges mount path so that the kernfs and sysfs parts are separate.

* As sysfs_super_info won't be visible outside kernfs proper,
  kernfs_super_ns() is added to allow kernfs users to access a
  super_block's namespace tag.

* Generic mount operation is separated out into kernfs_mount_ns().
  sysfs_mount() now just performs sysfs-specific permission check,
  acquires namespace tag, and invokes kernfs_mount_ns().

* Generic superblock release is separated out into kernfs_kill_sb()
  which can be used directly as file_system_type->kill_sb().  As sysfs
  needs to put the namespace tag, sysfs_kill_sb() wraps
  kernfs_kill_sb() with ns tag put.

* sysfs_dir_cachep init and sysfs_inode_init() are separated out into
  kernfs_init().  kernfs_init() uses only small amount of memory and
  trying to handle and propagate kernfs_init() failure doesn't make
  much sense.  Use SLAB_PANIC for sysfs_dir_cachep and make
  sysfs_inode_init() panic on failure.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/inode.c           |   5 ++-
 fs/kernfs/kernfs-internal.h |   2 +-
 fs/namespace.c              |   2 +
 fs/sysfs/mount.c            | 104 ++++++++++++++++++++++++++++++--------------
 include/linux/kernfs.h      |  28 ++++++++++++
 5 files changed, 106 insertions(+), 35 deletions(-)

diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 9d4fab4..b4cae6f 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -37,9 +37,10 @@ static const struct inode_operations sysfs_inode_operations = {
 	.setxattr	= sysfs_setxattr,
 };
 
-int __init sysfs_inode_init(void)
+void __init sysfs_inode_init(void)
 {
-	return bdi_init(&sysfs_backing_dev_info);
+	if (bdi_init(&sysfs_backing_dev_info))
+		panic("failed to init sysfs_backing_dev_info");
 }
 
 static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 466943d..0d94988 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -144,7 +144,7 @@ int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
 		  struct kstat *stat);
 int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
 		   size_t size, int flags);
-int sysfs_inode_init(void);
+void sysfs_inode_init(void);
 
 /*
  * dir.c
diff --git a/fs/namespace.c b/fs/namespace.c
index ac2ce8a..a511ea0 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2790,6 +2790,8 @@ void __init mnt_init(void)
 	for (u = 0; u < HASH_SIZE; u++)
 		INIT_LIST_HEAD(&mountpoint_hashtable[u]);
 
+	kernfs_init();
+
 	err = sysfs_init();
 	if (err)
 		printk(KERN_WARNING "%s: sysfs_init error: %d\n",
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index f143b20..5384732 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -86,18 +86,24 @@ static int sysfs_set_super(struct super_block *sb, void *data)
 	return error;
 }
 
-static void free_sysfs_super_info(struct sysfs_super_info *info)
+/**
+ * kernfs_super_ns - determine the namespace tag of a kernfs super_block
+ * @sb: super_block of interest
+ *
+ * Return the namespace tag associated with kernfs super_block @sb.
+ */
+const void *kernfs_super_ns(struct super_block *sb)
 {
-	kobj_ns_drop(KOBJ_NS_TYPE_NET, (void *)info->ns);
-	kfree(info);
+	struct sysfs_super_info *info = sysfs_info(sb);
+
+	return info->ns;
 }
 
 static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data)
 {
-	struct sysfs_super_info *info;
-	struct super_block *sb;
-	int error;
+	struct dentry *root;
+	void *ns;
 
 	if (!(flags & MS_KERNMOUNT)) {
 		if (!capable(CAP_SYS_ADMIN) && !fs_fully_visible(fs_type))
@@ -107,16 +113,44 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 			return ERR_PTR(-EPERM);
 	}
 
+	ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
+	root = kernfs_mount_ns(fs_type, flags, sysfs_root, ns);
+	if (IS_ERR(root))
+		kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
+	return root;
+}
+
+/**
+ * kernfs_mount_ns - kernfs mount helper
+ * @fs_type: file_system_type of the fs being mounted
+ * @flags: mount flags specified for the mount
+ * @root: kernfs_root of the hierarchy being mounted
+ * @ns: optional namespace tag of the mount
+ *
+ * This is to be called from each kernfs user's file_system_type->mount()
+ * implementation, which should pass through the specified @fs_type and
+ * @flags, and specify the hierarchy and namespace tag to mount via @root
+ * and @ns, respectively.
+ *
+ * The return value can be passed to the vfs layer verbatim.
+ */
+struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
+			       struct kernfs_root *root, const void *ns)
+{
+	struct super_block *sb;
+	struct sysfs_super_info *info;
+	int error;
+
 	info = kzalloc(sizeof(*info), GFP_KERNEL);
 	if (!info)
 		return ERR_PTR(-ENOMEM);
 
-	info->root = sysfs_root;
-	info->ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
+	info->root = root;
+	info->ns = ns;
 
 	sb = sget(fs_type, sysfs_test_super, sysfs_set_super, flags, info);
 	if (IS_ERR(sb) || sb->s_fs_info != info)
-		free_sysfs_super_info(info);
+		kfree(info);
 	if (IS_ERR(sb))
 		return ERR_CAST(sb);
 	if (!sb->s_root) {
@@ -133,6 +167,20 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 
 static void sysfs_kill_sb(struct super_block *sb)
 {
+	kernfs_kill_sb(sb);
+	kobj_ns_drop(KOBJ_NS_TYPE_NET, (void *)kernfs_super_ns(sb));
+}
+
+/**
+ * kernfs_kill_sb - kill_sb for kernfs
+ * @sb: super_block being killed
+ *
+ * This can be used directly for file_system_type->kill_sb().  If a kernfs
+ * user needs extra cleanup, it can implement its own kill_sb() and call
+ * this function at the end.
+ */
+void kernfs_kill_sb(struct super_block *sb)
+{
 	struct sysfs_super_info *info = sysfs_info(sb);
 	struct sysfs_dirent *root_sd = sb->s_root->d_fsdata;
 
@@ -141,7 +189,7 @@ static void sysfs_kill_sb(struct super_block *sb)
 	 * so we can't find it, before freeing sysfs_super_info.
 	 */
 	kill_anon_super(sb);
-	free_sysfs_super_info(info);
+	kfree(info);
 	kernfs_put(root_sd);
 }
 
@@ -152,37 +200,29 @@ static struct file_system_type sysfs_fs_type = {
 	.fs_flags	= FS_USERNS_MOUNT,
 };
 
-int __init sysfs_init(void)
+void __init kernfs_init(void)
 {
-	int err;
-
 	sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
 					      sizeof(struct sysfs_dirent),
-					      0, 0, NULL);
-	if (!sysfs_dir_cachep)
-		return -ENOMEM;
+					      0, SLAB_PANIC, NULL);
+	sysfs_inode_init();
+}
 
-	err = sysfs_inode_init();
-	if (err)
-		goto out_err;
+int __init sysfs_init(void)
+{
+	int err;
 
 	sysfs_root = kernfs_create_root(NULL);
-	if (IS_ERR(sysfs_root)) {
-		err = PTR_ERR(sysfs_root);
-		goto out_err;
-	}
+	if (IS_ERR(sysfs_root))
+		return PTR_ERR(sysfs_root);
+
 	sysfs_root_sd = sysfs_root->sd;
 
 	err = register_filesystem(&sysfs_fs_type);
-	if (err)
-		goto out_destroy_root;
+	if (err) {
+		kernfs_destroy_root(sysfs_root);
+		return err;
+	}
 
 	return 0;
-
-out_destroy_root:
-	kernfs_destroy_root(sysfs_root);
-out_err:
-	kmem_cache_destroy(sysfs_dir_cachep);
-	sysfs_dir_cachep = NULL;
-	return err;
 }
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index fad8b98..75fcbe5 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -18,6 +18,8 @@ struct file;
 struct iattr;
 struct seq_file;
 struct vm_area_struct;
+struct super_block;
+struct file_system_type;
 
 struct sysfs_dirent;
 
@@ -109,6 +111,13 @@ void kernfs_enable_ns(struct sysfs_dirent *sd);
 int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr);
 void kernfs_notify(struct sysfs_dirent *sd);
 
+const void *kernfs_super_ns(struct super_block *sb);
+struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
+			       struct kernfs_root *root, const void *ns);
+void kernfs_kill_sb(struct super_block *sb);
+
+void kernfs_init(void);
+
 #else	/* CONFIG_SYSFS */
 
 static inline struct sysfs_dirent *
@@ -160,6 +169,18 @@ static inline int kernfs_setattr(struct sysfs_dirent *sd,
 
 static inline void kernfs_notify(struct sysfs_dirent *sd) { }
 
+static inline const void *kernfs_super_ns(struct super_block *sb)
+{ return NULL; }
+
+static inline struct dentry *
+kernfs_mount_ns(struct file_system_type *fs_type, int flags,
+		struct kernfs_root *root, const void *ns)
+{ return ERR_PTR(-ENOSYS); }
+
+static inline void kernfs_kill_sb(struct super_block *sb) { }
+
+static inline void kernfs_init(void) { }
+
 #endif	/* CONFIG_SYSFS */
 
 static inline struct sysfs_dirent *
@@ -201,4 +222,11 @@ static inline int kernfs_remove_by_name(struct sysfs_dirent *parent,
 	return kernfs_remove_by_name_ns(parent, name, NULL);
 }
 
+static inline struct dentry *
+kernfs_mount(struct file_system_type *fs_type, int flags,
+	     struct kernfs_root *root)
+{
+	return kernfs_mount_ns(fs_type, flags, root, NULL);
+}
+
 #endif	/* __LINUX_KERNFS_H */
-- 
1.8.4.2

[PATCH 38/41] sysfs, kernfs: move mount core code to fs/kernfs/mount.c

[Tejun Heo]

Move core mount code to fs/kernfs/mount.c.  The respective
declarations in fs/sysfs/sysfs.h are moved to
fs/kernfs/kernfs-internal.h.

This is pure relocation.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/kernfs-internal.h |  22 +++++++
 fs/kernfs/mount.c           | 156 ++++++++++++++++++++++++++++++++++++++++++++
 fs/sysfs/mount.c            | 152 ------------------------------------------
 fs/sysfs/sysfs.h            |  18 -----
 4 files changed, 178 insertions(+), 170 deletions(-)

diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 0d94988..ced0d6d 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -134,6 +134,28 @@ struct sysfs_addrm_cxt {
 #include "../sysfs/sysfs.h"
 
 /*
+ * mount.c
+ */
+struct sysfs_super_info {
+	/*
+	 * The root associated with this super_block.  Each super_block is
+	 * identified by the root and ns it's associated with.
+	 */
+	struct kernfs_root	*root;
+
+	/*
+	 * Each sb is associated with one namespace tag, currently the network
+	 * namespace of the task which mounted this sysfs instance.  If multiple
+	 * tags become necessary, make the following an array and compare
+	 * sysfs_dirent tag against every entry.
+	 */
+	const void		*ns;
+};
+#define sysfs_info(SB) ((struct sysfs_super_info *)(SB->s_fs_info))
+
+extern struct kmem_cache *sysfs_dir_cachep;
+
+/*
  * inode.c
  */
 struct inode *sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd);
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 872e262..84c83e2 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -7,3 +7,159 @@
  *
  * This file is released under the GPLv2.
  */
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/init.h>
+#include <linux/magic.h>
+#include <linux/slab.h>
+#include <linux/pagemap.h>
+
+#include "kernfs-internal.h"
+
+struct kmem_cache *sysfs_dir_cachep;
+
+static const struct super_operations sysfs_ops = {
+	.statfs		= simple_statfs,
+	.drop_inode	= generic_delete_inode,
+	.evict_inode	= sysfs_evict_inode,
+};
+
+static int sysfs_fill_super(struct super_block *sb)
+{
+	struct sysfs_super_info *info = sysfs_info(sb);
+	struct inode *inode;
+	struct dentry *root;
+
+	sb->s_blocksize = PAGE_CACHE_SIZE;
+	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+	sb->s_magic = SYSFS_MAGIC;
+	sb->s_op = &sysfs_ops;
+	sb->s_time_gran = 1;
+
+	/* get root inode, initialize and unlock it */
+	mutex_lock(&sysfs_mutex);
+	inode = sysfs_get_inode(sb, info->root->sd);
+	mutex_unlock(&sysfs_mutex);
+	if (!inode) {
+		pr_debug("sysfs: could not get root inode\n");
+		return -ENOMEM;
+	}
+
+	/* instantiate and link root dentry */
+	root = d_make_root(inode);
+	if (!root) {
+		pr_debug("%s: could not get root dentry!\n", __func__);
+		return -ENOMEM;
+	}
+	kernfs_get(info->root->sd);
+	root->d_fsdata = info->root->sd;
+	sb->s_root = root;
+	sb->s_d_op = &sysfs_dentry_ops;
+	return 0;
+}
+
+static int sysfs_test_super(struct super_block *sb, void *data)
+{
+	struct sysfs_super_info *sb_info = sysfs_info(sb);
+	struct sysfs_super_info *info = data;
+
+	return sb_info->root == info->root && sb_info->ns == info->ns;
+}
+
+static int sysfs_set_super(struct super_block *sb, void *data)
+{
+	int error;
+	error = set_anon_super(sb, data);
+	if (!error)
+		sb->s_fs_info = data;
+	return error;
+}
+
+/**
+ * kernfs_super_ns - determine the namespace tag of a kernfs super_block
+ * @sb: super_block of interest
+ *
+ * Return the namespace tag associated with kernfs super_block @sb.
+ */
+const void *kernfs_super_ns(struct super_block *sb)
+{
+	struct sysfs_super_info *info = sysfs_info(sb);
+
+	return info->ns;
+}
+
+/**
+ * kernfs_mount_ns - kernfs mount helper
+ * @fs_type: file_system_type of the fs being mounted
+ * @flags: mount flags specified for the mount
+ * @root: kernfs_root of the hierarchy being mounted
+ * @ns: optional namespace tag of the mount
+ *
+ * This is to be called from each kernfs user's file_system_type->mount()
+ * implementation, which should pass through the specified @fs_type and
+ * @flags, and specify the hierarchy and namespace tag to mount via @root
+ * and @ns, respectively.
+ *
+ * The return value can be passed to the vfs layer verbatim.
+ */
+struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
+			       struct kernfs_root *root, const void *ns)
+{
+	struct super_block *sb;
+	struct sysfs_super_info *info;
+	int error;
+
+	info = kzalloc(sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return ERR_PTR(-ENOMEM);
+
+	info->root = root;
+	info->ns = ns;
+
+	sb = sget(fs_type, sysfs_test_super, sysfs_set_super, flags, info);
+	if (IS_ERR(sb) || sb->s_fs_info != info)
+		kfree(info);
+	if (IS_ERR(sb))
+		return ERR_CAST(sb);
+	if (!sb->s_root) {
+		error = sysfs_fill_super(sb);
+		if (error) {
+			deactivate_locked_super(sb);
+			return ERR_PTR(error);
+		}
+		sb->s_flags |= MS_ACTIVE;
+	}
+
+	return dget(sb->s_root);
+}
+
+/**
+ * kernfs_kill_sb - kill_sb for kernfs
+ * @sb: super_block being killed
+ *
+ * This can be used directly for file_system_type->kill_sb().  If a kernfs
+ * user needs extra cleanup, it can implement its own kill_sb() and call
+ * this function at the end.
+ */
+void kernfs_kill_sb(struct super_block *sb)
+{
+	struct sysfs_super_info *info = sysfs_info(sb);
+	struct sysfs_dirent *root_sd = sb->s_root->d_fsdata;
+
+	/*
+	 * Remove the superblock from fs_supers/s_instances
+	 * so we can't find it, before freeing sysfs_super_info.
+	 */
+	kill_anon_super(sb);
+	kfree(info);
+	kernfs_put(root_sd);
+}
+
+void __init kernfs_init(void)
+{
+	sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
+					      sizeof(struct sysfs_dirent),
+					      0, SLAB_PANIC, NULL);
+	sysfs_inode_init();
+}
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 5384732..e7e3aa8 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -14,91 +14,14 @@
 
 #include <linux/fs.h>
 #include <linux/mount.h>
-#include <linux/pagemap.h>
 #include <linux/init.h>
-#include <linux/module.h>
-#include <linux/magic.h>
-#include <linux/slab.h>
 #include <linux/user_namespace.h>
 
 #include "sysfs.h"
 
-
-struct kmem_cache *sysfs_dir_cachep;
-
-static const struct super_operations sysfs_ops = {
-	.statfs		= simple_statfs,
-	.drop_inode	= generic_delete_inode,
-	.evict_inode	= sysfs_evict_inode,
-};
-
 static struct kernfs_root *sysfs_root;
 struct sysfs_dirent *sysfs_root_sd;
 
-static int sysfs_fill_super(struct super_block *sb)
-{
-	struct sysfs_super_info *info = sysfs_info(sb);
-	struct inode *inode;
-	struct dentry *root;
-
-	sb->s_blocksize = PAGE_CACHE_SIZE;
-	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
-	sb->s_magic = SYSFS_MAGIC;
-	sb->s_op = &sysfs_ops;
-	sb->s_time_gran = 1;
-
-	/* get root inode, initialize and unlock it */
-	mutex_lock(&sysfs_mutex);
-	inode = sysfs_get_inode(sb, info->root->sd);
-	mutex_unlock(&sysfs_mutex);
-	if (!inode) {
-		pr_debug("sysfs: could not get root inode\n");
-		return -ENOMEM;
-	}
-
-	/* instantiate and link root dentry */
-	root = d_make_root(inode);
-	if (!root) {
-		pr_debug("%s: could not get root dentry!\n", __func__);
-		return -ENOMEM;
-	}
-	kernfs_get(info->root->sd);
-	root->d_fsdata = info->root->sd;
-	sb->s_root = root;
-	sb->s_d_op = &sysfs_dentry_ops;
-	return 0;
-}
-
-static int sysfs_test_super(struct super_block *sb, void *data)
-{
-	struct sysfs_super_info *sb_info = sysfs_info(sb);
-	struct sysfs_super_info *info = data;
-
-	return sb_info->root == info->root && sb_info->ns == info->ns;
-}
-
-static int sysfs_set_super(struct super_block *sb, void *data)
-{
-	int error;
-	error = set_anon_super(sb, data);
-	if (!error)
-		sb->s_fs_info = data;
-	return error;
-}
-
-/**
- * kernfs_super_ns - determine the namespace tag of a kernfs super_block
- * @sb: super_block of interest
- *
- * Return the namespace tag associated with kernfs super_block @sb.
- */
-const void *kernfs_super_ns(struct super_block *sb)
-{
-	struct sysfs_super_info *info = sysfs_info(sb);
-
-	return info->ns;
-}
-
 static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data)
 {
@@ -120,79 +43,12 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 	return root;
 }
 
-/**
- * kernfs_mount_ns - kernfs mount helper
- * @fs_type: file_system_type of the fs being mounted
- * @flags: mount flags specified for the mount
- * @root: kernfs_root of the hierarchy being mounted
- * @ns: optional namespace tag of the mount
- *
- * This is to be called from each kernfs user's file_system_type->mount()
- * implementation, which should pass through the specified @fs_type and
- * @flags, and specify the hierarchy and namespace tag to mount via @root
- * and @ns, respectively.
- *
- * The return value can be passed to the vfs layer verbatim.
- */
-struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
-			       struct kernfs_root *root, const void *ns)
-{
-	struct super_block *sb;
-	struct sysfs_super_info *info;
-	int error;
-
-	info = kzalloc(sizeof(*info), GFP_KERNEL);
-	if (!info)
-		return ERR_PTR(-ENOMEM);
-
-	info->root = root;
-	info->ns = ns;
-
-	sb = sget(fs_type, sysfs_test_super, sysfs_set_super, flags, info);
-	if (IS_ERR(sb) || sb->s_fs_info != info)
-		kfree(info);
-	if (IS_ERR(sb))
-		return ERR_CAST(sb);
-	if (!sb->s_root) {
-		error = sysfs_fill_super(sb);
-		if (error) {
-			deactivate_locked_super(sb);
-			return ERR_PTR(error);
-		}
-		sb->s_flags |= MS_ACTIVE;
-	}
-
-	return dget(sb->s_root);
-}
-
 static void sysfs_kill_sb(struct super_block *sb)
 {
 	kernfs_kill_sb(sb);
 	kobj_ns_drop(KOBJ_NS_TYPE_NET, (void *)kernfs_super_ns(sb));
 }
 
-/**
- * kernfs_kill_sb - kill_sb for kernfs
- * @sb: super_block being killed
- *
- * This can be used directly for file_system_type->kill_sb().  If a kernfs
- * user needs extra cleanup, it can implement its own kill_sb() and call
- * this function at the end.
- */
-void kernfs_kill_sb(struct super_block *sb)
-{
-	struct sysfs_super_info *info = sysfs_info(sb);
-	struct sysfs_dirent *root_sd = sb->s_root->d_fsdata;
-
-	/*
-	 * Remove the superblock from fs_supers/s_instances
-	 * so we can't find it, before freeing sysfs_super_info.
-	 */
-	kill_anon_super(sb);
-	kfree(info);
-	kernfs_put(root_sd);
-}
-
 static struct file_system_type sysfs_fs_type = {
 	.name		= "sysfs",
 	.mount		= sysfs_mount,
@@ -200,14 +56,6 @@ static struct file_system_type sysfs_fs_type = {
 	.fs_flags	= FS_USERNS_MOUNT,
 };
 
-void __init kernfs_init(void)
-{
-	sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
-					      sizeof(struct sysfs_dirent),
-					      0, SLAB_PANIC, NULL);
-	sysfs_inode_init();
-}
-
 int __init sysfs_init(void)
 {
 	int err;
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 93b4b68..6a82311 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -17,25 +17,7 @@
 /*
  * mount.c
  */
-
-struct sysfs_super_info {
-	/*
-	 * The root associated with this super_block.  Each super_block is
-	 * identified by the root and ns it's associated with.
-	 */
-	struct kernfs_root	*root;
-
-	/*
-	 * Each sb is associated with one namespace tag, currently the network
-	 * namespace of the task which mounted this sysfs instance.  If multiple
-	 * tags become necessary, make the following an array and compare
-	 * sysfs_dirent tag against every entry.
-	 */
-	const void		*ns;
-};
-#define sysfs_info(SB) ((struct sysfs_super_info *)(SB->s_fs_info))
 extern struct sysfs_dirent *sysfs_root_sd;
-extern struct kmem_cache *sysfs_dir_cachep;
 
 /*
  * dir.c
-- 
1.8.4.2

[PATCH 39/41] sysfs, kernfs: make sysfs_dirent definition public

[Tejun Heo]

sysfs_dirent includes some information which should be available to
kernfs users - the type, flags, name and parent pointer.  This patch
moves sysfs_dirent definition from kernfs/kernfs-internal.h to
include/linux/kernfs.h so that kernfs users can access them.

The type part of flags is exported as enum kernfs_node_type, the flags
kernfs_node_flag, sysfs_type() and kernfs_enable_ns() are moved to
include/linux/kernfs.h and the former is updated to return the enum
type.  sysfs_dirent->s_parent and ->s_name are marked explicitly as
public.

This patch doesn't introduce any functional changes.

v2: Flags exported too and kernfs_enable_ns() definition moved.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/dir.c             |  15 ------
 fs/kernfs/kernfs-internal.h |  85 +--------------------------------
 include/linux/kernfs.h      | 113 ++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 110 insertions(+), 103 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index eaffa83..7c5b517 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -895,21 +895,6 @@ int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
 	return error;
 }
 
-/**
- * kernfs_enable_ns - enable namespace under a directory
- * @sd: directory of interest, should be empty
- *
- * This is to be called right after @sd is created to enable namespace
- * under it.  All children of @sd must have non-NULL namespace tags and
- * only the ones which match the super_block's tag will be visible.
- */
-void kernfs_enable_ns(struct sysfs_dirent *sd)
-{
-	WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
-	WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));
-	sd->s_flags |= SYSFS_FLAG_NS;
-}
-
 /* Relationship between s_mode and the DT_xxx types */
 static inline unsigned char dt_type(struct sysfs_dirent *sd)
 {
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index ced0d6d..f33a784 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -13,102 +13,19 @@
 
 #include <linux/lockdep.h>
 #include <linux/fs.h>
-#include <linux/rbtree.h>
 #include <linux/mutex.h>
 
 #include <linux/kernfs.h>
 
-struct sysfs_open_dirent;
-
-/* type-specific structures for sysfs_dirent->s_* union members */
-struct sysfs_elem_dir {
-	unsigned long		subdirs;
-	/* children rbtree starts here and goes through sd->s_rb */
-	struct rb_root		children;
-
-	/*
-	 * The kernfs hierarchy this directory belongs to.  This fits
-	 * better directly in sysfs_dirent but is here to save space.
-	 */
-	struct kernfs_root	*root;
-};
-
-struct sysfs_elem_symlink {
-	struct sysfs_dirent	*target_sd;
-};
-
-struct sysfs_elem_attr {
-	const struct kernfs_ops	*ops;
-	struct sysfs_open_dirent *open;
-	loff_t			size;
-};
-
 struct sysfs_inode_attrs {
 	struct iattr	ia_iattr;
 	void		*ia_secdata;
 	u32		ia_secdata_len;
 };
 
-/*
- * sysfs_dirent - the building block of sysfs hierarchy.  Each and
- * every sysfs node is represented by single sysfs_dirent.
- *
- * As long as s_count reference is held, the sysfs_dirent itself is
- * accessible.  Dereferencing s_elem or any other outer entity
- * requires s_active reference.
- */
-struct sysfs_dirent {
-	atomic_t		s_count;
-	atomic_t		s_active;
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-	struct lockdep_map	dep_map;
-#endif
-	struct sysfs_dirent	*s_parent;
-	const char		*s_name;
-
-	struct rb_node		s_rb;
-
-	union {
-		struct completion	*completion;
-		struct sysfs_dirent	*removed_list;
-	} u;
-
-	const void		*s_ns; /* namespace tag */
-	unsigned int		s_hash; /* ns + name hash */
-	union {
-		struct sysfs_elem_dir		s_dir;
-		struct sysfs_elem_symlink	s_symlink;
-		struct sysfs_elem_attr		s_attr;
-	};
-
-	void			*priv;
-
-	unsigned short		s_flags;
-	umode_t			s_mode;
-	unsigned int		s_ino;
-	struct sysfs_inode_attrs *s_iattr;
-};
-
 #define SD_DEACTIVATED_BIAS		INT_MIN
 
-#define SYSFS_TYPE_MASK			0x000f
-#define SYSFS_DIR			0x0001
-#define SYSFS_KOBJ_ATTR			0x0002
-#define SYSFS_KOBJ_LINK			0x0004
-#define SYSFS_COPY_NAME			(SYSFS_DIR | SYSFS_KOBJ_LINK)
-#define SYSFS_ACTIVE_REF		SYSFS_KOBJ_ATTR
-
-#define SYSFS_FLAG_MASK			~SYSFS_TYPE_MASK
-#define SYSFS_FLAG_REMOVED		0x0010
-#define SYSFS_FLAG_NS			0x0020
-#define SYSFS_FLAG_HAS_SEQ_SHOW		0x0040
-#define SYSFS_FLAG_HAS_MMAP		0x0080
-#define SYSFS_FLAG_LOCKDEP		0x0100
-
-static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
-{
-	return sd->s_flags & SYSFS_TYPE_MASK;
-}
+/* SYSFS_TYPE_MASK and types are defined in include/linux/kernfs.h */
 
 /**
  * kernfs_root - find out the kernfs_root a sysfs_dirent belongs to
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 75fcbe5..f3f873e 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -13,6 +13,9 @@
 #include <linux/mutex.h>
 #include <linux/idr.h>
 #include <linux/lockdep.h>
+#include <linux/rbtree.h>
+#include <linux/atomic.h>
+#include <linux/completion.h>
 
 struct file;
 struct iattr;
@@ -21,7 +24,92 @@ struct vm_area_struct;
 struct super_block;
 struct file_system_type;
 
-struct sysfs_dirent;
+struct sysfs_open_dirent;
+struct sysfs_inode_attrs;
+
+enum kernfs_node_type {
+	SYSFS_DIR		= 0x0001,
+	SYSFS_KOBJ_ATTR		= 0x0002,
+	SYSFS_KOBJ_LINK		= 0x0004,
+};
+
+#define SYSFS_TYPE_MASK		0x000f
+#define SYSFS_COPY_NAME		(SYSFS_DIR | SYSFS_KOBJ_LINK)
+#define SYSFS_ACTIVE_REF	SYSFS_KOBJ_ATTR
+#define SYSFS_FLAG_MASK		~SYSFS_TYPE_MASK
+
+enum kernfs_node_flag {
+	SYSFS_FLAG_REMOVED	= 0x0010,
+	SYSFS_FLAG_NS		= 0x0020,
+	SYSFS_FLAG_HAS_SEQ_SHOW	= 0x0040,
+	SYSFS_FLAG_HAS_MMAP	= 0x0080,
+	SYSFS_FLAG_LOCKDEP	= 0x0100,
+};
+
+/* type-specific structures for sysfs_dirent->s_* union members */
+struct sysfs_elem_dir {
+	unsigned long		subdirs;
+	/* children rbtree starts here and goes through sd->s_rb */
+	struct rb_root		children;
+
+	/*
+	 * The kernfs hierarchy this directory belongs to.  This fits
+	 * better directly in sysfs_dirent but is here to save space.
+	 */
+	struct kernfs_root	*root;
+};
+
+struct sysfs_elem_symlink {
+	struct sysfs_dirent	*target_sd;
+};
+
+struct sysfs_elem_attr {
+	const struct kernfs_ops	*ops;
+	struct sysfs_open_dirent *open;
+	loff_t			size;
+};
+
+/*
+ * sysfs_dirent - the building block of sysfs hierarchy.  Each and every
+ * sysfs node is represented by single sysfs_dirent.  Most fields are
+ * private to kernfs and shouldn't be accessed directly by kernfs users.
+ *
+ * As long as s_count reference is held, the sysfs_dirent itself is
+ * accessible.  Dereferencing s_elem or any other outer entity
+ * requires s_active reference.
+ */
+struct sysfs_dirent {
+	atomic_t		s_count;
+	atomic_t		s_active;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lockdep_map	dep_map;
+#endif
+	/* the following two fields are published */
+	struct sysfs_dirent	*s_parent;
+	const char		*s_name;
+
+	struct rb_node		s_rb;
+
+	union {
+		struct completion	*completion;
+		struct sysfs_dirent	*removed_list;
+	} u;
+
+	const void		*s_ns; /* namespace tag */
+	unsigned int		s_hash; /* ns + name hash */
+	union {
+		struct sysfs_elem_dir		s_dir;
+		struct sysfs_elem_symlink	s_symlink;
+		struct sysfs_elem_attr		s_attr;
+	};
+
+	void			*priv;
+
+	unsigned short		s_flags;
+	umode_t			s_mode;
+	unsigned int		s_ino;
+	struct sysfs_inode_attrs *s_iattr;
+};
 
 struct kernfs_root {
 	/* published fields */
@@ -80,6 +168,26 @@ struct kernfs_ops {
 #endif
 };
 
+static inline enum kernfs_node_type sysfs_type(struct sysfs_dirent *sd)
+{
+	return sd->s_flags & SYSFS_TYPE_MASK;
+}
+
+/**
+ * kernfs_enable_ns - enable namespace under a directory
+ * @sd: directory of interest, should be empty
+ *
+ * This is to be called right after @sd is created to enable namespace
+ * under it.  All children of @sd must have non-NULL namespace tags and
+ * only the ones which match the super_block's tag will be visible.
+ */
+static inline void kernfs_enable_ns(struct sysfs_dirent *sd)
+{
+	WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
+	WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));
+	sd->s_flags |= SYSFS_FLAG_NS;
+}
+
 #ifdef CONFIG_SYSFS
 
 struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
@@ -107,7 +215,6 @@ int kernfs_remove_by_name_ns(struct sysfs_dirent *parent, const char *name,
 			     const void *ns);
 int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
 		     const char *new_name, const void *new_ns);
-void kernfs_enable_ns(struct sysfs_dirent *sd);
 int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr);
 void kernfs_notify(struct sysfs_dirent *sd);
 
@@ -161,8 +268,6 @@ static inline int kernfs_rename_ns(struct sysfs_dirent *sd,
 				   const char *new_name, const void *new_ns)
 { return -ENOSYS; }
 
-static inline void kernfs_enable_ns(struct sysfs_dirent *sd) { }
-
 static inline int kernfs_setattr(struct sysfs_dirent *sd,
 				 const struct iattr *iattr)
 { return -ENOSYS; }
-- 
1.8.4.2

[PATCH 40/41] sysfs, kernfs: implement kernfs_ns_enabled()

[Tejun Heo]

fs/sysfs/symlink.c::sysfs_delete_link() tests @sd->s_flags for
SYSFS_FLAG_NS.  Let's add kernfs_ns_enabled() so that sysfs doesn't
have to test sysfs_dirent flag directly.  This makes things tidier for
kernfs proper too.

This is purely cosmetic.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/dir.c        | 10 +++++-----
 fs/kernfs/symlink.c    |  2 +-
 fs/sysfs/symlink.c     |  2 +-
 include/linux/kernfs.h | 11 +++++++++++
 4 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 7c5b517..f51e062 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -291,7 +291,7 @@ static int sysfs_dentry_revalidate(struct dentry *dentry, unsigned int flags)
 		goto out_bad;
 
 	/* The sysfs dirent has been moved to a different namespace */
-	if (sd->s_parent && (sd->s_parent->s_flags & SYSFS_FLAG_NS) &&
+	if (sd->s_parent && kernfs_ns_enabled(sd->s_parent) &&
 	    sysfs_info(dentry->d_sb)->ns != sd->s_ns)
 		goto out_bad;
 
@@ -414,7 +414,7 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt)
 int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
 		  struct sysfs_dirent *parent_sd)
 {
-	bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS;
+	bool has_ns = kernfs_ns_enabled(parent_sd);
 	struct sysfs_inode_attrs *ps_iattr;
 	int ret;
 
@@ -535,7 +535,7 @@ static struct sysfs_dirent *kernfs_find_ns(struct sysfs_dirent *parent,
 					   const void *ns)
 {
 	struct rb_node *node = parent->s_dir.children.rb_node;
-	bool has_ns = parent->s_flags & SYSFS_FLAG_NS;
+	bool has_ns = kernfs_ns_enabled(parent);
 	unsigned int hash;
 
 	lockdep_assert_held(&sysfs_mutex);
@@ -685,7 +685,7 @@ static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry,
 
 	mutex_lock(&sysfs_mutex);
 
-	if (parent_sd->s_flags & SYSFS_FLAG_NS)
+	if (kernfs_ns_enabled(parent_sd))
 		ns = sysfs_info(dir->i_sb)->ns;
 
 	sd = kernfs_find_ns(parent_sd, dentry->d_name.name, ns);
@@ -968,7 +968,7 @@ static int sysfs_readdir(struct file *file, struct dir_context *ctx)
 		return 0;
 	mutex_lock(&sysfs_mutex);
 
-	if (parent_sd->s_flags & SYSFS_FLAG_NS)
+	if (kernfs_ns_enabled(parent_sd))
 		ns = sysfs_info(dentry->d_sb)->ns;
 
 	for (pos = sysfs_dir_pos(ns, parent_sd, ctx->pos, pos);
diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c
index 004c164..12569a7 100644
--- a/fs/kernfs/symlink.c
+++ b/fs/kernfs/symlink.c
@@ -35,7 +35,7 @@ struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
 	if (!sd)
 		return ERR_PTR(-ENOMEM);
 
-	if (parent->s_flags & SYSFS_FLAG_NS)
+	if (kernfs_ns_enabled(parent))
 		sd->s_ns = target->s_ns;
 	sd->s_symlink.target_sd = target;
 	kernfs_get(target);	/* ref owned by symlink */
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 62f0e01..1b8c9ed 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -128,7 +128,7 @@ void sysfs_delete_link(struct kobject *kobj, struct kobject *targ,
 	 * sysfs_remove_dir() for details.
 	 */
 	spin_lock(&sysfs_symlink_target_lock);
-	if (targ->sd && (kobj->sd->s_flags & SYSFS_FLAG_NS))
+	if (targ->sd && kernfs_ns_enabled(kobj->sd))
 		ns = targ->sd->s_ns;
 	spin_unlock(&sysfs_symlink_target_lock);
 	kernfs_remove_by_name_ns(kobj->sd, name, ns);
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index f3f873e..7cb636c 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -188,6 +188,17 @@ static inline void kernfs_enable_ns(struct sysfs_dirent *sd)
 	sd->s_flags |= SYSFS_FLAG_NS;
 }
 
+/**
+ * kernfs_ns_enabled - test whether namespace is enabled
+ * @sd: the node to test
+ *
+ * Test whether namespace filtering is enabled for the children of @ns.
+ */
+static inline bool kernfs_ns_enabled(struct sysfs_dirent *sd)
+{
+	return sd->s_flags & SYSFS_FLAG_NS;
+}
+
 #ifdef CONFIG_SYSFS
 
 struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
-- 
1.8.4.2

[PATCH 41/41] sysfs, kernfs: remove cross inclusions of internal headers

[Tejun Heo]

fs/kernfs/kernfs-internal.h needed to include fs/sysfs/sysfs.h because
part of kernfs core implementation was living in sysfs.

fs/sysfs/sysfs.h needed to include fs/kernfs/kernfs-internal.h because
include/linux/kernfs.h didn't expose enough interface.

The separation is complete and neither is true anymore.  Remove the
cross inclusion and make sysfs a proper user of kernfs.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/kernfs-internal.h | 2 --
 fs/sysfs/sysfs.h            | 1 -
 2 files changed, 3 deletions(-)

diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index f33a784..d1ff591 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -48,8 +48,6 @@ struct sysfs_addrm_cxt {
 	struct sysfs_dirent	*removed;
 };
 
-#include "../sysfs/sysfs.h"
-
 /*
  * mount.c
  */
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 6a82311..c8e395b 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -11,7 +11,6 @@
 #ifndef __SYSFS_INTERNAL_H
 #define __SYSFS_INTERNAL_H
 
-#include "../kernfs/kernfs-internal.h"
 #include <linux/sysfs.h>
 
 /*
-- 
1.8.4.2

Re: [PATCHSET driver-core-next] sysfs: separate out kernfs, take #3

[Tejun Heo]

Hello,

Please hold on a bit.  I have !CONFIG_SYSFS build failure.  I think I
forgot to add dummy interface for a newly added function.  I'm fixing
it right now.

Thanks.

-- 
tejun

[PATCH v2 01/41] sysfs: drop kobj_ns_type handling, take #2

[Tejun Heo]

>From 16a81407cf835109cb0ae7500de859d63c5e46c2 Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Sat, 23 Nov 2013 18:01:46 -0500

The way namespace tags are implemented in sysfs is more complicated
than necessary.  As each tag is a pointer value and required to be
non-NULL under a namespace enabled parent, there's no need to record
separately what type each tag is.  If multiple namespace types are
needed, which currently aren't, we can simply compare the tag to a set
of allowed tags in the superblock assuming that the tags, being
pointers, won't have the same value across multiple types.

This patch rips out kobj_ns_type handling from sysfs.  sysfs now has
an enable switch to turn on namespace under a node.  If enabled, all
children are required to have non-NULL namespace tags and filtered
against the super_block's tag.

kobject namespace determination is now performed in
lib/kobject.c::create_dir() making sysfs_read_ns_type() unnecessary.
The sanity checks are also moved.  create_dir() is restructured to
ease such addition.  This removes most kobject namespace knowledge
from sysfs proper which will enable proper separation and layering of
sysfs.

This is the second try.  The first one was cb26a311578e ("sysfs: drop
kobj_ns_type handling") which tried to automatically enable namespace
if there are children with non-NULL namespace tags; however, it was
broken for symlinks as they should inherit the target's tag iff
namespace is enabled in the parent.  This led to namespace filtering
enabled incorrectly for wireless net class devices through phy80211
symlinks and thus network configuration failure.  a1212d278c05
("Revert "sysfs: drop kobj_ns_type handling"") reverted the commit.

This shouldn't introduce any behavior changes, for real.

v2: Dummy implementation of sysfs_enable_ns() for !CONFIG_SYSFS was
    missing and caused build failure.  Reported by kbuild test robot.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: kbuild test robot <fengguang.wu@intel.com>
---
 fs/sysfs/dir.c        | 92 ++++++++++++++++++++-------------------------------
 fs/sysfs/mount.c      | 24 ++++----------
 fs/sysfs/symlink.c    | 26 ++++-----------
 fs/sysfs/sysfs.h      | 25 ++++----------
 include/linux/sysfs.h |  6 ++++
 lib/kobject.c         | 27 ++++++++++++---
 6 files changed, 83 insertions(+), 117 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 5e73d66..b3cf61d 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -279,7 +279,6 @@ static int sysfs_dentry_delete(const struct dentry *dentry)
 static int sysfs_dentry_revalidate(struct dentry *dentry, unsigned int flags)
 {
 	struct sysfs_dirent *sd;
-	int type;
 
 	if (flags & LOOKUP_RCU)
 		return -ECHILD;
@@ -300,13 +299,9 @@ static int sysfs_dentry_revalidate(struct dentry *dentry, unsigned int flags)
 		goto out_bad;
 
 	/* The sysfs dirent has been moved to a different namespace */
-	type = KOBJ_NS_TYPE_NONE;
-	if (sd->s_parent) {
-		type = sysfs_ns_type(sd->s_parent);
-		if (type != KOBJ_NS_TYPE_NONE &&
-				sysfs_info(dentry->d_sb)->ns[type] != sd->s_ns)
-			goto out_bad;
-	}
+	if (sd->s_parent && (sd->s_parent->s_flags & SYSFS_FLAG_NS) &&
+	    sysfs_info(dentry->d_sb)->ns != sd->s_ns)
+		goto out_bad;
 
 	mutex_unlock(&sysfs_mutex);
 out_valid:
@@ -423,13 +418,14 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt)
 int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
 		    struct sysfs_dirent *parent_sd)
 {
+	bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS;
 	struct sysfs_inode_attrs *ps_iattr;
 	int ret;
 
-	if (!!sysfs_ns_type(parent_sd) != !!sd->s_ns) {
+	if (has_ns != (bool)sd->s_ns) {
 		WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
-			sysfs_ns_type(parent_sd) ? "required" : "invalid",
-			parent_sd->s_name, sd->s_name);
+		     has_ns ? "required" : "invalid",
+		     parent_sd->s_name, sd->s_name);
 		return -EINVAL;
 	}
 
@@ -610,12 +606,13 @@ struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
 				       const void *ns)
 {
 	struct rb_node *node = parent_sd->s_dir.children.rb_node;
+	bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS;
 	unsigned int hash;
 
-	if (!!sysfs_ns_type(parent_sd) != !!ns) {
+	if (has_ns != (bool)ns) {
 		WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
-			sysfs_ns_type(parent_sd) ? "required" : "invalid",
-			parent_sd->s_name, name);
+		     has_ns ? "required" : "invalid",
+		     parent_sd->s_name, name);
 		return NULL;
 	}
 
@@ -667,7 +664,6 @@ struct sysfs_dirent *sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd,
 EXPORT_SYMBOL_GPL(sysfs_get_dirent_ns);
 
 static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
-		      enum kobj_ns_type type,
 		      const char *name, const void *ns,
 		      struct sysfs_dirent **p_sd)
 {
@@ -681,7 +677,6 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
 	if (!sd)
 		return -ENOMEM;
 
-	sd->s_flags |= (type << SYSFS_NS_TYPE_SHIFT);
 	sd->s_ns = ns;
 	sd->s_dir.kobj = kobj;
 
@@ -701,33 +696,7 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
 int sysfs_create_subdir(struct kobject *kobj, const char *name,
 			struct sysfs_dirent **p_sd)
 {
-	return create_dir(kobj, kobj->sd,
-			  KOBJ_NS_TYPE_NONE, name, NULL, p_sd);
-}
-
-/**
- *	sysfs_read_ns_type: return associated ns_type
- *	@kobj: the kobject being queried
- *
- *	Each kobject can be tagged with exactly one namespace type
- *	(i.e. network or user).  Return the ns_type associated with
- *	this object if any
- */
-static enum kobj_ns_type sysfs_read_ns_type(struct kobject *kobj)
-{
-	const struct kobj_ns_type_operations *ops;
-	enum kobj_ns_type type;
-
-	ops = kobj_child_ns_ops(kobj);
-	if (!ops)
-		return KOBJ_NS_TYPE_NONE;
-
-	type = ops->type;
-	BUG_ON(type <= KOBJ_NS_TYPE_NONE);
-	BUG_ON(type >= KOBJ_NS_TYPES);
-	BUG_ON(!kobj_ns_type_registered(type));
-
-	return type;
+	return create_dir(kobj, kobj->sd, name, NULL, p_sd);
 }
 
 /**
@@ -737,7 +706,6 @@ static enum kobj_ns_type sysfs_read_ns_type(struct kobject *kobj)
  */
 int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
 {
-	enum kobj_ns_type type;
 	struct sysfs_dirent *parent_sd, *sd;
 	int error = 0;
 
@@ -751,9 +719,7 @@ int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
 	if (!parent_sd)
 		return -ENOENT;
 
-	type = sysfs_read_ns_type(kobj);
-
-	error = create_dir(kobj, parent_sd, type, kobject_name(kobj), ns, &sd);
+	error = create_dir(kobj, parent_sd, kobject_name(kobj), ns, &sd);
 	if (!error)
 		kobj->sd = sd;
 	return error;
@@ -767,13 +733,12 @@ static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry,
 	struct sysfs_dirent *parent_sd = parent->d_fsdata;
 	struct sysfs_dirent *sd;
 	struct inode *inode;
-	enum kobj_ns_type type;
-	const void *ns;
+	const void *ns = NULL;
 
 	mutex_lock(&sysfs_mutex);
 
-	type = sysfs_ns_type(parent_sd);
-	ns = sysfs_info(dir->i_sb)->ns[type];
+	if (parent_sd->s_flags & SYSFS_FLAG_NS)
+		ns = sysfs_info(dir->i_sb)->ns;
 
 	sd = sysfs_find_dirent(parent_sd, dentry->d_name.name, ns);
 
@@ -1029,6 +994,21 @@ int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
 	return sysfs_rename(sd, new_parent_sd, sd->s_name, new_ns);
 }
 
+/**
+ * sysfs_enable_ns - enable namespace under a directory
+ * @sd: directory of interest, should be empty
+ *
+ * This is to be called right after @sd is created to enable namespace
+ * under it.  All children of @sd must have non-NULL namespace tags and
+ * only the ones which match the super_block's tag will be visible.
+ */
+void sysfs_enable_ns(struct sysfs_dirent *sd)
+{
+	WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
+	WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));
+	sd->s_flags |= SYSFS_FLAG_NS;
+}
+
 /* Relationship between s_mode and the DT_xxx types */
 static inline unsigned char dt_type(struct sysfs_dirent *sd)
 {
@@ -1096,15 +1076,15 @@ static int sysfs_readdir(struct file *file, struct dir_context *ctx)
 	struct dentry *dentry = file->f_path.dentry;
 	struct sysfs_dirent *parent_sd = dentry->d_fsdata;
 	struct sysfs_dirent *pos = file->private_data;
-	enum kobj_ns_type type;
-	const void *ns;
-
-	type = sysfs_ns_type(parent_sd);
-	ns = sysfs_info(dentry->d_sb)->ns[type];
+	const void *ns = NULL;
 
 	if (!dir_emit_dots(file, ctx))
 		return 0;
 	mutex_lock(&sysfs_mutex);
+
+	if (parent_sd->s_flags & SYSFS_FLAG_NS)
+		ns = sysfs_info(dentry->d_sb)->ns;
+
 	for (pos = sysfs_dir_pos(ns, parent_sd, ctx->pos, pos);
 	     pos;
 	     pos = sysfs_dir_next_pos(ns, parent_sd, ctx->pos, pos)) {
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 834ec2c..8c24bce 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -36,7 +36,7 @@ static const struct super_operations sysfs_ops = {
 struct sysfs_dirent sysfs_root = {
 	.s_name		= "",
 	.s_count	= ATOMIC_INIT(1),
-	.s_flags	= SYSFS_DIR | (KOBJ_NS_TYPE_NONE << SYSFS_NS_TYPE_SHIFT),
+	.s_flags	= SYSFS_DIR,
 	.s_mode		= S_IFDIR | S_IRUGO | S_IXUGO,
 	.s_ino		= 1,
 };
@@ -77,14 +77,8 @@ static int sysfs_test_super(struct super_block *sb, void *data)
 {
 	struct sysfs_super_info *sb_info = sysfs_info(sb);
 	struct sysfs_super_info *info = data;
-	enum kobj_ns_type type;
-	int found = 1;
 
-	for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) {
-		if (sb_info->ns[type] != info->ns[type])
-			found = 0;
-	}
-	return found;
+	return sb_info->ns == info->ns;
 }
 
 static int sysfs_set_super(struct super_block *sb, void *data)
@@ -98,9 +92,7 @@ static int sysfs_set_super(struct super_block *sb, void *data)
 
 static void free_sysfs_super_info(struct sysfs_super_info *info)
 {
-	int type;
-	for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
-		kobj_ns_drop(type, info->ns[type]);
+	kobj_ns_drop(KOBJ_NS_TYPE_NET, info->ns);
 	kfree(info);
 }
 
@@ -108,7 +100,6 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data)
 {
 	struct sysfs_super_info *info;
-	enum kobj_ns_type type;
 	struct super_block *sb;
 	int error;
 
@@ -116,18 +107,15 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 		if (!capable(CAP_SYS_ADMIN) && !fs_fully_visible(fs_type))
 			return ERR_PTR(-EPERM);
 
-		for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) {
-			if (!kobj_ns_current_may_mount(type))
-				return ERR_PTR(-EPERM);
-		}
+		if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))
+			return ERR_PTR(-EPERM);
 	}
 
 	info = kzalloc(sizeof(*info), GFP_KERNEL);
 	if (!info)
 		return ERR_PTR(-ENOMEM);
 
-	for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
-		info->ns[type] = kobj_ns_grab_current(type);
+	info->ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
 
 	sb = sget(fs_type, sysfs_test_super, sysfs_set_super, flags, info);
 	if (IS_ERR(sb) || sb->s_fs_info != info)
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 3ae3f1b..c660363 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -28,7 +28,6 @@ static int sysfs_do_create_link_sd(struct sysfs_dirent *parent_sd,
 	struct sysfs_dirent *target_sd = NULL;
 	struct sysfs_dirent *sd = NULL;
 	struct sysfs_addrm_cxt acxt;
-	enum kobj_ns_type ns_type;
 	int error;
 
 	BUG_ON(!name || !parent_sd);
@@ -52,29 +51,16 @@ static int sysfs_do_create_link_sd(struct sysfs_dirent *parent_sd,
 	if (!sd)
 		goto out_put;
 
-	ns_type = sysfs_ns_type(parent_sd);
-	if (ns_type)
+	if (parent_sd->s_flags & SYSFS_FLAG_NS)
 		sd->s_ns = target_sd->s_ns;
 	sd->s_symlink.target_sd = target_sd;
 	target_sd = NULL;	/* reference is now owned by the symlink */
 
 	sysfs_addrm_start(&acxt);
-	/* Symlinks must be between directories with the same ns_type */
-	if (!ns_type ||
-	    (ns_type == sysfs_ns_type(sd->s_symlink.target_sd->s_parent))) {
-		if (warn)
-			error = sysfs_add_one(&acxt, sd, parent_sd);
-		else
-			error = __sysfs_add_one(&acxt, sd, parent_sd);
-	} else {
-		error = -EINVAL;
-		WARN(1, KERN_WARNING
-			"sysfs: symlink across ns_types %s/%s -> %s/%s\n",
-			parent_sd->s_name,
-			sd->s_name,
-			sd->s_symlink.target_sd->s_parent->s_name,
-			sd->s_symlink.target_sd->s_name);
-	}
+	if (warn)
+		error = sysfs_add_one(&acxt, sd, parent_sd);
+	else
+		error = __sysfs_add_one(&acxt, sd, parent_sd);
 	sysfs_addrm_finish(&acxt);
 
 	if (error)
@@ -164,7 +150,7 @@ void sysfs_delete_link(struct kobject *kobj, struct kobject *targ,
 	 * sysfs_remove_dir() for details.
 	 */
 	spin_lock(&sysfs_symlink_target_lock);
-	if (targ->sd && sysfs_ns_type(kobj->sd))
+	if (targ->sd && (kobj->sd->s_flags & SYSFS_FLAG_NS))
 		ns = targ->sd->s_ns;
 	spin_unlock(&sysfs_symlink_target_lock);
 	sysfs_hash_and_remove(kobj->sd, name, ns);
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 0af09fb..e116c21 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -90,11 +90,8 @@ struct sysfs_dirent {
 #define SYSFS_COPY_NAME			(SYSFS_DIR | SYSFS_KOBJ_LINK)
 #define SYSFS_ACTIVE_REF		(SYSFS_KOBJ_ATTR | SYSFS_KOBJ_BIN_ATTR)
 
-/* identify any namespace tag on sysfs_dirents */
-#define SYSFS_NS_TYPE_MASK		0xf00
-#define SYSFS_NS_TYPE_SHIFT		8
-
-#define SYSFS_FLAG_MASK			~(SYSFS_NS_TYPE_MASK|SYSFS_TYPE_MASK)
+#define SYSFS_FLAG_MASK			~SYSFS_TYPE_MASK
+#define SYSFS_FLAG_NS			0x01000
 #define SYSFS_FLAG_REMOVED		0x02000
 
 static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
@@ -102,15 +99,6 @@ static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
 	return sd->s_flags & SYSFS_TYPE_MASK;
 }
 
-/*
- * Return any namespace tags on this dirent.
- * enum kobj_ns_type is defined in linux/kobject.h
- */
-static inline enum kobj_ns_type sysfs_ns_type(struct sysfs_dirent *sd)
-{
-	return (sd->s_flags & SYSFS_NS_TYPE_MASK) >> SYSFS_NS_TYPE_SHIFT;
-}
-
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 
 #define sysfs_dirent_init_lockdep(sd)				\
@@ -155,12 +143,13 @@ struct sysfs_addrm_cxt {
  */
 
 /*
- * Each sb is associated with a set of namespace tags (i.e.
- * the network namespace of the task which mounted this sysfs
- * instance).
+ * Each sb is associated with one namespace tag, currently the network
+ * namespace of the task which mounted this sysfs instance.  If multiple
+ * tags become necessary, make the following an array and compare
+ * sysfs_dirent tag against every entry.
  */
 struct sysfs_super_info {
-	void *ns[KOBJ_NS_TYPES];
+	void *ns;
 };
 #define sysfs_info(SB) ((struct sysfs_super_info *)(SB->s_fs_info))
 extern struct sysfs_dirent sysfs_root;
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 6695040..362a34d 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -220,6 +220,8 @@ int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *target,
 void sysfs_delete_link(struct kobject *dir, struct kobject *targ,
 			const char *name);
 
+void sysfs_enable_ns(struct sysfs_dirent *sd);
+
 int __must_check sysfs_create_group(struct kobject *kobj,
 				    const struct attribute_group *grp);
 int __must_check sysfs_create_groups(struct kobject *kobj,
@@ -353,6 +355,10 @@ static inline void sysfs_delete_link(struct kobject *k, struct kobject *t,
 {
 }
 
+static inline void sysfs_enable_ns(struct sysfs_dirent *sd)
+{
+}
+
 static inline int sysfs_create_group(struct kobject *kobj,
 				     const struct attribute_group *grp)
 {
diff --git a/lib/kobject.c b/lib/kobject.c
index 5b4b888..16e9335 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -65,13 +65,17 @@ static int populate_dir(struct kobject *kobj)
 
 static int create_dir(struct kobject *kobj)
 {
+	const struct kobj_ns_type_operations *ops;
 	int error;
 
 	error = sysfs_create_dir_ns(kobj, kobject_namespace(kobj));
-	if (!error) {
-		error = populate_dir(kobj);
-		if (error)
-			sysfs_remove_dir(kobj);
+	if (error)
+		return error;
+
+	error = populate_dir(kobj);
+	if (error) {
+		sysfs_remove_dir(kobj);
+		return error;
 	}
 
 	/*
@@ -80,7 +84,20 @@ static int create_dir(struct kobject *kobj)
 	 */
 	sysfs_get(kobj->sd);
 
-	return error;
+	/*
+	 * If @kobj has ns_ops, its children need to be filtered based on
+	 * their namespace tags.  Enable namespace support on @kobj->sd.
+	 */
+	ops = kobj_child_ns_ops(kobj);
+	if (ops) {
+		BUG_ON(ops->type <= KOBJ_NS_TYPE_NONE);
+		BUG_ON(ops->type >= KOBJ_NS_TYPES);
+		BUG_ON(!kobj_ns_type_registered(ops->type));
+
+		sysfs_enable_ns(kobj->sd);
+	}
+
+	return 0;
 }
 
 static int get_kobj_path_length(struct kobject *kobj)
-- 
1.8.4.2

[PATCH v4 09/41] sysfs, kernfs: introduce kernfs_create_dir[_ns]()

[Tejun Heo]

Introduce kernfs interface to manipulate a directory which takes and
returns sysfs_dirents.

create_dir() is renamed to kernfs_create_dir_ns() and its argumantes
and return value are updated.  create_dir() usages are replaced with
kernfs_create_dir_ns() and sysfs_create_subdir() usages are replaced
with kernfs_create_dir().  Dup warnings are handled explicitly by
sysfs users of the kernfs interface.

sysfs_enable_ns() is renamed to kernfs_enable_ns().

This patch doesn't introduce any behavior changes.

v2: Dummy implementation for !CONFIG_SYSFS updated to return -ENOSYS.

v3: kernfs_enable_ns() added.

v4: Refreshed on top of "sysfs: drop kobj_ns_type handling, take #2"
    so that this patch removes sysfs_enable_ns().

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/dir.c         | 54 ++++++++++++++++++++++++++++----------------------
 fs/sysfs/group.c       |  9 ++++++---
 fs/sysfs/sysfs.h       |  3 ---
 include/linux/kernfs.h | 17 ++++++++++++++++
 include/linux/sysfs.h  |  6 ------
 lib/kobject.c          |  2 +-
 6 files changed, 54 insertions(+), 37 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index aeb08bd..cfbf409 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -666,9 +666,18 @@ struct sysfs_dirent *sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd,
 }
 EXPORT_SYMBOL_GPL(sysfs_get_dirent_ns);
 
-static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
-		      const char *name, const void *ns,
-		      struct sysfs_dirent **p_sd)
+/**
+ * kernfs_create_dir_ns - create a directory
+ * @parent: parent in which to create a new directory
+ * @name: name of the new directory
+ * @priv: opaque data associated with the new directory
+ * @ns: optional namespace tag of the directory
+ *
+ * Returns the created node on success, ERR_PTR() value on failure.
+ */
+struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
+					  const char *name, void *priv,
+					  const void *ns)
 {
 	umode_t mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
 	struct sysfs_addrm_cxt acxt;
@@ -678,28 +687,21 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
 	/* allocate */
 	sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
 	if (!sd)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
 	sd->s_ns = ns;
-	sd->priv = kobj;
+	sd->priv = priv;
 
 	/* link in */
 	sysfs_addrm_start(&acxt);
-	rc = sysfs_add_one(&acxt, sd, parent_sd);
+	rc = __sysfs_add_one(&acxt, sd, parent);
 	sysfs_addrm_finish(&acxt);
 
-	if (rc == 0)
-		*p_sd = sd;
-	else
-		sysfs_put(sd);
+	if (!rc)
+		return sd;
 
-	return rc;
-}
-
-int sysfs_create_subdir(struct kobject *kobj, const char *name,
-			struct sysfs_dirent **p_sd)
-{
-	return create_dir(kobj, kobj->sd, name, NULL, p_sd);
+	sysfs_put(sd);
+	return ERR_PTR(rc);
 }
 
 /**
@@ -710,7 +712,6 @@ int sysfs_create_subdir(struct kobject *kobj, const char *name,
 int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
 {
 	struct sysfs_dirent *parent_sd, *sd;
-	int error = 0;
 
 	BUG_ON(!kobj);
 
@@ -722,10 +723,15 @@ int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
 	if (!parent_sd)
 		return -ENOENT;
 
-	error = create_dir(kobj, parent_sd, kobject_name(kobj), ns, &sd);
-	if (!error)
-		kobj->sd = sd;
-	return error;
+	sd = kernfs_create_dir_ns(parent_sd, kobject_name(kobj), kobj, ns);
+	if (IS_ERR(sd)) {
+		if (PTR_ERR(sd) == -EEXIST)
+			sysfs_warn_dup(parent_sd, kobject_name(kobj));
+		return PTR_ERR(sd);
+	}
+
+	kobj->sd = sd;
+	return 0;
 }
 
 static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry,
@@ -1005,14 +1011,14 @@ int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
 }
 
 /**
- * sysfs_enable_ns - enable namespace under a directory
+ * kernfs_enable_ns - enable namespace under a directory
  * @sd: directory of interest, should be empty
  *
  * This is to be called right after @sd is created to enable namespace
  * under it.  All children of @sd must have non-NULL namespace tags and
  * only the ones which match the super_block's tag will be visible.
  */
-void sysfs_enable_ns(struct sysfs_dirent *sd)
+void kernfs_enable_ns(struct sysfs_dirent *sd)
 {
 	WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
 	WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));
diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index 01657c5..11be6de 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -101,9 +101,12 @@ static int internal_create_group(struct kobject *kobj, int update,
 		return -EINVAL;
 	}
 	if (grp->name) {
-		error = sysfs_create_subdir(kobj, grp->name, &sd);
-		if (error)
-			return error;
+		sd = kernfs_create_dir(kobj->sd, grp->name, kobj);
+		if (IS_ERR(sd)) {
+			if (PTR_ERR(sd) == -EEXIST)
+				sysfs_warn_dup(kobj->sd, grp->name);
+			return PTR_ERR(sd);
+		}
 	} else
 		sd = kobj->sd;
 	sysfs_get(sd);
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index a6f3fa3..9ac234e 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -179,9 +179,6 @@ struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);
 
 void release_sysfs_dirent(struct sysfs_dirent *sd);
 
-int sysfs_create_subdir(struct kobject *kobj, const char *name,
-			struct sysfs_dirent **p_sd);
-
 static inline struct sysfs_dirent *__sysfs_get(struct sysfs_dirent *sd)
 {
 	if (sd) {
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 8cb6738..e8b73d4 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -17,6 +17,9 @@ struct sysfs_dirent;
 
 #ifdef CONFIG_SYSFS
 
+struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
+					  const char *name, void *priv,
+					  const void *ns);
 struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
 					const char *name,
 					struct sysfs_dirent *target);
@@ -25,11 +28,17 @@ int kernfs_remove_by_name_ns(struct sysfs_dirent *parent, const char *name,
 			     const void *ns);
 int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
 		     const char *new_name, const void *new_ns);
+void kernfs_enable_ns(struct sysfs_dirent *sd);
 int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr);
 
 #else	/* CONFIG_SYSFS */
 
 static inline struct sysfs_dirent *
+kernfs_create_dir_ns(struct sysfs_dirent *parent, const char *name, void *priv,
+		     const void *ns)
+{ return ERR_PTR(-ENOSYS); }
+
+static inline struct sysfs_dirent *
 kernfs_create_link(struct sysfs_dirent *parent, const char *name,
 		   struct sysfs_dirent *target)
 { return ERR_PTR(-ENOSYS); }
@@ -45,12 +54,20 @@ static inline int kernfs_rename_ns(struct sysfs_dirent *sd,
 				   const char *new_name, const void *new_ns)
 { return -ENOSYS; }
 
+static inline void kernfs_enable_ns(struct sysfs_dirent *sd) { }
+
 static inline int kernfs_setattr(struct sysfs_dirent *sd,
 				 const struct iattr *iattr)
 { return -ENOSYS; }
 
 #endif	/* CONFIG_SYSFS */
 
+static inline struct sysfs_dirent *
+kernfs_create_dir(struct sysfs_dirent *parent, const char *name, void *priv)
+{
+	return kernfs_create_dir_ns(parent, name, priv, NULL);
+}
+
 static inline int kernfs_remove_by_name(struct sysfs_dirent *parent,
 					const char *name)
 {
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index e17381a..2bc735d 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -219,8 +219,6 @@ int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *target,
 void sysfs_delete_link(struct kobject *dir, struct kobject *targ,
 			const char *name);
 
-void sysfs_enable_ns(struct sysfs_dirent *sd);
-
 int __must_check sysfs_create_group(struct kobject *kobj,
 				    const struct attribute_group *grp);
 int __must_check sysfs_create_groups(struct kobject *kobj,
@@ -354,10 +352,6 @@ static inline void sysfs_delete_link(struct kobject *k, struct kobject *t,
 {
 }
 
-static inline void sysfs_enable_ns(struct sysfs_dirent *sd)
-{
-}
-
 static inline int sysfs_create_group(struct kobject *kobj,
 				     const struct attribute_group *grp)
 {
diff --git a/lib/kobject.c b/lib/kobject.c
index 16e9335..b8d848f 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -94,7 +94,7 @@ static int create_dir(struct kobject *kobj)
 		BUG_ON(ops->type >= KOBJ_NS_TYPES);
 		BUG_ON(!kobj_ns_type_registered(ops->type));
 
-		sysfs_enable_ns(kobj->sd);
+		kernfs_enable_ns(kobj->sd);
 	}
 
 	return 0;
-- 
1.8.4.2

Re: [PATCHSET driver-core-next] sysfs: separate out kernfs, take #3

[Tejun Heo]

Hello,

On Sat, Nov 23, 2013 at 05:48:35PM -0500, Tejun Heo wrote:
> Please hold on a bit.  I have !CONFIG_SYSFS build failure.  I think I
> forgot to add dummy interface for a newly added function.  I'm fixing
> it right now.

Alright, the end result is the same.  0001 was missing dummy
implementation of sysfs_enable_ns() but 0009, while replacing it with
kernfs_enable_ns(), added the equivalent.  The patches are fixed so
that 0001 adds dummy sysfs_enable_ns() and 0009 replaces that with
kernfs_enable_ns(), but the end result is the same.

All the git branches are updated accordingly.

Thanks.

-- 
tejun

Re: [PATCHSET driver-core-next] sysfs: separate out kernfs, take #3

[Christoph Hellwig]

It would be highly useful if you could explain us what kernfs is
supposed to do and why we're cheerfully waiting for it.  Also given
that you touch VFS core files please Cc linux-fsdevel for those and
explain them in detail.

Re: [PATCHSET driver-core-next] sysfs: separate out kernfs, take #3

[Tejun Heo]

Hello,

On Sun, Nov 24, 2013 at 01:16:02AM -0800, Christoph Hellwig wrote:
> It would be highly useful if you could explain us what kernfs is
> supposed to do and why we're cheerfully waiting for it.  Also given

Oops, sorry about that.  It was explained in earlier series but I
probably should carry on a simplified explanation on later ones too.
It's just separating out the core features of sysfs into a separate
filesystem so that it can be used by non-kobject based users too.  So,
kernfs implements the core pseudo file functionality and sysfs becomes
kobject-wrapping layer on top of it.  I'm gonna convert cgroup to use
kernfs and Greg seems to have some plans for debugfs, IIUC.

> that you touch VFS core files please Cc linux-fsdevel for those and
> explain them in detail.

Does it?  Ah, okay, fs/Makefile and fs/namespace.c.  The former is
just adding kernfs/ directory and the latter is splitting out
kernfs_init() from sysfs_init() call.  Both are trivial.  Will cc
linux-fsdevel on those patches.

Thanks.

-- 
tejun

[PATCH REPOST 03/41] sysfs, kernfs: add skeletons for kernfs

[Tejun Heo]

Core sysfs implementation will be separated into kernfs so that it can
be used by other non-kobject users.

This patch creates fs/kernfs/ directory and makes boilerplate changes.
kernfs interface will be directly based on sysfs_dirent and its
forward declaration is moved to include/linux/kernfs.h which is
included from include/linux/sysfs.h.  sysfs core implementation will
be gradually separated out and moved to kernfs.

This patch doesn't introduce any functional changes.

v2: mount.c added.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: Christoph Hellwig <hch@infradead.org>
---
Reposting with linux-fsdevel and hch cc'd.  No content change.  git
branch updated accordingly.

Thanks.

 fs/Makefile            |  2 +-
 fs/kernfs/Makefile     |  5 +++++
 fs/kernfs/dir.c        |  9 +++++++++
 fs/kernfs/file.c       |  9 +++++++++
 fs/kernfs/inode.c      |  9 +++++++++
 fs/kernfs/mount.c      |  9 +++++++++
 fs/kernfs/symlink.c    |  9 +++++++++
 include/linux/kernfs.h | 12 ++++++++++++
 include/linux/sysfs.h  |  3 +--
 9 files changed, 64 insertions(+), 3 deletions(-)
 create mode 100644 fs/kernfs/Makefile
 create mode 100644 fs/kernfs/dir.c
 create mode 100644 fs/kernfs/file.c
 create mode 100644 fs/kernfs/inode.c
 create mode 100644 fs/kernfs/mount.c
 create mode 100644 fs/kernfs/symlink.c
 create mode 100644 include/linux/kernfs.h

diff --git a/fs/Makefile b/fs/Makefile
index 4fe6df3..39a824f 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -53,7 +53,7 @@ obj-$(CONFIG_FHANDLE)		+= fhandle.o
 obj-y				+= quota/
 
 obj-$(CONFIG_PROC_FS)		+= proc/
-obj-$(CONFIG_SYSFS)		+= sysfs/
+obj-$(CONFIG_SYSFS)		+= sysfs/ kernfs/
 obj-$(CONFIG_CONFIGFS_FS)	+= configfs/
 obj-y				+= devpts/
 
diff --git a/fs/kernfs/Makefile b/fs/kernfs/Makefile
new file mode 100644
index 0000000..674337c
--- /dev/null
+++ b/fs/kernfs/Makefile
@@ -0,0 +1,5 @@
+#
+# Makefile for the kernfs pseudo filesystem
+#
+
+obj-y		:= mount.o inode.o dir.o file.o symlink.o
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
new file mode 100644
index 0000000..1061602
--- /dev/null
+++ b/fs/kernfs/dir.c
@@ -0,0 +1,9 @@
+/*
+ * fs/kernfs/dir.c - kernfs directory implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
+ *
+ * This file is released under the GPLv2.
+ */
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
new file mode 100644
index 0000000..90b1e88
--- /dev/null
+++ b/fs/kernfs/file.c
@@ -0,0 +1,9 @@
+/*
+ * fs/kernfs/file.c - kernfs file implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
+ *
+ * This file is released under the GPLv2.
+ */
diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
new file mode 100644
index 0000000..86bfeea
--- /dev/null
+++ b/fs/kernfs/inode.c
@@ -0,0 +1,9 @@
+/*
+ * fs/kernfs/inode.c - kernfs inode implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
+ *
+ * This file is released under the GPLv2.
+ */
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
new file mode 100644
index 0000000..872e262
--- /dev/null
+++ b/fs/kernfs/mount.c
@@ -0,0 +1,9 @@
+/*
+ * fs/kernfs/mount.c - kernfs mount implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
+ *
+ * This file is released under the GPLv2.
+ */
diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c
new file mode 100644
index 0000000..2578715
--- /dev/null
+++ b/fs/kernfs/symlink.c
@@ -0,0 +1,9 @@
+/*
+ * fs/kernfs/symlink.c - kernfs symlink implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
+ *
+ * This file is released under the GPLv2.
+ */
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
new file mode 100644
index 0000000..254b9e8
--- /dev/null
+++ b/include/linux/kernfs.h
@@ -0,0 +1,12 @@
+/*
+ * kernfs.h - pseudo filesystem decoupled from vfs locking
+ *
+ * This file is released under the GPLv2.
+ */
+
+#ifndef __LINUX_KERNFS_H
+#define __LINUX_KERNFS_H
+
+struct sysfs_dirent;
+
+#endif	/* __LINUX_KERNFS_H */
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 362a34d..e17381a 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -12,6 +12,7 @@
 #ifndef _SYSFS_H_
 #define _SYSFS_H_
 
+#include <linux/kernfs.h>
 #include <linux/compiler.h>
 #include <linux/errno.h>
 #include <linux/list.h>
@@ -175,8 +176,6 @@ struct sysfs_ops {
 	ssize_t	(*store)(struct kobject *, struct attribute *, const char *, size_t);
 };
 
-struct sysfs_dirent;
-
 #ifdef CONFIG_SYSFS
 
 int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
-- 
1.8.4.2

[PATCH REPOST 37/41] sysfs, kernfs: prepare mount path for kernfs

[Tejun Heo]

We're in the process of separating out core sysfs functionality into
kernfs which will deal with sysfs_dirents directly.  This patch
rearranges mount path so that the kernfs and sysfs parts are separate.

* As sysfs_super_info won't be visible outside kernfs proper,
  kernfs_super_ns() is added to allow kernfs users to access a
  super_block's namespace tag.

* Generic mount operation is separated out into kernfs_mount_ns().
  sysfs_mount() now just performs sysfs-specific permission check,
  acquires namespace tag, and invokes kernfs_mount_ns().

* Generic superblock release is separated out into kernfs_kill_sb()
  which can be used directly as file_system_type->kill_sb().  As sysfs
  needs to put the namespace tag, sysfs_kill_sb() wraps
  kernfs_kill_sb() with ns tag put.

* sysfs_dir_cachep init and sysfs_inode_init() are separated out into
  kernfs_init().  kernfs_init() uses only small amount of memory and
  trying to handle and propagate kernfs_init() failure doesn't make
  much sense.  Use SLAB_PANIC for sysfs_dir_cachep and make
  sysfs_inode_init() panic on failure.

  After this change, kernfs_init() should be called before
  sysfs_init(), fs/namespace.c::mnt_init() modified accordingly.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: Christoph Hellwig <hch@infradead.org>
---
Reposting w/ linux-fsdevel and hch cc'd.  Updated description
slightly.  No content change.  git branch updated accordingly.

Thanks.

 fs/kernfs/inode.c           |   5 ++-
 fs/kernfs/kernfs-internal.h |   2 +-
 fs/namespace.c              |   2 +
 fs/sysfs/mount.c            | 104 ++++++++++++++++++++++++++++++--------------
 include/linux/kernfs.h      |  28 ++++++++++++
 5 files changed, 106 insertions(+), 35 deletions(-)

diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 9d4fab4..b4cae6f 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -37,9 +37,10 @@ static const struct inode_operations sysfs_inode_operations = {
 	.setxattr	= sysfs_setxattr,
 };
 
-int __init sysfs_inode_init(void)
+void __init sysfs_inode_init(void)
 {
-	return bdi_init(&sysfs_backing_dev_info);
+	if (bdi_init(&sysfs_backing_dev_info))
+		panic("failed to init sysfs_backing_dev_info");
 }
 
 static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 466943d..0d94988 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -144,7 +144,7 @@ int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
 		  struct kstat *stat);
 int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
 		   size_t size, int flags);
-int sysfs_inode_init(void);
+void sysfs_inode_init(void);
 
 /*
  * dir.c
diff --git a/fs/namespace.c b/fs/namespace.c
index ac2ce8a..a511ea0 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2790,6 +2790,8 @@ void __init mnt_init(void)
 	for (u = 0; u < HASH_SIZE; u++)
 		INIT_LIST_HEAD(&mountpoint_hashtable[u]);
 
+	kernfs_init();
+
 	err = sysfs_init();
 	if (err)
 		printk(KERN_WARNING "%s: sysfs_init error: %d\n",
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index f143b20..5384732 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -86,18 +86,24 @@ static int sysfs_set_super(struct super_block *sb, void *data)
 	return error;
 }
 
-static void free_sysfs_super_info(struct sysfs_super_info *info)
+/**
+ * kernfs_super_ns - determine the namespace tag of a kernfs super_block
+ * @sb: super_block of interest
+ *
+ * Return the namespace tag associated with kernfs super_block @sb.
+ */
+const void *kernfs_super_ns(struct super_block *sb)
 {
-	kobj_ns_drop(KOBJ_NS_TYPE_NET, (void *)info->ns);
-	kfree(info);
+	struct sysfs_super_info *info = sysfs_info(sb);
+
+	return info->ns;
 }
 
 static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data)
 {
-	struct sysfs_super_info *info;
-	struct super_block *sb;
-	int error;
+	struct dentry *root;
+	void *ns;
 
 	if (!(flags & MS_KERNMOUNT)) {
 		if (!capable(CAP_SYS_ADMIN) && !fs_fully_visible(fs_type))
@@ -107,16 +113,44 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 			return ERR_PTR(-EPERM);
 	}
 
+	ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
+	root = kernfs_mount_ns(fs_type, flags, sysfs_root, ns);
+	if (IS_ERR(root))
+		kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
+	return root;
+}
+
+/**
+ * kernfs_mount_ns - kernfs mount helper
+ * @fs_type: file_system_type of the fs being mounted
+ * @flags: mount flags specified for the mount
+ * @root: kernfs_root of the hierarchy being mounted
+ * @ns: optional namespace tag of the mount
+ *
+ * This is to be called from each kernfs user's file_system_type->mount()
+ * implementation, which should pass through the specified @fs_type and
+ * @flags, and specify the hierarchy and namespace tag to mount via @root
+ * and @ns, respectively.
+ *
+ * The return value can be passed to the vfs layer verbatim.
+ */
+struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
+			       struct kernfs_root *root, const void *ns)
+{
+	struct super_block *sb;
+	struct sysfs_super_info *info;
+	int error;
+
 	info = kzalloc(sizeof(*info), GFP_KERNEL);
 	if (!info)
 		return ERR_PTR(-ENOMEM);
 
-	info->root = sysfs_root;
-	info->ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
+	info->root = root;
+	info->ns = ns;
 
 	sb = sget(fs_type, sysfs_test_super, sysfs_set_super, flags, info);
 	if (IS_ERR(sb) || sb->s_fs_info != info)
-		free_sysfs_super_info(info);
+		kfree(info);
 	if (IS_ERR(sb))
 		return ERR_CAST(sb);
 	if (!sb->s_root) {
@@ -133,6 +167,20 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 
 static void sysfs_kill_sb(struct super_block *sb)
 {
+	kernfs_kill_sb(sb);
+	kobj_ns_drop(KOBJ_NS_TYPE_NET, (void *)kernfs_super_ns(sb));
+}
+
+/**
+ * kernfs_kill_sb - kill_sb for kernfs
+ * @sb: super_block being killed
+ *
+ * This can be used directly for file_system_type->kill_sb().  If a kernfs
+ * user needs extra cleanup, it can implement its own kill_sb() and call
+ * this function at the end.
+ */
+void kernfs_kill_sb(struct super_block *sb)
+{
 	struct sysfs_super_info *info = sysfs_info(sb);
 	struct sysfs_dirent *root_sd = sb->s_root->d_fsdata;
 
@@ -141,7 +189,7 @@ static void sysfs_kill_sb(struct super_block *sb)
 	 * so we can't find it, before freeing sysfs_super_info.
 	 */
 	kill_anon_super(sb);
-	free_sysfs_super_info(info);
+	kfree(info);
 	kernfs_put(root_sd);
 }
 
@@ -152,37 +200,29 @@ static struct file_system_type sysfs_fs_type = {
 	.fs_flags	= FS_USERNS_MOUNT,
 };
 
-int __init sysfs_init(void)
+void __init kernfs_init(void)
 {
-	int err;
-
 	sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
 					      sizeof(struct sysfs_dirent),
-					      0, 0, NULL);
-	if (!sysfs_dir_cachep)
-		return -ENOMEM;
+					      0, SLAB_PANIC, NULL);
+	sysfs_inode_init();
+}
 
-	err = sysfs_inode_init();
-	if (err)
-		goto out_err;
+int __init sysfs_init(void)
+{
+	int err;
 
 	sysfs_root = kernfs_create_root(NULL);
-	if (IS_ERR(sysfs_root)) {
-		err = PTR_ERR(sysfs_root);
-		goto out_err;
-	}
+	if (IS_ERR(sysfs_root))
+		return PTR_ERR(sysfs_root);
+
 	sysfs_root_sd = sysfs_root->sd;
 
 	err = register_filesystem(&sysfs_fs_type);
-	if (err)
-		goto out_destroy_root;
+	if (err) {
+		kernfs_destroy_root(sysfs_root);
+		return err;
+	}
 
 	return 0;
-
-out_destroy_root:
-	kernfs_destroy_root(sysfs_root);
-out_err:
-	kmem_cache_destroy(sysfs_dir_cachep);
-	sysfs_dir_cachep = NULL;
-	return err;
 }
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index fad8b98..75fcbe5 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -18,6 +18,8 @@ struct file;
 struct iattr;
 struct seq_file;
 struct vm_area_struct;
+struct super_block;
+struct file_system_type;
 
 struct sysfs_dirent;
 
@@ -109,6 +111,13 @@ void kernfs_enable_ns(struct sysfs_dirent *sd);
 int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr);
 void kernfs_notify(struct sysfs_dirent *sd);
 
+const void *kernfs_super_ns(struct super_block *sb);
+struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
+			       struct kernfs_root *root, const void *ns);
+void kernfs_kill_sb(struct super_block *sb);
+
+void kernfs_init(void);
+
 #else	/* CONFIG_SYSFS */
 
 static inline struct sysfs_dirent *
@@ -160,6 +169,18 @@ static inline int kernfs_setattr(struct sysfs_dirent *sd,
 
 static inline void kernfs_notify(struct sysfs_dirent *sd) { }
 
+static inline const void *kernfs_super_ns(struct super_block *sb)
+{ return NULL; }
+
+static inline struct dentry *
+kernfs_mount_ns(struct file_system_type *fs_type, int flags,
+		struct kernfs_root *root, const void *ns)
+{ return ERR_PTR(-ENOSYS); }
+
+static inline void kernfs_kill_sb(struct super_block *sb) { }
+
+static inline void kernfs_init(void) { }
+
 #endif	/* CONFIG_SYSFS */
 
 static inline struct sysfs_dirent *
@@ -201,4 +222,11 @@ static inline int kernfs_remove_by_name(struct sysfs_dirent *parent,
 	return kernfs_remove_by_name_ns(parent, name, NULL);
 }
 
+static inline struct dentry *
+kernfs_mount(struct file_system_type *fs_type, int flags,
+	     struct kernfs_root *root)
+{
+	return kernfs_mount_ns(fs_type, flags, root, NULL);
+}
+
 #endif	/* __LINUX_KERNFS_H */
-- 
1.8.4.2

Re: [PATCH v4 09/41] sysfs, kernfs: introduce kernfs_create_dir[_ns]()

[Greg KH]

On Sat, Nov 23, 2013 at 06:07:04PM -0500, Tejun Heo wrote:
> Introduce kernfs interface to manipulate a directory which takes and
> returns sysfs_dirents.
> 
> create_dir() is renamed to kernfs_create_dir_ns() and its argumantes
> and return value are updated.  create_dir() usages are replaced with
> kernfs_create_dir_ns() and sysfs_create_subdir() usages are replaced
> with kernfs_create_dir().  Dup warnings are handled explicitly by
> sysfs users of the kernfs interface.
> 
> sysfs_enable_ns() is renamed to kernfs_enable_ns().
> 
> This patch doesn't introduce any behavior changes.
> 
> v2: Dummy implementation for !CONFIG_SYSFS updated to return -ENOSYS.
> 
> v3: kernfs_enable_ns() added.
> 
> v4: Refreshed on top of "sysfs: drop kobj_ns_type handling, take #2"
>     so that this patch removes sysfs_enable_ns().

Care to go for v5?  This doesn't apply on my tree anymore, I'm pretty
sure due to the other fixes in fs/sysfs/dir.c.

I tried to do the merge myself, but I don't think I got it right at all,
so could you just check out my driver-core.git tree on the
driver-core-next branch and refresh this patch?

thanks so much, I've applied the other 8 patches in this series already,
they seem fine.

greg k-h

[PATCHSET PARTIAL REPOST driver-core-next] sysfs: separate out kernfs, take #3

[Tejun Heo]

Hello, Greg.

For some reason, quilt can rebase the patches automatically here.  I'm
reposting the rest of the series (patches 07-41) here just in case.
git branches for both pending patchsets are updated accordingly.

 git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git review-separate-out-kernfs
 git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git review-kernfs-xattr

Thanks.

--
tejun

[PATCH 01/34] sysfs, kernfs: replace sysfs_dirent->s_dir.kobj and ->s_attr.[bin_]attr with ->priv

[Tejun Heo]

A directory sysfs_dirent points to the associated kobj.  A regular or
bin file points to the associated [bin_]attribute.  This patch
replaces sysfs_dirent->s_dir.kobj and ->s_attr.[bin_]attr with void *
->priv.

This is to prepare for kernfs interface so that sysfs can specify the
private data in the same way for directories and files.  This lower
debuggability but not by much - the whole thing was overlaid in a
union anyway.  If debuggability becomes an issue, we can later add
->priv accessors which explicitly check for the sysfs_dirent type and
performs casting.

This patch doesn't introduce any behavior difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/dir.c     |  2 +-
 fs/sysfs/file.c    | 26 +++++++++++++-------------
 fs/sysfs/inode.c   |  2 +-
 fs/sysfs/symlink.c |  2 +-
 fs/sysfs/sysfs.h   | 13 +++++--------
 5 files changed, 21 insertions(+), 24 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 5ba8966..aeb08bd 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -681,7 +681,7 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
 		return -ENOMEM;
 
 	sd->s_ns = ns;
-	sd->s_dir.kobj = kobj;
+	sd->priv = kobj;
 
 	/* link in */
 	sysfs_addrm_start(&acxt);
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 0f3f0a2..9b58d87 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -74,7 +74,7 @@ static struct sysfs_open_file *sysfs_of(struct file *file)
  */
 static const struct sysfs_ops *sysfs_file_ops(struct sysfs_dirent *sd)
 {
-	struct kobject *kobj = sd->s_parent->s_dir.kobj;
+	struct kobject *kobj = sd->s_parent->priv;
 
 	if (!sysfs_ignore_lockdep(sd))
 		lockdep_assert_held(sd);
@@ -89,7 +89,7 @@ static const struct sysfs_ops *sysfs_file_ops(struct sysfs_dirent *sd)
 static int sysfs_seq_show(struct seq_file *sf, void *v)
 {
 	struct sysfs_open_file *of = sf->private;
-	struct kobject *kobj = of->sd->s_parent->s_dir.kobj;
+	struct kobject *kobj = of->sd->s_parent->priv;
 	const struct sysfs_ops *ops;
 	char *buf;
 	ssize_t count;
@@ -120,7 +120,7 @@ static int sysfs_seq_show(struct seq_file *sf, void *v)
 	 */
 	ops = sysfs_file_ops(of->sd);
 	if (ops->show)
-		count = ops->show(kobj, of->sd->s_attr.attr, buf);
+		count = ops->show(kobj, of->sd->priv, buf);
 	else
 		count = 0;
 
@@ -154,8 +154,8 @@ static ssize_t sysfs_bin_read(struct file *file, char __user *userbuf,
 			      size_t bytes, loff_t *off)
 {
 	struct sysfs_open_file *of = sysfs_of(file);
-	struct bin_attribute *battr = of->sd->s_attr.bin_attr;
-	struct kobject *kobj = of->sd->s_parent->s_dir.kobj;
+	struct bin_attribute *battr = of->sd->priv;
+	struct kobject *kobj = of->sd->s_parent->priv;
 	loff_t size = file_inode(file)->i_size;
 	int count = min_t(size_t, bytes, PAGE_SIZE);
 	loff_t offs = *off;
@@ -221,7 +221,7 @@ static ssize_t sysfs_bin_read(struct file *file, char __user *userbuf,
 static int flush_write_buffer(struct sysfs_open_file *of, char *buf, loff_t off,
 			      size_t count)
 {
-	struct kobject *kobj = of->sd->s_parent->s_dir.kobj;
+	struct kobject *kobj = of->sd->s_parent->priv;
 	int rc = 0;
 
 	/*
@@ -236,7 +236,7 @@ static int flush_write_buffer(struct sysfs_open_file *of, char *buf, loff_t off,
 	}
 
 	if (sysfs_is_bin(of->sd)) {
-		struct bin_attribute *battr = of->sd->s_attr.bin_attr;
+		struct bin_attribute *battr = of->sd->priv;
 
 		rc = -EIO;
 		if (battr->write)
@@ -245,7 +245,7 @@ static int flush_write_buffer(struct sysfs_open_file *of, char *buf, loff_t off,
 	} else {
 		const struct sysfs_ops *ops = sysfs_file_ops(of->sd);
 
-		rc = ops->store(kobj, of->sd->s_attr.attr, buf, count);
+		rc = ops->store(kobj, of->sd->priv, buf, count);
 	}
 
 	sysfs_put_active(of->sd);
@@ -466,8 +466,8 @@ static const struct vm_operations_struct sysfs_bin_vm_ops = {
 static int sysfs_bin_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	struct sysfs_open_file *of = sysfs_of(file);
-	struct bin_attribute *battr = of->sd->s_attr.bin_attr;
-	struct kobject *kobj = of->sd->s_parent->s_dir.kobj;
+	struct bin_attribute *battr = of->sd->priv;
+	struct kobject *kobj = of->sd->s_parent->priv;
 	int rc;
 
 	mutex_lock(&of->mutex);
@@ -607,7 +607,7 @@ static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
 static int sysfs_open_file(struct inode *inode, struct file *file)
 {
 	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
-	struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
+	struct kobject *kobj = attr_sd->s_parent->priv;
 	struct sysfs_open_file *of;
 	bool has_read, has_write, has_mmap;
 	int error = -EACCES;
@@ -617,7 +617,7 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
 		return -ENODEV;
 
 	if (sysfs_is_bin(attr_sd)) {
-		struct bin_attribute *battr = attr_sd->s_attr.bin_attr;
+		struct bin_attribute *battr = attr_sd->priv;
 
 		has_read = battr->read || battr->mmap;
 		has_write = battr->write || battr->mmap;
@@ -848,7 +848,7 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 		return -ENOMEM;
 
 	sd->s_ns = ns;
-	sd->s_attr.attr = (void *)attr;
+	sd->priv = (void *)attr;
 	sysfs_dirent_init_lockdep(sd);
 
 	sysfs_addrm_start(&acxt);
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index 5f7e2af..81cc858 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -275,7 +275,7 @@ static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
 		inode->i_fop = &sysfs_file_operations;
 		break;
 	case SYSFS_KOBJ_BIN_ATTR:
-		bin_attr = sd->s_attr.bin_attr;
+		bin_attr = sd->priv;
 		inode->i_size = bin_attr->size;
 		inode->i_fop = &sysfs_bin_operations;
 		break;
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 0922c53..352fbbb 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -223,7 +223,7 @@ int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *targ,
 	result = -EINVAL;
 	if (sysfs_type(sd) != SYSFS_KOBJ_LINK)
 		goto out;
-	if (sd->s_symlink.target_sd->s_dir.kobj != targ)
+	if (sd->s_symlink.target_sd->priv != targ)
 		goto out;
 
 	result = kernfs_rename_ns(sd, parent_sd, new, new_ns);
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 2abccfd..a6f3fa3 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -17,8 +17,6 @@ struct sysfs_open_dirent;
 
 /* type-specific structures for sysfs_dirent->s_* union members */
 struct sysfs_elem_dir {
-	struct kobject		*kobj;
-
 	unsigned long		subdirs;
 	/* children rbtree starts here and goes through sd->s_rb */
 	struct rb_root		children;
@@ -29,10 +27,6 @@ struct sysfs_elem_symlink {
 };
 
 struct sysfs_elem_attr {
-	union {
-		struct attribute	*attr;
-		struct bin_attribute	*bin_attr;
-	};
 	struct sysfs_open_dirent *open;
 };
 
@@ -74,6 +68,8 @@ struct sysfs_dirent {
 		struct sysfs_elem_attr		s_attr;
 	};
 
+	void			*priv;
+
 	unsigned short		s_flags;
 	umode_t			s_mode;
 	unsigned int		s_ino;
@@ -103,7 +99,7 @@ static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
 
 #define sysfs_dirent_init_lockdep(sd)				\
 do {								\
-	struct attribute *attr = sd->s_attr.attr;		\
+	struct attribute *attr = sd->priv;			\
 	struct lock_class_key *key = attr->key;			\
 	if (!key)						\
 		key = &attr->skey;				\
@@ -114,10 +110,11 @@ do {								\
 /* Test for attributes that want to ignore lockdep for read-locking */
 static inline bool sysfs_ignore_lockdep(struct sysfs_dirent *sd)
 {
+	struct attribute *attr = sd->priv;
 	int type = sysfs_type(sd);
 
 	return (type == SYSFS_KOBJ_ATTR || type == SYSFS_KOBJ_BIN_ATTR) &&
-		sd->s_attr.attr->ignore_lockdep;
+		attr->ignore_lockdep;
 }
 
 #else
-- 
1.8.4.2

[PATCH 02/34] sysfs, kernfs: introduce kernfs_create_dir[_ns]()

[Tejun Heo]

Introduce kernfs interface to manipulate a directory which takes and
returns sysfs_dirents.

create_dir() is renamed to kernfs_create_dir_ns() and its argumantes
and return value are updated.  create_dir() usages are replaced with
kernfs_create_dir_ns() and sysfs_create_subdir() usages are replaced
with kernfs_create_dir().  Dup warnings are handled explicitly by
sysfs users of the kernfs interface.

sysfs_enable_ns() is renamed to kernfs_enable_ns().

This patch doesn't introduce any behavior changes.

v2: Dummy implementation for !CONFIG_SYSFS updated to return -ENOSYS.

v3: kernfs_enable_ns() added.

v4: Refreshed on top of "sysfs: drop kobj_ns_type handling, take #2"
    so that this patch removes sysfs_enable_ns().

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/dir.c         | 54 ++++++++++++++++++++++++++++----------------------
 fs/sysfs/group.c       |  9 ++++++---
 fs/sysfs/sysfs.h       |  3 ---
 include/linux/kernfs.h | 17 ++++++++++++++++
 include/linux/sysfs.h  |  6 ------
 lib/kobject.c          |  2 +-
 6 files changed, 54 insertions(+), 37 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index aeb08bd..cfbf409 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -666,9 +666,18 @@ struct sysfs_dirent *sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd,
 }
 EXPORT_SYMBOL_GPL(sysfs_get_dirent_ns);
 
-static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
-		      const char *name, const void *ns,
-		      struct sysfs_dirent **p_sd)
+/**
+ * kernfs_create_dir_ns - create a directory
+ * @parent: parent in which to create a new directory
+ * @name: name of the new directory
+ * @priv: opaque data associated with the new directory
+ * @ns: optional namespace tag of the directory
+ *
+ * Returns the created node on success, ERR_PTR() value on failure.
+ */
+struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
+					  const char *name, void *priv,
+					  const void *ns)
 {
 	umode_t mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
 	struct sysfs_addrm_cxt acxt;
@@ -678,28 +687,21 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
 	/* allocate */
 	sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
 	if (!sd)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
 	sd->s_ns = ns;
-	sd->priv = kobj;
+	sd->priv = priv;
 
 	/* link in */
 	sysfs_addrm_start(&acxt);
-	rc = sysfs_add_one(&acxt, sd, parent_sd);
+	rc = __sysfs_add_one(&acxt, sd, parent);
 	sysfs_addrm_finish(&acxt);
 
-	if (rc == 0)
-		*p_sd = sd;
-	else
-		sysfs_put(sd);
+	if (!rc)
+		return sd;
 
-	return rc;
-}
-
-int sysfs_create_subdir(struct kobject *kobj, const char *name,
-			struct sysfs_dirent **p_sd)
-{
-	return create_dir(kobj, kobj->sd, name, NULL, p_sd);
+	sysfs_put(sd);
+	return ERR_PTR(rc);
 }
 
 /**
@@ -710,7 +712,6 @@ int sysfs_create_subdir(struct kobject *kobj, const char *name,
 int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
 {
 	struct sysfs_dirent *parent_sd, *sd;
-	int error = 0;
 
 	BUG_ON(!kobj);
 
@@ -722,10 +723,15 @@ int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
 	if (!parent_sd)
 		return -ENOENT;
 
-	error = create_dir(kobj, parent_sd, kobject_name(kobj), ns, &sd);
-	if (!error)
-		kobj->sd = sd;
-	return error;
+	sd = kernfs_create_dir_ns(parent_sd, kobject_name(kobj), kobj, ns);
+	if (IS_ERR(sd)) {
+		if (PTR_ERR(sd) == -EEXIST)
+			sysfs_warn_dup(parent_sd, kobject_name(kobj));
+		return PTR_ERR(sd);
+	}
+
+	kobj->sd = sd;
+	return 0;
 }
 
 static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry,
@@ -1005,14 +1011,14 @@ int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
 }
 
 /**
- * sysfs_enable_ns - enable namespace under a directory
+ * kernfs_enable_ns - enable namespace under a directory
  * @sd: directory of interest, should be empty
  *
  * This is to be called right after @sd is created to enable namespace
  * under it.  All children of @sd must have non-NULL namespace tags and
  * only the ones which match the super_block's tag will be visible.
  */
-void sysfs_enable_ns(struct sysfs_dirent *sd)
+void kernfs_enable_ns(struct sysfs_dirent *sd)
 {
 	WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
 	WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));
diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index 4bd9973..065689d 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -101,9 +101,12 @@ static int internal_create_group(struct kobject *kobj, int update,
 		return -EINVAL;
 	}
 	if (grp->name) {
-		error = sysfs_create_subdir(kobj, grp->name, &sd);
-		if (error)
-			return error;
+		sd = kernfs_create_dir(kobj->sd, grp->name, kobj);
+		if (IS_ERR(sd)) {
+			if (PTR_ERR(sd) == -EEXIST)
+				sysfs_warn_dup(kobj->sd, grp->name);
+			return PTR_ERR(sd);
+		}
 	} else
 		sd = kobj->sd;
 	sysfs_get(sd);
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index a6f3fa3..9ac234e 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -179,9 +179,6 @@ struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);
 
 void release_sysfs_dirent(struct sysfs_dirent *sd);
 
-int sysfs_create_subdir(struct kobject *kobj, const char *name,
-			struct sysfs_dirent **p_sd);
-
 static inline struct sysfs_dirent *__sysfs_get(struct sysfs_dirent *sd)
 {
 	if (sd) {
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 8cb6738..e8b73d4 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -17,6 +17,9 @@ struct sysfs_dirent;
 
 #ifdef CONFIG_SYSFS
 
+struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
+					  const char *name, void *priv,
+					  const void *ns);
 struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
 					const char *name,
 					struct sysfs_dirent *target);
@@ -25,11 +28,17 @@ int kernfs_remove_by_name_ns(struct sysfs_dirent *parent, const char *name,
 			     const void *ns);
 int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
 		     const char *new_name, const void *new_ns);
+void kernfs_enable_ns(struct sysfs_dirent *sd);
 int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr);
 
 #else	/* CONFIG_SYSFS */
 
 static inline struct sysfs_dirent *
+kernfs_create_dir_ns(struct sysfs_dirent *parent, const char *name, void *priv,
+		     const void *ns)
+{ return ERR_PTR(-ENOSYS); }
+
+static inline struct sysfs_dirent *
 kernfs_create_link(struct sysfs_dirent *parent, const char *name,
 		   struct sysfs_dirent *target)
 { return ERR_PTR(-ENOSYS); }
@@ -45,12 +54,20 @@ static inline int kernfs_rename_ns(struct sysfs_dirent *sd,
 				   const char *new_name, const void *new_ns)
 { return -ENOSYS; }
 
+static inline void kernfs_enable_ns(struct sysfs_dirent *sd) { }
+
 static inline int kernfs_setattr(struct sysfs_dirent *sd,
 				 const struct iattr *iattr)
 { return -ENOSYS; }
 
 #endif	/* CONFIG_SYSFS */
 
+static inline struct sysfs_dirent *
+kernfs_create_dir(struct sysfs_dirent *parent, const char *name, void *priv)
+{
+	return kernfs_create_dir_ns(parent, name, priv, NULL);
+}
+
 static inline int kernfs_remove_by_name(struct sysfs_dirent *parent,
 					const char *name)
 {
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index e17381a..2bc735d 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -219,8 +219,6 @@ int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *target,
 void sysfs_delete_link(struct kobject *dir, struct kobject *targ,
 			const char *name);
 
-void sysfs_enable_ns(struct sysfs_dirent *sd);
-
 int __must_check sysfs_create_group(struct kobject *kobj,
 				    const struct attribute_group *grp);
 int __must_check sysfs_create_groups(struct kobject *kobj,
@@ -354,10 +352,6 @@ static inline void sysfs_delete_link(struct kobject *k, struct kobject *t,
 {
 }
 
-static inline void sysfs_enable_ns(struct sysfs_dirent *sd)
-{
-}
-
 static inline int sysfs_create_group(struct kobject *kobj,
 				     const struct attribute_group *grp)
 {
diff --git a/lib/kobject.c b/lib/kobject.c
index 16e9335..b8d848f 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -94,7 +94,7 @@ static int create_dir(struct kobject *kobj)
 		BUG_ON(ops->type >= KOBJ_NS_TYPES);
 		BUG_ON(!kobj_ns_type_registered(ops->type));
 
-		sysfs_enable_ns(kobj->sd);
+		kernfs_enable_ns(kobj->sd);
 	}
 
 	return 0;
-- 
1.8.4.2

[PATCH 03/34] sysfs, kernfs: prepare read path for kernfs

[Tejun Heo]

We're in the process of separating out core sysfs functionality into
kernfs which will deal with sysfs_dirents directly.  This patch
rearranges read path so that the kernfs and sysfs parts are separate.

* Regular file read path is refactored such that
  kernfs_seq_start/next/stop/show() handle all the boilerplate work
  including locking and updating event count for poll, while
  sysfs_kf_seq_show() deals with interaction with kobj show method.

* Bin file read path is refactored such that kernfs_file_direct_read()
  handles all the boilerplate work including buffer management and
  locking, while sysfs_kf_bin_read() deals with interaction with
  bin_attribute read method.

kernfs_file_read() is added.  It invokes either the seq_file or direct
read path depending on the file type.  This will eventually allow
using the same file_operations for both file types, which is necessary
to separate out kernfs.

While this patch changes the order of some operations, it shouldn't
change any visible behavior.

v2: Dropped unnecessary zeroing of @count from sysfs_kf_seq_show().
    Add comments explaining single_open() behavior.  Both suggested by
    Pavel.

v3: seq_stop() is called even after seq_start() failed.
    kernfs_seq_start() updated so that it doesn't unlock
    sysfs_open_file->mutex on failure so that kernfs_seq_stop()
    doesn't try to unlock an already unlocked mutex.  Reported by
    Fengguang.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Fengguang Wu <fengguang.wu@intel.com>
---
 fs/sysfs/file.c | 191 +++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 126 insertions(+), 65 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 9b58d87..b695b8b 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -86,13 +86,13 @@ static const struct sysfs_ops *sysfs_file_ops(struct sysfs_dirent *sd)
  * details like buffering and seeking.  The following function pipes
  * sysfs_ops->show() result through seq_file.
  */
-static int sysfs_seq_show(struct seq_file *sf, void *v)
+static int sysfs_kf_seq_show(struct seq_file *sf, void *v)
 {
 	struct sysfs_open_file *of = sf->private;
 	struct kobject *kobj = of->sd->s_parent->priv;
-	const struct sysfs_ops *ops;
-	char *buf;
+	const struct sysfs_ops *ops = sysfs_file_ops(of->sd);
 	ssize_t count;
+	char *buf;
 
 	/* acquire buffer and ensure that it's >= PAGE_SIZE */
 	count = seq_get_buf(sf, &buf);
@@ -102,33 +102,14 @@ static int sysfs_seq_show(struct seq_file *sf, void *v)
 	}
 
 	/*
-	 * Need @of->sd for attr and ops, its parent for kobj.  @of->mutex
-	 * nests outside active ref and is just to ensure that the ops
-	 * aren't called concurrently for the same open file.
+	 * Invoke show().  Control may reach here via seq file lseek even
+	 * if @ops->show() isn't implemented.
 	 */
-	mutex_lock(&of->mutex);
-	if (!sysfs_get_active(of->sd)) {
-		mutex_unlock(&of->mutex);
-		return -ENODEV;
-	}
-
-	of->event = atomic_read(&of->sd->s_attr.open->event);
-
-	/*
-	 * Lookup @ops and invoke show().  Control may reach here via seq
-	 * file lseek even if @ops->show() isn't implemented.
-	 */
-	ops = sysfs_file_ops(of->sd);
-	if (ops->show)
+	if (ops->show) {
 		count = ops->show(kobj, of->sd->priv, buf);
-	else
-		count = 0;
-
-	sysfs_put_active(of->sd);
-	mutex_unlock(&of->mutex);
-
-	if (count < 0)
-		return count;
+		if (count < 0)
+			return count;
+	}
 
 	/*
 	 * The code works fine with PAGE_SIZE return but it's likely to
@@ -144,68 +125,146 @@ static int sysfs_seq_show(struct seq_file *sf, void *v)
 	return 0;
 }
 
-/*
- * Read method for bin files.  As reading a bin file can have side-effects,
- * the exact offset and bytes specified in read(2) call should be passed to
- * the read callback making it difficult to use seq_file.  Implement
- * simplistic custom buffering for bin files.
- */
-static ssize_t sysfs_bin_read(struct file *file, char __user *userbuf,
-			      size_t bytes, loff_t *off)
+static ssize_t sysfs_kf_bin_read(struct sysfs_open_file *of, char *buf,
+				 size_t count, loff_t pos)
 {
-	struct sysfs_open_file *of = sysfs_of(file);
 	struct bin_attribute *battr = of->sd->priv;
 	struct kobject *kobj = of->sd->s_parent->priv;
-	loff_t size = file_inode(file)->i_size;
-	int count = min_t(size_t, bytes, PAGE_SIZE);
-	loff_t offs = *off;
-	char *buf;
+	loff_t size = file_inode(of->file)->i_size;
 
-	if (!bytes)
+	if (!count)
 		return 0;
 
 	if (size) {
-		if (offs > size)
+		if (pos > size)
 			return 0;
-		if (offs + count > size)
-			count = size - offs;
+		if (pos + count > size)
+			count = size - pos;
 	}
 
-	buf = kmalloc(count, GFP_KERNEL);
+	if (!battr->read)
+		return -EIO;
+
+	return battr->read(of->file, kobj, battr, buf, pos, count);
+}
+
+static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos)
+{
+	struct sysfs_open_file *of = sf->private;
+
+	/*
+	 * @of->mutex nests outside active ref and is just to ensure that
+	 * the ops aren't called concurrently for the same open file.
+	 */
+	mutex_lock(&of->mutex);
+	if (!sysfs_get_active(of->sd))
+		return ERR_PTR(-ENODEV);
+
+	/*
+	 * The same behavior and code as single_open().  Returns !NULL if
+	 * pos is at the beginning; otherwise, NULL.
+	 */
+	return NULL + !*ppos;
+}
+
+static void *kernfs_seq_next(struct seq_file *sf, void *v, loff_t *ppos)
+{
+	/*
+	 * The same behavior and code as single_open(), always terminate
+	 * after the initial read.
+	 */
+	++*ppos;
+	return NULL;
+}
+
+static void kernfs_seq_stop(struct seq_file *sf, void *v)
+{
+	struct sysfs_open_file *of = sf->private;
+
+	sysfs_put_active(of->sd);
+	mutex_unlock(&of->mutex);
+}
+
+static int kernfs_seq_show(struct seq_file *sf, void *v)
+{
+	struct sysfs_open_file *of = sf->private;
+
+	of->event = atomic_read(&of->sd->s_attr.open->event);
+
+	return sysfs_kf_seq_show(sf, v);
+}
+
+static const struct seq_operations kernfs_seq_ops = {
+	.start = kernfs_seq_start,
+	.next = kernfs_seq_next,
+	.stop = kernfs_seq_stop,
+	.show = kernfs_seq_show,
+};
+
+/*
+ * As reading a bin file can have side-effects, the exact offset and bytes
+ * specified in read(2) call should be passed to the read callback making
+ * it difficult to use seq_file.  Implement simplistic custom buffering for
+ * bin files.
+ */
+static ssize_t kernfs_file_direct_read(struct sysfs_open_file *of,
+				       char __user *user_buf, size_t count,
+				       loff_t *ppos)
+{
+	ssize_t len = min_t(size_t, count, PAGE_SIZE);
+	char *buf;
+
+	buf = kmalloc(len, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
-	/* need of->sd for battr, its parent for kobj */
+	/*
+	 * @of->mutex nests outside active ref and is just to ensure that
+	 * the ops aren't called concurrently for the same open file.
+	 */
 	mutex_lock(&of->mutex);
 	if (!sysfs_get_active(of->sd)) {
-		count = -ENODEV;
+		len = -ENODEV;
 		mutex_unlock(&of->mutex);
 		goto out_free;
 	}
 
-	if (battr->read)
-		count = battr->read(file, kobj, battr, buf, offs, count);
-	else
-		count = -EIO;
+	len = sysfs_kf_bin_read(of, buf, len, *ppos);
 
 	sysfs_put_active(of->sd);
 	mutex_unlock(&of->mutex);
 
-	if (count < 0)
+	if (len < 0)
 		goto out_free;
 
-	if (copy_to_user(userbuf, buf, count)) {
-		count = -EFAULT;
+	if (copy_to_user(user_buf, buf, len)) {
+		len = -EFAULT;
 		goto out_free;
 	}
 
-	pr_debug("offs = %lld, *off = %lld, count = %d\n", offs, *off, count);
-
-	*off = offs + count;
+	*ppos += len;
 
  out_free:
 	kfree(buf);
-	return count;
+	return len;
+}
+
+/**
+ * kernfs_file_read - kernfs vfs read callback
+ * @file: file pointer
+ * @user_buf: data to write
+ * @count: number of bytes
+ * @ppos: starting offset
+ */
+static ssize_t kernfs_file_read(struct file *file, char __user *user_buf,
+				size_t count, loff_t *ppos)
+{
+	struct sysfs_open_file *of = sysfs_of(file);
+
+	if (sysfs_is_bin(of->sd))
+		return kernfs_file_direct_read(of, user_buf, count, ppos);
+	else
+		return seq_read(file, user_buf, count, ppos);
 }
 
 /**
@@ -677,12 +736,14 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
 	 * and readable regular files are the vast majority anyway.
 	 */
 	if (sysfs_is_bin(attr_sd))
-		error = single_open(file, NULL, of);
+		error = seq_open(file, NULL);
 	else
-		error = single_open(file, sysfs_seq_show, of);
+		error = seq_open(file, &kernfs_seq_ops);
 	if (error)
 		goto err_free;
 
+	((struct seq_file *)file->private_data)->private = of;
+
 	/* seq_file clears PWRITE unconditionally, restore it if WRITE */
 	if (file->f_mode & FMODE_WRITE)
 		file->f_mode |= FMODE_PWRITE;
@@ -697,7 +758,7 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
 	return 0;
 
 err_close:
-	single_release(inode, file);
+	seq_release(inode, file);
 err_free:
 	kfree(of);
 err_out:
@@ -711,7 +772,7 @@ static int sysfs_release(struct inode *inode, struct file *filp)
 	struct sysfs_open_file *of = sysfs_of(filp);
 
 	sysfs_put_open_dirent(sd, of);
-	single_release(inode, filp);
+	seq_release(inode, filp);
 	kfree(of);
 
 	return 0;
@@ -816,7 +877,7 @@ void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
 EXPORT_SYMBOL_GPL(sysfs_notify);
 
 const struct file_operations sysfs_file_operations = {
-	.read		= seq_read,
+	.read		= kernfs_file_read,
 	.write		= sysfs_write_file,
 	.llseek		= generic_file_llseek,
 	.open		= sysfs_open_file,
@@ -825,7 +886,7 @@ const struct file_operations sysfs_file_operations = {
 };
 
 const struct file_operations sysfs_bin_operations = {
-	.read		= sysfs_bin_read,
+	.read		= kernfs_file_read,
 	.write		= sysfs_write_file,
 	.llseek		= generic_file_llseek,
 	.mmap		= sysfs_bin_mmap,
-- 
1.8.4.2

[PATCH 04/34] sysfs, kernfs: prepare write path for kernfs

[Tejun Heo]

We're in the process of separating out core sysfs functionality into
kernfs which will deal with sysfs_dirents directly.  This patch
rearranges write path so that the kernfs and sysfs parts are separate.

kernfs_file_write() handles all boilerplate work including buffer
management and locking and invokes sysfs_kf_write() or
sysfs_kf_bin_write() depending on the file type which deals with the
interaction with kobj store or bin_attribute write method.

While this patch changes the order of some operations, it shouldn't
change any visible behavior.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c | 103 +++++++++++++++++++++++++++-----------------------------
 1 file changed, 50 insertions(+), 53 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index b695b8b..2f849e8 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -267,61 +267,50 @@ static ssize_t kernfs_file_read(struct file *file, char __user *user_buf,
 		return seq_read(file, user_buf, count, ppos);
 }
 
-/**
- * flush_write_buffer - push buffer to kobject
- * @of: open file
- * @buf: data buffer for file
- * @off: file offset to write to
- * @count: number of bytes
- *
- * Get the correct pointers for the kobject and the attribute we're dealing
- * with, then call the store() method for it with @buf.
- */
-static int flush_write_buffer(struct sysfs_open_file *of, char *buf, loff_t off,
-			      size_t count)
+/* kernfs write callback for regular sysfs files */
+static ssize_t sysfs_kf_write(struct sysfs_open_file *of, char *buf,
+			      size_t count, loff_t pos)
 {
+	const struct sysfs_ops *ops = sysfs_file_ops(of->sd);
 	struct kobject *kobj = of->sd->s_parent->priv;
-	int rc = 0;
 
-	/*
-	 * Need @of->sd for attr and ops, its parent for kobj.  @of->mutex
-	 * nests outside active ref and is just to ensure that the ops
-	 * aren't called concurrently for the same open file.
-	 */
-	mutex_lock(&of->mutex);
-	if (!sysfs_get_active(of->sd)) {
-		mutex_unlock(&of->mutex);
-		return -ENODEV;
-	}
+	if (!count)
+		return 0;
 
-	if (sysfs_is_bin(of->sd)) {
-		struct bin_attribute *battr = of->sd->priv;
+	return ops->store(kobj, of->sd->priv, buf, count);
+}
 
-		rc = -EIO;
-		if (battr->write)
-			rc = battr->write(of->file, kobj, battr, buf, off,
-					  count);
-	} else {
-		const struct sysfs_ops *ops = sysfs_file_ops(of->sd);
+/* kernfs write callback for bin sysfs files */
+static ssize_t sysfs_kf_bin_write(struct sysfs_open_file *of, char *buf,
+				  size_t count, loff_t pos)
+{
+	struct bin_attribute *battr = of->sd->priv;
+	struct kobject *kobj = of->sd->s_parent->priv;
+	loff_t size = file_inode(of->file)->i_size;
 
-		rc = ops->store(kobj, of->sd->priv, buf, count);
+	if (size) {
+		if (size <= pos)
+			return 0;
+		count = min_t(ssize_t, count, size - pos);
 	}
+	if (!count)
+		return 0;
 
-	sysfs_put_active(of->sd);
-	mutex_unlock(&of->mutex);
+	if (!battr->write)
+		return -EIO;
 
-	return rc;
+	return battr->write(of->file, kobj, battr, buf, pos, count);
 }
 
 /**
- * sysfs_write_file - write an attribute
+ * kernfs_file_write - kernfs vfs write callback
  * @file: file pointer
  * @user_buf: data to write
  * @count: number of bytes
  * @ppos: starting offset
  *
- * Copy data in from userland and pass it to the matching
- * sysfs_ops->store() by invoking flush_write_buffer().
+ * Copy data in from userland and pass it to the matching kernfs write
+ * operation.
  *
  * There is no easy way for us to know if userspace is only doing a partial
  * write, so we don't support them. We expect the entire buffer to come on
@@ -329,23 +318,13 @@ static int flush_write_buffer(struct sysfs_open_file *of, char *buf, loff_t off,
  * modify only the the value you're changing, then write entire buffer
  * back.
  */
-static ssize_t sysfs_write_file(struct file *file, const char __user *user_buf,
-				size_t count, loff_t *ppos)
+static ssize_t kernfs_file_write(struct file *file, const char __user *user_buf,
+				 size_t count, loff_t *ppos)
 {
 	struct sysfs_open_file *of = sysfs_of(file);
 	ssize_t len = min_t(size_t, count, PAGE_SIZE);
-	loff_t size = file_inode(file)->i_size;
 	char *buf;
 
-	if (sysfs_is_bin(of->sd) && size) {
-		if (size <= *ppos)
-			return 0;
-		len = min_t(ssize_t, len, size - *ppos);
-	}
-
-	if (!len)
-		return 0;
-
 	buf = kmalloc(len + 1, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
@@ -356,7 +335,25 @@ static ssize_t sysfs_write_file(struct file *file, const char __user *user_buf,
 	}
 	buf[len] = '\0';	/* guarantee string termination */
 
-	len = flush_write_buffer(of, buf, *ppos, len);
+	/*
+	 * @of->mutex nests outside active ref and is just to ensure that
+	 * the ops aren't called concurrently for the same open file.
+	 */
+	mutex_lock(&of->mutex);
+	if (!sysfs_get_active(of->sd)) {
+		mutex_unlock(&of->mutex);
+		len = -ENODEV;
+		goto out_free;
+	}
+
+	if (sysfs_is_bin(of->sd))
+		len = sysfs_kf_bin_write(of, buf, len, *ppos);
+	else
+		len = sysfs_kf_write(of, buf, len, *ppos);
+
+	sysfs_put_active(of->sd);
+	mutex_unlock(&of->mutex);
+
 	if (len > 0)
 		*ppos += len;
 out_free:
@@ -878,7 +875,7 @@ EXPORT_SYMBOL_GPL(sysfs_notify);
 
 const struct file_operations sysfs_file_operations = {
 	.read		= kernfs_file_read,
-	.write		= sysfs_write_file,
+	.write		= kernfs_file_write,
 	.llseek		= generic_file_llseek,
 	.open		= sysfs_open_file,
 	.release	= sysfs_release,
@@ -887,7 +884,7 @@ const struct file_operations sysfs_file_operations = {
 
 const struct file_operations sysfs_bin_operations = {
 	.read		= kernfs_file_read,
-	.write		= sysfs_write_file,
+	.write		= kernfs_file_write,
 	.llseek		= generic_file_llseek,
 	.mmap		= sysfs_bin_mmap,
 	.open		= sysfs_open_file,
-- 
1.8.4.2

[PATCH 05/34] sysfs, kernfs: prepare mmap path for kernfs

[Tejun Heo]

We're in the process of separating out core sysfs functionality into
kernfs which will deal with sysfs_dirents directly.  This patch
rearranges mmap path so that the kernfs and sysfs parts are separate.

sysfs_kf_bin_mmap() which handles the interaction with bin_attribute
mmap method is factored out of sysfs_bin_mmap(), which is renamed to
kernfs_file_mmap().  All vma ops are renamed accordingly.

sysfs_bin_mmap() is updated such that it can be used for both file
types.  This will eventually allow using the same file_operations for
both file types, which is necessary to separate out kernfs.

This patch doesn't introduce any behavior changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c | 69 ++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 39 insertions(+), 30 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 2f849e8..2e24e89 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -361,7 +361,19 @@ out_free:
 	return len;
 }
 
-static void sysfs_bin_vma_open(struct vm_area_struct *vma)
+static int sysfs_kf_bin_mmap(struct sysfs_open_file *of,
+			     struct vm_area_struct *vma)
+{
+	struct bin_attribute *battr = of->sd->priv;
+	struct kobject *kobj = of->sd->s_parent->priv;
+
+	if (!battr->mmap)
+		return -ENODEV;
+
+	return battr->mmap(of->file, kobj, battr, vma);
+}
+
+static void kernfs_vma_open(struct vm_area_struct *vma)
 {
 	struct file *file = vma->vm_file;
 	struct sysfs_open_file *of = sysfs_of(file);
@@ -378,7 +390,7 @@ static void sysfs_bin_vma_open(struct vm_area_struct *vma)
 	sysfs_put_active(of->sd);
 }
 
-static int sysfs_bin_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+static int kernfs_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	struct file *file = vma->vm_file;
 	struct sysfs_open_file *of = sysfs_of(file);
@@ -398,8 +410,8 @@ static int sysfs_bin_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 	return ret;
 }
 
-static int sysfs_bin_page_mkwrite(struct vm_area_struct *vma,
-				  struct vm_fault *vmf)
+static int kernfs_vma_page_mkwrite(struct vm_area_struct *vma,
+				   struct vm_fault *vmf)
 {
 	struct file *file = vma->vm_file;
 	struct sysfs_open_file *of = sysfs_of(file);
@@ -421,8 +433,8 @@ static int sysfs_bin_page_mkwrite(struct vm_area_struct *vma,
 	return ret;
 }
 
-static int sysfs_bin_access(struct vm_area_struct *vma, unsigned long addr,
-			    void *buf, int len, int write)
+static int kernfs_vma_access(struct vm_area_struct *vma, unsigned long addr,
+			     void *buf, int len, int write)
 {
 	struct file *file = vma->vm_file;
 	struct sysfs_open_file *of = sysfs_of(file);
@@ -443,8 +455,8 @@ static int sysfs_bin_access(struct vm_area_struct *vma, unsigned long addr,
 }
 
 #ifdef CONFIG_NUMA
-static int sysfs_bin_set_policy(struct vm_area_struct *vma,
-				struct mempolicy *new)
+static int kernfs_vma_set_policy(struct vm_area_struct *vma,
+				 struct mempolicy *new)
 {
 	struct file *file = vma->vm_file;
 	struct sysfs_open_file *of = sysfs_of(file);
@@ -464,8 +476,8 @@ static int sysfs_bin_set_policy(struct vm_area_struct *vma,
 	return ret;
 }
 
-static struct mempolicy *sysfs_bin_get_policy(struct vm_area_struct *vma,
-					      unsigned long addr)
+static struct mempolicy *kernfs_vma_get_policy(struct vm_area_struct *vma,
+					       unsigned long addr)
 {
 	struct file *file = vma->vm_file;
 	struct sysfs_open_file *of = sysfs_of(file);
@@ -485,8 +497,9 @@ static struct mempolicy *sysfs_bin_get_policy(struct vm_area_struct *vma,
 	return pol;
 }
 
-static int sysfs_bin_migrate(struct vm_area_struct *vma, const nodemask_t *from,
-			     const nodemask_t *to, unsigned long flags)
+static int kernfs_vma_migrate(struct vm_area_struct *vma,
+			      const nodemask_t *from, const nodemask_t *to,
+			      unsigned long flags)
 {
 	struct file *file = vma->vm_file;
 	struct sysfs_open_file *of = sysfs_of(file);
@@ -507,36 +520,31 @@ static int sysfs_bin_migrate(struct vm_area_struct *vma, const nodemask_t *from,
 }
 #endif
 
-static const struct vm_operations_struct sysfs_bin_vm_ops = {
-	.open		= sysfs_bin_vma_open,
-	.fault		= sysfs_bin_fault,
-	.page_mkwrite	= sysfs_bin_page_mkwrite,
-	.access		= sysfs_bin_access,
+static const struct vm_operations_struct kernfs_vm_ops = {
+	.open		= kernfs_vma_open,
+	.fault		= kernfs_vma_fault,
+	.page_mkwrite	= kernfs_vma_page_mkwrite,
+	.access		= kernfs_vma_access,
 #ifdef CONFIG_NUMA
-	.set_policy	= sysfs_bin_set_policy,
-	.get_policy	= sysfs_bin_get_policy,
-	.migrate	= sysfs_bin_migrate,
+	.set_policy	= kernfs_vma_set_policy,
+	.get_policy	= kernfs_vma_get_policy,
+	.migrate	= kernfs_vma_migrate,
 #endif
 };
 
-static int sysfs_bin_mmap(struct file *file, struct vm_area_struct *vma)
+static int kernfs_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	struct sysfs_open_file *of = sysfs_of(file);
-	struct bin_attribute *battr = of->sd->priv;
-	struct kobject *kobj = of->sd->s_parent->priv;
 	int rc;
 
 	mutex_lock(&of->mutex);
 
-	/* need of->sd for battr, its parent for kobj */
 	rc = -ENODEV;
 	if (!sysfs_get_active(of->sd))
 		goto out_unlock;
 
-	if (!battr->mmap)
-		goto out_put;
-
-	rc = battr->mmap(file, kobj, battr, vma);
+	if (sysfs_is_bin(of->sd))
+		rc = sysfs_kf_bin_mmap(of, vma);
 	if (rc)
 		goto out_put;
 
@@ -563,7 +571,7 @@ static int sysfs_bin_mmap(struct file *file, struct vm_area_struct *vma)
 	rc = 0;
 	of->mmapped = 1;
 	of->vm_ops = vma->vm_ops;
-	vma->vm_ops = &sysfs_bin_vm_ops;
+	vma->vm_ops = &kernfs_vm_ops;
 out_put:
 	sysfs_put_active(of->sd);
 out_unlock:
@@ -877,6 +885,7 @@ const struct file_operations sysfs_file_operations = {
 	.read		= kernfs_file_read,
 	.write		= kernfs_file_write,
 	.llseek		= generic_file_llseek,
+	.mmap		= kernfs_file_mmap,
 	.open		= sysfs_open_file,
 	.release	= sysfs_release,
 	.poll		= sysfs_poll,
@@ -886,7 +895,7 @@ const struct file_operations sysfs_bin_operations = {
 	.read		= kernfs_file_read,
 	.write		= kernfs_file_write,
 	.llseek		= generic_file_llseek,
-	.mmap		= sysfs_bin_mmap,
+	.mmap		= kernfs_file_mmap,
 	.open		= sysfs_open_file,
 	.release	= sysfs_release,
 	.poll		= sysfs_poll,
-- 
1.8.4.2

[PATCH 06/34] sysfs, kernfs: prepare open, release, poll paths for kernfs

[Tejun Heo]

We're in the process of separating out core sysfs functionality into
kernfs which will deal with sysfs_dirents directly.  This patch
prepares the rest - open, release and poll.  There isn't much to do.
Just renaming is enough.  As sysfs_file_operations and
sysfs_bin_operations are identical now, use the same file_operations
for both - kernfs_file_operations.

This patch doesn't introduce any behavior changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c  | 24 +++++++-----------------
 fs/sysfs/inode.c |  4 ++--
 fs/sysfs/sysfs.h |  3 +--
 3 files changed, 10 insertions(+), 21 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 2e24e89..a43df04 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -668,7 +668,7 @@ static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
 	kfree(od);
 }
 
-static int sysfs_open_file(struct inode *inode, struct file *file)
+static int kernfs_file_open(struct inode *inode, struct file *file)
 {
 	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 	struct kobject *kobj = attr_sd->s_parent->priv;
@@ -771,7 +771,7 @@ err_out:
 	return error;
 }
 
-static int sysfs_release(struct inode *inode, struct file *filp)
+static int kernfs_file_release(struct inode *inode, struct file *filp)
 {
 	struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata;
 	struct sysfs_open_file *of = sysfs_of(filp);
@@ -822,7 +822,7 @@ void sysfs_unmap_bin_file(struct sysfs_dirent *sd)
  * to see if it supports poll (Neither 'poll' nor 'select' return
  * an appropriate error code).  When in doubt, set a suitable timeout value.
  */
-static unsigned int sysfs_poll(struct file *filp, poll_table *wait)
+static unsigned int kernfs_file_poll(struct file *filp, poll_table *wait)
 {
 	struct sysfs_open_file *of = sysfs_of(filp);
 	struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
@@ -881,24 +881,14 @@ void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
 }
 EXPORT_SYMBOL_GPL(sysfs_notify);
 
-const struct file_operations sysfs_file_operations = {
+const struct file_operations kernfs_file_operations = {
 	.read		= kernfs_file_read,
 	.write		= kernfs_file_write,
 	.llseek		= generic_file_llseek,
 	.mmap		= kernfs_file_mmap,
-	.open		= sysfs_open_file,
-	.release	= sysfs_release,
-	.poll		= sysfs_poll,
-};
-
-const struct file_operations sysfs_bin_operations = {
-	.read		= kernfs_file_read,
-	.write		= kernfs_file_write,
-	.llseek		= generic_file_llseek,
-	.mmap		= kernfs_file_mmap,
-	.open		= sysfs_open_file,
-	.release	= sysfs_release,
-	.poll		= sysfs_poll,
+	.open		= kernfs_file_open,
+	.release	= kernfs_file_release,
+	.poll		= kernfs_file_poll,
 };
 
 int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index 81cc858..4c463da 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -272,12 +272,12 @@ static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
 		break;
 	case SYSFS_KOBJ_ATTR:
 		inode->i_size = PAGE_SIZE;
-		inode->i_fop = &sysfs_file_operations;
+		inode->i_fop = &kernfs_file_operations;
 		break;
 	case SYSFS_KOBJ_BIN_ATTR:
 		bin_attr = sd->priv;
 		inode->i_size = bin_attr->size;
-		inode->i_fop = &sysfs_bin_operations;
+		inode->i_fop = &kernfs_file_operations;
 		break;
 	case SYSFS_KOBJ_LINK:
 		inode->i_op = &sysfs_symlink_inode_operations;
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 9ac234e..619250d 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -212,8 +212,7 @@ int sysfs_inode_init(void);
 /*
  * file.c
  */
-extern const struct file_operations sysfs_file_operations;
-extern const struct file_operations sysfs_bin_operations;
+extern const struct file_operations kernfs_file_operations;
 
 int sysfs_add_file(struct sysfs_dirent *dir_sd,
 		   const struct attribute *attr, int type);
-- 
1.8.4.2

[PATCH 07/34] sysfs, kernfs: move sysfs_open_file to include/linux/kernfs.h

[Tejun Heo]

sysfs_open_file will be used as the primary handle for kernfs methods.
Move its definition from fs/sysfs/file.c to include/linux/kernfs.h and
mark the public and private fields.

This is pure relocation.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c        | 11 -----------
 include/linux/kernfs.h | 18 ++++++++++++++++++
 2 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index a43df04..acba583 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -47,17 +47,6 @@ struct sysfs_open_dirent {
 	struct list_head	files; /* goes through sysfs_open_file.list */
 };
 
-struct sysfs_open_file {
-	struct sysfs_dirent	*sd;
-	struct file		*file;
-	struct mutex		mutex;
-	int			event;
-	struct list_head	list;
-
-	bool			mmapped;
-	const struct vm_operations_struct *vm_ops;
-};
-
 static bool sysfs_is_bin(struct sysfs_dirent *sd)
 {
 	return sysfs_type(sd) == SYSFS_KOBJ_BIN_ATTR;
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index e8b73d4..b923052 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -9,12 +9,30 @@
 
 #include <linux/kernel.h>
 #include <linux/err.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
 
 struct file;
 struct iattr;
+struct seq_file;
+struct vm_area_struct;
 
 struct sysfs_dirent;
 
+struct sysfs_open_file {
+	/* published fields */
+	struct sysfs_dirent	*sd;
+	struct file		*file;
+
+	/* private fields, do not use outside kernfs proper */
+	struct mutex		mutex;
+	int			event;
+	struct list_head	list;
+
+	bool			mmapped;
+	const struct vm_operations_struct *vm_ops;
+};
+
 #ifdef CONFIG_SYSFS
 
 struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
-- 
1.8.4.2

[PATCH 08/34] sysfs, kernfs: introduce kernfs_ops

[Tejun Heo]

We're in the process of separating out core sysfs functionality into
kernfs which will deal with sysfs_dirents directly.  This patch
introduces kernfs_ops which hosts methods kernfs users implement and
updates fs/sysfs/file.c such that sysfs_kf_*() functions populate
kernfs_ops and kernfs_file_*() functions call the matching entries
from kernfs_ops.

kernfs_ops contains the following groups of methods.

* seq_show() - for kernfs files which use seq_file for reads.

* read() - for direct read implementations.  Used iff seq_show() is
  not implemented.

* write() - for writes.

* mmap() - for mmaps.

Notes:

* sysfs_elem_attr->ops is added so that kernfs_ops can be accessed
  from sysfs_dirent.  kernfs_ops() helper is added to verify locking
  and access the field.

* SYSFS_FLAG_HAS_(SEQ_SHOW|MMAP) added.  sd->s_attr->ops is accessible
  only while holding active_ref and there are cases where we want to
  take different actions depending on which ops are implemented.
  These two flags cache whether the two ops are implemented for those.

* kernfs_file_*() no longer test sysfs type but chooses different
  behaviors depending on which methods in kernfs_ops are implemented.
  The conversions are trivial except for the open path.  As
  kernfs_file_open() now decides whether to allow read/write accesses
  depending on the kernfs_ops implemented, the presence of methods in
  kobjs and attribute_bin should be propagated to kernfs_ops.
  sysfs_add_file_mode_ns() is updated so that it propagates presence /
  absence of the callbacks through _empty, _ro, _wo, _rw kernfs_ops.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c        | 146 +++++++++++++++++++++++++++++++++++++------------
 fs/sysfs/sysfs.h       |   3 +
 include/linux/kernfs.h |  26 +++++++++
 3 files changed, 141 insertions(+), 34 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index acba583..cbebc33 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -58,6 +58,17 @@ static struct sysfs_open_file *sysfs_of(struct file *file)
 }
 
 /*
+ * Determine the kernfs_ops for the given sysfs_dirent.  This function must
+ * be called while holding an active reference.
+ */
+static const struct kernfs_ops *kernfs_ops(struct sysfs_dirent *sd)
+{
+	if (!sysfs_ignore_lockdep(sd))
+		lockdep_assert_held(sd);
+	return sd->s_attr.ops;
+}
+
+/*
  * Determine ktype->sysfs_ops for the given sysfs_dirent.  This function
  * must be called while holding an active reference.
  */
@@ -180,7 +191,7 @@ static int kernfs_seq_show(struct seq_file *sf, void *v)
 
 	of->event = atomic_read(&of->sd->s_attr.open->event);
 
-	return sysfs_kf_seq_show(sf, v);
+	return of->sd->s_attr.ops->seq_show(sf, v);
 }
 
 static const struct seq_operations kernfs_seq_ops = {
@@ -201,6 +212,7 @@ static ssize_t kernfs_file_direct_read(struct sysfs_open_file *of,
 				       loff_t *ppos)
 {
 	ssize_t len = min_t(size_t, count, PAGE_SIZE);
+	const struct kernfs_ops *ops;
 	char *buf;
 
 	buf = kmalloc(len, GFP_KERNEL);
@@ -218,7 +230,11 @@ static ssize_t kernfs_file_direct_read(struct sysfs_open_file *of,
 		goto out_free;
 	}
 
-	len = sysfs_kf_bin_read(of, buf, len, *ppos);
+	ops = kernfs_ops(of->sd);
+	if (ops->read)
+		len = ops->read(of, buf, len, *ppos);
+	else
+		len = -EINVAL;
 
 	sysfs_put_active(of->sd);
 	mutex_unlock(&of->mutex);
@@ -250,10 +266,10 @@ static ssize_t kernfs_file_read(struct file *file, char __user *user_buf,
 {
 	struct sysfs_open_file *of = sysfs_of(file);
 
-	if (sysfs_is_bin(of->sd))
-		return kernfs_file_direct_read(of, user_buf, count, ppos);
-	else
+	if (of->sd->s_flags & SYSFS_FLAG_HAS_SEQ_SHOW)
 		return seq_read(file, user_buf, count, ppos);
+	else
+		return kernfs_file_direct_read(of, user_buf, count, ppos);
 }
 
 /* kernfs write callback for regular sysfs files */
@@ -312,6 +328,7 @@ static ssize_t kernfs_file_write(struct file *file, const char __user *user_buf,
 {
 	struct sysfs_open_file *of = sysfs_of(file);
 	ssize_t len = min_t(size_t, count, PAGE_SIZE);
+	const struct kernfs_ops *ops;
 	char *buf;
 
 	buf = kmalloc(len + 1, GFP_KERNEL);
@@ -335,10 +352,11 @@ static ssize_t kernfs_file_write(struct file *file, const char __user *user_buf,
 		goto out_free;
 	}
 
-	if (sysfs_is_bin(of->sd))
-		len = sysfs_kf_bin_write(of, buf, len, *ppos);
+	ops = kernfs_ops(of->sd);
+	if (ops->write)
+		len = ops->write(of, buf, len, *ppos);
 	else
-		len = sysfs_kf_write(of, buf, len, *ppos);
+		len = -EINVAL;
 
 	sysfs_put_active(of->sd);
 	mutex_unlock(&of->mutex);
@@ -524,6 +542,7 @@ static const struct vm_operations_struct kernfs_vm_ops = {
 static int kernfs_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	struct sysfs_open_file *of = sysfs_of(file);
+	const struct kernfs_ops *ops;
 	int rc;
 
 	mutex_lock(&of->mutex);
@@ -532,8 +551,9 @@ static int kernfs_file_mmap(struct file *file, struct vm_area_struct *vma)
 	if (!sysfs_get_active(of->sd))
 		goto out_unlock;
 
-	if (sysfs_is_bin(of->sd))
-		rc = sysfs_kf_bin_mmap(of, vma);
+	ops = kernfs_ops(of->sd);
+	if (ops->mmap)
+		rc = ops->mmap(of, vma);
 	if (rc)
 		goto out_put;
 
@@ -660,34 +680,19 @@ static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
 static int kernfs_file_open(struct inode *inode, struct file *file)
 {
 	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
-	struct kobject *kobj = attr_sd->s_parent->priv;
+	const struct kernfs_ops *ops;
 	struct sysfs_open_file *of;
 	bool has_read, has_write, has_mmap;
 	int error = -EACCES;
 
-	/* need attr_sd for attr and ops, its parent for kobj */
 	if (!sysfs_get_active(attr_sd))
 		return -ENODEV;
 
-	if (sysfs_is_bin(attr_sd)) {
-		struct bin_attribute *battr = attr_sd->priv;
+	ops = kernfs_ops(attr_sd);
 
-		has_read = battr->read || battr->mmap;
-		has_write = battr->write || battr->mmap;
-		has_mmap = battr->mmap;
-	} else {
-		const struct sysfs_ops *ops = sysfs_file_ops(attr_sd);
-
-		/* every kobject with an attribute needs a ktype assigned */
-		if (WARN(!ops, KERN_ERR
-			 "missing sysfs attribute operations for kobject: %s\n",
-			 kobject_name(kobj)))
-			goto err_out;
-
-		has_read = ops->show;
-		has_write = ops->store;
-		has_mmap = false;
-	}
+	has_read = ops->seq_show || ops->read || ops->mmap;
+	has_write = ops->write || ops->mmap;
+	has_mmap = ops->mmap;
 
 	/* check perms and supported operations */
 	if ((file->f_mode & FMODE_WRITE) &&
@@ -729,10 +734,10 @@ static int kernfs_file_open(struct inode *inode, struct file *file)
 	 * seq_file or is not requested.  This unifies private data access
 	 * and readable regular files are the vast majority anyway.
 	 */
-	if (sysfs_is_bin(attr_sd))
-		error = seq_open(file, NULL);
-	else
+	if (ops->seq_show)
 		error = seq_open(file, &kernfs_seq_ops);
+	else
+		error = seq_open(file, NULL);
 	if (error)
 		goto err_free;
 
@@ -777,7 +782,7 @@ void sysfs_unmap_bin_file(struct sysfs_dirent *sd)
 	struct sysfs_open_dirent *od;
 	struct sysfs_open_file *of;
 
-	if (!sysfs_is_bin(sd))
+	if (!(sd->s_flags & SYSFS_FLAG_HAS_MMAP))
 		return;
 
 	spin_lock_irq(&sysfs_open_dirent_lock);
@@ -880,23 +885,96 @@ const struct file_operations kernfs_file_operations = {
 	.poll		= kernfs_file_poll,
 };
 
+static const struct kernfs_ops sysfs_file_kfops_empty = {
+};
+
+static const struct kernfs_ops sysfs_file_kfops_ro = {
+	.seq_show	= sysfs_kf_seq_show,
+};
+
+static const struct kernfs_ops sysfs_file_kfops_wo = {
+	.write		= sysfs_kf_write,
+};
+
+static const struct kernfs_ops sysfs_file_kfops_rw = {
+	.seq_show	= sysfs_kf_seq_show,
+	.write		= sysfs_kf_write,
+};
+
+static const struct kernfs_ops sysfs_bin_kfops_ro = {
+	.read		= sysfs_kf_bin_read,
+};
+
+static const struct kernfs_ops sysfs_bin_kfops_wo = {
+	.write		= sysfs_kf_bin_write,
+};
+
+static const struct kernfs_ops sysfs_bin_kfops_rw = {
+	.read		= sysfs_kf_bin_read,
+	.write		= sysfs_kf_bin_write,
+	.mmap		= sysfs_kf_bin_mmap,
+};
+
 int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 			   const struct attribute *attr, int type,
 			   umode_t amode, const void *ns)
 {
 	umode_t mode = (amode & S_IALLUGO) | S_IFREG;
+	const struct kernfs_ops *ops;
 	struct sysfs_addrm_cxt acxt;
 	struct sysfs_dirent *sd;
 	int rc;
 
+	if (type == SYSFS_KOBJ_ATTR) {
+		struct kobject *kobj = dir_sd->priv;
+		const struct sysfs_ops *sysfs_ops = kobj->ktype->sysfs_ops;
+
+		/* every kobject with an attribute needs a ktype assigned */
+		if (WARN(!sysfs_ops, KERN_ERR
+			 "missing sysfs attribute operations for kobject: %s\n",
+			 kobject_name(kobj)))
+			return -EINVAL;
+
+		if (sysfs_ops->show && sysfs_ops->store)
+			ops = &sysfs_file_kfops_rw;
+		else if (sysfs_ops->show)
+			ops = &sysfs_file_kfops_ro;
+		else if (sysfs_ops->store)
+			ops = &sysfs_file_kfops_wo;
+		else
+			ops = &sysfs_file_kfops_empty;
+	} else {
+		struct bin_attribute *battr = (void *)attr;
+
+		if ((battr->read && battr->write) || battr->mmap)
+			ops = &sysfs_bin_kfops_rw;
+		else if (battr->read)
+			ops = &sysfs_bin_kfops_ro;
+		else if (battr->write)
+			ops = &sysfs_bin_kfops_wo;
+		else
+			ops = &sysfs_file_kfops_empty;
+	}
+
 	sd = sysfs_new_dirent(attr->name, mode, type);
 	if (!sd)
 		return -ENOMEM;
 
+	sd->s_attr.ops = ops;
 	sd->s_ns = ns;
 	sd->priv = (void *)attr;
 	sysfs_dirent_init_lockdep(sd);
 
+	/*
+	 * sd->s_attr.ops is accesible only while holding active ref.  We
+	 * need to know whether some ops are implemented outside active
+	 * ref.  Cache their existence in flags.
+	 */
+	if (ops->seq_show)
+		sd->s_flags |= SYSFS_FLAG_HAS_SEQ_SHOW;
+	if (ops->mmap)
+		sd->s_flags |= SYSFS_FLAG_HAS_MMAP;
+
 	sysfs_addrm_start(&acxt);
 	rc = sysfs_add_one(&acxt, sd, dir_sd);
 	sysfs_addrm_finish(&acxt);
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 619250d..c05e0dd 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -27,6 +27,7 @@ struct sysfs_elem_symlink {
 };
 
 struct sysfs_elem_attr {
+	const struct kernfs_ops	*ops;
 	struct sysfs_open_dirent *open;
 };
 
@@ -89,6 +90,8 @@ struct sysfs_dirent {
 #define SYSFS_FLAG_MASK			~SYSFS_TYPE_MASK
 #define SYSFS_FLAG_NS			0x01000
 #define SYSFS_FLAG_REMOVED		0x02000
+#define SYSFS_FLAG_HAS_SEQ_SHOW		0x04000
+#define SYSFS_FLAG_HAS_MMAP		0x08000
 
 static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
 {
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index b923052..97c6c0f 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -33,6 +33,32 @@ struct sysfs_open_file {
 	const struct vm_operations_struct *vm_ops;
 };
 
+struct kernfs_ops {
+	/*
+	 * Read is handled by either seq_file or raw_read().
+	 *
+	 * If seq_show() is present, seq_file path is active.  The behavior
+	 * is equivalent to single_open().  @sf->private points to the
+	 * associated sysfs_open_file.
+	 *
+	 * read() is bounced through kernel buffer and a read larger than
+	 * PAGE_SIZE results in partial operation of PAGE_SIZE.
+	 */
+	int (*seq_show)(struct seq_file *sf, void *v);
+
+	ssize_t (*read)(struct sysfs_open_file *of, char *buf, size_t bytes,
+			loff_t off);
+
+	/*
+	 * write() is bounced through kernel buffer and a write larger than
+	 * PAGE_SIZE results in partial operation of PAGE_SIZE.
+	 */
+	ssize_t (*write)(struct sysfs_open_file *of, char *buf, size_t bytes,
+			 loff_t off);
+
+	int (*mmap)(struct sysfs_open_file *of, struct vm_area_struct *vma);
+};
+
 #ifdef CONFIG_SYSFS
 
 struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
-- 
1.8.4.2

[PATCH 09/34] sysfs, kernfs: add sysfs_dirent->s_attr.size

[Tejun Heo]

sysfs sets the size of regular files unconditionally at PAGE_SIZE and
takes the size of bin files from bin_attribute.  The latter is a
pretty bad interface which forces bin_attribute users to create a
separate copy of bin_attribute for each instance of the file -
e.g. pci resource files.

Add sysfs_dirent->s_attr.size so that the size can be specified
separately.  This unifies inode init paths of ATTR and BIN_ATTR
identical and allows for generic size handling for kernfs.

Unfortunately, this grows the size of sysfs_dirent by sizeof(loff_t).

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c  | 6 ++++++
 fs/sysfs/inode.c | 8 +-------
 fs/sysfs/sysfs.h | 1 +
 3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index cbebc33..0b0cec8 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -923,6 +923,7 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 	const struct kernfs_ops *ops;
 	struct sysfs_addrm_cxt acxt;
 	struct sysfs_dirent *sd;
+	loff_t size;
 	int rc;
 
 	if (type == SYSFS_KOBJ_ATTR) {
@@ -943,6 +944,8 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 			ops = &sysfs_file_kfops_wo;
 		else
 			ops = &sysfs_file_kfops_empty;
+
+		size = PAGE_SIZE;
 	} else {
 		struct bin_attribute *battr = (void *)attr;
 
@@ -954,6 +957,8 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 			ops = &sysfs_bin_kfops_wo;
 		else
 			ops = &sysfs_file_kfops_empty;
+
+		size = battr->size;
 	}
 
 	sd = sysfs_new_dirent(attr->name, mode, type);
@@ -961,6 +966,7 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 		return -ENOMEM;
 
 	sd->s_attr.ops = ops;
+	sd->s_attr.size = size;
 	sd->s_ns = ns;
 	sd->priv = (void *)attr;
 	sysfs_dirent_init_lockdep(sd);
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index 4c463da..037a892 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -254,8 +254,6 @@ int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
 
 static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
 {
-	struct bin_attribute *bin_attr;
-
 	inode->i_private = sysfs_get(sd);
 	inode->i_mapping->a_ops = &sysfs_aops;
 	inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
@@ -271,12 +269,8 @@ static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
 		inode->i_fop = &sysfs_dir_operations;
 		break;
 	case SYSFS_KOBJ_ATTR:
-		inode->i_size = PAGE_SIZE;
-		inode->i_fop = &kernfs_file_operations;
-		break;
 	case SYSFS_KOBJ_BIN_ATTR:
-		bin_attr = sd->priv;
-		inode->i_size = bin_attr->size;
+		inode->i_size = sd->s_attr.size;
 		inode->i_fop = &kernfs_file_operations;
 		break;
 	case SYSFS_KOBJ_LINK:
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index c05e0dd..d40e85e 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -29,6 +29,7 @@ struct sysfs_elem_symlink {
 struct sysfs_elem_attr {
 	const struct kernfs_ops	*ops;
 	struct sysfs_open_dirent *open;
+	loff_t			size;
 };
 
 struct sysfs_inode_attrs {
-- 
1.8.4.2

[PATCH 10/34] sysfs, kernfs: remove SYSFS_KOBJ_BIN_ATTR

[Tejun Heo]

After kernfs_ops and sysfs_dirent->s_attr.size addition, the
distinction between SYSFS_KOBJ_BIN_ATTR and SYSFS_KOBJ_ATTR is only
necessary while creating files to decide which kernfs_ops to use.
Afterwards, they behave exactly the same.

This patch removes SYSFS_KOBJ_BIN_ATTR along with sysfs_is_bin().
sysfs_add_file[_mode_ns]() are updated to take bool @is_bin instead of
@type.

This patch doesn't introduce any behavior changes.  This completely
isolates the distinction between the two sysfs file types in the sysfs
layer proper.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c  | 23 ++++++++---------------
 fs/sysfs/group.c |  5 ++---
 fs/sysfs/inode.c |  1 -
 fs/sysfs/sysfs.h | 11 ++++-------
 4 files changed, 14 insertions(+), 26 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 0b0cec8..e2ce674 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -47,11 +47,6 @@ struct sysfs_open_dirent {
 	struct list_head	files; /* goes through sysfs_open_file.list */
 };
 
-static bool sysfs_is_bin(struct sysfs_dirent *sd)
-{
-	return sysfs_type(sd) == SYSFS_KOBJ_BIN_ATTR;
-}
-
 static struct sysfs_open_file *sysfs_of(struct file *file)
 {
 	return ((struct seq_file *)file->private_data)->private;
@@ -916,7 +911,7 @@ static const struct kernfs_ops sysfs_bin_kfops_rw = {
 };
 
 int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
-			   const struct attribute *attr, int type,
+			   const struct attribute *attr, bool is_bin,
 			   umode_t amode, const void *ns)
 {
 	umode_t mode = (amode & S_IALLUGO) | S_IFREG;
@@ -926,7 +921,7 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 	loff_t size;
 	int rc;
 
-	if (type == SYSFS_KOBJ_ATTR) {
+	if (!is_bin) {
 		struct kobject *kobj = dir_sd->priv;
 		const struct sysfs_ops *sysfs_ops = kobj->ktype->sysfs_ops;
 
@@ -961,7 +956,7 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 		size = battr->size;
 	}
 
-	sd = sysfs_new_dirent(attr->name, mode, type);
+	sd = sysfs_new_dirent(attr->name, mode, SYSFS_KOBJ_ATTR);
 	if (!sd)
 		return -ENOMEM;
 
@@ -991,11 +986,10 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 	return rc;
 }
 
-
 int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
-		   int type)
+		   bool is_bin)
 {
-	return sysfs_add_file_mode_ns(dir_sd, attr, type, attr->mode, NULL);
+	return sysfs_add_file_mode_ns(dir_sd, attr, is_bin, attr->mode, NULL);
 }
 
 /**
@@ -1009,8 +1003,7 @@ int sysfs_create_file_ns(struct kobject *kobj, const struct attribute *attr,
 {
 	BUG_ON(!kobj || !kobj->sd || !attr);
 
-	return sysfs_add_file_mode_ns(kobj->sd, attr, SYSFS_KOBJ_ATTR,
-				      attr->mode, ns);
+	return sysfs_add_file_mode_ns(kobj->sd, attr, false, attr->mode, ns);
 
 }
 EXPORT_SYMBOL_GPL(sysfs_create_file_ns);
@@ -1049,7 +1042,7 @@ int sysfs_add_file_to_group(struct kobject *kobj,
 	if (!dir_sd)
 		return -ENOENT;
 
-	error = sysfs_add_file(dir_sd, attr, SYSFS_KOBJ_ATTR);
+	error = sysfs_add_file(dir_sd, attr, false);
 	sysfs_put(dir_sd);
 
 	return error;
@@ -1141,7 +1134,7 @@ int sysfs_create_bin_file(struct kobject *kobj,
 {
 	BUG_ON(!kobj || !kobj->sd || !attr);
 
-	return sysfs_add_file(kobj->sd, &attr->attr, SYSFS_KOBJ_BIN_ATTR);
+	return sysfs_add_file(kobj->sd, &attr->attr, true);
 }
 EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
 
diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index 065689d..9f65cd9 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -55,8 +55,7 @@ static int create_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,
 				if (!mode)
 					continue;
 			}
-			error = sysfs_add_file_mode_ns(dir_sd, *attr,
-						       SYSFS_KOBJ_ATTR,
+			error = sysfs_add_file_mode_ns(dir_sd, *attr, false,
 						       (*attr)->mode | mode,
 						       NULL);
 			if (unlikely(error))
@@ -269,7 +268,7 @@ int sysfs_merge_group(struct kobject *kobj,
 		return -ENOENT;
 
 	for ((i = 0, attr = grp->attrs); *attr && !error; (++i, ++attr))
-		error = sysfs_add_file(dir_sd, *attr, SYSFS_KOBJ_ATTR);
+		error = sysfs_add_file(dir_sd, *attr, false);
 	if (error) {
 		while (--i >= 0)
 			kernfs_remove_by_name(dir_sd, (*--attr)->name);
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index 037a892..b3c717a 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -269,7 +269,6 @@ static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
 		inode->i_fop = &sysfs_dir_operations;
 		break;
 	case SYSFS_KOBJ_ATTR:
-	case SYSFS_KOBJ_BIN_ATTR:
 		inode->i_size = sd->s_attr.size;
 		inode->i_fop = &kernfs_file_operations;
 		break;
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index d40e85e..28898fa 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -83,10 +83,9 @@ struct sysfs_dirent {
 #define SYSFS_TYPE_MASK			0x00ff
 #define SYSFS_DIR			0x0001
 #define SYSFS_KOBJ_ATTR			0x0002
-#define SYSFS_KOBJ_BIN_ATTR		0x0004
 #define SYSFS_KOBJ_LINK			0x0008
 #define SYSFS_COPY_NAME			(SYSFS_DIR | SYSFS_KOBJ_LINK)
-#define SYSFS_ACTIVE_REF		(SYSFS_KOBJ_ATTR | SYSFS_KOBJ_BIN_ATTR)
+#define SYSFS_ACTIVE_REF		SYSFS_KOBJ_ATTR
 
 #define SYSFS_FLAG_MASK			~SYSFS_TYPE_MASK
 #define SYSFS_FLAG_NS			0x01000
@@ -115,10 +114,8 @@ do {								\
 static inline bool sysfs_ignore_lockdep(struct sysfs_dirent *sd)
 {
 	struct attribute *attr = sd->priv;
-	int type = sysfs_type(sd);
 
-	return (type == SYSFS_KOBJ_ATTR || type == SYSFS_KOBJ_BIN_ATTR) &&
-		attr->ignore_lockdep;
+	return sysfs_type(sd) == SYSFS_KOBJ_ATTR && attr->ignore_lockdep;
 }
 
 #else
@@ -219,10 +216,10 @@ int sysfs_inode_init(void);
 extern const struct file_operations kernfs_file_operations;
 
 int sysfs_add_file(struct sysfs_dirent *dir_sd,
-		   const struct attribute *attr, int type);
+		   const struct attribute *attr, bool is_bin);
 
 int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
-			   const struct attribute *attr, int type,
+			   const struct attribute *attr, bool is_bin,
 			   umode_t amode, const void *ns);
 void sysfs_unmap_bin_file(struct sysfs_dirent *sd);
 
-- 
1.8.4.2

[PATCH 11/34] sysfs, kernfs: introduce kernfs_create_file[_ns]()

[Tejun Heo]

Introduce kernfs interface to create a file which takes and returns
sysfs_dirents.

The actual file creation part is separated out from
sysfs_add_file_mode_ns() into kernfs_create_file_ns().  The former now
only decides the kernfs_ops to use and the file's size and invokes the
latter.

This patch doesn't introduce behavior changes.

v2: Dummy implementation for !CONFIG_SYSFS updated to return -ENOSYS.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c        | 53 +++++++++++++++++++++++++++++++++++++++-----------
 include/linux/kernfs.h | 18 +++++++++++++++++
 2 files changed, 60 insertions(+), 11 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index e2ce674..69cca0f 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -912,14 +912,11 @@ static const struct kernfs_ops sysfs_bin_kfops_rw = {
 
 int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 			   const struct attribute *attr, bool is_bin,
-			   umode_t amode, const void *ns)
+			   umode_t mode, const void *ns)
 {
-	umode_t mode = (amode & S_IALLUGO) | S_IFREG;
 	const struct kernfs_ops *ops;
-	struct sysfs_addrm_cxt acxt;
 	struct sysfs_dirent *sd;
 	loff_t size;
-	int rc;
 
 	if (!is_bin) {
 		struct kobject *kobj = dir_sd->priv;
@@ -956,14 +953,47 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 		size = battr->size;
 	}
 
-	sd = sysfs_new_dirent(attr->name, mode, SYSFS_KOBJ_ATTR);
+	sd = kernfs_create_file_ns(dir_sd, attr->name, mode, size,
+				   ops, (void *)attr, ns);
+	if (IS_ERR(sd)) {
+		if (PTR_ERR(sd) == -EEXIST)
+			sysfs_warn_dup(dir_sd, attr->name);
+		return PTR_ERR(sd);
+	}
+	return 0;
+}
+
+/**
+ * kernfs_create_file_ns - create a file
+ * @parent: directory to create the file in
+ * @name: name of the file
+ * @mode: mode of the file
+ * @size: size of the file
+ * @ops: kernfs operations for the file
+ * @priv: private data for the file
+ * @ns: optional namespace tag of the file
+ *
+ * Returns the created node on success, ERR_PTR() value on error.
+ */
+struct sysfs_dirent *kernfs_create_file_ns(struct sysfs_dirent *parent,
+					   const char *name,
+					   umode_t mode, loff_t size,
+					   const struct kernfs_ops *ops,
+					   void *priv, const void *ns)
+{
+	struct sysfs_addrm_cxt acxt;
+	struct sysfs_dirent *sd;
+	int rc;
+
+	sd = sysfs_new_dirent(name, (mode & S_IALLUGO) | S_IFREG,
+			      SYSFS_KOBJ_ATTR);
 	if (!sd)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
 	sd->s_attr.ops = ops;
 	sd->s_attr.size = size;
 	sd->s_ns = ns;
-	sd->priv = (void *)attr;
+	sd->priv = priv;
 	sysfs_dirent_init_lockdep(sd);
 
 	/*
@@ -977,13 +1007,14 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 		sd->s_flags |= SYSFS_FLAG_HAS_MMAP;
 
 	sysfs_addrm_start(&acxt);
-	rc = sysfs_add_one(&acxt, sd, dir_sd);
+	rc = __sysfs_add_one(&acxt, sd, parent);
 	sysfs_addrm_finish(&acxt);
 
-	if (rc)
+	if (rc) {
 		sysfs_put(sd);
-
-	return rc;
+		return ERR_PTR(rc);
+	}
+	return sd;
 }
 
 int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 97c6c0f..d0912cf 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -64,6 +64,11 @@ struct kernfs_ops {
 struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
 					  const char *name, void *priv,
 					  const void *ns);
+struct sysfs_dirent *kernfs_create_file_ns(struct sysfs_dirent *parent,
+					   const char *name,
+					   umode_t mode, loff_t size,
+					   const struct kernfs_ops *ops,
+					   void *priv, const void *ns);
 struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
 					const char *name,
 					struct sysfs_dirent *target);
@@ -83,6 +88,12 @@ kernfs_create_dir_ns(struct sysfs_dirent *parent, const char *name, void *priv,
 { return ERR_PTR(-ENOSYS); }
 
 static inline struct sysfs_dirent *
+kernfs_create_file_ns(struct sysfs_dirent *parent, const char *name,
+		      umode_t mode, loff_t size, const struct kernfs_ops *ops,
+		      void *priv, const void *ns)
+{ return ERR_PTR(-ENOSYS); }
+
+static inline struct sysfs_dirent *
 kernfs_create_link(struct sysfs_dirent *parent, const char *name,
 		   struct sysfs_dirent *target)
 { return ERR_PTR(-ENOSYS); }
@@ -112,6 +123,13 @@ kernfs_create_dir(struct sysfs_dirent *parent, const char *name, void *priv)
 	return kernfs_create_dir_ns(parent, name, priv, NULL);
 }
 
+static inline struct sysfs_dirent *
+kernfs_create_file(struct sysfs_dirent *parent, const char *name, umode_t mode,
+		   loff_t size, const struct kernfs_ops *ops, void *priv)
+{
+	return kernfs_create_file_ns(parent, name, mode, size, ops, priv, NULL);
+}
+
 static inline int kernfs_remove_by_name(struct sysfs_dirent *parent,
 					const char *name)
 {
-- 
1.8.4.2

[PATCH 12/34] sysfs, kernfs: remove sysfs_add_one()

[Tejun Heo]

sysfs_add_one() is a wrapper around __sysfs_add_one() which prints out
duplicate name warning if __sysfs_add_one() fails with -EEXIST.  The
previous kernfs conversions moved all dup warnings to sysfs interface
functions and sysfs_add_one() doesn't have any user left.

Remove sysfs_add_one() and update __sysfs_add_one() to take its name.

This patch doesn't make any functional changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/dir.c     | 41 ++++-------------------------------------
 fs/sysfs/file.c    |  2 +-
 fs/sysfs/symlink.c |  2 +-
 fs/sysfs/sysfs.h   |  2 --
 4 files changed, 6 insertions(+), 41 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index cfbf409..e88e9a9 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -395,7 +395,7 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt)
 }
 
 /**
- *	__sysfs_add_one - add sysfs_dirent to parent without warning
+ *	sysfs_add_one - add sysfs_dirent to parent without warning
  *	@acxt: addrm context to use
  *	@sd: sysfs_dirent to be added
  *	@parent_sd: the parent sysfs_dirent to add @sd to
@@ -415,8 +415,8 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt)
  *	0 on success, -EEXIST if entry with the given name already
  *	exists.
  */
-int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
-		    struct sysfs_dirent *parent_sd)
+int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
+		  struct sysfs_dirent *parent_sd)
 {
 	bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS;
 	struct sysfs_inode_attrs *ps_iattr;
@@ -488,39 +488,6 @@ void sysfs_warn_dup(struct sysfs_dirent *parent, const char *name)
 }
 
 /**
- *	sysfs_add_one - add sysfs_dirent to parent
- *	@acxt: addrm context to use
- *	@sd: sysfs_dirent to be added
- *	@parent_sd: the parent sysfs_dirent to add @sd to
- *
- *	Get @parent_sd and set @sd->s_parent to it and increment nlink of
- *	the parent inode if @sd is a directory and link into the children
- *	list of the parent.
- *
- *	This function should be called between calls to
- *	sysfs_addrm_start() and sysfs_addrm_finish() and should be
- *	passed the same @acxt as passed to sysfs_addrm_start().
- *
- *	LOCKING:
- *	Determined by sysfs_addrm_start().
- *
- *	RETURNS:
- *	0 on success, -EEXIST if entry with the given name already
- *	exists.
- */
-int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
-		  struct sysfs_dirent *parent_sd)
-{
-	int ret;
-
-	ret = __sysfs_add_one(acxt, sd, parent_sd);
-
-	if (ret == -EEXIST)
-		sysfs_warn_dup(parent_sd, sd->s_name);
-	return ret;
-}
-
-/**
  *	sysfs_remove_one - remove sysfs_dirent from parent
  *	@acxt: addrm context to use
  *	@sd: sysfs_dirent to be removed
@@ -694,7 +661,7 @@ struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
 
 	/* link in */
 	sysfs_addrm_start(&acxt);
-	rc = __sysfs_add_one(&acxt, sd, parent);
+	rc = sysfs_add_one(&acxt, sd, parent);
 	sysfs_addrm_finish(&acxt);
 
 	if (!rc)
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 69cca0f..9852450 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -1007,7 +1007,7 @@ struct sysfs_dirent *kernfs_create_file_ns(struct sysfs_dirent *parent,
 		sd->s_flags |= SYSFS_FLAG_HAS_MMAP;
 
 	sysfs_addrm_start(&acxt);
-	rc = __sysfs_add_one(&acxt, sd, parent);
+	rc = sysfs_add_one(&acxt, sd, parent);
 	sysfs_addrm_finish(&acxt);
 
 	if (rc) {
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 352fbbb..76efeab 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -47,7 +47,7 @@ struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
 	sysfs_get(target);	/* ref owned by symlink */
 
 	sysfs_addrm_start(&acxt);
-	error = __sysfs_add_one(&acxt, sd, parent);
+	error = sysfs_add_one(&acxt, sd, parent);
 	sysfs_addrm_finish(&acxt);
 
 	if (!error)
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 28898fa..a6542d2 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -167,8 +167,6 @@ struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd);
 void sysfs_put_active(struct sysfs_dirent *sd);
 void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt);
 void sysfs_warn_dup(struct sysfs_dirent *parent, const char *name);
-int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
-		    struct sysfs_dirent *parent_sd);
 int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
 		  struct sysfs_dirent *parent_sd);
 void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
-- 
1.8.4.2

[PATCH 13/34] sysfs, kernfs: add kernfs_ops->seq_{start|next|stop}()

[Tejun Heo]

kernfs_ops currently only supports single_open() behavior which is
pretty restrictive.  Add optional callbacks ->seq_{start|next|stop}()
which, when implemented, are invoked for seq_file traversal.  This
allows full seq_file functionality for kernfs users.  This currently
doesn't have any user and doesn't change any behavior.

v2: Refreshed on top of the updated "sysfs, kernfs: prepare read path
    for kernfs".

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c        | 39 ++++++++++++++++++++++++++++-----------
 include/linux/kernfs.h |  9 +++++++--
 2 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 9852450..74e3478 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -146,6 +146,7 @@ static ssize_t sysfs_kf_bin_read(struct sysfs_open_file *of, char *buf,
 static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos)
 {
 	struct sysfs_open_file *of = sf->private;
+	const struct kernfs_ops *ops;
 
 	/*
 	 * @of->mutex nests outside active ref and is just to ensure that
@@ -155,26 +156,42 @@ static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos)
 	if (!sysfs_get_active(of->sd))
 		return ERR_PTR(-ENODEV);
 
-	/*
-	 * The same behavior and code as single_open().  Returns !NULL if
-	 * pos is at the beginning; otherwise, NULL.
-	 */
-	return NULL + !*ppos;
+	ops = kernfs_ops(of->sd);
+	if (ops->seq_start) {
+		return ops->seq_start(sf, ppos);
+	} else {
+		/*
+		 * The same behavior and code as single_open().  Returns
+		 * !NULL if pos is at the beginning; otherwise, NULL.
+		 */
+		return NULL + !*ppos;
+	}
 }
 
 static void *kernfs_seq_next(struct seq_file *sf, void *v, loff_t *ppos)
 {
-	/*
-	 * The same behavior and code as single_open(), always terminate
-	 * after the initial read.
-	 */
-	++*ppos;
-	return NULL;
+	struct sysfs_open_file *of = sf->private;
+	const struct kernfs_ops *ops = kernfs_ops(of->sd);
+
+	if (ops->seq_next) {
+		return ops->seq_next(sf, v, ppos);
+	} else {
+		/*
+		 * The same behavior and code as single_open(), always
+		 * terminate after the initial read.
+		 */
+		++*ppos;
+		return NULL;
+	}
 }
 
 static void kernfs_seq_stop(struct seq_file *sf, void *v)
 {
 	struct sysfs_open_file *of = sf->private;
+	const struct kernfs_ops *ops = kernfs_ops(of->sd);
+
+	if (ops->seq_stop)
+		ops->seq_stop(sf, v);
 
 	sysfs_put_active(of->sd);
 	mutex_unlock(&of->mutex);
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index d0912cf..ba993eb 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -37,8 +37,9 @@ struct kernfs_ops {
 	/*
 	 * Read is handled by either seq_file or raw_read().
 	 *
-	 * If seq_show() is present, seq_file path is active.  The behavior
-	 * is equivalent to single_open().  @sf->private points to the
+	 * If seq_show() is present, seq_file path is active.  Other seq
+	 * operations are optional and if not implemented, the behavior is
+	 * equivalent to single_open().  @sf->private points to the
 	 * associated sysfs_open_file.
 	 *
 	 * read() is bounced through kernel buffer and a read larger than
@@ -46,6 +47,10 @@ struct kernfs_ops {
 	 */
 	int (*seq_show)(struct seq_file *sf, void *v);
 
+	void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
+	void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
+	void (*seq_stop)(struct seq_file *sf, void *v);
+
 	ssize_t (*read)(struct sysfs_open_file *of, char *buf, size_t bytes,
 			loff_t off);
 
-- 
1.8.4.2

[PATCH 14/34] sysfs, kernfs: introduce kernfs_notify()

[Tejun Heo]

Introduce kernfs interface to wake up poll(2) which takes and returns
sysfs_dirents.

sysfs_notify_dirent() is renamed to kernfs_notify() and sysfs_notify()
is updated so that it doesn't directly grab sysfs_mutex but acquires
the target sysfs_dirents using sysfs_get_dirent().
sysfs_notify_dirent() is reimplemented as a dumb inline wrapper around
kernfs_notify().

This patch doesn't introduce any behavior changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/file.c        | 33 ++++++++++++++++++++++-----------
 include/linux/kernfs.h |  3 +++
 include/linux/sysfs.h  |  9 +++++----
 3 files changed, 30 insertions(+), 15 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 74e3478..a68cbef 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -851,7 +851,13 @@ static unsigned int kernfs_file_poll(struct file *filp, poll_table *wait)
 	return DEFAULT_POLLMASK|POLLERR|POLLPRI;
 }
 
-void sysfs_notify_dirent(struct sysfs_dirent *sd)
+/**
+ * kernfs_notify - notify a kernfs file
+ * @sd: file to notify
+ *
+ * Notify @sd such that poll(2) on @sd wakes up.
+ */
+void kernfs_notify(struct sysfs_dirent *sd)
 {
 	struct sysfs_open_dirent *od;
 	unsigned long flags;
@@ -868,22 +874,27 @@ void sysfs_notify_dirent(struct sysfs_dirent *sd)
 
 	spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
 }
-EXPORT_SYMBOL_GPL(sysfs_notify_dirent);
+EXPORT_SYMBOL_GPL(kernfs_notify);
 
 void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
 {
-	struct sysfs_dirent *sd = k->sd;
-
-	mutex_lock(&sysfs_mutex);
+	struct sysfs_dirent *sd = k->sd, *tmp;
 
 	if (sd && dir)
-		sd = sysfs_find_dirent(sd, dir, NULL);
-	if (sd && attr)
-		sd = sysfs_find_dirent(sd, attr, NULL);
-	if (sd)
-		sysfs_notify_dirent(sd);
+		sd = sysfs_get_dirent(sd, dir);
+	else
+		sysfs_get(sd);
 
-	mutex_unlock(&sysfs_mutex);
+	if (sd && attr) {
+		tmp = sysfs_get_dirent(sd, attr);
+		sysfs_put(sd);
+		sd = tmp;
+	}
+
+	if (sd) {
+		kernfs_notify(sd);
+		sysfs_put(sd);
+	}
 }
 EXPORT_SYMBOL_GPL(sysfs_notify);
 
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index ba993eb..f20796e 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -84,6 +84,7 @@ int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
 		     const char *new_name, const void *new_ns);
 void kernfs_enable_ns(struct sysfs_dirent *sd);
 int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr);
+void kernfs_notify(struct sysfs_dirent *sd);
 
 #else	/* CONFIG_SYSFS */
 
@@ -120,6 +121,8 @@ static inline int kernfs_setattr(struct sysfs_dirent *sd,
 				 const struct iattr *iattr)
 { return -ENOSYS; }
 
+static inline void kernfs_notify(struct sysfs_dirent *sd) { }
+
 #endif	/* CONFIG_SYSFS */
 
 static inline struct sysfs_dirent *
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 2bc735d..0ab2b02 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -243,7 +243,6 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
 				  const char *link_name);
 
 void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr);
-void sysfs_notify_dirent(struct sysfs_dirent *sd);
 struct sysfs_dirent *sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd,
 					 const unsigned char *name,
 					 const void *ns);
@@ -418,9 +417,6 @@ static inline void sysfs_notify(struct kobject *kobj, const char *dir,
 				const char *attr)
 {
 }
-static inline void sysfs_notify_dirent(struct sysfs_dirent *sd)
-{
-}
 static inline struct sysfs_dirent *
 sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd, const unsigned char *name,
 		    const void *ns)
@@ -466,4 +462,9 @@ sysfs_get_dirent(struct sysfs_dirent *parent_sd, const unsigned char *name)
 	return sysfs_get_dirent_ns(parent_sd, name, NULL);
 }
 
+static inline void sysfs_notify_dirent(struct sysfs_dirent *sd)
+{
+	kernfs_notify(sd);
+}
+
 #endif /* _SYSFS_H_ */
-- 
1.8.4.2

[PATCH 15/34] sysfs, kernfs: reorganize SYSFS_* constants

[Tejun Heo]

We want to add one more SYSFS_FLAG_* but we can't use the next higher
bit, 0x10000, as the flag field is 16bits wide.  The flags are
currently arranged weirdly - 8 bits are set aside for the type flags
when there are only three three used, the first flag starts at 0x1000
instead of 0x0100 and flag literals have 5 digits (20 bits) when only
4 digits can be used.

Rearrange them so that type bits are only the lowest four, flags start
at 0x0010 and similar flags are grouped.

This patch doesn't cause any behavior difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/sysfs.h | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index a6542d2..c86456c 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -80,18 +80,18 @@ struct sysfs_dirent {
 
 #define SD_DEACTIVATED_BIAS		INT_MIN
 
-#define SYSFS_TYPE_MASK			0x00ff
+#define SYSFS_TYPE_MASK			0x000f
 #define SYSFS_DIR			0x0001
 #define SYSFS_KOBJ_ATTR			0x0002
-#define SYSFS_KOBJ_LINK			0x0008
+#define SYSFS_KOBJ_LINK			0x0004
 #define SYSFS_COPY_NAME			(SYSFS_DIR | SYSFS_KOBJ_LINK)
 #define SYSFS_ACTIVE_REF		SYSFS_KOBJ_ATTR
 
 #define SYSFS_FLAG_MASK			~SYSFS_TYPE_MASK
-#define SYSFS_FLAG_NS			0x01000
-#define SYSFS_FLAG_REMOVED		0x02000
-#define SYSFS_FLAG_HAS_SEQ_SHOW		0x04000
-#define SYSFS_FLAG_HAS_MMAP		0x08000
+#define SYSFS_FLAG_REMOVED		0x0010
+#define SYSFS_FLAG_NS			0x0020
+#define SYSFS_FLAG_HAS_SEQ_SHOW		0x0040
+#define SYSFS_FLAG_HAS_MMAP		0x0080
 
 static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
 {
-- 
1.8.4.2

[PATCH 16/34] sysfs, kernfs: revamp sysfs_dirent active_ref lockdep annotation

[Tejun Heo]

Currently, sysfs_dirent active_ref lockdep annotation uses
attribute->[s]key as the lockdep key, which forces
kernfs_create_file_ns() to assume that sysfs_dirent->priv is pointing
to a struct attribute which may not be true for non-sysfs users.  This
patch restructures the lockdep annotation such that

* kernfs_ops contains lockdep_key which is used by default for files
  created kernfs_create_file_ns().

* kernfs_create_file_ns_key() is introduced which takes an extra @key
  argument.  The created file will use the specified key for
  active_ref lockdep annotation.  If NULL is specified, lockdep for
  the file is disabled.

* sysfs_add_file_mode_ns() is updated to use
  kernfs_create_file_ns_key() with the appropriate key from the
  attribute or NULL if ignore_lockdep is set.

This makes the lockdep annotation properly contained in kernfs while
allowing sysfs to cleanly keep its current behavior.  This patch
doesn't introduce any behavior differences.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/dir.c         |  4 ++--
 fs/sysfs/file.c        | 35 ++++++++++++++++++++++++-----------
 fs/sysfs/sysfs.h       | 32 +-------------------------------
 include/linux/kernfs.h | 37 +++++++++++++++++++++++++++++--------
 4 files changed, 56 insertions(+), 52 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index e88e9a9..8f2d577 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -150,7 +150,7 @@ struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
 	if (!atomic_inc_unless_negative(&sd->s_active))
 		return NULL;
 
-	if (likely(!sysfs_ignore_lockdep(sd)))
+	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
 		rwsem_acquire_read(&sd->dep_map, 0, 1, _RET_IP_);
 	return sd;
 }
@@ -169,7 +169,7 @@ void sysfs_put_active(struct sysfs_dirent *sd)
 	if (unlikely(!sd))
 		return;
 
-	if (likely(!sysfs_ignore_lockdep(sd)))
+	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
 		rwsem_release(&sd->dep_map, 1, _RET_IP_);
 	v = atomic_dec_return(&sd->s_active);
 	if (likely(v != SD_DEACTIVATED_BIAS))
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index a68cbef..e4eca28 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -58,7 +58,7 @@ static struct sysfs_open_file *sysfs_of(struct file *file)
  */
 static const struct kernfs_ops *kernfs_ops(struct sysfs_dirent *sd)
 {
-	if (!sysfs_ignore_lockdep(sd))
+	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
 		lockdep_assert_held(sd);
 	return sd->s_attr.ops;
 }
@@ -71,7 +71,7 @@ static const struct sysfs_ops *sysfs_file_ops(struct sysfs_dirent *sd)
 {
 	struct kobject *kobj = sd->s_parent->priv;
 
-	if (!sysfs_ignore_lockdep(sd))
+	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
 		lockdep_assert_held(sd);
 	return kobj->ktype ? kobj->ktype->sysfs_ops : NULL;
 }
@@ -942,6 +942,7 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 			   const struct attribute *attr, bool is_bin,
 			   umode_t mode, const void *ns)
 {
+	struct lock_class_key *key = NULL;
 	const struct kernfs_ops *ops;
 	struct sysfs_dirent *sd;
 	loff_t size;
@@ -981,8 +982,12 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 		size = battr->size;
 	}
 
-	sd = kernfs_create_file_ns(dir_sd, attr->name, mode, size,
-				   ops, (void *)attr, ns);
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	if (!attr->ignore_lockdep)
+		key = attr->key ?: (struct lock_class_key *)&attr->skey;
+#endif
+	sd = kernfs_create_file_ns_key(dir_sd, attr->name, mode, size,
+				       ops, (void *)attr, ns, key);
 	if (IS_ERR(sd)) {
 		if (PTR_ERR(sd) == -EEXIST)
 			sysfs_warn_dup(dir_sd, attr->name);
@@ -992,7 +997,7 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 }
 
 /**
- * kernfs_create_file_ns - create a file
+ * kernfs_create_file_ns_key - create a file
  * @parent: directory to create the file in
  * @name: name of the file
  * @mode: mode of the file
@@ -1000,14 +1005,16 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
  * @ops: kernfs operations for the file
  * @priv: private data for the file
  * @ns: optional namespace tag of the file
+ * @key: lockdep key for the file's active_ref, %NULL to disable lockdep
  *
  * Returns the created node on success, ERR_PTR() value on error.
  */
-struct sysfs_dirent *kernfs_create_file_ns(struct sysfs_dirent *parent,
-					   const char *name,
-					   umode_t mode, loff_t size,
-					   const struct kernfs_ops *ops,
-					   void *priv, const void *ns)
+struct sysfs_dirent *kernfs_create_file_ns_key(struct sysfs_dirent *parent,
+					       const char *name,
+					       umode_t mode, loff_t size,
+					       const struct kernfs_ops *ops,
+					       void *priv, const void *ns,
+					       struct lock_class_key *key)
 {
 	struct sysfs_addrm_cxt acxt;
 	struct sysfs_dirent *sd;
@@ -1022,7 +1029,13 @@ struct sysfs_dirent *kernfs_create_file_ns(struct sysfs_dirent *parent,
 	sd->s_attr.size = size;
 	sd->s_ns = ns;
 	sd->priv = priv;
-	sysfs_dirent_init_lockdep(sd);
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	if (key) {
+		lockdep_init_map(&sd->dep_map, "s_active", key, 0);
+		sd->s_flags |= SYSFS_FLAG_LOCKDEP;
+	}
+#endif
 
 	/*
 	 * sd->s_attr.ops is accesible only while holding active ref.  We
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index c86456c..e93f8b8 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -92,43 +92,13 @@ struct sysfs_dirent {
 #define SYSFS_FLAG_NS			0x0020
 #define SYSFS_FLAG_HAS_SEQ_SHOW		0x0040
 #define SYSFS_FLAG_HAS_MMAP		0x0080
+#define SYSFS_FLAG_LOCKDEP		0x0100
 
 static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
 {
 	return sd->s_flags & SYSFS_TYPE_MASK;
 }
 
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-
-#define sysfs_dirent_init_lockdep(sd)				\
-do {								\
-	struct attribute *attr = sd->priv;			\
-	struct lock_class_key *key = attr->key;			\
-	if (!key)						\
-		key = &attr->skey;				\
-								\
-	lockdep_init_map(&sd->dep_map, "s_active", key, 0);	\
-} while (0)
-
-/* Test for attributes that want to ignore lockdep for read-locking */
-static inline bool sysfs_ignore_lockdep(struct sysfs_dirent *sd)
-{
-	struct attribute *attr = sd->priv;
-
-	return sysfs_type(sd) == SYSFS_KOBJ_ATTR && attr->ignore_lockdep;
-}
-
-#else
-
-#define sysfs_dirent_init_lockdep(sd) do {} while (0)
-
-static inline bool sysfs_ignore_lockdep(struct sysfs_dirent *sd)
-{
-	return true;
-}
-
-#endif
-
 /*
  * Context structure to be used while adding/removing nodes.
  */
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index f20796e..105d09d 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -11,6 +11,7 @@
 #include <linux/err.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
+#include <linux/lockdep.h>
 
 struct file;
 struct iattr;
@@ -62,6 +63,10 @@ struct kernfs_ops {
 			 loff_t off);
 
 	int (*mmap)(struct sysfs_open_file *of, struct vm_area_struct *vma);
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lock_class_key	lockdep_key;
+#endif
 };
 
 #ifdef CONFIG_SYSFS
@@ -69,11 +74,12 @@ struct kernfs_ops {
 struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
 					  const char *name, void *priv,
 					  const void *ns);
-struct sysfs_dirent *kernfs_create_file_ns(struct sysfs_dirent *parent,
-					   const char *name,
-					   umode_t mode, loff_t size,
-					   const struct kernfs_ops *ops,
-					   void *priv, const void *ns);
+struct sysfs_dirent *kernfs_create_file_ns_key(struct sysfs_dirent *parent,
+					       const char *name,
+					       umode_t mode, loff_t size,
+					       const struct kernfs_ops *ops,
+					       void *priv, const void *ns,
+					       struct lock_class_key *key);
 struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
 					const char *name,
 					struct sysfs_dirent *target);
@@ -94,9 +100,10 @@ kernfs_create_dir_ns(struct sysfs_dirent *parent, const char *name, void *priv,
 { return ERR_PTR(-ENOSYS); }
 
 static inline struct sysfs_dirent *
-kernfs_create_file_ns(struct sysfs_dirent *parent, const char *name,
-		      umode_t mode, loff_t size, const struct kernfs_ops *ops,
-		      void *priv, const void *ns)
+kernfs_create_file_ns_key(struct sysfs_dirent *parent, const char *name,
+			  umode_t mode, loff_t size,
+			  const struct kernfs_ops *ops, void *priv,
+			  const void *ns, struct lock_class_key *key)
 { return ERR_PTR(-ENOSYS); }
 
 static inline struct sysfs_dirent *
@@ -132,6 +139,20 @@ kernfs_create_dir(struct sysfs_dirent *parent, const char *name, void *priv)
 }
 
 static inline struct sysfs_dirent *
+kernfs_create_file_ns(struct sysfs_dirent *parent, const char *name,
+		      umode_t mode, loff_t size, const struct kernfs_ops *ops,
+		      void *priv, const void *ns)
+{
+	struct lock_class_key *key = NULL;
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	key = (struct lock_class_key *)&ops->lockdep_key;
+#endif
+	return kernfs_create_file_ns_key(parent, name, mode, size, ops, priv,
+					 ns, key);
+}
+
+static inline struct sysfs_dirent *
 kernfs_create_file(struct sysfs_dirent *parent, const char *name, umode_t mode,
 		   loff_t size, const struct kernfs_ops *ops, void *priv)
 {
-- 
1.8.4.2

[PATCH 17/34] sysfs, kernfs: introduce kernfs[_find_and]_get() and kernfs_put()

[Tejun Heo]

Introduce kernfs interface for finding, getting and putting
sysfs_dirents.

* sysfs_find_dirent() is renamed to kernfs_find_ns() and lockdep
  assertion for sysfs_mutex is added.

* sysfs_get_dirent_ns() is renamed to kernfs_find_and_get().

* Macro inline dancing around __sysfs_get/put() are removed and
  kernfs_get/put() are made proper functions implemented in
  fs/sysfs/dir.c.

While the conversions are mostly equivalent, there's one difference -
kernfs_get() doesn't return the input param as its return value.  This
change is intentional.  While passing through the input increases
writability in some areas, it is unnecessary and has been shown to
cause confusion regarding how the last ref is handled.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/dir.c         | 117 ++++++++++++++++++++++++++++---------------------
 fs/sysfs/file.c        |  41 +++++++++--------
 fs/sysfs/group.c       |  30 +++++++------
 fs/sysfs/inode.c       |   5 ++-
 fs/sysfs/mount.c       |  14 ------
 fs/sysfs/symlink.c     |  16 ++++---
 fs/sysfs/sysfs.h       |  22 ----------
 include/linux/kernfs.h |  19 ++++++++
 include/linux/sysfs.h  |  35 ++++++---------
 9 files changed, 151 insertions(+), 148 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 8f2d577..0d806ef 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -240,10 +240,31 @@ static void sysfs_free_ino(unsigned int ino)
 	spin_unlock(&sysfs_ino_lock);
 }
 
-void release_sysfs_dirent(struct sysfs_dirent *sd)
+/**
+ * kernfs_get - get a reference count on a sysfs_dirent
+ * @sd: the target sysfs_dirent
+ */
+void kernfs_get(struct sysfs_dirent *sd)
+{
+	if (sd) {
+		WARN_ON(!atomic_read(&sd->s_count));
+		atomic_inc(&sd->s_count);
+	}
+}
+EXPORT_SYMBOL_GPL(kernfs_get);
+
+/**
+ * kernfs_put - put a reference count on a sysfs_dirent
+ * @sd: the target sysfs_dirent
+ *
+ * Put a reference count of @sd and destroy it if it reached zero.
+ */
+void kernfs_put(struct sysfs_dirent *sd)
 {
 	struct sysfs_dirent *parent_sd;
 
+	if (!sd || !atomic_dec_and_test(&sd->s_count))
+		return;
  repeat:
 	/* Moving/renaming is always done while holding reference.
 	 * sd->s_parent won't change beneath us.
@@ -255,7 +276,7 @@ void release_sysfs_dirent(struct sysfs_dirent *sd)
 		parent_sd ? parent_sd->s_name : "", sd->s_name);
 
 	if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
-		sysfs_put(sd->s_symlink.target_sd);
+		kernfs_put(sd->s_symlink.target_sd);
 	if (sysfs_type(sd) & SYSFS_COPY_NAME)
 		kfree(sd->s_name);
 	if (sd->s_iattr && sd->s_iattr->ia_secdata)
@@ -269,6 +290,7 @@ void release_sysfs_dirent(struct sysfs_dirent *sd)
 	if (sd && atomic_dec_and_test(&sd->s_count))
 		goto repeat;
 }
+EXPORT_SYMBOL_GPL(kernfs_put);
 
 static int sysfs_dentry_delete(const struct dentry *dentry)
 {
@@ -331,7 +353,7 @@ out_bad:
 
 static void sysfs_dentry_release(struct dentry *dentry)
 {
-	sysfs_put(dentry->d_fsdata);
+	kernfs_put(dentry->d_fsdata);
 }
 
 const struct dentry_operations sysfs_dentry_ops = {
@@ -433,7 +455,8 @@ int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
 		return -EINVAL;
 
 	sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
-	sd->s_parent = sysfs_get(parent_sd);
+	sd->s_parent = parent_sd;
+	kernfs_get(parent_sd);
 
 	ret = sysfs_link_sibling(sd);
 	if (ret)
@@ -553,36 +576,33 @@ void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
 
 		sysfs_deactivate(sd);
 		sysfs_unmap_bin_file(sd);
-		sysfs_put(sd);
+		kernfs_put(sd);
 	}
 }
 
 /**
- *	sysfs_find_dirent - find sysfs_dirent with the given name
- *	@parent_sd: sysfs_dirent to search under
- *	@name: name to look for
- *	@ns: the namespace tag to use
- *
- *	Look for sysfs_dirent with name @name under @parent_sd.
- *
- *	LOCKING:
- *	mutex_lock(sysfs_mutex)
+ * kernfs_find_ns - find sysfs_dirent with the given name
+ * @parent: sysfs_dirent to search under
+ * @name: name to look for
+ * @ns: the namespace tag to use
  *
- *	RETURNS:
- *	Pointer to sysfs_dirent if found, NULL if not.
+ * Look for sysfs_dirent with name @name under @parent.  Returns pointer to
+ * the found sysfs_dirent on success, %NULL on failure.
  */
-struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
-				       const unsigned char *name,
-				       const void *ns)
+static struct sysfs_dirent *kernfs_find_ns(struct sysfs_dirent *parent,
+					   const unsigned char *name,
+					   const void *ns)
 {
-	struct rb_node *node = parent_sd->s_dir.children.rb_node;
-	bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS;
+	struct rb_node *node = parent->s_dir.children.rb_node;
+	bool has_ns = parent->s_flags & SYSFS_FLAG_NS;
 	unsigned int hash;
 
+	lockdep_assert_held(&sysfs_mutex);
+
 	if (has_ns != (bool)ns) {
 		WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
 		     has_ns ? "required" : "invalid",
-		     parent_sd->s_name, name);
+		     parent->s_name, name);
 		return NULL;
 	}
 
@@ -604,34 +624,28 @@ struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
 }
 
 /**
- *	sysfs_get_dirent_ns - find and get sysfs_dirent with the given name
- *	@parent_sd: sysfs_dirent to search under
- *	@name: name to look for
- *	@ns: the namespace tag to use
- *
- *	Look for sysfs_dirent with name @name under @parent_sd and get
- *	it if found.
- *
- *	LOCKING:
- *	Kernel thread context (may sleep).  Grabs sysfs_mutex.
+ * kernfs_find_and_get_ns - find and get sysfs_dirent with the given name
+ * @parent: sysfs_dirent to search under
+ * @name: name to look for
+ * @ns: the namespace tag to use
  *
- *	RETURNS:
- *	Pointer to sysfs_dirent if found, NULL if not.
+ * Look for sysfs_dirent with name @name under @parent and get a reference
+ * if found.  This function may sleep and returns pointer to the found
+ * sysfs_dirent on success, %NULL on failure.
  */
-struct sysfs_dirent *sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd,
-					 const unsigned char *name,
-					 const void *ns)
+struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
+					    const char *name, const void *ns)
 {
 	struct sysfs_dirent *sd;
 
 	mutex_lock(&sysfs_mutex);
-	sd = sysfs_find_dirent(parent_sd, name, ns);
-	sysfs_get(sd);
+	sd = kernfs_find_ns(parent, name, ns);
+	kernfs_get(sd);
 	mutex_unlock(&sysfs_mutex);
 
 	return sd;
 }
-EXPORT_SYMBOL_GPL(sysfs_get_dirent_ns);
+EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns);
 
 /**
  * kernfs_create_dir_ns - create a directory
@@ -667,7 +681,7 @@ struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
 	if (!rc)
 		return sd;
 
-	sysfs_put(sd);
+	kernfs_put(sd);
 	return ERR_PTR(rc);
 }
 
@@ -716,14 +730,15 @@ static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry,
 	if (parent_sd->s_flags & SYSFS_FLAG_NS)
 		ns = sysfs_info(dir->i_sb)->ns;
 
-	sd = sysfs_find_dirent(parent_sd, dentry->d_name.name, ns);
+	sd = kernfs_find_ns(parent_sd, dentry->d_name.name, ns);
 
 	/* no such entry */
 	if (!sd) {
 		ret = ERR_PTR(-ENOENT);
 		goto out_unlock;
 	}
-	dentry->d_fsdata = sysfs_get(sd);
+	kernfs_get(sd);
+	dentry->d_fsdata = sd;
 
 	/* attach dentry and inode */
 	inode = sysfs_get_inode(dir->i_sb, sd);
@@ -859,7 +874,7 @@ int kernfs_remove_by_name_ns(struct sysfs_dirent *dir_sd, const char *name,
 
 	sysfs_addrm_start(&acxt);
 
-	sd = sysfs_find_dirent(dir_sd, name, ns);
+	sd = kernfs_find_ns(dir_sd, name, ns);
 	if (sd)
 		__kernfs_remove(&acxt, sd);
 
@@ -925,7 +940,7 @@ int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
 		goto out;	/* nothing to rename */
 
 	error = -EEXIST;
-	if (sysfs_find_dirent(new_parent, new_name, new_ns))
+	if (kernfs_find_ns(new_parent, new_name, new_ns))
 		goto out;
 
 	/* rename sysfs_dirent */
@@ -943,8 +958,8 @@ int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
 	 * Move to the appropriate place in the appropriate directories rbtree.
 	 */
 	sysfs_unlink_sibling(sd);
-	sysfs_get(new_parent);
-	sysfs_put(sd->s_parent);
+	kernfs_get(new_parent);
+	kernfs_put(sd->s_parent);
 	sd->s_ns = new_ns;
 	sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
 	sd->s_parent = new_parent;
@@ -1000,7 +1015,7 @@ static inline unsigned char dt_type(struct sysfs_dirent *sd)
 
 static int sysfs_dir_release(struct inode *inode, struct file *filp)
 {
-	sysfs_put(filp->private_data);
+	kernfs_put(filp->private_data);
 	return 0;
 }
 
@@ -1011,7 +1026,7 @@ static struct sysfs_dirent *sysfs_dir_pos(const void *ns,
 		int valid = !(pos->s_flags & SYSFS_FLAG_REMOVED) &&
 			pos->s_parent == parent_sd &&
 			hash == pos->s_hash;
-		sysfs_put(pos);
+		kernfs_put(pos);
 		if (!valid)
 			pos = NULL;
 	}
@@ -1075,8 +1090,10 @@ static int sysfs_readdir(struct file *file, struct dir_context *ctx)
 		unsigned int type = dt_type(pos);
 		int len = strlen(name);
 		ino_t ino = pos->s_ino;
+
 		ctx->pos = pos->s_hash;
-		file->private_data = sysfs_get(pos);
+		file->private_data = pos;
+		kernfs_get(pos);
 
 		mutex_unlock(&sysfs_mutex);
 		if (!dir_emit(ctx, name, len, ino, type))
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index e4eca28..7f0a79f 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -881,19 +881,19 @@ void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
 	struct sysfs_dirent *sd = k->sd, *tmp;
 
 	if (sd && dir)
-		sd = sysfs_get_dirent(sd, dir);
+		sd = kernfs_find_and_get(sd, dir);
 	else
-		sysfs_get(sd);
+		kernfs_get(sd);
 
 	if (sd && attr) {
-		tmp = sysfs_get_dirent(sd, attr);
-		sysfs_put(sd);
+		tmp = kernfs_find_and_get(sd, attr);
+		kernfs_put(sd);
 		sd = tmp;
 	}
 
 	if (sd) {
 		kernfs_notify(sd);
-		sysfs_put(sd);
+		kernfs_put(sd);
 	}
 }
 EXPORT_SYMBOL_GPL(sysfs_notify);
@@ -1052,7 +1052,7 @@ struct sysfs_dirent *kernfs_create_file_ns_key(struct sysfs_dirent *parent,
 	sysfs_addrm_finish(&acxt);
 
 	if (rc) {
-		sysfs_put(sd);
+		kernfs_put(sd);
 		return ERR_PTR(rc);
 	}
 	return sd;
@@ -1106,16 +1106,18 @@ int sysfs_add_file_to_group(struct kobject *kobj,
 	struct sysfs_dirent *dir_sd;
 	int error;
 
-	if (group)
-		dir_sd = sysfs_get_dirent(kobj->sd, group);
-	else
-		dir_sd = sysfs_get(kobj->sd);
+	if (group) {
+		dir_sd = kernfs_find_and_get(kobj->sd, group);
+	} else {
+		dir_sd = kobj->sd;
+		kernfs_get(dir_sd);
+	}
 
 	if (!dir_sd)
 		return -ENOENT;
 
 	error = sysfs_add_file(dir_sd, attr, false);
-	sysfs_put(dir_sd);
+	kernfs_put(dir_sd);
 
 	return error;
 }
@@ -1135,7 +1137,7 @@ int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
 	struct iattr newattrs;
 	int rc;
 
-	sd = sysfs_get_dirent(kobj->sd, attr->name);
+	sd = kernfs_find_and_get(kobj->sd, attr->name);
 	if (!sd)
 		return -ENOENT;
 
@@ -1144,7 +1146,7 @@ int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
 
 	rc = kernfs_setattr(sd, &newattrs);
 
-	sysfs_put(sd);
+	kernfs_put(sd);
 	return rc;
 }
 EXPORT_SYMBOL_GPL(sysfs_chmod_file);
@@ -1185,13 +1187,16 @@ void sysfs_remove_file_from_group(struct kobject *kobj,
 {
 	struct sysfs_dirent *dir_sd;
 
-	if (group)
-		dir_sd = sysfs_get_dirent(kobj->sd, group);
-	else
-		dir_sd = sysfs_get(kobj->sd);
+	if (group) {
+		dir_sd = kernfs_find_and_get(kobj->sd, group);
+	} else {
+		dir_sd = kobj->sd;
+		kernfs_get(dir_sd);
+	}
+
 	if (dir_sd) {
 		kernfs_remove_by_name(dir_sd, attr->name);
-		sysfs_put(dir_sd);
+		kernfs_put(dir_sd);
 	}
 }
 EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index 9f65cd9..7177532 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -108,13 +108,13 @@ static int internal_create_group(struct kobject *kobj, int update,
 		}
 	} else
 		sd = kobj->sd;
-	sysfs_get(sd);
+	kernfs_get(sd);
 	error = create_files(sd, kobj, grp, update);
 	if (error) {
 		if (grp->name)
 			kernfs_remove(sd);
 	}
-	sysfs_put(sd);
+	kernfs_put(sd);
 	return error;
 }
 
@@ -208,21 +208,23 @@ void sysfs_remove_group(struct kobject *kobj,
 	struct sysfs_dirent *sd;
 
 	if (grp->name) {
-		sd = sysfs_get_dirent(dir_sd, grp->name);
+		sd = kernfs_find_and_get(dir_sd, grp->name);
 		if (!sd) {
 			WARN(!sd, KERN_WARNING
 			     "sysfs group %p not found for kobject '%s'\n",
 			     grp, kobject_name(kobj));
 			return;
 		}
-	} else
-		sd = sysfs_get(dir_sd);
+	} else {
+		sd = dir_sd;
+		kernfs_get(sd);
+	}
 
 	remove_files(sd, kobj, grp);
 	if (grp->name)
 		kernfs_remove(sd);
 
-	sysfs_put(sd);
+	kernfs_put(sd);
 }
 EXPORT_SYMBOL_GPL(sysfs_remove_group);
 
@@ -263,7 +265,7 @@ int sysfs_merge_group(struct kobject *kobj,
 	struct attribute *const *attr;
 	int i;
 
-	dir_sd = sysfs_get_dirent(kobj->sd, grp->name);
+	dir_sd = kernfs_find_and_get(kobj->sd, grp->name);
 	if (!dir_sd)
 		return -ENOENT;
 
@@ -273,7 +275,7 @@ int sysfs_merge_group(struct kobject *kobj,
 		while (--i >= 0)
 			kernfs_remove_by_name(dir_sd, (*--attr)->name);
 	}
-	sysfs_put(dir_sd);
+	kernfs_put(dir_sd);
 
 	return error;
 }
@@ -290,11 +292,11 @@ void sysfs_unmerge_group(struct kobject *kobj,
 	struct sysfs_dirent *dir_sd;
 	struct attribute *const *attr;
 
-	dir_sd = sysfs_get_dirent(kobj->sd, grp->name);
+	dir_sd = kernfs_find_and_get(kobj->sd, grp->name);
 	if (dir_sd) {
 		for (attr = grp->attrs; *attr; ++attr)
 			kernfs_remove_by_name(dir_sd, (*attr)->name);
-		sysfs_put(dir_sd);
+		kernfs_put(dir_sd);
 	}
 }
 EXPORT_SYMBOL_GPL(sysfs_unmerge_group);
@@ -312,12 +314,12 @@ int sysfs_add_link_to_group(struct kobject *kobj, const char *group_name,
 	struct sysfs_dirent *dir_sd;
 	int error = 0;
 
-	dir_sd = sysfs_get_dirent(kobj->sd, group_name);
+	dir_sd = kernfs_find_and_get(kobj->sd, group_name);
 	if (!dir_sd)
 		return -ENOENT;
 
 	error = sysfs_create_link_sd(dir_sd, target, link_name);
-	sysfs_put(dir_sd);
+	kernfs_put(dir_sd);
 
 	return error;
 }
@@ -334,10 +336,10 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
 {
 	struct sysfs_dirent *dir_sd;
 
-	dir_sd = sysfs_get_dirent(kobj->sd, group_name);
+	dir_sd = kernfs_find_and_get(kobj->sd, group_name);
 	if (dir_sd) {
 		kernfs_remove_by_name(dir_sd, link_name);
-		sysfs_put(dir_sd);
+		kernfs_put(dir_sd);
 	}
 }
 EXPORT_SYMBOL_GPL(sysfs_remove_link_from_group);
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index b3c717a..bfe4478 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -254,7 +254,8 @@ int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
 
 static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
 {
-	inode->i_private = sysfs_get(sd);
+	kernfs_get(sd);
+	inode->i_private = sd;
 	inode->i_mapping->a_ops = &sysfs_aops;
 	inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
 	inode->i_op = &sysfs_inode_operations;
@@ -321,7 +322,7 @@ void sysfs_evict_inode(struct inode *inode)
 
 	truncate_inode_pages(&inode->i_data, 0);
 	clear_inode(inode);
-	sysfs_put(sd);
+	kernfs_put(sd);
 }
 
 int sysfs_permission(struct inode *inode, int mask)
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 8c24bce..852d115 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -184,17 +184,3 @@ out_err:
 	sysfs_dir_cachep = NULL;
 	goto out;
 }
-
-#undef sysfs_get
-struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
-{
-	return __sysfs_get(sd);
-}
-EXPORT_SYMBOL_GPL(sysfs_get);
-
-#undef sysfs_put
-void sysfs_put(struct sysfs_dirent *sd)
-{
-	__sysfs_put(sd);
-}
-EXPORT_SYMBOL_GPL(sysfs_put);
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 76efeab..b137aa3 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -44,7 +44,7 @@ struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
 	if (parent->s_flags & SYSFS_FLAG_NS)
 		sd->s_ns = target->s_ns;
 	sd->s_symlink.target_sd = target;
-	sysfs_get(target);	/* ref owned by symlink */
+	kernfs_get(target);	/* ref owned by symlink */
 
 	sysfs_addrm_start(&acxt);
 	error = sysfs_add_one(&acxt, sd, parent);
@@ -53,7 +53,7 @@ struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
 	if (!error)
 		return sd;
 
-	sysfs_put(sd);
+	kernfs_put(sd);
 	return ERR_PTR(error);
 }
 
@@ -72,15 +72,17 @@ static int sysfs_do_create_link_sd(struct sysfs_dirent *parent_sd,
 	 * sysfs_remove_dir() for details.
 	 */
 	spin_lock(&sysfs_symlink_target_lock);
-	if (target->sd)
-		target_sd = sysfs_get(target->sd);
+	if (target->sd) {
+		target_sd = target->sd;
+		kernfs_get(target_sd);
+	}
 	spin_unlock(&sysfs_symlink_target_lock);
 
 	if (!target_sd)
 		return -ENOENT;
 
 	sd = kernfs_create_link(parent_sd, name, target_sd);
-	sysfs_put(target_sd);
+	kernfs_put(target_sd);
 
 	if (!IS_ERR(sd))
 		return 0;
@@ -216,7 +218,7 @@ int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *targ,
 		old_ns = targ->sd->s_ns;
 
 	result = -ENOENT;
-	sd = sysfs_get_dirent_ns(parent_sd, old, old_ns);
+	sd = kernfs_find_and_get_ns(parent_sd, old, old_ns);
 	if (!sd)
 		goto out;
 
@@ -229,7 +231,7 @@ int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *targ,
 	result = kernfs_rename_ns(sd, parent_sd, new, new_ns);
 
 out:
-	sysfs_put(sd);
+	kernfs_put(sd);
 	return result;
 }
 EXPORT_SYMBOL_GPL(sysfs_rename_link_ns);
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index e93f8b8..85315e2 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -141,30 +141,8 @@ int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
 		  struct sysfs_dirent *parent_sd);
 void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
 
-struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
-				       const unsigned char *name,
-				       const void *ns);
 struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);
 
-void release_sysfs_dirent(struct sysfs_dirent *sd);
-
-static inline struct sysfs_dirent *__sysfs_get(struct sysfs_dirent *sd)
-{
-	if (sd) {
-		WARN_ON(!atomic_read(&sd->s_count));
-		atomic_inc(&sd->s_count);
-	}
-	return sd;
-}
-#define sysfs_get(sd) __sysfs_get(sd)
-
-static inline void __sysfs_put(struct sysfs_dirent *sd)
-{
-	if (sd && atomic_dec_and_test(&sd->s_count))
-		release_sysfs_dirent(sd);
-}
-#define sysfs_put(sd) __sysfs_put(sd)
-
 /*
  * inode.c
  */
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 105d09d..fd8f574 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -71,6 +71,11 @@ struct kernfs_ops {
 
 #ifdef CONFIG_SYSFS
 
+struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
+					    const char *name, const void *ns);
+void kernfs_get(struct sysfs_dirent *sd);
+void kernfs_put(struct sysfs_dirent *sd);
+
 struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
 					  const char *name, void *priv,
 					  const void *ns);
@@ -95,6 +100,14 @@ void kernfs_notify(struct sysfs_dirent *sd);
 #else	/* CONFIG_SYSFS */
 
 static inline struct sysfs_dirent *
+kernfs_find_and_get_ns(struct sysfs_dirent *parent, const char *name,
+		       const void *ns)
+{ return NULL; }
+
+static inline void kernfs_get(struct sysfs_dirent *sd) { }
+static inline void kernfs_put(struct sysfs_dirent *sd) { }
+
+static inline struct sysfs_dirent *
 kernfs_create_dir_ns(struct sysfs_dirent *parent, const char *name, void *priv,
 		     const void *ns)
 { return ERR_PTR(-ENOSYS); }
@@ -133,6 +146,12 @@ static inline void kernfs_notify(struct sysfs_dirent *sd) { }
 #endif	/* CONFIG_SYSFS */
 
 static inline struct sysfs_dirent *
+kernfs_find_and_get(struct sysfs_dirent *sd, const char *name)
+{
+	return kernfs_find_and_get_ns(sd, name, NULL);
+}
+
+static inline struct sysfs_dirent *
 kernfs_create_dir(struct sysfs_dirent *parent, const char *name, void *priv)
 {
 	return kernfs_create_dir_ns(parent, name, priv, NULL);
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 0ab2b02..cd8f90b 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -243,11 +243,6 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
 				  const char *link_name);
 
 void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr);
-struct sysfs_dirent *sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd,
-					 const unsigned char *name,
-					 const void *ns);
-struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd);
-void sysfs_put(struct sysfs_dirent *sd);
 
 int __must_check sysfs_init(void);
 
@@ -417,19 +412,6 @@ static inline void sysfs_notify(struct kobject *kobj, const char *dir,
 				const char *attr)
 {
 }
-static inline struct sysfs_dirent *
-sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd, const unsigned char *name,
-		    const void *ns)
-{
-	return NULL;
-}
-static inline struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
-{
-	return NULL;
-}
-static inline void sysfs_put(struct sysfs_dirent *sd)
-{
-}
 
 static inline int __must_check sysfs_init(void)
 {
@@ -456,15 +438,26 @@ static inline int sysfs_rename_link(struct kobject *kobj, struct kobject *target
 	return sysfs_rename_link_ns(kobj, target, old_name, new_name, NULL);
 }
 
+static inline void sysfs_notify_dirent(struct sysfs_dirent *sd)
+{
+	kernfs_notify(sd);
+}
+
 static inline struct sysfs_dirent *
 sysfs_get_dirent(struct sysfs_dirent *parent_sd, const unsigned char *name)
 {
-	return sysfs_get_dirent_ns(parent_sd, name, NULL);
+	return kernfs_find_and_get(parent_sd, name);
 }
 
-static inline void sysfs_notify_dirent(struct sysfs_dirent *sd)
+static inline struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
 {
-	kernfs_notify(sd);
+	kernfs_get(sd);
+	return sd;
+}
+
+static inline void sysfs_put(struct sysfs_dirent *sd)
+{
+	kernfs_put(sd);
 }
 
 #endif /* _SYSFS_H_ */
-- 
1.8.4.2

[PATCH 18/34] sysfs, kernfs: move internal decls to fs/kernfs/kernfs-internal.h

[Tejun Heo]

Move data structure, constant and basic accessor declarations from
fs/sysfs/sysfs.h to fs/kernfs/kernfs-internal.h.  The two files
currently include each other.  Once kernfs / sysfs separation is
complete, the cross inclusions will be removed.  Inclusion protectors
are added to fs/sysfs/sysfs.h to allow cross-inclusion.

This patch doesn't introduce any functional changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/kernfs-internal.h | 115 ++++++++++++++++++++++++++++++++++++++++++++
 fs/sysfs/sysfs.h            | 102 +++------------------------------------
 2 files changed, 121 insertions(+), 96 deletions(-)
 create mode 100644 fs/kernfs/kernfs-internal.h

diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
new file mode 100644
index 0000000..5a2c3a1
--- /dev/null
+++ b/fs/kernfs/kernfs-internal.h
@@ -0,0 +1,115 @@
+/*
+ * fs/kernfs/kernfs-internal.h - kernfs internal header file
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007, 2013 Tejun Heo <teheo@suse.de>
+ *
+ * This file is released under the GPLv2.
+ */
+
+#ifndef __KERNFS_INTERNAL_H
+#define __KERNFS_INTERNAL_H
+
+#include <linux/lockdep.h>
+#include <linux/fs.h>
+#include <linux/rbtree.h>
+
+#include <linux/kernfs.h>
+
+struct sysfs_open_dirent;
+
+/* type-specific structures for sysfs_dirent->s_* union members */
+struct sysfs_elem_dir {
+	unsigned long		subdirs;
+	/* children rbtree starts here and goes through sd->s_rb */
+	struct rb_root		children;
+};
+
+struct sysfs_elem_symlink {
+	struct sysfs_dirent	*target_sd;
+};
+
+struct sysfs_elem_attr {
+	const struct kernfs_ops	*ops;
+	struct sysfs_open_dirent *open;
+	loff_t			size;
+};
+
+struct sysfs_inode_attrs {
+	struct iattr	ia_iattr;
+	void		*ia_secdata;
+	u32		ia_secdata_len;
+};
+
+/*
+ * sysfs_dirent - the building block of sysfs hierarchy.  Each and
+ * every sysfs node is represented by single sysfs_dirent.
+ *
+ * As long as s_count reference is held, the sysfs_dirent itself is
+ * accessible.  Dereferencing s_elem or any other outer entity
+ * requires s_active reference.
+ */
+struct sysfs_dirent {
+	atomic_t		s_count;
+	atomic_t		s_active;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lockdep_map	dep_map;
+#endif
+	struct sysfs_dirent	*s_parent;
+	const char		*s_name;
+
+	struct rb_node		s_rb;
+
+	union {
+		struct completion	*completion;
+		struct sysfs_dirent	*removed_list;
+	} u;
+
+	const void		*s_ns; /* namespace tag */
+	unsigned int		s_hash; /* ns + name hash */
+	union {
+		struct sysfs_elem_dir		s_dir;
+		struct sysfs_elem_symlink	s_symlink;
+		struct sysfs_elem_attr		s_attr;
+	};
+
+	void			*priv;
+
+	unsigned short		s_flags;
+	umode_t			s_mode;
+	unsigned int		s_ino;
+	struct sysfs_inode_attrs *s_iattr;
+};
+
+#define SD_DEACTIVATED_BIAS		INT_MIN
+
+#define SYSFS_TYPE_MASK			0x000f
+#define SYSFS_DIR			0x0001
+#define SYSFS_KOBJ_ATTR			0x0002
+#define SYSFS_KOBJ_LINK			0x0004
+#define SYSFS_COPY_NAME			(SYSFS_DIR | SYSFS_KOBJ_LINK)
+#define SYSFS_ACTIVE_REF		SYSFS_KOBJ_ATTR
+
+#define SYSFS_FLAG_MASK			~SYSFS_TYPE_MASK
+#define SYSFS_FLAG_REMOVED		0x0010
+#define SYSFS_FLAG_NS			0x0020
+#define SYSFS_FLAG_HAS_SEQ_SHOW		0x0040
+#define SYSFS_FLAG_HAS_MMAP		0x0080
+#define SYSFS_FLAG_LOCKDEP		0x0100
+
+static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
+{
+	return sd->s_flags & SYSFS_TYPE_MASK;
+}
+
+/*
+ * Context structure to be used while adding/removing nodes.
+ */
+struct sysfs_addrm_cxt {
+	struct sysfs_dirent	*removed;
+};
+
+#include "../sysfs/sysfs.h"
+
+#endif	/* __KERNFS_INTERNAL_H */
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 85315e2..f8c936f 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -8,103 +8,11 @@
  * This file is released under the GPLv2.
  */
 
-#include <linux/lockdep.h>
-#include <linux/kobject_ns.h>
-#include <linux/fs.h>
-#include <linux/rbtree.h>
+#ifndef __SYSFS_INTERNAL_H
+#define __SYSFS_INTERNAL_H
 
-struct sysfs_open_dirent;
-
-/* type-specific structures for sysfs_dirent->s_* union members */
-struct sysfs_elem_dir {
-	unsigned long		subdirs;
-	/* children rbtree starts here and goes through sd->s_rb */
-	struct rb_root		children;
-};
-
-struct sysfs_elem_symlink {
-	struct sysfs_dirent	*target_sd;
-};
-
-struct sysfs_elem_attr {
-	const struct kernfs_ops	*ops;
-	struct sysfs_open_dirent *open;
-	loff_t			size;
-};
-
-struct sysfs_inode_attrs {
-	struct iattr	ia_iattr;
-	void		*ia_secdata;
-	u32		ia_secdata_len;
-};
-
-/*
- * sysfs_dirent - the building block of sysfs hierarchy.  Each and
- * every sysfs node is represented by single sysfs_dirent.
- *
- * As long as s_count reference is held, the sysfs_dirent itself is
- * accessible.  Dereferencing s_elem or any other outer entity
- * requires s_active reference.
- */
-struct sysfs_dirent {
-	atomic_t		s_count;
-	atomic_t		s_active;
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-	struct lockdep_map	dep_map;
-#endif
-	struct sysfs_dirent	*s_parent;
-	const char		*s_name;
-
-	struct rb_node		s_rb;
-
-	union {
-		struct completion	*completion;
-		struct sysfs_dirent	*removed_list;
-	} u;
-
-	const void		*s_ns; /* namespace tag */
-	unsigned int		s_hash; /* ns + name hash */
-	union {
-		struct sysfs_elem_dir		s_dir;
-		struct sysfs_elem_symlink	s_symlink;
-		struct sysfs_elem_attr		s_attr;
-	};
-
-	void			*priv;
-
-	unsigned short		s_flags;
-	umode_t			s_mode;
-	unsigned int		s_ino;
-	struct sysfs_inode_attrs *s_iattr;
-};
-
-#define SD_DEACTIVATED_BIAS		INT_MIN
-
-#define SYSFS_TYPE_MASK			0x000f
-#define SYSFS_DIR			0x0001
-#define SYSFS_KOBJ_ATTR			0x0002
-#define SYSFS_KOBJ_LINK			0x0004
-#define SYSFS_COPY_NAME			(SYSFS_DIR | SYSFS_KOBJ_LINK)
-#define SYSFS_ACTIVE_REF		SYSFS_KOBJ_ATTR
-
-#define SYSFS_FLAG_MASK			~SYSFS_TYPE_MASK
-#define SYSFS_FLAG_REMOVED		0x0010
-#define SYSFS_FLAG_NS			0x0020
-#define SYSFS_FLAG_HAS_SEQ_SHOW		0x0040
-#define SYSFS_FLAG_HAS_MMAP		0x0080
-#define SYSFS_FLAG_LOCKDEP		0x0100
-
-static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
-{
-	return sd->s_flags & SYSFS_TYPE_MASK;
-}
-
-/*
- * Context structure to be used while adding/removing nodes.
- */
-struct sysfs_addrm_cxt {
-	struct sysfs_dirent	*removed;
-};
+#include "../kernfs/kernfs-internal.h"
+#include <linux/sysfs.h>
 
 /*
  * mount.c
@@ -175,3 +83,5 @@ void sysfs_unmap_bin_file(struct sysfs_dirent *sd);
 extern const struct inode_operations sysfs_symlink_inode_operations;
 int sysfs_create_link_sd(struct sysfs_dirent *sd, struct kobject *target,
 			 const char *name);
+
+#endif	/* __SYSFS_INTERNAL_H */
-- 
1.8.4.2

[PATCH 19/34] sysfs, kernfs: move inode code to fs/kernfs/inode.c

[Tejun Heo]

There's nothing sysfs-specific in fs/sysfs/inode.c.  Move everything
in it to fs/kernfs/inode.c.  The respective declarations in
fs/sysfs/sysfs.h are moved to fs/kernfs/kernfs-internal.h.

This is pure relocation.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/inode.c           | 327 ++++++++++++++++++++++++++++++++++++++++++
 fs/kernfs/kernfs-internal.h |  13 ++
 fs/sysfs/Makefile           |   2 +-
 fs/sysfs/inode.c            | 342 --------------------------------------------
 fs/sysfs/sysfs.h            |  13 --
 5 files changed, 341 insertions(+), 356 deletions(-)
 delete mode 100644 fs/sysfs/inode.c

diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 86bfeea..9d4fab4 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -7,3 +7,330 @@
  *
  * This file is released under the GPLv2.
  */
+
+#include <linux/pagemap.h>
+#include <linux/backing-dev.h>
+#include <linux/capability.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/xattr.h>
+#include <linux/security.h>
+
+#include "kernfs-internal.h"
+
+static const struct address_space_operations sysfs_aops = {
+	.readpage	= simple_readpage,
+	.write_begin	= simple_write_begin,
+	.write_end	= simple_write_end,
+};
+
+static struct backing_dev_info sysfs_backing_dev_info = {
+	.name		= "sysfs",
+	.ra_pages	= 0,	/* No readahead */
+	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK,
+};
+
+static const struct inode_operations sysfs_inode_operations = {
+	.permission	= sysfs_permission,
+	.setattr	= sysfs_setattr,
+	.getattr	= sysfs_getattr,
+	.setxattr	= sysfs_setxattr,
+};
+
+int __init sysfs_inode_init(void)
+{
+	return bdi_init(&sysfs_backing_dev_info);
+}
+
+static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
+{
+	struct sysfs_inode_attrs *attrs;
+	struct iattr *iattrs;
+
+	attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
+	if (!attrs)
+		return NULL;
+	iattrs = &attrs->ia_iattr;
+
+	/* assign default attributes */
+	iattrs->ia_mode = sd->s_mode;
+	iattrs->ia_uid = GLOBAL_ROOT_UID;
+	iattrs->ia_gid = GLOBAL_ROOT_GID;
+	iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
+
+	return attrs;
+}
+
+static int __kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
+{
+	struct sysfs_inode_attrs *sd_attrs;
+	struct iattr *iattrs;
+	unsigned int ia_valid = iattr->ia_valid;
+
+	sd_attrs = sd->s_iattr;
+
+	if (!sd_attrs) {
+		/* setting attributes for the first time, allocate now */
+		sd_attrs = sysfs_init_inode_attrs(sd);
+		if (!sd_attrs)
+			return -ENOMEM;
+		sd->s_iattr = sd_attrs;
+	}
+	/* attributes were changed at least once in past */
+	iattrs = &sd_attrs->ia_iattr;
+
+	if (ia_valid & ATTR_UID)
+		iattrs->ia_uid = iattr->ia_uid;
+	if (ia_valid & ATTR_GID)
+		iattrs->ia_gid = iattr->ia_gid;
+	if (ia_valid & ATTR_ATIME)
+		iattrs->ia_atime = iattr->ia_atime;
+	if (ia_valid & ATTR_MTIME)
+		iattrs->ia_mtime = iattr->ia_mtime;
+	if (ia_valid & ATTR_CTIME)
+		iattrs->ia_ctime = iattr->ia_ctime;
+	if (ia_valid & ATTR_MODE) {
+		umode_t mode = iattr->ia_mode;
+		iattrs->ia_mode = sd->s_mode = mode;
+	}
+	return 0;
+}
+
+/**
+ * kernfs_setattr - set iattr on a node
+ * @sd: target node
+ * @iattr: iattr to set
+ *
+ * Returns 0 on success, -errno on failure.
+ */
+int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
+{
+	int ret;
+
+	mutex_lock(&sysfs_mutex);
+	ret = __kernfs_setattr(sd, iattr);
+	mutex_unlock(&sysfs_mutex);
+	return ret;
+}
+
+int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
+{
+	struct inode *inode = dentry->d_inode;
+	struct sysfs_dirent *sd = dentry->d_fsdata;
+	int error;
+
+	if (!sd)
+		return -EINVAL;
+
+	mutex_lock(&sysfs_mutex);
+	error = inode_change_ok(inode, iattr);
+	if (error)
+		goto out;
+
+	error = __kernfs_setattr(sd, iattr);
+	if (error)
+		goto out;
+
+	/* this ignores size changes */
+	setattr_copy(inode, iattr);
+
+out:
+	mutex_unlock(&sysfs_mutex);
+	return error;
+}
+
+static int sysfs_sd_setsecdata(struct sysfs_dirent *sd, void **secdata,
+			       u32 *secdata_len)
+{
+	struct sysfs_inode_attrs *iattrs;
+	void *old_secdata;
+	size_t old_secdata_len;
+
+	if (!sd->s_iattr) {
+		sd->s_iattr = sysfs_init_inode_attrs(sd);
+		if (!sd->s_iattr)
+			return -ENOMEM;
+	}
+
+	iattrs = sd->s_iattr;
+	old_secdata = iattrs->ia_secdata;
+	old_secdata_len = iattrs->ia_secdata_len;
+
+	iattrs->ia_secdata = *secdata;
+	iattrs->ia_secdata_len = *secdata_len;
+
+	*secdata = old_secdata;
+	*secdata_len = old_secdata_len;
+	return 0;
+}
+
+int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
+		size_t size, int flags)
+{
+	struct sysfs_dirent *sd = dentry->d_fsdata;
+	void *secdata;
+	int error;
+	u32 secdata_len = 0;
+
+	if (!sd)
+		return -EINVAL;
+
+	if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
+		const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
+		error = security_inode_setsecurity(dentry->d_inode, suffix,
+						value, size, flags);
+		if (error)
+			goto out;
+		error = security_inode_getsecctx(dentry->d_inode,
+						&secdata, &secdata_len);
+		if (error)
+			goto out;
+
+		mutex_lock(&sysfs_mutex);
+		error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
+		mutex_unlock(&sysfs_mutex);
+
+		if (secdata)
+			security_release_secctx(secdata, secdata_len);
+	} else
+		return -EINVAL;
+out:
+	return error;
+}
+
+static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
+{
+	inode->i_mode = mode;
+	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+}
+
+static inline void set_inode_attr(struct inode *inode, struct iattr *iattr)
+{
+	inode->i_uid = iattr->ia_uid;
+	inode->i_gid = iattr->ia_gid;
+	inode->i_atime = iattr->ia_atime;
+	inode->i_mtime = iattr->ia_mtime;
+	inode->i_ctime = iattr->ia_ctime;
+}
+
+static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
+{
+	struct sysfs_inode_attrs *iattrs = sd->s_iattr;
+
+	inode->i_mode = sd->s_mode;
+	if (iattrs) {
+		/* sysfs_dirent has non-default attributes
+		 * get them from persistent copy in sysfs_dirent
+		 */
+		set_inode_attr(inode, &iattrs->ia_iattr);
+		security_inode_notifysecctx(inode,
+					    iattrs->ia_secdata,
+					    iattrs->ia_secdata_len);
+	}
+
+	if (sysfs_type(sd) == SYSFS_DIR)
+		set_nlink(inode, sd->s_dir.subdirs + 2);
+}
+
+int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
+		  struct kstat *stat)
+{
+	struct sysfs_dirent *sd = dentry->d_fsdata;
+	struct inode *inode = dentry->d_inode;
+
+	mutex_lock(&sysfs_mutex);
+	sysfs_refresh_inode(sd, inode);
+	mutex_unlock(&sysfs_mutex);
+
+	generic_fillattr(inode, stat);
+	return 0;
+}
+
+static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
+{
+	kernfs_get(sd);
+	inode->i_private = sd;
+	inode->i_mapping->a_ops = &sysfs_aops;
+	inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
+	inode->i_op = &sysfs_inode_operations;
+
+	set_default_inode_attr(inode, sd->s_mode);
+	sysfs_refresh_inode(sd, inode);
+
+	/* initialize inode according to type */
+	switch (sysfs_type(sd)) {
+	case SYSFS_DIR:
+		inode->i_op = &sysfs_dir_inode_operations;
+		inode->i_fop = &sysfs_dir_operations;
+		break;
+	case SYSFS_KOBJ_ATTR:
+		inode->i_size = sd->s_attr.size;
+		inode->i_fop = &kernfs_file_operations;
+		break;
+	case SYSFS_KOBJ_LINK:
+		inode->i_op = &sysfs_symlink_inode_operations;
+		break;
+	default:
+		BUG();
+	}
+
+	unlock_new_inode(inode);
+}
+
+/**
+ *	sysfs_get_inode - get inode for sysfs_dirent
+ *	@sb: super block
+ *	@sd: sysfs_dirent to allocate inode for
+ *
+ *	Get inode for @sd.  If such inode doesn't exist, a new inode
+ *	is allocated and basics are initialized.  New inode is
+ *	returned locked.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	Pointer to allocated inode on success, NULL on failure.
+ */
+struct inode *sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd)
+{
+	struct inode *inode;
+
+	inode = iget_locked(sb, sd->s_ino);
+	if (inode && (inode->i_state & I_NEW))
+		sysfs_init_inode(sd, inode);
+
+	return inode;
+}
+
+/*
+ * The sysfs_dirent serves as both an inode and a directory entry for sysfs.
+ * To prevent the sysfs inode numbers from being freed prematurely we take a
+ * reference to sysfs_dirent from the sysfs inode.  A
+ * super_operations.evict_inode() implementation is needed to drop that
+ * reference upon inode destruction.
+ */
+void sysfs_evict_inode(struct inode *inode)
+{
+	struct sysfs_dirent *sd  = inode->i_private;
+
+	truncate_inode_pages(&inode->i_data, 0);
+	clear_inode(inode);
+	kernfs_put(sd);
+}
+
+int sysfs_permission(struct inode *inode, int mask)
+{
+	struct sysfs_dirent *sd;
+
+	if (mask & MAY_NOT_BLOCK)
+		return -ECHILD;
+
+	sd = inode->i_private;
+
+	mutex_lock(&sysfs_mutex);
+	sysfs_refresh_inode(sd, inode);
+	mutex_unlock(&sysfs_mutex);
+
+	return generic_permission(inode, mask);
+}
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 5a2c3a1..933ac8d 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -112,4 +112,17 @@ struct sysfs_addrm_cxt {
 
 #include "../sysfs/sysfs.h"
 
+/*
+ * inode.c
+ */
+struct inode *sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd);
+void sysfs_evict_inode(struct inode *inode);
+int sysfs_permission(struct inode *inode, int mask);
+int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
+int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
+		  struct kstat *stat);
+int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
+		   size_t size, int flags);
+int sysfs_inode_init(void);
+
 #endif	/* __KERNFS_INTERNAL_H */
diff --git a/fs/sysfs/Makefile b/fs/sysfs/Makefile
index 8876ac1..6eff6e1 100644
--- a/fs/sysfs/Makefile
+++ b/fs/sysfs/Makefile
@@ -2,4 +2,4 @@
 # Makefile for the sysfs virtual filesystem
 #
 
-obj-y		:= inode.o file.o dir.o symlink.o mount.o group.o
+obj-y		:= file.o dir.o symlink.o mount.o group.o
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
deleted file mode 100644
index bfe4478..0000000
--- a/fs/sysfs/inode.c
+++ /dev/null
@@ -1,342 +0,0 @@
-/*
- * fs/sysfs/inode.c - basic sysfs inode and dentry operations
- *
- * Copyright (c) 2001-3 Patrick Mochel
- * Copyright (c) 2007 SUSE Linux Products GmbH
- * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
- *
- * This file is released under the GPLv2.
- *
- * Please see Documentation/filesystems/sysfs.txt for more information.
- */
-
-#undef DEBUG
-
-#include <linux/pagemap.h>
-#include <linux/namei.h>
-#include <linux/backing-dev.h>
-#include <linux/capability.h>
-#include <linux/errno.h>
-#include <linux/sched.h>
-#include <linux/slab.h>
-#include <linux/sysfs.h>
-#include <linux/xattr.h>
-#include <linux/security.h>
-#include "sysfs.h"
-
-static const struct address_space_operations sysfs_aops = {
-	.readpage	= simple_readpage,
-	.write_begin	= simple_write_begin,
-	.write_end	= simple_write_end,
-};
-
-static struct backing_dev_info sysfs_backing_dev_info = {
-	.name		= "sysfs",
-	.ra_pages	= 0,	/* No readahead */
-	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK,
-};
-
-static const struct inode_operations sysfs_inode_operations = {
-	.permission	= sysfs_permission,
-	.setattr	= sysfs_setattr,
-	.getattr	= sysfs_getattr,
-	.setxattr	= sysfs_setxattr,
-};
-
-int __init sysfs_inode_init(void)
-{
-	return bdi_init(&sysfs_backing_dev_info);
-}
-
-static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
-{
-	struct sysfs_inode_attrs *attrs;
-	struct iattr *iattrs;
-
-	attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
-	if (!attrs)
-		return NULL;
-	iattrs = &attrs->ia_iattr;
-
-	/* assign default attributes */
-	iattrs->ia_mode = sd->s_mode;
-	iattrs->ia_uid = GLOBAL_ROOT_UID;
-	iattrs->ia_gid = GLOBAL_ROOT_GID;
-	iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
-
-	return attrs;
-}
-
-static int __kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
-{
-	struct sysfs_inode_attrs *sd_attrs;
-	struct iattr *iattrs;
-	unsigned int ia_valid = iattr->ia_valid;
-
-	sd_attrs = sd->s_iattr;
-
-	if (!sd_attrs) {
-		/* setting attributes for the first time, allocate now */
-		sd_attrs = sysfs_init_inode_attrs(sd);
-		if (!sd_attrs)
-			return -ENOMEM;
-		sd->s_iattr = sd_attrs;
-	}
-	/* attributes were changed at least once in past */
-	iattrs = &sd_attrs->ia_iattr;
-
-	if (ia_valid & ATTR_UID)
-		iattrs->ia_uid = iattr->ia_uid;
-	if (ia_valid & ATTR_GID)
-		iattrs->ia_gid = iattr->ia_gid;
-	if (ia_valid & ATTR_ATIME)
-		iattrs->ia_atime = iattr->ia_atime;
-	if (ia_valid & ATTR_MTIME)
-		iattrs->ia_mtime = iattr->ia_mtime;
-	if (ia_valid & ATTR_CTIME)
-		iattrs->ia_ctime = iattr->ia_ctime;
-	if (ia_valid & ATTR_MODE) {
-		umode_t mode = iattr->ia_mode;
-		iattrs->ia_mode = sd->s_mode = mode;
-	}
-	return 0;
-}
-
-/**
- * kernfs_setattr - set iattr on a node
- * @sd: target node
- * @iattr: iattr to set
- *
- * Returns 0 on success, -errno on failure.
- */
-int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
-{
-	int ret;
-
-	mutex_lock(&sysfs_mutex);
-	ret = __kernfs_setattr(sd, iattr);
-	mutex_unlock(&sysfs_mutex);
-	return ret;
-}
-
-int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
-{
-	struct inode *inode = dentry->d_inode;
-	struct sysfs_dirent *sd = dentry->d_fsdata;
-	int error;
-
-	if (!sd)
-		return -EINVAL;
-
-	mutex_lock(&sysfs_mutex);
-	error = inode_change_ok(inode, iattr);
-	if (error)
-		goto out;
-
-	error = __kernfs_setattr(sd, iattr);
-	if (error)
-		goto out;
-
-	/* this ignores size changes */
-	setattr_copy(inode, iattr);
-
-out:
-	mutex_unlock(&sysfs_mutex);
-	return error;
-}
-
-static int sysfs_sd_setsecdata(struct sysfs_dirent *sd, void **secdata,
-			       u32 *secdata_len)
-{
-	struct sysfs_inode_attrs *iattrs;
-	void *old_secdata;
-	size_t old_secdata_len;
-
-	if (!sd->s_iattr) {
-		sd->s_iattr = sysfs_init_inode_attrs(sd);
-		if (!sd->s_iattr)
-			return -ENOMEM;
-	}
-
-	iattrs = sd->s_iattr;
-	old_secdata = iattrs->ia_secdata;
-	old_secdata_len = iattrs->ia_secdata_len;
-
-	iattrs->ia_secdata = *secdata;
-	iattrs->ia_secdata_len = *secdata_len;
-
-	*secdata = old_secdata;
-	*secdata_len = old_secdata_len;
-	return 0;
-}
-
-int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
-		size_t size, int flags)
-{
-	struct sysfs_dirent *sd = dentry->d_fsdata;
-	void *secdata;
-	int error;
-	u32 secdata_len = 0;
-
-	if (!sd)
-		return -EINVAL;
-
-	if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
-		const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
-		error = security_inode_setsecurity(dentry->d_inode, suffix,
-						value, size, flags);
-		if (error)
-			goto out;
-		error = security_inode_getsecctx(dentry->d_inode,
-						&secdata, &secdata_len);
-		if (error)
-			goto out;
-
-		mutex_lock(&sysfs_mutex);
-		error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
-		mutex_unlock(&sysfs_mutex);
-
-		if (secdata)
-			security_release_secctx(secdata, secdata_len);
-	} else
-		return -EINVAL;
-out:
-	return error;
-}
-
-static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
-{
-	inode->i_mode = mode;
-	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
-}
-
-static inline void set_inode_attr(struct inode *inode, struct iattr *iattr)
-{
-	inode->i_uid = iattr->ia_uid;
-	inode->i_gid = iattr->ia_gid;
-	inode->i_atime = iattr->ia_atime;
-	inode->i_mtime = iattr->ia_mtime;
-	inode->i_ctime = iattr->ia_ctime;
-}
-
-static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
-{
-	struct sysfs_inode_attrs *iattrs = sd->s_iattr;
-
-	inode->i_mode = sd->s_mode;
-	if (iattrs) {
-		/* sysfs_dirent has non-default attributes
-		 * get them from persistent copy in sysfs_dirent
-		 */
-		set_inode_attr(inode, &iattrs->ia_iattr);
-		security_inode_notifysecctx(inode,
-					    iattrs->ia_secdata,
-					    iattrs->ia_secdata_len);
-	}
-
-	if (sysfs_type(sd) == SYSFS_DIR)
-		set_nlink(inode, sd->s_dir.subdirs + 2);
-}
-
-int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
-		  struct kstat *stat)
-{
-	struct sysfs_dirent *sd = dentry->d_fsdata;
-	struct inode *inode = dentry->d_inode;
-
-	mutex_lock(&sysfs_mutex);
-	sysfs_refresh_inode(sd, inode);
-	mutex_unlock(&sysfs_mutex);
-
-	generic_fillattr(inode, stat);
-	return 0;
-}
-
-static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
-{
-	kernfs_get(sd);
-	inode->i_private = sd;
-	inode->i_mapping->a_ops = &sysfs_aops;
-	inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
-	inode->i_op = &sysfs_inode_operations;
-
-	set_default_inode_attr(inode, sd->s_mode);
-	sysfs_refresh_inode(sd, inode);
-
-	/* initialize inode according to type */
-	switch (sysfs_type(sd)) {
-	case SYSFS_DIR:
-		inode->i_op = &sysfs_dir_inode_operations;
-		inode->i_fop = &sysfs_dir_operations;
-		break;
-	case SYSFS_KOBJ_ATTR:
-		inode->i_size = sd->s_attr.size;
-		inode->i_fop = &kernfs_file_operations;
-		break;
-	case SYSFS_KOBJ_LINK:
-		inode->i_op = &sysfs_symlink_inode_operations;
-		break;
-	default:
-		BUG();
-	}
-
-	unlock_new_inode(inode);
-}
-
-/**
- *	sysfs_get_inode - get inode for sysfs_dirent
- *	@sb: super block
- *	@sd: sysfs_dirent to allocate inode for
- *
- *	Get inode for @sd.  If such inode doesn't exist, a new inode
- *	is allocated and basics are initialized.  New inode is
- *	returned locked.
- *
- *	LOCKING:
- *	Kernel thread context (may sleep).
- *
- *	RETURNS:
- *	Pointer to allocated inode on success, NULL on failure.
- */
-struct inode *sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd)
-{
-	struct inode *inode;
-
-	inode = iget_locked(sb, sd->s_ino);
-	if (inode && (inode->i_state & I_NEW))
-		sysfs_init_inode(sd, inode);
-
-	return inode;
-}
-
-/*
- * The sysfs_dirent serves as both an inode and a directory entry for sysfs.
- * To prevent the sysfs inode numbers from being freed prematurely we take a
- * reference to sysfs_dirent from the sysfs inode.  A
- * super_operations.evict_inode() implementation is needed to drop that
- * reference upon inode destruction.
- */
-void sysfs_evict_inode(struct inode *inode)
-{
-	struct sysfs_dirent *sd  = inode->i_private;
-
-	truncate_inode_pages(&inode->i_data, 0);
-	clear_inode(inode);
-	kernfs_put(sd);
-}
-
-int sysfs_permission(struct inode *inode, int mask)
-{
-	struct sysfs_dirent *sd;
-
-	if (mask & MAY_NOT_BLOCK)
-		return -ECHILD;
-
-	sd = inode->i_private;
-
-	mutex_lock(&sysfs_mutex);
-	sysfs_refresh_inode(sd, inode);
-	mutex_unlock(&sysfs_mutex);
-
-	return generic_permission(inode, mask);
-}
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index f8c936f..93c1910 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -52,19 +52,6 @@ void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
 struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);
 
 /*
- * inode.c
- */
-struct inode *sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd);
-void sysfs_evict_inode(struct inode *inode);
-int sysfs_permission(struct inode *inode, int mask);
-int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
-int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
-		  struct kstat *stat);
-int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
-		   size_t size, int flags);
-int sysfs_inode_init(void);
-
-/*
  * file.c
  */
 extern const struct file_operations kernfs_file_operations;
-- 
1.8.4.2

[PATCH 20/34] sysfs, kernfs: move dir core code to fs/kernfs/dir.c

[Tejun Heo]

Move core dir code to fs/kernfs/dir.c.  fs/sysfs/dir.c now only
contains sysfs_warn_dup() and sysfs wrappers around kernfs interfaces.
The respective declarations in fs/sysfs/sysfs.h are moved to
fs/kernfs/kernfs-internal.h.

This is pure relocation.

v2: sysfs_symlink_target_lock was mistakenly relocated to kernfs.  It
    should remain with sysfs.  Fixed.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/dir.c             | 988 ++++++++++++++++++++++++++++++++++++++++++++
 fs/kernfs/kernfs-internal.h |  17 +
 fs/sysfs/dir.c              | 986 -------------------------------------------
 fs/sysfs/sysfs.h            |  13 -
 4 files changed, 1005 insertions(+), 999 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 1061602..a4ca4de 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -7,3 +7,991 @@
  *
  * This file is released under the GPLv2.
  */
+
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/idr.h>
+#include <linux/slab.h>
+#include <linux/security.h>
+#include <linux/hash.h>
+
+#include "kernfs-internal.h"
+
+DEFINE_MUTEX(sysfs_mutex);
+
+#define to_sysfs_dirent(X) rb_entry((X), struct sysfs_dirent, s_rb)
+
+static DEFINE_SPINLOCK(sysfs_ino_lock);
+static DEFINE_IDA(sysfs_ino_ida);
+
+/**
+ *	sysfs_name_hash
+ *	@name: Null terminated string to hash
+ *	@ns:   Namespace tag to hash
+ *
+ *	Returns 31 bit hash of ns + name (so it fits in an off_t )
+ */
+static unsigned int sysfs_name_hash(const char *name, const void *ns)
+{
+	unsigned long hash = init_name_hash();
+	unsigned int len = strlen(name);
+	while (len--)
+		hash = partial_name_hash(*name++, hash);
+	hash = (end_name_hash(hash) ^ hash_ptr((void *)ns, 31));
+	hash &= 0x7fffffffU;
+	/* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */
+	if (hash < 1)
+		hash += 2;
+	if (hash >= INT_MAX)
+		hash = INT_MAX - 1;
+	return hash;
+}
+
+static int sysfs_name_compare(unsigned int hash, const char *name,
+			      const void *ns, const struct sysfs_dirent *sd)
+{
+	if (hash != sd->s_hash)
+		return hash - sd->s_hash;
+	if (ns != sd->s_ns)
+		return ns - sd->s_ns;
+	return strcmp(name, sd->s_name);
+}
+
+static int sysfs_sd_compare(const struct sysfs_dirent *left,
+			    const struct sysfs_dirent *right)
+{
+	return sysfs_name_compare(left->s_hash, left->s_name, left->s_ns,
+				  right);
+}
+
+/**
+ *	sysfs_link_sibling - link sysfs_dirent into sibling rbtree
+ *	@sd: sysfs_dirent of interest
+ *
+ *	Link @sd into its sibling rbtree which starts from
+ *	sd->s_parent->s_dir.children.
+ *
+ *	Locking:
+ *	mutex_lock(sysfs_mutex)
+ *
+ *	RETURNS:
+ *	0 on susccess -EEXIST on failure.
+ */
+static int sysfs_link_sibling(struct sysfs_dirent *sd)
+{
+	struct rb_node **node = &sd->s_parent->s_dir.children.rb_node;
+	struct rb_node *parent = NULL;
+
+	if (sysfs_type(sd) == SYSFS_DIR)
+		sd->s_parent->s_dir.subdirs++;
+
+	while (*node) {
+		struct sysfs_dirent *pos;
+		int result;
+
+		pos = to_sysfs_dirent(*node);
+		parent = *node;
+		result = sysfs_sd_compare(sd, pos);
+		if (result < 0)
+			node = &pos->s_rb.rb_left;
+		else if (result > 0)
+			node = &pos->s_rb.rb_right;
+		else
+			return -EEXIST;
+	}
+	/* add new node and rebalance the tree */
+	rb_link_node(&sd->s_rb, parent, node);
+	rb_insert_color(&sd->s_rb, &sd->s_parent->s_dir.children);
+	return 0;
+}
+
+/**
+ *	sysfs_unlink_sibling - unlink sysfs_dirent from sibling rbtree
+ *	@sd: sysfs_dirent of interest
+ *
+ *	Unlink @sd from its sibling rbtree which starts from
+ *	sd->s_parent->s_dir.children.
+ *
+ *	Locking:
+ *	mutex_lock(sysfs_mutex)
+ */
+static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
+{
+	if (sysfs_type(sd) == SYSFS_DIR)
+		sd->s_parent->s_dir.subdirs--;
+
+	rb_erase(&sd->s_rb, &sd->s_parent->s_dir.children);
+}
+
+/**
+ *	sysfs_get_active - get an active reference to sysfs_dirent
+ *	@sd: sysfs_dirent to get an active reference to
+ *
+ *	Get an active reference of @sd.  This function is noop if @sd
+ *	is NULL.
+ *
+ *	RETURNS:
+ *	Pointer to @sd on success, NULL on failure.
+ */
+struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
+{
+	if (unlikely(!sd))
+		return NULL;
+
+	if (!atomic_inc_unless_negative(&sd->s_active))
+		return NULL;
+
+	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
+		rwsem_acquire_read(&sd->dep_map, 0, 1, _RET_IP_);
+	return sd;
+}
+
+/**
+ *	sysfs_put_active - put an active reference to sysfs_dirent
+ *	@sd: sysfs_dirent to put an active reference to
+ *
+ *	Put an active reference to @sd.  This function is noop if @sd
+ *	is NULL.
+ */
+void sysfs_put_active(struct sysfs_dirent *sd)
+{
+	int v;
+
+	if (unlikely(!sd))
+		return;
+
+	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
+		rwsem_release(&sd->dep_map, 1, _RET_IP_);
+	v = atomic_dec_return(&sd->s_active);
+	if (likely(v != SD_DEACTIVATED_BIAS))
+		return;
+
+	/* atomic_dec_return() is a mb(), we'll always see the updated
+	 * sd->u.completion.
+	 */
+	complete(sd->u.completion);
+}
+
+/**
+ *	sysfs_deactivate - deactivate sysfs_dirent
+ *	@sd: sysfs_dirent to deactivate
+ *
+ *	Deny new active references and drain existing ones.
+ */
+static void sysfs_deactivate(struct sysfs_dirent *sd)
+{
+	DECLARE_COMPLETION_ONSTACK(wait);
+	int v;
+
+	BUG_ON(!(sd->s_flags & SYSFS_FLAG_REMOVED));
+
+	if (!(sysfs_type(sd) & SYSFS_ACTIVE_REF))
+		return;
+
+	sd->u.completion = (void *)&wait;
+
+	rwsem_acquire(&sd->dep_map, 0, 0, _RET_IP_);
+	/* atomic_add_return() is a mb(), put_active() will always see
+	 * the updated sd->u.completion.
+	 */
+	v = atomic_add_return(SD_DEACTIVATED_BIAS, &sd->s_active);
+
+	if (v != SD_DEACTIVATED_BIAS) {
+		lock_contended(&sd->dep_map, _RET_IP_);
+		wait_for_completion(&wait);
+	}
+
+	lock_acquired(&sd->dep_map, _RET_IP_);
+	rwsem_release(&sd->dep_map, 1, _RET_IP_);
+}
+
+static int sysfs_alloc_ino(unsigned int *pino)
+{
+	int ino, rc;
+
+ retry:
+	spin_lock(&sysfs_ino_lock);
+	rc = ida_get_new_above(&sysfs_ino_ida, 2, &ino);
+	spin_unlock(&sysfs_ino_lock);
+
+	if (rc == -EAGAIN) {
+		if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL))
+			goto retry;
+		rc = -ENOMEM;
+	}
+
+	*pino = ino;
+	return rc;
+}
+
+static void sysfs_free_ino(unsigned int ino)
+{
+	spin_lock(&sysfs_ino_lock);
+	ida_remove(&sysfs_ino_ida, ino);
+	spin_unlock(&sysfs_ino_lock);
+}
+
+/**
+ * kernfs_get - get a reference count on a sysfs_dirent
+ * @sd: the target sysfs_dirent
+ */
+void kernfs_get(struct sysfs_dirent *sd)
+{
+	if (sd) {
+		WARN_ON(!atomic_read(&sd->s_count));
+		atomic_inc(&sd->s_count);
+	}
+}
+EXPORT_SYMBOL_GPL(kernfs_get);
+
+/**
+ * kernfs_put - put a reference count on a sysfs_dirent
+ * @sd: the target sysfs_dirent
+ *
+ * Put a reference count of @sd and destroy it if it reached zero.
+ */
+void kernfs_put(struct sysfs_dirent *sd)
+{
+	struct sysfs_dirent *parent_sd;
+
+	if (!sd || !atomic_dec_and_test(&sd->s_count))
+		return;
+ repeat:
+	/* Moving/renaming is always done while holding reference.
+	 * sd->s_parent won't change beneath us.
+	 */
+	parent_sd = sd->s_parent;
+
+	WARN(!(sd->s_flags & SYSFS_FLAG_REMOVED),
+		"sysfs: free using entry: %s/%s\n",
+		parent_sd ? parent_sd->s_name : "", sd->s_name);
+
+	if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
+		kernfs_put(sd->s_symlink.target_sd);
+	if (sysfs_type(sd) & SYSFS_COPY_NAME)
+		kfree(sd->s_name);
+	if (sd->s_iattr && sd->s_iattr->ia_secdata)
+		security_release_secctx(sd->s_iattr->ia_secdata,
+					sd->s_iattr->ia_secdata_len);
+	kfree(sd->s_iattr);
+	sysfs_free_ino(sd->s_ino);
+	kmem_cache_free(sysfs_dir_cachep, sd);
+
+	sd = parent_sd;
+	if (sd && atomic_dec_and_test(&sd->s_count))
+		goto repeat;
+}
+EXPORT_SYMBOL_GPL(kernfs_put);
+
+static int sysfs_dentry_delete(const struct dentry *dentry)
+{
+	struct sysfs_dirent *sd = dentry->d_fsdata;
+	return !(sd && !(sd->s_flags & SYSFS_FLAG_REMOVED));
+}
+
+static int sysfs_dentry_revalidate(struct dentry *dentry, unsigned int flags)
+{
+	struct sysfs_dirent *sd;
+
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
+
+	sd = dentry->d_fsdata;
+	mutex_lock(&sysfs_mutex);
+
+	/* The sysfs dirent has been deleted */
+	if (sd->s_flags & SYSFS_FLAG_REMOVED)
+		goto out_bad;
+
+	/* The sysfs dirent has been moved? */
+	if (dentry->d_parent->d_fsdata != sd->s_parent)
+		goto out_bad;
+
+	/* The sysfs dirent has been renamed */
+	if (strcmp(dentry->d_name.name, sd->s_name) != 0)
+		goto out_bad;
+
+	/* The sysfs dirent has been moved to a different namespace */
+	if (sd->s_parent && (sd->s_parent->s_flags & SYSFS_FLAG_NS) &&
+	    sysfs_info(dentry->d_sb)->ns != sd->s_ns)
+		goto out_bad;
+
+	mutex_unlock(&sysfs_mutex);
+out_valid:
+	return 1;
+out_bad:
+	/* Remove the dentry from the dcache hashes.
+	 * If this is a deleted dentry we use d_drop instead of d_delete
+	 * so sysfs doesn't need to cope with negative dentries.
+	 *
+	 * If this is a dentry that has simply been renamed we
+	 * use d_drop to remove it from the dcache lookup on its
+	 * old parent.  If this dentry persists later when a lookup
+	 * is performed at its new name the dentry will be readded
+	 * to the dcache hashes.
+	 */
+	mutex_unlock(&sysfs_mutex);
+
+	/* If we have submounts we must allow the vfs caches
+	 * to lie about the state of the filesystem to prevent
+	 * leaks and other nasty things.
+	 */
+	if (check_submounts_and_drop(dentry) != 0)
+		goto out_valid;
+
+	return 0;
+}
+
+static void sysfs_dentry_release(struct dentry *dentry)
+{
+	kernfs_put(dentry->d_fsdata);
+}
+
+const struct dentry_operations sysfs_dentry_ops = {
+	.d_revalidate	= sysfs_dentry_revalidate,
+	.d_delete	= sysfs_dentry_delete,
+	.d_release	= sysfs_dentry_release,
+};
+
+struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
+{
+	char *dup_name = NULL;
+	struct sysfs_dirent *sd;
+
+	if (type & SYSFS_COPY_NAME) {
+		name = dup_name = kstrdup(name, GFP_KERNEL);
+		if (!name)
+			return NULL;
+	}
+
+	sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL);
+	if (!sd)
+		goto err_out1;
+
+	if (sysfs_alloc_ino(&sd->s_ino))
+		goto err_out2;
+
+	atomic_set(&sd->s_count, 1);
+	atomic_set(&sd->s_active, 0);
+
+	sd->s_name = name;
+	sd->s_mode = mode;
+	sd->s_flags = type | SYSFS_FLAG_REMOVED;
+
+	return sd;
+
+ err_out2:
+	kmem_cache_free(sysfs_dir_cachep, sd);
+ err_out1:
+	kfree(dup_name);
+	return NULL;
+}
+
+/**
+ *	sysfs_addrm_start - prepare for sysfs_dirent add/remove
+ *	@acxt: pointer to sysfs_addrm_cxt to be used
+ *
+ *	This function is called when the caller is about to add or remove
+ *	sysfs_dirent.  This function acquires sysfs_mutex.  @acxt is used
+ *	to keep and pass context to other addrm functions.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).  sysfs_mutex is locked on
+ *	return.
+ */
+void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt)
+	__acquires(sysfs_mutex)
+{
+	memset(acxt, 0, sizeof(*acxt));
+
+	mutex_lock(&sysfs_mutex);
+}
+
+/**
+ *	sysfs_add_one - add sysfs_dirent to parent without warning
+ *	@acxt: addrm context to use
+ *	@sd: sysfs_dirent to be added
+ *	@parent_sd: the parent sysfs_dirent to add @sd to
+ *
+ *	Get @parent_sd and set @sd->s_parent to it and increment nlink of
+ *	the parent inode if @sd is a directory and link into the children
+ *	list of the parent.
+ *
+ *	This function should be called between calls to
+ *	sysfs_addrm_start() and sysfs_addrm_finish() and should be
+ *	passed the same @acxt as passed to sysfs_addrm_start().
+ *
+ *	LOCKING:
+ *	Determined by sysfs_addrm_start().
+ *
+ *	RETURNS:
+ *	0 on success, -EEXIST if entry with the given name already
+ *	exists.
+ */
+int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
+		  struct sysfs_dirent *parent_sd)
+{
+	bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS;
+	struct sysfs_inode_attrs *ps_iattr;
+	int ret;
+
+	if (has_ns != (bool)sd->s_ns) {
+		WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
+		     has_ns ? "required" : "invalid",
+		     parent_sd->s_name, sd->s_name);
+		return -EINVAL;
+	}
+
+	if (sysfs_type(parent_sd) != SYSFS_DIR)
+		return -EINVAL;
+
+	sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
+	sd->s_parent = parent_sd;
+	kernfs_get(parent_sd);
+
+	ret = sysfs_link_sibling(sd);
+	if (ret)
+		return ret;
+
+	/* Update timestamps on the parent */
+	ps_iattr = parent_sd->s_iattr;
+	if (ps_iattr) {
+		struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
+		ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
+	}
+
+	/* Mark the entry added into directory tree */
+	sd->s_flags &= ~SYSFS_FLAG_REMOVED;
+
+	return 0;
+}
+
+/**
+ *	sysfs_remove_one - remove sysfs_dirent from parent
+ *	@acxt: addrm context to use
+ *	@sd: sysfs_dirent to be removed
+ *
+ *	Mark @sd removed and drop nlink of parent inode if @sd is a
+ *	directory.  @sd is unlinked from the children list.
+ *
+ *	This function should be called between calls to
+ *	sysfs_addrm_start() and sysfs_addrm_finish() and should be
+ *	passed the same @acxt as passed to sysfs_addrm_start().
+ *
+ *	LOCKING:
+ *	Determined by sysfs_addrm_start().
+ */
+static void sysfs_remove_one(struct sysfs_addrm_cxt *acxt,
+			     struct sysfs_dirent *sd)
+{
+	struct sysfs_inode_attrs *ps_iattr;
+
+	/*
+	 * Removal can be called multiple times on the same node.  Only the
+	 * first invocation is effective and puts the base ref.
+	 */
+	if (sd->s_flags & SYSFS_FLAG_REMOVED)
+		return;
+
+	sysfs_unlink_sibling(sd);
+
+	/* Update timestamps on the parent */
+	ps_iattr = sd->s_parent->s_iattr;
+	if (ps_iattr) {
+		struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
+		ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
+	}
+
+	sd->s_flags |= SYSFS_FLAG_REMOVED;
+	sd->u.removed_list = acxt->removed;
+	acxt->removed = sd;
+}
+
+/**
+ *	sysfs_addrm_finish - finish up sysfs_dirent add/remove
+ *	@acxt: addrm context to finish up
+ *
+ *	Finish up sysfs_dirent add/remove.  Resources acquired by
+ *	sysfs_addrm_start() are released and removed sysfs_dirents are
+ *	cleaned up.
+ *
+ *	LOCKING:
+ *	sysfs_mutex is released.
+ */
+void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
+	__releases(sysfs_mutex)
+{
+	/* release resources acquired by sysfs_addrm_start() */
+	mutex_unlock(&sysfs_mutex);
+
+	/* kill removed sysfs_dirents */
+	while (acxt->removed) {
+		struct sysfs_dirent *sd = acxt->removed;
+
+		acxt->removed = sd->u.removed_list;
+
+		sysfs_deactivate(sd);
+		sysfs_unmap_bin_file(sd);
+		kernfs_put(sd);
+	}
+}
+
+/**
+ * kernfs_find_ns - find sysfs_dirent with the given name
+ * @parent: sysfs_dirent to search under
+ * @name: name to look for
+ * @ns: the namespace tag to use
+ *
+ * Look for sysfs_dirent with name @name under @parent.  Returns pointer to
+ * the found sysfs_dirent on success, %NULL on failure.
+ */
+static struct sysfs_dirent *kernfs_find_ns(struct sysfs_dirent *parent,
+					   const unsigned char *name,
+					   const void *ns)
+{
+	struct rb_node *node = parent->s_dir.children.rb_node;
+	bool has_ns = parent->s_flags & SYSFS_FLAG_NS;
+	unsigned int hash;
+
+	lockdep_assert_held(&sysfs_mutex);
+
+	if (has_ns != (bool)ns) {
+		WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
+		     has_ns ? "required" : "invalid",
+		     parent->s_name, name);
+		return NULL;
+	}
+
+	hash = sysfs_name_hash(name, ns);
+	while (node) {
+		struct sysfs_dirent *sd;
+		int result;
+
+		sd = to_sysfs_dirent(node);
+		result = sysfs_name_compare(hash, name, ns, sd);
+		if (result < 0)
+			node = node->rb_left;
+		else if (result > 0)
+			node = node->rb_right;
+		else
+			return sd;
+	}
+	return NULL;
+}
+
+/**
+ * kernfs_find_and_get_ns - find and get sysfs_dirent with the given name
+ * @parent: sysfs_dirent to search under
+ * @name: name to look for
+ * @ns: the namespace tag to use
+ *
+ * Look for sysfs_dirent with name @name under @parent and get a reference
+ * if found.  This function may sleep and returns pointer to the found
+ * sysfs_dirent on success, %NULL on failure.
+ */
+struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
+					    const char *name, const void *ns)
+{
+	struct sysfs_dirent *sd;
+
+	mutex_lock(&sysfs_mutex);
+	sd = kernfs_find_ns(parent, name, ns);
+	kernfs_get(sd);
+	mutex_unlock(&sysfs_mutex);
+
+	return sd;
+}
+EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns);
+
+/**
+ * kernfs_create_dir_ns - create a directory
+ * @parent: parent in which to create a new directory
+ * @name: name of the new directory
+ * @priv: opaque data associated with the new directory
+ * @ns: optional namespace tag of the directory
+ *
+ * Returns the created node on success, ERR_PTR() value on failure.
+ */
+struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
+					  const char *name, void *priv,
+					  const void *ns)
+{
+	umode_t mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
+	struct sysfs_addrm_cxt acxt;
+	struct sysfs_dirent *sd;
+	int rc;
+
+	/* allocate */
+	sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
+	if (!sd)
+		return ERR_PTR(-ENOMEM);
+
+	sd->s_ns = ns;
+	sd->priv = priv;
+
+	/* link in */
+	sysfs_addrm_start(&acxt);
+	rc = sysfs_add_one(&acxt, sd, parent);
+	sysfs_addrm_finish(&acxt);
+
+	if (!rc)
+		return sd;
+
+	kernfs_put(sd);
+	return ERR_PTR(rc);
+}
+
+static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry,
+				   unsigned int flags)
+{
+	struct dentry *ret = NULL;
+	struct dentry *parent = dentry->d_parent;
+	struct sysfs_dirent *parent_sd = parent->d_fsdata;
+	struct sysfs_dirent *sd;
+	struct inode *inode;
+	const void *ns = NULL;
+
+	mutex_lock(&sysfs_mutex);
+
+	if (parent_sd->s_flags & SYSFS_FLAG_NS)
+		ns = sysfs_info(dir->i_sb)->ns;
+
+	sd = kernfs_find_ns(parent_sd, dentry->d_name.name, ns);
+
+	/* no such entry */
+	if (!sd) {
+		ret = ERR_PTR(-ENOENT);
+		goto out_unlock;
+	}
+	kernfs_get(sd);
+	dentry->d_fsdata = sd;
+
+	/* attach dentry and inode */
+	inode = sysfs_get_inode(dir->i_sb, sd);
+	if (!inode) {
+		ret = ERR_PTR(-ENOMEM);
+		goto out_unlock;
+	}
+
+	/* instantiate and hash dentry */
+	ret = d_materialise_unique(dentry, inode);
+ out_unlock:
+	mutex_unlock(&sysfs_mutex);
+	return ret;
+}
+
+const struct inode_operations sysfs_dir_inode_operations = {
+	.lookup		= sysfs_lookup,
+	.permission	= sysfs_permission,
+	.setattr	= sysfs_setattr,
+	.getattr	= sysfs_getattr,
+	.setxattr	= sysfs_setxattr,
+};
+
+static struct sysfs_dirent *sysfs_leftmost_descendant(struct sysfs_dirent *pos)
+{
+	struct sysfs_dirent *last;
+
+	while (true) {
+		struct rb_node *rbn;
+
+		last = pos;
+
+		if (sysfs_type(pos) != SYSFS_DIR)
+			break;
+
+		rbn = rb_first(&pos->s_dir.children);
+		if (!rbn)
+			break;
+
+		pos = to_sysfs_dirent(rbn);
+	}
+
+	return last;
+}
+
+/**
+ * sysfs_next_descendant_post - find the next descendant for post-order walk
+ * @pos: the current position (%NULL to initiate traversal)
+ * @root: sysfs_dirent whose descendants to walk
+ *
+ * Find the next descendant to visit for post-order traversal of @root's
+ * descendants.  @root is included in the iteration and the last node to be
+ * visited.
+ */
+static struct sysfs_dirent *sysfs_next_descendant_post(struct sysfs_dirent *pos,
+						       struct sysfs_dirent *root)
+{
+	struct rb_node *rbn;
+
+	lockdep_assert_held(&sysfs_mutex);
+
+	/* if first iteration, visit leftmost descendant which may be root */
+	if (!pos)
+		return sysfs_leftmost_descendant(root);
+
+	/* if we visited @root, we're done */
+	if (pos == root)
+		return NULL;
+
+	/* if there's an unvisited sibling, visit its leftmost descendant */
+	rbn = rb_next(&pos->s_rb);
+	if (rbn)
+		return sysfs_leftmost_descendant(to_sysfs_dirent(rbn));
+
+	/* no sibling left, visit parent */
+	return pos->s_parent;
+}
+
+static void __kernfs_remove(struct sysfs_addrm_cxt *acxt,
+			    struct sysfs_dirent *sd)
+{
+	struct sysfs_dirent *pos, *next;
+
+	if (!sd)
+		return;
+
+	pr_debug("sysfs %s: removing\n", sd->s_name);
+
+	next = NULL;
+	do {
+		pos = next;
+		next = sysfs_next_descendant_post(pos, sd);
+		if (pos)
+			sysfs_remove_one(acxt, pos);
+	} while (next);
+}
+
+/**
+ * kernfs_remove - remove a sysfs_dirent recursively
+ * @sd: the sysfs_dirent to remove
+ *
+ * Remove @sd along with all its subdirectories and files.
+ */
+void kernfs_remove(struct sysfs_dirent *sd)
+{
+	struct sysfs_addrm_cxt acxt;
+
+	sysfs_addrm_start(&acxt);
+	__kernfs_remove(&acxt, sd);
+	sysfs_addrm_finish(&acxt);
+}
+
+/**
+ * kernfs_remove_by_name_ns - find a sysfs_dirent by name and remove it
+ * @dir_sd: parent of the target
+ * @name: name of the sysfs_dirent to remove
+ * @ns: namespace tag of the sysfs_dirent to remove
+ *
+ * Look for the sysfs_dirent with @name and @ns under @dir_sd and remove
+ * it.  Returns 0 on success, -ENOENT if such entry doesn't exist.
+ */
+int kernfs_remove_by_name_ns(struct sysfs_dirent *dir_sd, const char *name,
+			     const void *ns)
+{
+	struct sysfs_addrm_cxt acxt;
+	struct sysfs_dirent *sd;
+
+	if (!dir_sd) {
+		WARN(1, KERN_WARNING "sysfs: can not remove '%s', no directory\n",
+			name);
+		return -ENOENT;
+	}
+
+	sysfs_addrm_start(&acxt);
+
+	sd = kernfs_find_ns(dir_sd, name, ns);
+	if (sd)
+		__kernfs_remove(&acxt, sd);
+
+	sysfs_addrm_finish(&acxt);
+
+	if (sd)
+		return 0;
+	else
+		return -ENOENT;
+}
+
+/**
+ * kernfs_rename_ns - move and rename a kernfs_node
+ * @sd: target node
+ * @new_parent: new parent to put @sd under
+ * @new_name: new name
+ * @new_ns: new namespace tag
+ */
+int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
+		     const char *new_name, const void *new_ns)
+{
+	int error;
+
+	mutex_lock(&sysfs_mutex);
+
+	error = 0;
+	if ((sd->s_parent == new_parent) && (sd->s_ns == new_ns) &&
+	    (strcmp(sd->s_name, new_name) == 0))
+		goto out;	/* nothing to rename */
+
+	error = -EEXIST;
+	if (kernfs_find_ns(new_parent, new_name, new_ns))
+		goto out;
+
+	/* rename sysfs_dirent */
+	if (strcmp(sd->s_name, new_name) != 0) {
+		error = -ENOMEM;
+		new_name = kstrdup(new_name, GFP_KERNEL);
+		if (!new_name)
+			goto out;
+
+		kfree(sd->s_name);
+		sd->s_name = new_name;
+	}
+
+	/*
+	 * Move to the appropriate place in the appropriate directories rbtree.
+	 */
+	sysfs_unlink_sibling(sd);
+	kernfs_get(new_parent);
+	kernfs_put(sd->s_parent);
+	sd->s_ns = new_ns;
+	sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
+	sd->s_parent = new_parent;
+	sysfs_link_sibling(sd);
+
+	error = 0;
+ out:
+	mutex_unlock(&sysfs_mutex);
+	return error;
+}
+
+/**
+ * kernfs_enable_ns - enable namespace under a directory
+ * @sd: directory of interest, should be empty
+ *
+ * This is to be called right after @sd is created to enable namespace
+ * under it.  All children of @sd must have non-NULL namespace tags and
+ * only the ones which match the super_block's tag will be visible.
+ */
+void kernfs_enable_ns(struct sysfs_dirent *sd)
+{
+	WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
+	WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));
+	sd->s_flags |= SYSFS_FLAG_NS;
+}
+
+/* Relationship between s_mode and the DT_xxx types */
+static inline unsigned char dt_type(struct sysfs_dirent *sd)
+{
+	return (sd->s_mode >> 12) & 15;
+}
+
+static int sysfs_dir_release(struct inode *inode, struct file *filp)
+{
+	kernfs_put(filp->private_data);
+	return 0;
+}
+
+static struct sysfs_dirent *sysfs_dir_pos(const void *ns,
+	struct sysfs_dirent *parent_sd,	loff_t hash, struct sysfs_dirent *pos)
+{
+	if (pos) {
+		int valid = !(pos->s_flags & SYSFS_FLAG_REMOVED) &&
+			pos->s_parent == parent_sd &&
+			hash == pos->s_hash;
+		kernfs_put(pos);
+		if (!valid)
+			pos = NULL;
+	}
+	if (!pos && (hash > 1) && (hash < INT_MAX)) {
+		struct rb_node *node = parent_sd->s_dir.children.rb_node;
+		while (node) {
+			pos = to_sysfs_dirent(node);
+
+			if (hash < pos->s_hash)
+				node = node->rb_left;
+			else if (hash > pos->s_hash)
+				node = node->rb_right;
+			else
+				break;
+		}
+	}
+	/* Skip over entries in the wrong namespace */
+	while (pos && pos->s_ns != ns) {
+		struct rb_node *node = rb_next(&pos->s_rb);
+		if (!node)
+			pos = NULL;
+		else
+			pos = to_sysfs_dirent(node);
+	}
+	return pos;
+}
+
+static struct sysfs_dirent *sysfs_dir_next_pos(const void *ns,
+	struct sysfs_dirent *parent_sd,	ino_t ino, struct sysfs_dirent *pos)
+{
+	pos = sysfs_dir_pos(ns, parent_sd, ino, pos);
+	if (pos)
+		do {
+			struct rb_node *node = rb_next(&pos->s_rb);
+			if (!node)
+				pos = NULL;
+			else
+				pos = to_sysfs_dirent(node);
+		} while (pos && pos->s_ns != ns);
+	return pos;
+}
+
+static int sysfs_readdir(struct file *file, struct dir_context *ctx)
+{
+	struct dentry *dentry = file->f_path.dentry;
+	struct sysfs_dirent *parent_sd = dentry->d_fsdata;
+	struct sysfs_dirent *pos = file->private_data;
+	const void *ns = NULL;
+
+	if (!dir_emit_dots(file, ctx))
+		return 0;
+	mutex_lock(&sysfs_mutex);
+
+	if (parent_sd->s_flags & SYSFS_FLAG_NS)
+		ns = sysfs_info(dentry->d_sb)->ns;
+
+	for (pos = sysfs_dir_pos(ns, parent_sd, ctx->pos, pos);
+	     pos;
+	     pos = sysfs_dir_next_pos(ns, parent_sd, ctx->pos, pos)) {
+		const char *name = pos->s_name;
+		unsigned int type = dt_type(pos);
+		int len = strlen(name);
+		ino_t ino = pos->s_ino;
+
+		ctx->pos = pos->s_hash;
+		file->private_data = pos;
+		kernfs_get(pos);
+
+		mutex_unlock(&sysfs_mutex);
+		if (!dir_emit(ctx, name, len, ino, type))
+			return 0;
+		mutex_lock(&sysfs_mutex);
+	}
+	mutex_unlock(&sysfs_mutex);
+	file->private_data = NULL;
+	ctx->pos = INT_MAX;
+	return 0;
+}
+
+static loff_t sysfs_dir_llseek(struct file *file, loff_t offset, int whence)
+{
+	struct inode *inode = file_inode(file);
+	loff_t ret;
+
+	mutex_lock(&inode->i_mutex);
+	ret = generic_file_llseek(file, offset, whence);
+	mutex_unlock(&inode->i_mutex);
+
+	return ret;
+}
+
+const struct file_operations sysfs_dir_operations = {
+	.read		= generic_read_dir,
+	.iterate	= sysfs_readdir,
+	.release	= sysfs_dir_release,
+	.llseek		= sysfs_dir_llseek,
+};
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 933ac8d..31f0dbe 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -14,6 +14,7 @@
 #include <linux/lockdep.h>
 #include <linux/fs.h>
 #include <linux/rbtree.h>
+#include <linux/mutex.h>
 
 #include <linux/kernfs.h>
 
@@ -125,4 +126,20 @@ int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
 		   size_t size, int flags);
 int sysfs_inode_init(void);
 
+/*
+ * dir.c
+ */
+extern struct mutex sysfs_mutex;
+extern const struct dentry_operations sysfs_dentry_ops;
+extern const struct file_operations sysfs_dir_operations;
+extern const struct inode_operations sysfs_dir_inode_operations;
+
+struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd);
+void sysfs_put_active(struct sysfs_dirent *sd);
+void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt);
+int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
+		  struct sysfs_dirent *parent_sd);
+void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
+struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);
+
 #endif	/* __KERNFS_INTERNAL_H */
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 0d806ef..e5c4e71 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -13,468 +13,12 @@
 #undef DEBUG
 
 #include <linux/fs.h>
-#include <linux/mount.h>
-#include <linux/module.h>
 #include <linux/kobject.h>
-#include <linux/namei.h>
-#include <linux/idr.h>
-#include <linux/completion.h>
-#include <linux/mutex.h>
 #include <linux/slab.h>
-#include <linux/security.h>
-#include <linux/hash.h>
 #include "sysfs.h"
 
-DEFINE_MUTEX(sysfs_mutex);
 DEFINE_SPINLOCK(sysfs_symlink_target_lock);
 
-#define to_sysfs_dirent(X) rb_entry((X), struct sysfs_dirent, s_rb)
-
-static DEFINE_SPINLOCK(sysfs_ino_lock);
-static DEFINE_IDA(sysfs_ino_ida);
-
-/**
- *	sysfs_name_hash
- *	@name: Null terminated string to hash
- *	@ns:   Namespace tag to hash
- *
- *	Returns 31 bit hash of ns + name (so it fits in an off_t )
- */
-static unsigned int sysfs_name_hash(const char *name, const void *ns)
-{
-	unsigned long hash = init_name_hash();
-	unsigned int len = strlen(name);
-	while (len--)
-		hash = partial_name_hash(*name++, hash);
-	hash = (end_name_hash(hash) ^ hash_ptr((void *)ns, 31));
-	hash &= 0x7fffffffU;
-	/* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */
-	if (hash < 1)
-		hash += 2;
-	if (hash >= INT_MAX)
-		hash = INT_MAX - 1;
-	return hash;
-}
-
-static int sysfs_name_compare(unsigned int hash, const char *name,
-			      const void *ns, const struct sysfs_dirent *sd)
-{
-	if (hash != sd->s_hash)
-		return hash - sd->s_hash;
-	if (ns != sd->s_ns)
-		return ns - sd->s_ns;
-	return strcmp(name, sd->s_name);
-}
-
-static int sysfs_sd_compare(const struct sysfs_dirent *left,
-			    const struct sysfs_dirent *right)
-{
-	return sysfs_name_compare(left->s_hash, left->s_name, left->s_ns,
-				  right);
-}
-
-/**
- *	sysfs_link_sibling - link sysfs_dirent into sibling rbtree
- *	@sd: sysfs_dirent of interest
- *
- *	Link @sd into its sibling rbtree which starts from
- *	sd->s_parent->s_dir.children.
- *
- *	Locking:
- *	mutex_lock(sysfs_mutex)
- *
- *	RETURNS:
- *	0 on susccess -EEXIST on failure.
- */
-static int sysfs_link_sibling(struct sysfs_dirent *sd)
-{
-	struct rb_node **node = &sd->s_parent->s_dir.children.rb_node;
-	struct rb_node *parent = NULL;
-
-	if (sysfs_type(sd) == SYSFS_DIR)
-		sd->s_parent->s_dir.subdirs++;
-
-	while (*node) {
-		struct sysfs_dirent *pos;
-		int result;
-
-		pos = to_sysfs_dirent(*node);
-		parent = *node;
-		result = sysfs_sd_compare(sd, pos);
-		if (result < 0)
-			node = &pos->s_rb.rb_left;
-		else if (result > 0)
-			node = &pos->s_rb.rb_right;
-		else
-			return -EEXIST;
-	}
-	/* add new node and rebalance the tree */
-	rb_link_node(&sd->s_rb, parent, node);
-	rb_insert_color(&sd->s_rb, &sd->s_parent->s_dir.children);
-	return 0;
-}
-
-/**
- *	sysfs_unlink_sibling - unlink sysfs_dirent from sibling rbtree
- *	@sd: sysfs_dirent of interest
- *
- *	Unlink @sd from its sibling rbtree which starts from
- *	sd->s_parent->s_dir.children.
- *
- *	Locking:
- *	mutex_lock(sysfs_mutex)
- */
-static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
-{
-	if (sysfs_type(sd) == SYSFS_DIR)
-		sd->s_parent->s_dir.subdirs--;
-
-	rb_erase(&sd->s_rb, &sd->s_parent->s_dir.children);
-}
-
-/**
- *	sysfs_get_active - get an active reference to sysfs_dirent
- *	@sd: sysfs_dirent to get an active reference to
- *
- *	Get an active reference of @sd.  This function is noop if @sd
- *	is NULL.
- *
- *	RETURNS:
- *	Pointer to @sd on success, NULL on failure.
- */
-struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
-{
-	if (unlikely(!sd))
-		return NULL;
-
-	if (!atomic_inc_unless_negative(&sd->s_active))
-		return NULL;
-
-	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
-		rwsem_acquire_read(&sd->dep_map, 0, 1, _RET_IP_);
-	return sd;
-}
-
-/**
- *	sysfs_put_active - put an active reference to sysfs_dirent
- *	@sd: sysfs_dirent to put an active reference to
- *
- *	Put an active reference to @sd.  This function is noop if @sd
- *	is NULL.
- */
-void sysfs_put_active(struct sysfs_dirent *sd)
-{
-	int v;
-
-	if (unlikely(!sd))
-		return;
-
-	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
-		rwsem_release(&sd->dep_map, 1, _RET_IP_);
-	v = atomic_dec_return(&sd->s_active);
-	if (likely(v != SD_DEACTIVATED_BIAS))
-		return;
-
-	/* atomic_dec_return() is a mb(), we'll always see the updated
-	 * sd->u.completion.
-	 */
-	complete(sd->u.completion);
-}
-
-/**
- *	sysfs_deactivate - deactivate sysfs_dirent
- *	@sd: sysfs_dirent to deactivate
- *
- *	Deny new active references and drain existing ones.
- */
-static void sysfs_deactivate(struct sysfs_dirent *sd)
-{
-	DECLARE_COMPLETION_ONSTACK(wait);
-	int v;
-
-	BUG_ON(!(sd->s_flags & SYSFS_FLAG_REMOVED));
-
-	if (!(sysfs_type(sd) & SYSFS_ACTIVE_REF))
-		return;
-
-	sd->u.completion = (void *)&wait;
-
-	rwsem_acquire(&sd->dep_map, 0, 0, _RET_IP_);
-	/* atomic_add_return() is a mb(), put_active() will always see
-	 * the updated sd->u.completion.
-	 */
-	v = atomic_add_return(SD_DEACTIVATED_BIAS, &sd->s_active);
-
-	if (v != SD_DEACTIVATED_BIAS) {
-		lock_contended(&sd->dep_map, _RET_IP_);
-		wait_for_completion(&wait);
-	}
-
-	lock_acquired(&sd->dep_map, _RET_IP_);
-	rwsem_release(&sd->dep_map, 1, _RET_IP_);
-}
-
-static int sysfs_alloc_ino(unsigned int *pino)
-{
-	int ino, rc;
-
- retry:
-	spin_lock(&sysfs_ino_lock);
-	rc = ida_get_new_above(&sysfs_ino_ida, 2, &ino);
-	spin_unlock(&sysfs_ino_lock);
-
-	if (rc == -EAGAIN) {
-		if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL))
-			goto retry;
-		rc = -ENOMEM;
-	}
-
-	*pino = ino;
-	return rc;
-}
-
-static void sysfs_free_ino(unsigned int ino)
-{
-	spin_lock(&sysfs_ino_lock);
-	ida_remove(&sysfs_ino_ida, ino);
-	spin_unlock(&sysfs_ino_lock);
-}
-
-/**
- * kernfs_get - get a reference count on a sysfs_dirent
- * @sd: the target sysfs_dirent
- */
-void kernfs_get(struct sysfs_dirent *sd)
-{
-	if (sd) {
-		WARN_ON(!atomic_read(&sd->s_count));
-		atomic_inc(&sd->s_count);
-	}
-}
-EXPORT_SYMBOL_GPL(kernfs_get);
-
-/**
- * kernfs_put - put a reference count on a sysfs_dirent
- * @sd: the target sysfs_dirent
- *
- * Put a reference count of @sd and destroy it if it reached zero.
- */
-void kernfs_put(struct sysfs_dirent *sd)
-{
-	struct sysfs_dirent *parent_sd;
-
-	if (!sd || !atomic_dec_and_test(&sd->s_count))
-		return;
- repeat:
-	/* Moving/renaming is always done while holding reference.
-	 * sd->s_parent won't change beneath us.
-	 */
-	parent_sd = sd->s_parent;
-
-	WARN(!(sd->s_flags & SYSFS_FLAG_REMOVED),
-		"sysfs: free using entry: %s/%s\n",
-		parent_sd ? parent_sd->s_name : "", sd->s_name);
-
-	if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
-		kernfs_put(sd->s_symlink.target_sd);
-	if (sysfs_type(sd) & SYSFS_COPY_NAME)
-		kfree(sd->s_name);
-	if (sd->s_iattr && sd->s_iattr->ia_secdata)
-		security_release_secctx(sd->s_iattr->ia_secdata,
-					sd->s_iattr->ia_secdata_len);
-	kfree(sd->s_iattr);
-	sysfs_free_ino(sd->s_ino);
-	kmem_cache_free(sysfs_dir_cachep, sd);
-
-	sd = parent_sd;
-	if (sd && atomic_dec_and_test(&sd->s_count))
-		goto repeat;
-}
-EXPORT_SYMBOL_GPL(kernfs_put);
-
-static int sysfs_dentry_delete(const struct dentry *dentry)
-{
-	struct sysfs_dirent *sd = dentry->d_fsdata;
-	return !(sd && !(sd->s_flags & SYSFS_FLAG_REMOVED));
-}
-
-static int sysfs_dentry_revalidate(struct dentry *dentry, unsigned int flags)
-{
-	struct sysfs_dirent *sd;
-
-	if (flags & LOOKUP_RCU)
-		return -ECHILD;
-
-	sd = dentry->d_fsdata;
-	mutex_lock(&sysfs_mutex);
-
-	/* The sysfs dirent has been deleted */
-	if (sd->s_flags & SYSFS_FLAG_REMOVED)
-		goto out_bad;
-
-	/* The sysfs dirent has been moved? */
-	if (dentry->d_parent->d_fsdata != sd->s_parent)
-		goto out_bad;
-
-	/* The sysfs dirent has been renamed */
-	if (strcmp(dentry->d_name.name, sd->s_name) != 0)
-		goto out_bad;
-
-	/* The sysfs dirent has been moved to a different namespace */
-	if (sd->s_parent && (sd->s_parent->s_flags & SYSFS_FLAG_NS) &&
-	    sysfs_info(dentry->d_sb)->ns != sd->s_ns)
-		goto out_bad;
-
-	mutex_unlock(&sysfs_mutex);
-out_valid:
-	return 1;
-out_bad:
-	/* Remove the dentry from the dcache hashes.
-	 * If this is a deleted dentry we use d_drop instead of d_delete
-	 * so sysfs doesn't need to cope with negative dentries.
-	 *
-	 * If this is a dentry that has simply been renamed we
-	 * use d_drop to remove it from the dcache lookup on its
-	 * old parent.  If this dentry persists later when a lookup
-	 * is performed at its new name the dentry will be readded
-	 * to the dcache hashes.
-	 */
-	mutex_unlock(&sysfs_mutex);
-
-	/* If we have submounts we must allow the vfs caches
-	 * to lie about the state of the filesystem to prevent
-	 * leaks and other nasty things.
-	 */
-	if (check_submounts_and_drop(dentry) != 0)
-		goto out_valid;
-
-	return 0;
-}
-
-static void sysfs_dentry_release(struct dentry *dentry)
-{
-	kernfs_put(dentry->d_fsdata);
-}
-
-const struct dentry_operations sysfs_dentry_ops = {
-	.d_revalidate	= sysfs_dentry_revalidate,
-	.d_delete	= sysfs_dentry_delete,
-	.d_release	= sysfs_dentry_release,
-};
-
-struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
-{
-	char *dup_name = NULL;
-	struct sysfs_dirent *sd;
-
-	if (type & SYSFS_COPY_NAME) {
-		name = dup_name = kstrdup(name, GFP_KERNEL);
-		if (!name)
-			return NULL;
-	}
-
-	sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL);
-	if (!sd)
-		goto err_out1;
-
-	if (sysfs_alloc_ino(&sd->s_ino))
-		goto err_out2;
-
-	atomic_set(&sd->s_count, 1);
-	atomic_set(&sd->s_active, 0);
-
-	sd->s_name = name;
-	sd->s_mode = mode;
-	sd->s_flags = type | SYSFS_FLAG_REMOVED;
-
-	return sd;
-
- err_out2:
-	kmem_cache_free(sysfs_dir_cachep, sd);
- err_out1:
-	kfree(dup_name);
-	return NULL;
-}
-
-/**
- *	sysfs_addrm_start - prepare for sysfs_dirent add/remove
- *	@acxt: pointer to sysfs_addrm_cxt to be used
- *
- *	This function is called when the caller is about to add or remove
- *	sysfs_dirent.  This function acquires sysfs_mutex.  @acxt is used
- *	to keep and pass context to other addrm functions.
- *
- *	LOCKING:
- *	Kernel thread context (may sleep).  sysfs_mutex is locked on
- *	return.
- */
-void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt)
-	__acquires(sysfs_mutex)
-{
-	memset(acxt, 0, sizeof(*acxt));
-
-	mutex_lock(&sysfs_mutex);
-}
-
-/**
- *	sysfs_add_one - add sysfs_dirent to parent without warning
- *	@acxt: addrm context to use
- *	@sd: sysfs_dirent to be added
- *	@parent_sd: the parent sysfs_dirent to add @sd to
- *
- *	Get @parent_sd and set @sd->s_parent to it and increment nlink of
- *	the parent inode if @sd is a directory and link into the children
- *	list of the parent.
- *
- *	This function should be called between calls to
- *	sysfs_addrm_start() and sysfs_addrm_finish() and should be
- *	passed the same @acxt as passed to sysfs_addrm_start().
- *
- *	LOCKING:
- *	Determined by sysfs_addrm_start().
- *
- *	RETURNS:
- *	0 on success, -EEXIST if entry with the given name already
- *	exists.
- */
-int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
-		  struct sysfs_dirent *parent_sd)
-{
-	bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS;
-	struct sysfs_inode_attrs *ps_iattr;
-	int ret;
-
-	if (has_ns != (bool)sd->s_ns) {
-		WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
-		     has_ns ? "required" : "invalid",
-		     parent_sd->s_name, sd->s_name);
-		return -EINVAL;
-	}
-
-	if (sysfs_type(parent_sd) != SYSFS_DIR)
-		return -EINVAL;
-
-	sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
-	sd->s_parent = parent_sd;
-	kernfs_get(parent_sd);
-
-	ret = sysfs_link_sibling(sd);
-	if (ret)
-		return ret;
-
-	/* Update timestamps on the parent */
-	ps_iattr = parent_sd->s_iattr;
-	if (ps_iattr) {
-		struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
-		ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
-	}
-
-	/* Mark the entry added into directory tree */
-	sd->s_flags &= ~SYSFS_FLAG_REMOVED;
-
-	return 0;
-}
-
 /**
  *	sysfs_pathname - return full path to sysfs dirent
  *	@sd: sysfs_dirent whose path we want
@@ -511,181 +55,6 @@ void sysfs_warn_dup(struct sysfs_dirent *parent, const char *name)
 }
 
 /**
- *	sysfs_remove_one - remove sysfs_dirent from parent
- *	@acxt: addrm context to use
- *	@sd: sysfs_dirent to be removed
- *
- *	Mark @sd removed and drop nlink of parent inode if @sd is a
- *	directory.  @sd is unlinked from the children list.
- *
- *	This function should be called between calls to
- *	sysfs_addrm_start() and sysfs_addrm_finish() and should be
- *	passed the same @acxt as passed to sysfs_addrm_start().
- *
- *	LOCKING:
- *	Determined by sysfs_addrm_start().
- */
-static void sysfs_remove_one(struct sysfs_addrm_cxt *acxt,
-			     struct sysfs_dirent *sd)
-{
-	struct sysfs_inode_attrs *ps_iattr;
-
-	/*
-	 * Removal can be called multiple times on the same node.  Only the
-	 * first invocation is effective and puts the base ref.
-	 */
-	if (sd->s_flags & SYSFS_FLAG_REMOVED)
-		return;
-
-	sysfs_unlink_sibling(sd);
-
-	/* Update timestamps on the parent */
-	ps_iattr = sd->s_parent->s_iattr;
-	if (ps_iattr) {
-		struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
-		ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
-	}
-
-	sd->s_flags |= SYSFS_FLAG_REMOVED;
-	sd->u.removed_list = acxt->removed;
-	acxt->removed = sd;
-}
-
-/**
- *	sysfs_addrm_finish - finish up sysfs_dirent add/remove
- *	@acxt: addrm context to finish up
- *
- *	Finish up sysfs_dirent add/remove.  Resources acquired by
- *	sysfs_addrm_start() are released and removed sysfs_dirents are
- *	cleaned up.
- *
- *	LOCKING:
- *	sysfs_mutex is released.
- */
-void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
-	__releases(sysfs_mutex)
-{
-	/* release resources acquired by sysfs_addrm_start() */
-	mutex_unlock(&sysfs_mutex);
-
-	/* kill removed sysfs_dirents */
-	while (acxt->removed) {
-		struct sysfs_dirent *sd = acxt->removed;
-
-		acxt->removed = sd->u.removed_list;
-
-		sysfs_deactivate(sd);
-		sysfs_unmap_bin_file(sd);
-		kernfs_put(sd);
-	}
-}
-
-/**
- * kernfs_find_ns - find sysfs_dirent with the given name
- * @parent: sysfs_dirent to search under
- * @name: name to look for
- * @ns: the namespace tag to use
- *
- * Look for sysfs_dirent with name @name under @parent.  Returns pointer to
- * the found sysfs_dirent on success, %NULL on failure.
- */
-static struct sysfs_dirent *kernfs_find_ns(struct sysfs_dirent *parent,
-					   const unsigned char *name,
-					   const void *ns)
-{
-	struct rb_node *node = parent->s_dir.children.rb_node;
-	bool has_ns = parent->s_flags & SYSFS_FLAG_NS;
-	unsigned int hash;
-
-	lockdep_assert_held(&sysfs_mutex);
-
-	if (has_ns != (bool)ns) {
-		WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n",
-		     has_ns ? "required" : "invalid",
-		     parent->s_name, name);
-		return NULL;
-	}
-
-	hash = sysfs_name_hash(name, ns);
-	while (node) {
-		struct sysfs_dirent *sd;
-		int result;
-
-		sd = to_sysfs_dirent(node);
-		result = sysfs_name_compare(hash, name, ns, sd);
-		if (result < 0)
-			node = node->rb_left;
-		else if (result > 0)
-			node = node->rb_right;
-		else
-			return sd;
-	}
-	return NULL;
-}
-
-/**
- * kernfs_find_and_get_ns - find and get sysfs_dirent with the given name
- * @parent: sysfs_dirent to search under
- * @name: name to look for
- * @ns: the namespace tag to use
- *
- * Look for sysfs_dirent with name @name under @parent and get a reference
- * if found.  This function may sleep and returns pointer to the found
- * sysfs_dirent on success, %NULL on failure.
- */
-struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
-					    const char *name, const void *ns)
-{
-	struct sysfs_dirent *sd;
-
-	mutex_lock(&sysfs_mutex);
-	sd = kernfs_find_ns(parent, name, ns);
-	kernfs_get(sd);
-	mutex_unlock(&sysfs_mutex);
-
-	return sd;
-}
-EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns);
-
-/**
- * kernfs_create_dir_ns - create a directory
- * @parent: parent in which to create a new directory
- * @name: name of the new directory
- * @priv: opaque data associated with the new directory
- * @ns: optional namespace tag of the directory
- *
- * Returns the created node on success, ERR_PTR() value on failure.
- */
-struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
-					  const char *name, void *priv,
-					  const void *ns)
-{
-	umode_t mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
-	struct sysfs_addrm_cxt acxt;
-	struct sysfs_dirent *sd;
-	int rc;
-
-	/* allocate */
-	sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
-	if (!sd)
-		return ERR_PTR(-ENOMEM);
-
-	sd->s_ns = ns;
-	sd->priv = priv;
-
-	/* link in */
-	sysfs_addrm_start(&acxt);
-	rc = sysfs_add_one(&acxt, sd, parent);
-	sysfs_addrm_finish(&acxt);
-
-	if (!rc)
-		return sd;
-
-	kernfs_put(sd);
-	return ERR_PTR(rc);
-}
-
-/**
  * sysfs_create_dir_ns - create a directory for an object with a namespace tag
  * @kobj: object we're creating directory for
  * @ns: the namespace tag to use
@@ -715,177 +84,6 @@ int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
 	return 0;
 }
 
-static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry,
-				   unsigned int flags)
-{
-	struct dentry *ret = NULL;
-	struct dentry *parent = dentry->d_parent;
-	struct sysfs_dirent *parent_sd = parent->d_fsdata;
-	struct sysfs_dirent *sd;
-	struct inode *inode;
-	const void *ns = NULL;
-
-	mutex_lock(&sysfs_mutex);
-
-	if (parent_sd->s_flags & SYSFS_FLAG_NS)
-		ns = sysfs_info(dir->i_sb)->ns;
-
-	sd = kernfs_find_ns(parent_sd, dentry->d_name.name, ns);
-
-	/* no such entry */
-	if (!sd) {
-		ret = ERR_PTR(-ENOENT);
-		goto out_unlock;
-	}
-	kernfs_get(sd);
-	dentry->d_fsdata = sd;
-
-	/* attach dentry and inode */
-	inode = sysfs_get_inode(dir->i_sb, sd);
-	if (!inode) {
-		ret = ERR_PTR(-ENOMEM);
-		goto out_unlock;
-	}
-
-	/* instantiate and hash dentry */
-	ret = d_materialise_unique(dentry, inode);
- out_unlock:
-	mutex_unlock(&sysfs_mutex);
-	return ret;
-}
-
-const struct inode_operations sysfs_dir_inode_operations = {
-	.lookup		= sysfs_lookup,
-	.permission	= sysfs_permission,
-	.setattr	= sysfs_setattr,
-	.getattr	= sysfs_getattr,
-	.setxattr	= sysfs_setxattr,
-};
-
-static struct sysfs_dirent *sysfs_leftmost_descendant(struct sysfs_dirent *pos)
-{
-	struct sysfs_dirent *last;
-
-	while (true) {
-		struct rb_node *rbn;
-
-		last = pos;
-
-		if (sysfs_type(pos) != SYSFS_DIR)
-			break;
-
-		rbn = rb_first(&pos->s_dir.children);
-		if (!rbn)
-			break;
-
-		pos = to_sysfs_dirent(rbn);
-	}
-
-	return last;
-}
-
-/**
- * sysfs_next_descendant_post - find the next descendant for post-order walk
- * @pos: the current position (%NULL to initiate traversal)
- * @root: sysfs_dirent whose descendants to walk
- *
- * Find the next descendant to visit for post-order traversal of @root's
- * descendants.  @root is included in the iteration and the last node to be
- * visited.
- */
-static struct sysfs_dirent *sysfs_next_descendant_post(struct sysfs_dirent *pos,
-						       struct sysfs_dirent *root)
-{
-	struct rb_node *rbn;
-
-	lockdep_assert_held(&sysfs_mutex);
-
-	/* if first iteration, visit leftmost descendant which may be root */
-	if (!pos)
-		return sysfs_leftmost_descendant(root);
-
-	/* if we visited @root, we're done */
-	if (pos == root)
-		return NULL;
-
-	/* if there's an unvisited sibling, visit its leftmost descendant */
-	rbn = rb_next(&pos->s_rb);
-	if (rbn)
-		return sysfs_leftmost_descendant(to_sysfs_dirent(rbn));
-
-	/* no sibling left, visit parent */
-	return pos->s_parent;
-}
-
-static void __kernfs_remove(struct sysfs_addrm_cxt *acxt,
-			    struct sysfs_dirent *sd)
-{
-	struct sysfs_dirent *pos, *next;
-
-	if (!sd)
-		return;
-
-	pr_debug("sysfs %s: removing\n", sd->s_name);
-
-	next = NULL;
-	do {
-		pos = next;
-		next = sysfs_next_descendant_post(pos, sd);
-		if (pos)
-			sysfs_remove_one(acxt, pos);
-	} while (next);
-}
-
-/**
- * kernfs_remove - remove a sysfs_dirent recursively
- * @sd: the sysfs_dirent to remove
- *
- * Remove @sd along with all its subdirectories and files.
- */
-void kernfs_remove(struct sysfs_dirent *sd)
-{
-	struct sysfs_addrm_cxt acxt;
-
-	sysfs_addrm_start(&acxt);
-	__kernfs_remove(&acxt, sd);
-	sysfs_addrm_finish(&acxt);
-}
-
-/**
- * kernfs_remove_by_name_ns - find a sysfs_dirent by name and remove it
- * @dir_sd: parent of the target
- * @name: name of the sysfs_dirent to remove
- * @ns: namespace tag of the sysfs_dirent to remove
- *
- * Look for the sysfs_dirent with @name and @ns under @dir_sd and remove
- * it.  Returns 0 on success, -ENOENT if such entry doesn't exist.
- */
-int kernfs_remove_by_name_ns(struct sysfs_dirent *dir_sd, const char *name,
-			     const void *ns)
-{
-	struct sysfs_addrm_cxt acxt;
-	struct sysfs_dirent *sd;
-
-	if (!dir_sd) {
-		WARN(1, KERN_WARNING "sysfs: can not remove '%s', no directory\n",
-			name);
-		return -ENOENT;
-	}
-
-	sysfs_addrm_start(&acxt);
-
-	sd = kernfs_find_ns(dir_sd, name, ns);
-	if (sd)
-		__kernfs_remove(&acxt, sd);
-
-	sysfs_addrm_finish(&acxt);
-
-	if (sd)
-		return 0;
-	else
-		return -ENOENT;
-}
-
 /**
  *	sysfs_remove_dir - remove an object's directory.
  *	@kobj:	object.
@@ -920,57 +118,6 @@ void sysfs_remove_dir(struct kobject *kobj)
 	}
 }
 
-/**
- * kernfs_rename_ns - move and rename a kernfs_node
- * @sd: target node
- * @new_parent: new parent to put @sd under
- * @new_name: new name
- * @new_ns: new namespace tag
- */
-int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
-		     const char *new_name, const void *new_ns)
-{
-	int error;
-
-	mutex_lock(&sysfs_mutex);
-
-	error = 0;
-	if ((sd->s_parent == new_parent) && (sd->s_ns == new_ns) &&
-	    (strcmp(sd->s_name, new_name) == 0))
-		goto out;	/* nothing to rename */
-
-	error = -EEXIST;
-	if (kernfs_find_ns(new_parent, new_name, new_ns))
-		goto out;
-
-	/* rename sysfs_dirent */
-	if (strcmp(sd->s_name, new_name) != 0) {
-		error = -ENOMEM;
-		new_name = kstrdup(new_name, GFP_KERNEL);
-		if (!new_name)
-			goto out;
-
-		kfree(sd->s_name);
-		sd->s_name = new_name;
-	}
-
-	/*
-	 * Move to the appropriate place in the appropriate directories rbtree.
-	 */
-	sysfs_unlink_sibling(sd);
-	kernfs_get(new_parent);
-	kernfs_put(sd->s_parent);
-	sd->s_ns = new_ns;
-	sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns);
-	sd->s_parent = new_parent;
-	sysfs_link_sibling(sd);
-
-	error = 0;
- out:
-	mutex_unlock(&sysfs_mutex);
-	return error;
-}
-
 int sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name,
 			const void *new_ns)
 {
@@ -991,136 +138,3 @@ int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
 
 	return kernfs_rename_ns(sd, new_parent_sd, sd->s_name, new_ns);
 }
-
-/**
- * kernfs_enable_ns - enable namespace under a directory
- * @sd: directory of interest, should be empty
- *
- * This is to be called right after @sd is created to enable namespace
- * under it.  All children of @sd must have non-NULL namespace tags and
- * only the ones which match the super_block's tag will be visible.
- */
-void kernfs_enable_ns(struct sysfs_dirent *sd)
-{
-	WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
-	WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));
-	sd->s_flags |= SYSFS_FLAG_NS;
-}
-
-/* Relationship between s_mode and the DT_xxx types */
-static inline unsigned char dt_type(struct sysfs_dirent *sd)
-{
-	return (sd->s_mode >> 12) & 15;
-}
-
-static int sysfs_dir_release(struct inode *inode, struct file *filp)
-{
-	kernfs_put(filp->private_data);
-	return 0;
-}
-
-static struct sysfs_dirent *sysfs_dir_pos(const void *ns,
-	struct sysfs_dirent *parent_sd,	loff_t hash, struct sysfs_dirent *pos)
-{
-	if (pos) {
-		int valid = !(pos->s_flags & SYSFS_FLAG_REMOVED) &&
-			pos->s_parent == parent_sd &&
-			hash == pos->s_hash;
-		kernfs_put(pos);
-		if (!valid)
-			pos = NULL;
-	}
-	if (!pos && (hash > 1) && (hash < INT_MAX)) {
-		struct rb_node *node = parent_sd->s_dir.children.rb_node;
-		while (node) {
-			pos = to_sysfs_dirent(node);
-
-			if (hash < pos->s_hash)
-				node = node->rb_left;
-			else if (hash > pos->s_hash)
-				node = node->rb_right;
-			else
-				break;
-		}
-	}
-	/* Skip over entries in the wrong namespace */
-	while (pos && pos->s_ns != ns) {
-		struct rb_node *node = rb_next(&pos->s_rb);
-		if (!node)
-			pos = NULL;
-		else
-			pos = to_sysfs_dirent(node);
-	}
-	return pos;
-}
-
-static struct sysfs_dirent *sysfs_dir_next_pos(const void *ns,
-	struct sysfs_dirent *parent_sd,	ino_t ino, struct sysfs_dirent *pos)
-{
-	pos = sysfs_dir_pos(ns, parent_sd, ino, pos);
-	if (pos)
-		do {
-			struct rb_node *node = rb_next(&pos->s_rb);
-			if (!node)
-				pos = NULL;
-			else
-				pos = to_sysfs_dirent(node);
-		} while (pos && pos->s_ns != ns);
-	return pos;
-}
-
-static int sysfs_readdir(struct file *file, struct dir_context *ctx)
-{
-	struct dentry *dentry = file->f_path.dentry;
-	struct sysfs_dirent *parent_sd = dentry->d_fsdata;
-	struct sysfs_dirent *pos = file->private_data;
-	const void *ns = NULL;
-
-	if (!dir_emit_dots(file, ctx))
-		return 0;
-	mutex_lock(&sysfs_mutex);
-
-	if (parent_sd->s_flags & SYSFS_FLAG_NS)
-		ns = sysfs_info(dentry->d_sb)->ns;
-
-	for (pos = sysfs_dir_pos(ns, parent_sd, ctx->pos, pos);
-	     pos;
-	     pos = sysfs_dir_next_pos(ns, parent_sd, ctx->pos, pos)) {
-		const char *name = pos->s_name;
-		unsigned int type = dt_type(pos);
-		int len = strlen(name);
-		ino_t ino = pos->s_ino;
-
-		ctx->pos = pos->s_hash;
-		file->private_data = pos;
-		kernfs_get(pos);
-
-		mutex_unlock(&sysfs_mutex);
-		if (!dir_emit(ctx, name, len, ino, type))
-			return 0;
-		mutex_lock(&sysfs_mutex);
-	}
-	mutex_unlock(&sysfs_mutex);
-	file->private_data = NULL;
-	ctx->pos = INT_MAX;
-	return 0;
-}
-
-static loff_t sysfs_dir_llseek(struct file *file, loff_t offset, int whence)
-{
-	struct inode *inode = file_inode(file);
-	loff_t ret;
-
-	mutex_lock(&inode->i_mutex);
-	ret = generic_file_llseek(file, offset, whence);
-	mutex_unlock(&inode->i_mutex);
-
-	return ret;
-}
-
-const struct file_operations sysfs_dir_operations = {
-	.read		= generic_read_dir,
-	.iterate	= sysfs_readdir,
-	.release	= sysfs_dir_release,
-	.llseek		= sysfs_dir_llseek,
-};
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 93c1910..972b4a4 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -34,22 +34,9 @@ extern struct kmem_cache *sysfs_dir_cachep;
 /*
  * dir.c
  */
-extern struct mutex sysfs_mutex;
 extern spinlock_t sysfs_symlink_target_lock;
-extern const struct dentry_operations sysfs_dentry_ops;
 
-extern const struct file_operations sysfs_dir_operations;
-extern const struct inode_operations sysfs_dir_inode_operations;
-
-struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd);
-void sysfs_put_active(struct sysfs_dirent *sd);
-void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt);
 void sysfs_warn_dup(struct sysfs_dirent *parent, const char *name);
-int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
-		  struct sysfs_dirent *parent_sd);
-void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
-
-struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);
 
 /*
  * file.c
-- 
1.8.4.2

[PATCH 21/34] sysfs, kernfs: move file core code to fs/kernfs/file.c

[Tejun Heo]

Move core file code to fs/kernfs/file.c.  fs/sysfs/file.c now contains
sysfs kernfs_ops callbacks, sysfs wrappers around kernfs interfaces,
and sysfs_schedule_callback().  The respective declarations in
fs/sysfs/sysfs.h are moved to fs/kernfs/kernfs-internal.h.

This is pure relocation.

v2: Refreshed on top of the v2 of "sysfs, kernfs: prepare read path
    for kernfs".

v3: Refreshed on top of the v3 of "sysfs, kernfs: prepare read path
    for kernfs".

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/file.c            | 805 ++++++++++++++++++++++++++++++++++++++++++++
 fs/kernfs/kernfs-internal.h |   7 +
 fs/sysfs/file.c             | 802 +------------------------------------------
 fs/sysfs/sysfs.h            |   4 -
 4 files changed, 813 insertions(+), 805 deletions(-)

diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index 90b1e88..fa172e8 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -7,3 +7,808 @@
  *
  * This file is released under the GPLv2.
  */
+
+#include <linux/fs.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include <linux/poll.h>
+#include <linux/pagemap.h>
+#include <linux/poll.h>
+#include <linux/sched.h>
+
+#include "kernfs-internal.h"
+
+/*
+ * There's one sysfs_open_file for each open file and one sysfs_open_dirent
+ * for each sysfs_dirent with one or more open files.
+ *
+ * sysfs_dirent->s_attr.open points to sysfs_open_dirent.  s_attr.open is
+ * protected by sysfs_open_dirent_lock.
+ *
+ * filp->private_data points to seq_file whose ->private points to
+ * sysfs_open_file.  sysfs_open_files are chained at
+ * sysfs_open_dirent->files, which is protected by sysfs_open_file_mutex.
+ */
+static DEFINE_SPINLOCK(sysfs_open_dirent_lock);
+static DEFINE_MUTEX(sysfs_open_file_mutex);
+
+struct sysfs_open_dirent {
+	atomic_t		refcnt;
+	atomic_t		event;
+	wait_queue_head_t	poll;
+	struct list_head	files; /* goes through sysfs_open_file.list */
+};
+
+static struct sysfs_open_file *sysfs_of(struct file *file)
+{
+	return ((struct seq_file *)file->private_data)->private;
+}
+
+/*
+ * Determine the kernfs_ops for the given sysfs_dirent.  This function must
+ * be called while holding an active reference.
+ */
+static const struct kernfs_ops *kernfs_ops(struct sysfs_dirent *sd)
+{
+	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
+		lockdep_assert_held(sd);
+	return sd->s_attr.ops;
+}
+
+static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos)
+{
+	struct sysfs_open_file *of = sf->private;
+	const struct kernfs_ops *ops;
+
+	/*
+	 * @of->mutex nests outside active ref and is just to ensure that
+	 * the ops aren't called concurrently for the same open file.
+	 */
+	mutex_lock(&of->mutex);
+	if (!sysfs_get_active(of->sd))
+		return ERR_PTR(-ENODEV);
+
+	ops = kernfs_ops(of->sd);
+	if (ops->seq_start) {
+		return ops->seq_start(sf, ppos);
+	} else {
+		/*
+		 * The same behavior and code as single_open().  Returns
+		 * !NULL if pos is at the beginning; otherwise, NULL.
+		 */
+		return NULL + !*ppos;
+	}
+}
+
+static void *kernfs_seq_next(struct seq_file *sf, void *v, loff_t *ppos)
+{
+	struct sysfs_open_file *of = sf->private;
+	const struct kernfs_ops *ops = kernfs_ops(of->sd);
+
+	if (ops->seq_next) {
+		return ops->seq_next(sf, v, ppos);
+	} else {
+		/*
+		 * The same behavior and code as single_open(), always
+		 * terminate after the initial read.
+		 */
+		++*ppos;
+		return NULL;
+	}
+}
+
+static void kernfs_seq_stop(struct seq_file *sf, void *v)
+{
+	struct sysfs_open_file *of = sf->private;
+	const struct kernfs_ops *ops = kernfs_ops(of->sd);
+
+	if (ops->seq_stop)
+		ops->seq_stop(sf, v);
+
+	sysfs_put_active(of->sd);
+	mutex_unlock(&of->mutex);
+}
+
+static int kernfs_seq_show(struct seq_file *sf, void *v)
+{
+	struct sysfs_open_file *of = sf->private;
+
+	of->event = atomic_read(&of->sd->s_attr.open->event);
+
+	return of->sd->s_attr.ops->seq_show(sf, v);
+}
+
+static const struct seq_operations kernfs_seq_ops = {
+	.start = kernfs_seq_start,
+	.next = kernfs_seq_next,
+	.stop = kernfs_seq_stop,
+	.show = kernfs_seq_show,
+};
+
+/*
+ * As reading a bin file can have side-effects, the exact offset and bytes
+ * specified in read(2) call should be passed to the read callback making
+ * it difficult to use seq_file.  Implement simplistic custom buffering for
+ * bin files.
+ */
+static ssize_t kernfs_file_direct_read(struct sysfs_open_file *of,
+				       char __user *user_buf, size_t count,
+				       loff_t *ppos)
+{
+	ssize_t len = min_t(size_t, count, PAGE_SIZE);
+	const struct kernfs_ops *ops;
+	char *buf;
+
+	buf = kmalloc(len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	/*
+	 * @of->mutex nests outside active ref and is just to ensure that
+	 * the ops aren't called concurrently for the same open file.
+	 */
+	mutex_lock(&of->mutex);
+	if (!sysfs_get_active(of->sd)) {
+		len = -ENODEV;
+		mutex_unlock(&of->mutex);
+		goto out_free;
+	}
+
+	ops = kernfs_ops(of->sd);
+	if (ops->read)
+		len = ops->read(of, buf, len, *ppos);
+	else
+		len = -EINVAL;
+
+	sysfs_put_active(of->sd);
+	mutex_unlock(&of->mutex);
+
+	if (len < 0)
+		goto out_free;
+
+	if (copy_to_user(user_buf, buf, len)) {
+		len = -EFAULT;
+		goto out_free;
+	}
+
+	*ppos += len;
+
+ out_free:
+	kfree(buf);
+	return len;
+}
+
+/**
+ * kernfs_file_read - kernfs vfs read callback
+ * @file: file pointer
+ * @user_buf: data to write
+ * @count: number of bytes
+ * @ppos: starting offset
+ */
+static ssize_t kernfs_file_read(struct file *file, char __user *user_buf,
+				size_t count, loff_t *ppos)
+{
+	struct sysfs_open_file *of = sysfs_of(file);
+
+	if (of->sd->s_flags & SYSFS_FLAG_HAS_SEQ_SHOW)
+		return seq_read(file, user_buf, count, ppos);
+	else
+		return kernfs_file_direct_read(of, user_buf, count, ppos);
+}
+
+/**
+ * kernfs_file_write - kernfs vfs write callback
+ * @file: file pointer
+ * @user_buf: data to write
+ * @count: number of bytes
+ * @ppos: starting offset
+ *
+ * Copy data in from userland and pass it to the matching kernfs write
+ * operation.
+ *
+ * There is no easy way for us to know if userspace is only doing a partial
+ * write, so we don't support them. We expect the entire buffer to come on
+ * the first write.  Hint: if you're writing a value, first read the file,
+ * modify only the the value you're changing, then write entire buffer
+ * back.
+ */
+static ssize_t kernfs_file_write(struct file *file, const char __user *user_buf,
+				 size_t count, loff_t *ppos)
+{
+	struct sysfs_open_file *of = sysfs_of(file);
+	ssize_t len = min_t(size_t, count, PAGE_SIZE);
+	const struct kernfs_ops *ops;
+	char *buf;
+
+	buf = kmalloc(len + 1, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	if (copy_from_user(buf, user_buf, len)) {
+		len = -EFAULT;
+		goto out_free;
+	}
+	buf[len] = '\0';	/* guarantee string termination */
+
+	/*
+	 * @of->mutex nests outside active ref and is just to ensure that
+	 * the ops aren't called concurrently for the same open file.
+	 */
+	mutex_lock(&of->mutex);
+	if (!sysfs_get_active(of->sd)) {
+		mutex_unlock(&of->mutex);
+		len = -ENODEV;
+		goto out_free;
+	}
+
+	ops = kernfs_ops(of->sd);
+	if (ops->write)
+		len = ops->write(of, buf, len, *ppos);
+	else
+		len = -EINVAL;
+
+	sysfs_put_active(of->sd);
+	mutex_unlock(&of->mutex);
+
+	if (len > 0)
+		*ppos += len;
+out_free:
+	kfree(buf);
+	return len;
+}
+
+static void kernfs_vma_open(struct vm_area_struct *vma)
+{
+	struct file *file = vma->vm_file;
+	struct sysfs_open_file *of = sysfs_of(file);
+
+	if (!of->vm_ops)
+		return;
+
+	if (!sysfs_get_active(of->sd))
+		return;
+
+	if (of->vm_ops->open)
+		of->vm_ops->open(vma);
+
+	sysfs_put_active(of->sd);
+}
+
+static int kernfs_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	struct file *file = vma->vm_file;
+	struct sysfs_open_file *of = sysfs_of(file);
+	int ret;
+
+	if (!of->vm_ops)
+		return VM_FAULT_SIGBUS;
+
+	if (!sysfs_get_active(of->sd))
+		return VM_FAULT_SIGBUS;
+
+	ret = VM_FAULT_SIGBUS;
+	if (of->vm_ops->fault)
+		ret = of->vm_ops->fault(vma, vmf);
+
+	sysfs_put_active(of->sd);
+	return ret;
+}
+
+static int kernfs_vma_page_mkwrite(struct vm_area_struct *vma,
+				   struct vm_fault *vmf)
+{
+	struct file *file = vma->vm_file;
+	struct sysfs_open_file *of = sysfs_of(file);
+	int ret;
+
+	if (!of->vm_ops)
+		return VM_FAULT_SIGBUS;
+
+	if (!sysfs_get_active(of->sd))
+		return VM_FAULT_SIGBUS;
+
+	ret = 0;
+	if (of->vm_ops->page_mkwrite)
+		ret = of->vm_ops->page_mkwrite(vma, vmf);
+	else
+		file_update_time(file);
+
+	sysfs_put_active(of->sd);
+	return ret;
+}
+
+static int kernfs_vma_access(struct vm_area_struct *vma, unsigned long addr,
+			     void *buf, int len, int write)
+{
+	struct file *file = vma->vm_file;
+	struct sysfs_open_file *of = sysfs_of(file);
+	int ret;
+
+	if (!of->vm_ops)
+		return -EINVAL;
+
+	if (!sysfs_get_active(of->sd))
+		return -EINVAL;
+
+	ret = -EINVAL;
+	if (of->vm_ops->access)
+		ret = of->vm_ops->access(vma, addr, buf, len, write);
+
+	sysfs_put_active(of->sd);
+	return ret;
+}
+
+#ifdef CONFIG_NUMA
+static int kernfs_vma_set_policy(struct vm_area_struct *vma,
+				 struct mempolicy *new)
+{
+	struct file *file = vma->vm_file;
+	struct sysfs_open_file *of = sysfs_of(file);
+	int ret;
+
+	if (!of->vm_ops)
+		return 0;
+
+	if (!sysfs_get_active(of->sd))
+		return -EINVAL;
+
+	ret = 0;
+	if (of->vm_ops->set_policy)
+		ret = of->vm_ops->set_policy(vma, new);
+
+	sysfs_put_active(of->sd);
+	return ret;
+}
+
+static struct mempolicy *kernfs_vma_get_policy(struct vm_area_struct *vma,
+					       unsigned long addr)
+{
+	struct file *file = vma->vm_file;
+	struct sysfs_open_file *of = sysfs_of(file);
+	struct mempolicy *pol;
+
+	if (!of->vm_ops)
+		return vma->vm_policy;
+
+	if (!sysfs_get_active(of->sd))
+		return vma->vm_policy;
+
+	pol = vma->vm_policy;
+	if (of->vm_ops->get_policy)
+		pol = of->vm_ops->get_policy(vma, addr);
+
+	sysfs_put_active(of->sd);
+	return pol;
+}
+
+static int kernfs_vma_migrate(struct vm_area_struct *vma,
+			      const nodemask_t *from, const nodemask_t *to,
+			      unsigned long flags)
+{
+	struct file *file = vma->vm_file;
+	struct sysfs_open_file *of = sysfs_of(file);
+	int ret;
+
+	if (!of->vm_ops)
+		return 0;
+
+	if (!sysfs_get_active(of->sd))
+		return 0;
+
+	ret = 0;
+	if (of->vm_ops->migrate)
+		ret = of->vm_ops->migrate(vma, from, to, flags);
+
+	sysfs_put_active(of->sd);
+	return ret;
+}
+#endif
+
+static const struct vm_operations_struct kernfs_vm_ops = {
+	.open		= kernfs_vma_open,
+	.fault		= kernfs_vma_fault,
+	.page_mkwrite	= kernfs_vma_page_mkwrite,
+	.access		= kernfs_vma_access,
+#ifdef CONFIG_NUMA
+	.set_policy	= kernfs_vma_set_policy,
+	.get_policy	= kernfs_vma_get_policy,
+	.migrate	= kernfs_vma_migrate,
+#endif
+};
+
+static int kernfs_file_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct sysfs_open_file *of = sysfs_of(file);
+	const struct kernfs_ops *ops;
+	int rc;
+
+	mutex_lock(&of->mutex);
+
+	rc = -ENODEV;
+	if (!sysfs_get_active(of->sd))
+		goto out_unlock;
+
+	ops = kernfs_ops(of->sd);
+	if (ops->mmap)
+		rc = ops->mmap(of, vma);
+	if (rc)
+		goto out_put;
+
+	/*
+	 * PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup()
+	 * to satisfy versions of X which crash if the mmap fails: that
+	 * substitutes a new vm_file, and we don't then want bin_vm_ops.
+	 */
+	if (vma->vm_file != file)
+		goto out_put;
+
+	rc = -EINVAL;
+	if (of->mmapped && of->vm_ops != vma->vm_ops)
+		goto out_put;
+
+	/*
+	 * It is not possible to successfully wrap close.
+	 * So error if someone is trying to use close.
+	 */
+	rc = -EINVAL;
+	if (vma->vm_ops && vma->vm_ops->close)
+		goto out_put;
+
+	rc = 0;
+	of->mmapped = 1;
+	of->vm_ops = vma->vm_ops;
+	vma->vm_ops = &kernfs_vm_ops;
+out_put:
+	sysfs_put_active(of->sd);
+out_unlock:
+	mutex_unlock(&of->mutex);
+
+	return rc;
+}
+
+/**
+ *	sysfs_get_open_dirent - get or create sysfs_open_dirent
+ *	@sd: target sysfs_dirent
+ *	@of: sysfs_open_file for this instance of open
+ *
+ *	If @sd->s_attr.open exists, increment its reference count;
+ *	otherwise, create one.  @of is chained to the files list.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+static int sysfs_get_open_dirent(struct sysfs_dirent *sd,
+				 struct sysfs_open_file *of)
+{
+	struct sysfs_open_dirent *od, *new_od = NULL;
+
+ retry:
+	mutex_lock(&sysfs_open_file_mutex);
+	spin_lock_irq(&sysfs_open_dirent_lock);
+
+	if (!sd->s_attr.open && new_od) {
+		sd->s_attr.open = new_od;
+		new_od = NULL;
+	}
+
+	od = sd->s_attr.open;
+	if (od) {
+		atomic_inc(&od->refcnt);
+		list_add_tail(&of->list, &od->files);
+	}
+
+	spin_unlock_irq(&sysfs_open_dirent_lock);
+	mutex_unlock(&sysfs_open_file_mutex);
+
+	if (od) {
+		kfree(new_od);
+		return 0;
+	}
+
+	/* not there, initialize a new one and retry */
+	new_od = kmalloc(sizeof(*new_od), GFP_KERNEL);
+	if (!new_od)
+		return -ENOMEM;
+
+	atomic_set(&new_od->refcnt, 0);
+	atomic_set(&new_od->event, 1);
+	init_waitqueue_head(&new_od->poll);
+	INIT_LIST_HEAD(&new_od->files);
+	goto retry;
+}
+
+/**
+ *	sysfs_put_open_dirent - put sysfs_open_dirent
+ *	@sd: target sysfs_dirent
+ *	@of: associated sysfs_open_file
+ *
+ *	Put @sd->s_attr.open and unlink @of from the files list.  If
+ *	reference count reaches zero, disassociate and free it.
+ *
+ *	LOCKING:
+ *	None.
+ */
+static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
+				  struct sysfs_open_file *of)
+{
+	struct sysfs_open_dirent *od = sd->s_attr.open;
+	unsigned long flags;
+
+	mutex_lock(&sysfs_open_file_mutex);
+	spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
+
+	if (of)
+		list_del(&of->list);
+
+	if (atomic_dec_and_test(&od->refcnt))
+		sd->s_attr.open = NULL;
+	else
+		od = NULL;
+
+	spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
+	mutex_unlock(&sysfs_open_file_mutex);
+
+	kfree(od);
+}
+
+static int kernfs_file_open(struct inode *inode, struct file *file)
+{
+	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
+	const struct kernfs_ops *ops;
+	struct sysfs_open_file *of;
+	bool has_read, has_write, has_mmap;
+	int error = -EACCES;
+
+	if (!sysfs_get_active(attr_sd))
+		return -ENODEV;
+
+	ops = kernfs_ops(attr_sd);
+
+	has_read = ops->seq_show || ops->read || ops->mmap;
+	has_write = ops->write || ops->mmap;
+	has_mmap = ops->mmap;
+
+	/* check perms and supported operations */
+	if ((file->f_mode & FMODE_WRITE) &&
+	    (!(inode->i_mode & S_IWUGO) || !has_write))
+		goto err_out;
+
+	if ((file->f_mode & FMODE_READ) &&
+	    (!(inode->i_mode & S_IRUGO) || !has_read))
+		goto err_out;
+
+	/* allocate a sysfs_open_file for the file */
+	error = -ENOMEM;
+	of = kzalloc(sizeof(struct sysfs_open_file), GFP_KERNEL);
+	if (!of)
+		goto err_out;
+
+	/*
+	 * The following is done to give a different lockdep key to
+	 * @of->mutex for files which implement mmap.  This is a rather
+	 * crude way to avoid false positive lockdep warning around
+	 * mm->mmap_sem - mmap nests @of->mutex under mm->mmap_sem and
+	 * reading /sys/block/sda/trace/act_mask grabs sr_mutex, under
+	 * which mm->mmap_sem nests, while holding @of->mutex.  As each
+	 * open file has a separate mutex, it's okay as long as those don't
+	 * happen on the same file.  At this point, we can't easily give
+	 * each file a separate locking class.  Let's differentiate on
+	 * whether the file has mmap or not for now.
+	 */
+	if (has_mmap)
+		mutex_init(&of->mutex);
+	else
+		mutex_init(&of->mutex);
+
+	of->sd = attr_sd;
+	of->file = file;
+
+	/*
+	 * Always instantiate seq_file even if read access doesn't use
+	 * seq_file or is not requested.  This unifies private data access
+	 * and readable regular files are the vast majority anyway.
+	 */
+	if (ops->seq_show)
+		error = seq_open(file, &kernfs_seq_ops);
+	else
+		error = seq_open(file, NULL);
+	if (error)
+		goto err_free;
+
+	((struct seq_file *)file->private_data)->private = of;
+
+	/* seq_file clears PWRITE unconditionally, restore it if WRITE */
+	if (file->f_mode & FMODE_WRITE)
+		file->f_mode |= FMODE_PWRITE;
+
+	/* make sure we have open dirent struct */
+	error = sysfs_get_open_dirent(attr_sd, of);
+	if (error)
+		goto err_close;
+
+	/* open succeeded, put active references */
+	sysfs_put_active(attr_sd);
+	return 0;
+
+err_close:
+	seq_release(inode, file);
+err_free:
+	kfree(of);
+err_out:
+	sysfs_put_active(attr_sd);
+	return error;
+}
+
+static int kernfs_file_release(struct inode *inode, struct file *filp)
+{
+	struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata;
+	struct sysfs_open_file *of = sysfs_of(filp);
+
+	sysfs_put_open_dirent(sd, of);
+	seq_release(inode, filp);
+	kfree(of);
+
+	return 0;
+}
+
+void sysfs_unmap_bin_file(struct sysfs_dirent *sd)
+{
+	struct sysfs_open_dirent *od;
+	struct sysfs_open_file *of;
+
+	if (!(sd->s_flags & SYSFS_FLAG_HAS_MMAP))
+		return;
+
+	spin_lock_irq(&sysfs_open_dirent_lock);
+	od = sd->s_attr.open;
+	if (od)
+		atomic_inc(&od->refcnt);
+	spin_unlock_irq(&sysfs_open_dirent_lock);
+	if (!od)
+		return;
+
+	mutex_lock(&sysfs_open_file_mutex);
+	list_for_each_entry(of, &od->files, list) {
+		struct inode *inode = file_inode(of->file);
+		unmap_mapping_range(inode->i_mapping, 0, 0, 1);
+	}
+	mutex_unlock(&sysfs_open_file_mutex);
+
+	sysfs_put_open_dirent(sd, NULL);
+}
+
+/* Sysfs attribute files are pollable.  The idea is that you read
+ * the content and then you use 'poll' or 'select' to wait for
+ * the content to change.  When the content changes (assuming the
+ * manager for the kobject supports notification), poll will
+ * return POLLERR|POLLPRI, and select will return the fd whether
+ * it is waiting for read, write, or exceptions.
+ * Once poll/select indicates that the value has changed, you
+ * need to close and re-open the file, or seek to 0 and read again.
+ * Reminder: this only works for attributes which actively support
+ * it, and it is not possible to test an attribute from userspace
+ * to see if it supports poll (Neither 'poll' nor 'select' return
+ * an appropriate error code).  When in doubt, set a suitable timeout value.
+ */
+static unsigned int kernfs_file_poll(struct file *filp, poll_table *wait)
+{
+	struct sysfs_open_file *of = sysfs_of(filp);
+	struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
+	struct sysfs_open_dirent *od = attr_sd->s_attr.open;
+
+	/* need parent for the kobj, grab both */
+	if (!sysfs_get_active(attr_sd))
+		goto trigger;
+
+	poll_wait(filp, &od->poll, wait);
+
+	sysfs_put_active(attr_sd);
+
+	if (of->event != atomic_read(&od->event))
+		goto trigger;
+
+	return DEFAULT_POLLMASK;
+
+ trigger:
+	return DEFAULT_POLLMASK|POLLERR|POLLPRI;
+}
+
+/**
+ * kernfs_notify - notify a kernfs file
+ * @sd: file to notify
+ *
+ * Notify @sd such that poll(2) on @sd wakes up.
+ */
+void kernfs_notify(struct sysfs_dirent *sd)
+{
+	struct sysfs_open_dirent *od;
+	unsigned long flags;
+
+	spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
+
+	if (!WARN_ON(sysfs_type(sd) != SYSFS_KOBJ_ATTR)) {
+		od = sd->s_attr.open;
+		if (od) {
+			atomic_inc(&od->event);
+			wake_up_interruptible(&od->poll);
+		}
+	}
+
+	spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
+}
+EXPORT_SYMBOL_GPL(kernfs_notify);
+
+const struct file_operations kernfs_file_operations = {
+	.read		= kernfs_file_read,
+	.write		= kernfs_file_write,
+	.llseek		= generic_file_llseek,
+	.mmap		= kernfs_file_mmap,
+	.open		= kernfs_file_open,
+	.release	= kernfs_file_release,
+	.poll		= kernfs_file_poll,
+};
+
+/**
+ * kernfs_create_file_ns_key - create a file
+ * @parent: directory to create the file in
+ * @name: name of the file
+ * @mode: mode of the file
+ * @size: size of the file
+ * @ops: kernfs operations for the file
+ * @priv: private data for the file
+ * @ns: optional namespace tag of the file
+ * @key: lockdep key for the file's active_ref, %NULL to disable lockdep
+ *
+ * Returns the created node on success, ERR_PTR() value on error.
+ */
+struct sysfs_dirent *kernfs_create_file_ns_key(struct sysfs_dirent *parent,
+					       const char *name,
+					       umode_t mode, loff_t size,
+					       const struct kernfs_ops *ops,
+					       void *priv, const void *ns,
+					       struct lock_class_key *key)
+{
+	struct sysfs_addrm_cxt acxt;
+	struct sysfs_dirent *sd;
+	int rc;
+
+	sd = sysfs_new_dirent(name, (mode & S_IALLUGO) | S_IFREG,
+			      SYSFS_KOBJ_ATTR);
+	if (!sd)
+		return ERR_PTR(-ENOMEM);
+
+	sd->s_attr.ops = ops;
+	sd->s_attr.size = size;
+	sd->s_ns = ns;
+	sd->priv = priv;
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	if (key) {
+		lockdep_init_map(&sd->dep_map, "s_active", key, 0);
+		sd->s_flags |= SYSFS_FLAG_LOCKDEP;
+	}
+#endif
+
+	/*
+	 * sd->s_attr.ops is accesible only while holding active ref.  We
+	 * need to know whether some ops are implemented outside active
+	 * ref.  Cache their existence in flags.
+	 */
+	if (ops->seq_show)
+		sd->s_flags |= SYSFS_FLAG_HAS_SEQ_SHOW;
+	if (ops->mmap)
+		sd->s_flags |= SYSFS_FLAG_HAS_MMAP;
+
+	sysfs_addrm_start(&acxt);
+	rc = sysfs_add_one(&acxt, sd, parent);
+	sysfs_addrm_finish(&acxt);
+
+	if (rc) {
+		kernfs_put(sd);
+		return ERR_PTR(rc);
+	}
+	return sd;
+}
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 31f0dbe..38e3a16 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -142,4 +142,11 @@ int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
 void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
 struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);
 
+/*
+ * file.c
+ */
+extern const struct file_operations kernfs_file_operations;
+
+void sysfs_unmap_bin_file(struct sysfs_dirent *sd);
+
 #endif	/* __KERNFS_INTERNAL_H */
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 7f0a79f..ac77d2b 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -14,54 +14,12 @@
 #include <linux/kobject.h>
 #include <linux/kallsyms.h>
 #include <linux/slab.h>
-#include <linux/fsnotify.h>
-#include <linux/namei.h>
-#include <linux/poll.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
-#include <linux/limits.h>
-#include <linux/uaccess.h>
 #include <linux/seq_file.h>
-#include <linux/mm.h>
 
 #include "sysfs.h"
-
-/*
- * There's one sysfs_open_file for each open file and one sysfs_open_dirent
- * for each sysfs_dirent with one or more open files.
- *
- * sysfs_dirent->s_attr.open points to sysfs_open_dirent.  s_attr.open is
- * protected by sysfs_open_dirent_lock.
- *
- * filp->private_data points to seq_file whose ->private points to
- * sysfs_open_file.  sysfs_open_files are chained at
- * sysfs_open_dirent->files, which is protected by sysfs_open_file_mutex.
- */
-static DEFINE_SPINLOCK(sysfs_open_dirent_lock);
-static DEFINE_MUTEX(sysfs_open_file_mutex);
-
-struct sysfs_open_dirent {
-	atomic_t		refcnt;
-	atomic_t		event;
-	wait_queue_head_t	poll;
-	struct list_head	files; /* goes through sysfs_open_file.list */
-};
-
-static struct sysfs_open_file *sysfs_of(struct file *file)
-{
-	return ((struct seq_file *)file->private_data)->private;
-}
-
-/*
- * Determine the kernfs_ops for the given sysfs_dirent.  This function must
- * be called while holding an active reference.
- */
-static const struct kernfs_ops *kernfs_ops(struct sysfs_dirent *sd)
-{
-	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
-		lockdep_assert_held(sd);
-	return sd->s_attr.ops;
-}
+#include "../kernfs/kernfs-internal.h"
 
 /*
  * Determine ktype->sysfs_ops for the given sysfs_dirent.  This function
@@ -143,147 +101,6 @@ static ssize_t sysfs_kf_bin_read(struct sysfs_open_file *of, char *buf,
 	return battr->read(of->file, kobj, battr, buf, pos, count);
 }
 
-static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos)
-{
-	struct sysfs_open_file *of = sf->private;
-	const struct kernfs_ops *ops;
-
-	/*
-	 * @of->mutex nests outside active ref and is just to ensure that
-	 * the ops aren't called concurrently for the same open file.
-	 */
-	mutex_lock(&of->mutex);
-	if (!sysfs_get_active(of->sd))
-		return ERR_PTR(-ENODEV);
-
-	ops = kernfs_ops(of->sd);
-	if (ops->seq_start) {
-		return ops->seq_start(sf, ppos);
-	} else {
-		/*
-		 * The same behavior and code as single_open().  Returns
-		 * !NULL if pos is at the beginning; otherwise, NULL.
-		 */
-		return NULL + !*ppos;
-	}
-}
-
-static void *kernfs_seq_next(struct seq_file *sf, void *v, loff_t *ppos)
-{
-	struct sysfs_open_file *of = sf->private;
-	const struct kernfs_ops *ops = kernfs_ops(of->sd);
-
-	if (ops->seq_next) {
-		return ops->seq_next(sf, v, ppos);
-	} else {
-		/*
-		 * The same behavior and code as single_open(), always
-		 * terminate after the initial read.
-		 */
-		++*ppos;
-		return NULL;
-	}
-}
-
-static void kernfs_seq_stop(struct seq_file *sf, void *v)
-{
-	struct sysfs_open_file *of = sf->private;
-	const struct kernfs_ops *ops = kernfs_ops(of->sd);
-
-	if (ops->seq_stop)
-		ops->seq_stop(sf, v);
-
-	sysfs_put_active(of->sd);
-	mutex_unlock(&of->mutex);
-}
-
-static int kernfs_seq_show(struct seq_file *sf, void *v)
-{
-	struct sysfs_open_file *of = sf->private;
-
-	of->event = atomic_read(&of->sd->s_attr.open->event);
-
-	return of->sd->s_attr.ops->seq_show(sf, v);
-}
-
-static const struct seq_operations kernfs_seq_ops = {
-	.start = kernfs_seq_start,
-	.next = kernfs_seq_next,
-	.stop = kernfs_seq_stop,
-	.show = kernfs_seq_show,
-};
-
-/*
- * As reading a bin file can have side-effects, the exact offset and bytes
- * specified in read(2) call should be passed to the read callback making
- * it difficult to use seq_file.  Implement simplistic custom buffering for
- * bin files.
- */
-static ssize_t kernfs_file_direct_read(struct sysfs_open_file *of,
-				       char __user *user_buf, size_t count,
-				       loff_t *ppos)
-{
-	ssize_t len = min_t(size_t, count, PAGE_SIZE);
-	const struct kernfs_ops *ops;
-	char *buf;
-
-	buf = kmalloc(len, GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
-
-	/*
-	 * @of->mutex nests outside active ref and is just to ensure that
-	 * the ops aren't called concurrently for the same open file.
-	 */
-	mutex_lock(&of->mutex);
-	if (!sysfs_get_active(of->sd)) {
-		len = -ENODEV;
-		mutex_unlock(&of->mutex);
-		goto out_free;
-	}
-
-	ops = kernfs_ops(of->sd);
-	if (ops->read)
-		len = ops->read(of, buf, len, *ppos);
-	else
-		len = -EINVAL;
-
-	sysfs_put_active(of->sd);
-	mutex_unlock(&of->mutex);
-
-	if (len < 0)
-		goto out_free;
-
-	if (copy_to_user(user_buf, buf, len)) {
-		len = -EFAULT;
-		goto out_free;
-	}
-
-	*ppos += len;
-
- out_free:
-	kfree(buf);
-	return len;
-}
-
-/**
- * kernfs_file_read - kernfs vfs read callback
- * @file: file pointer
- * @user_buf: data to write
- * @count: number of bytes
- * @ppos: starting offset
- */
-static ssize_t kernfs_file_read(struct file *file, char __user *user_buf,
-				size_t count, loff_t *ppos)
-{
-	struct sysfs_open_file *of = sysfs_of(file);
-
-	if (of->sd->s_flags & SYSFS_FLAG_HAS_SEQ_SHOW)
-		return seq_read(file, user_buf, count, ppos);
-	else
-		return kernfs_file_direct_read(of, user_buf, count, ppos);
-}
-
 /* kernfs write callback for regular sysfs files */
 static ssize_t sysfs_kf_write(struct sysfs_open_file *of, char *buf,
 			      size_t count, loff_t pos)
@@ -319,67 +136,6 @@ static ssize_t sysfs_kf_bin_write(struct sysfs_open_file *of, char *buf,
 	return battr->write(of->file, kobj, battr, buf, pos, count);
 }
 
-/**
- * kernfs_file_write - kernfs vfs write callback
- * @file: file pointer
- * @user_buf: data to write
- * @count: number of bytes
- * @ppos: starting offset
- *
- * Copy data in from userland and pass it to the matching kernfs write
- * operation.
- *
- * There is no easy way for us to know if userspace is only doing a partial
- * write, so we don't support them. We expect the entire buffer to come on
- * the first write.  Hint: if you're writing a value, first read the file,
- * modify only the the value you're changing, then write entire buffer
- * back.
- */
-static ssize_t kernfs_file_write(struct file *file, const char __user *user_buf,
-				 size_t count, loff_t *ppos)
-{
-	struct sysfs_open_file *of = sysfs_of(file);
-	ssize_t len = min_t(size_t, count, PAGE_SIZE);
-	const struct kernfs_ops *ops;
-	char *buf;
-
-	buf = kmalloc(len + 1, GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
-
-	if (copy_from_user(buf, user_buf, len)) {
-		len = -EFAULT;
-		goto out_free;
-	}
-	buf[len] = '\0';	/* guarantee string termination */
-
-	/*
-	 * @of->mutex nests outside active ref and is just to ensure that
-	 * the ops aren't called concurrently for the same open file.
-	 */
-	mutex_lock(&of->mutex);
-	if (!sysfs_get_active(of->sd)) {
-		mutex_unlock(&of->mutex);
-		len = -ENODEV;
-		goto out_free;
-	}
-
-	ops = kernfs_ops(of->sd);
-	if (ops->write)
-		len = ops->write(of, buf, len, *ppos);
-	else
-		len = -EINVAL;
-
-	sysfs_put_active(of->sd);
-	mutex_unlock(&of->mutex);
-
-	if (len > 0)
-		*ppos += len;
-out_free:
-	kfree(buf);
-	return len;
-}
-
 static int sysfs_kf_bin_mmap(struct sysfs_open_file *of,
 			     struct vm_area_struct *vma)
 {
@@ -392,490 +148,6 @@ static int sysfs_kf_bin_mmap(struct sysfs_open_file *of,
 	return battr->mmap(of->file, kobj, battr, vma);
 }
 
-static void kernfs_vma_open(struct vm_area_struct *vma)
-{
-	struct file *file = vma->vm_file;
-	struct sysfs_open_file *of = sysfs_of(file);
-
-	if (!of->vm_ops)
-		return;
-
-	if (!sysfs_get_active(of->sd))
-		return;
-
-	if (of->vm_ops->open)
-		of->vm_ops->open(vma);
-
-	sysfs_put_active(of->sd);
-}
-
-static int kernfs_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
-{
-	struct file *file = vma->vm_file;
-	struct sysfs_open_file *of = sysfs_of(file);
-	int ret;
-
-	if (!of->vm_ops)
-		return VM_FAULT_SIGBUS;
-
-	if (!sysfs_get_active(of->sd))
-		return VM_FAULT_SIGBUS;
-
-	ret = VM_FAULT_SIGBUS;
-	if (of->vm_ops->fault)
-		ret = of->vm_ops->fault(vma, vmf);
-
-	sysfs_put_active(of->sd);
-	return ret;
-}
-
-static int kernfs_vma_page_mkwrite(struct vm_area_struct *vma,
-				   struct vm_fault *vmf)
-{
-	struct file *file = vma->vm_file;
-	struct sysfs_open_file *of = sysfs_of(file);
-	int ret;
-
-	if (!of->vm_ops)
-		return VM_FAULT_SIGBUS;
-
-	if (!sysfs_get_active(of->sd))
-		return VM_FAULT_SIGBUS;
-
-	ret = 0;
-	if (of->vm_ops->page_mkwrite)
-		ret = of->vm_ops->page_mkwrite(vma, vmf);
-	else
-		file_update_time(file);
-
-	sysfs_put_active(of->sd);
-	return ret;
-}
-
-static int kernfs_vma_access(struct vm_area_struct *vma, unsigned long addr,
-			     void *buf, int len, int write)
-{
-	struct file *file = vma->vm_file;
-	struct sysfs_open_file *of = sysfs_of(file);
-	int ret;
-
-	if (!of->vm_ops)
-		return -EINVAL;
-
-	if (!sysfs_get_active(of->sd))
-		return -EINVAL;
-
-	ret = -EINVAL;
-	if (of->vm_ops->access)
-		ret = of->vm_ops->access(vma, addr, buf, len, write);
-
-	sysfs_put_active(of->sd);
-	return ret;
-}
-
-#ifdef CONFIG_NUMA
-static int kernfs_vma_set_policy(struct vm_area_struct *vma,
-				 struct mempolicy *new)
-{
-	struct file *file = vma->vm_file;
-	struct sysfs_open_file *of = sysfs_of(file);
-	int ret;
-
-	if (!of->vm_ops)
-		return 0;
-
-	if (!sysfs_get_active(of->sd))
-		return -EINVAL;
-
-	ret = 0;
-	if (of->vm_ops->set_policy)
-		ret = of->vm_ops->set_policy(vma, new);
-
-	sysfs_put_active(of->sd);
-	return ret;
-}
-
-static struct mempolicy *kernfs_vma_get_policy(struct vm_area_struct *vma,
-					       unsigned long addr)
-{
-	struct file *file = vma->vm_file;
-	struct sysfs_open_file *of = sysfs_of(file);
-	struct mempolicy *pol;
-
-	if (!of->vm_ops)
-		return vma->vm_policy;
-
-	if (!sysfs_get_active(of->sd))
-		return vma->vm_policy;
-
-	pol = vma->vm_policy;
-	if (of->vm_ops->get_policy)
-		pol = of->vm_ops->get_policy(vma, addr);
-
-	sysfs_put_active(of->sd);
-	return pol;
-}
-
-static int kernfs_vma_migrate(struct vm_area_struct *vma,
-			      const nodemask_t *from, const nodemask_t *to,
-			      unsigned long flags)
-{
-	struct file *file = vma->vm_file;
-	struct sysfs_open_file *of = sysfs_of(file);
-	int ret;
-
-	if (!of->vm_ops)
-		return 0;
-
-	if (!sysfs_get_active(of->sd))
-		return 0;
-
-	ret = 0;
-	if (of->vm_ops->migrate)
-		ret = of->vm_ops->migrate(vma, from, to, flags);
-
-	sysfs_put_active(of->sd);
-	return ret;
-}
-#endif
-
-static const struct vm_operations_struct kernfs_vm_ops = {
-	.open		= kernfs_vma_open,
-	.fault		= kernfs_vma_fault,
-	.page_mkwrite	= kernfs_vma_page_mkwrite,
-	.access		= kernfs_vma_access,
-#ifdef CONFIG_NUMA
-	.set_policy	= kernfs_vma_set_policy,
-	.get_policy	= kernfs_vma_get_policy,
-	.migrate	= kernfs_vma_migrate,
-#endif
-};
-
-static int kernfs_file_mmap(struct file *file, struct vm_area_struct *vma)
-{
-	struct sysfs_open_file *of = sysfs_of(file);
-	const struct kernfs_ops *ops;
-	int rc;
-
-	mutex_lock(&of->mutex);
-
-	rc = -ENODEV;
-	if (!sysfs_get_active(of->sd))
-		goto out_unlock;
-
-	ops = kernfs_ops(of->sd);
-	if (ops->mmap)
-		rc = ops->mmap(of, vma);
-	if (rc)
-		goto out_put;
-
-	/*
-	 * PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup()
-	 * to satisfy versions of X which crash if the mmap fails: that
-	 * substitutes a new vm_file, and we don't then want bin_vm_ops.
-	 */
-	if (vma->vm_file != file)
-		goto out_put;
-
-	rc = -EINVAL;
-	if (of->mmapped && of->vm_ops != vma->vm_ops)
-		goto out_put;
-
-	/*
-	 * It is not possible to successfully wrap close.
-	 * So error if someone is trying to use close.
-	 */
-	rc = -EINVAL;
-	if (vma->vm_ops && vma->vm_ops->close)
-		goto out_put;
-
-	rc = 0;
-	of->mmapped = 1;
-	of->vm_ops = vma->vm_ops;
-	vma->vm_ops = &kernfs_vm_ops;
-out_put:
-	sysfs_put_active(of->sd);
-out_unlock:
-	mutex_unlock(&of->mutex);
-
-	return rc;
-}
-
-/**
- *	sysfs_get_open_dirent - get or create sysfs_open_dirent
- *	@sd: target sysfs_dirent
- *	@of: sysfs_open_file for this instance of open
- *
- *	If @sd->s_attr.open exists, increment its reference count;
- *	otherwise, create one.  @of is chained to the files list.
- *
- *	LOCKING:
- *	Kernel thread context (may sleep).
- *
- *	RETURNS:
- *	0 on success, -errno on failure.
- */
-static int sysfs_get_open_dirent(struct sysfs_dirent *sd,
-				 struct sysfs_open_file *of)
-{
-	struct sysfs_open_dirent *od, *new_od = NULL;
-
- retry:
-	mutex_lock(&sysfs_open_file_mutex);
-	spin_lock_irq(&sysfs_open_dirent_lock);
-
-	if (!sd->s_attr.open && new_od) {
-		sd->s_attr.open = new_od;
-		new_od = NULL;
-	}
-
-	od = sd->s_attr.open;
-	if (od) {
-		atomic_inc(&od->refcnt);
-		list_add_tail(&of->list, &od->files);
-	}
-
-	spin_unlock_irq(&sysfs_open_dirent_lock);
-	mutex_unlock(&sysfs_open_file_mutex);
-
-	if (od) {
-		kfree(new_od);
-		return 0;
-	}
-
-	/* not there, initialize a new one and retry */
-	new_od = kmalloc(sizeof(*new_od), GFP_KERNEL);
-	if (!new_od)
-		return -ENOMEM;
-
-	atomic_set(&new_od->refcnt, 0);
-	atomic_set(&new_od->event, 1);
-	init_waitqueue_head(&new_od->poll);
-	INIT_LIST_HEAD(&new_od->files);
-	goto retry;
-}
-
-/**
- *	sysfs_put_open_dirent - put sysfs_open_dirent
- *	@sd: target sysfs_dirent
- *	@of: associated sysfs_open_file
- *
- *	Put @sd->s_attr.open and unlink @of from the files list.  If
- *	reference count reaches zero, disassociate and free it.
- *
- *	LOCKING:
- *	None.
- */
-static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
-				  struct sysfs_open_file *of)
-{
-	struct sysfs_open_dirent *od = sd->s_attr.open;
-	unsigned long flags;
-
-	mutex_lock(&sysfs_open_file_mutex);
-	spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
-
-	if (of)
-		list_del(&of->list);
-
-	if (atomic_dec_and_test(&od->refcnt))
-		sd->s_attr.open = NULL;
-	else
-		od = NULL;
-
-	spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
-	mutex_unlock(&sysfs_open_file_mutex);
-
-	kfree(od);
-}
-
-static int kernfs_file_open(struct inode *inode, struct file *file)
-{
-	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
-	const struct kernfs_ops *ops;
-	struct sysfs_open_file *of;
-	bool has_read, has_write, has_mmap;
-	int error = -EACCES;
-
-	if (!sysfs_get_active(attr_sd))
-		return -ENODEV;
-
-	ops = kernfs_ops(attr_sd);
-
-	has_read = ops->seq_show || ops->read || ops->mmap;
-	has_write = ops->write || ops->mmap;
-	has_mmap = ops->mmap;
-
-	/* check perms and supported operations */
-	if ((file->f_mode & FMODE_WRITE) &&
-	    (!(inode->i_mode & S_IWUGO) || !has_write))
-		goto err_out;
-
-	if ((file->f_mode & FMODE_READ) &&
-	    (!(inode->i_mode & S_IRUGO) || !has_read))
-		goto err_out;
-
-	/* allocate a sysfs_open_file for the file */
-	error = -ENOMEM;
-	of = kzalloc(sizeof(struct sysfs_open_file), GFP_KERNEL);
-	if (!of)
-		goto err_out;
-
-	/*
-	 * The following is done to give a different lockdep key to
-	 * @of->mutex for files which implement mmap.  This is a rather
-	 * crude way to avoid false positive lockdep warning around
-	 * mm->mmap_sem - mmap nests @of->mutex under mm->mmap_sem and
-	 * reading /sys/block/sda/trace/act_mask grabs sr_mutex, under
-	 * which mm->mmap_sem nests, while holding @of->mutex.  As each
-	 * open file has a separate mutex, it's okay as long as those don't
-	 * happen on the same file.  At this point, we can't easily give
-	 * each file a separate locking class.  Let's differentiate on
-	 * whether the file has mmap or not for now.
-	 */
-	if (has_mmap)
-		mutex_init(&of->mutex);
-	else
-		mutex_init(&of->mutex);
-
-	of->sd = attr_sd;
-	of->file = file;
-
-	/*
-	 * Always instantiate seq_file even if read access doesn't use
-	 * seq_file or is not requested.  This unifies private data access
-	 * and readable regular files are the vast majority anyway.
-	 */
-	if (ops->seq_show)
-		error = seq_open(file, &kernfs_seq_ops);
-	else
-		error = seq_open(file, NULL);
-	if (error)
-		goto err_free;
-
-	((struct seq_file *)file->private_data)->private = of;
-
-	/* seq_file clears PWRITE unconditionally, restore it if WRITE */
-	if (file->f_mode & FMODE_WRITE)
-		file->f_mode |= FMODE_PWRITE;
-
-	/* make sure we have open dirent struct */
-	error = sysfs_get_open_dirent(attr_sd, of);
-	if (error)
-		goto err_close;
-
-	/* open succeeded, put active references */
-	sysfs_put_active(attr_sd);
-	return 0;
-
-err_close:
-	seq_release(inode, file);
-err_free:
-	kfree(of);
-err_out:
-	sysfs_put_active(attr_sd);
-	return error;
-}
-
-static int kernfs_file_release(struct inode *inode, struct file *filp)
-{
-	struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata;
-	struct sysfs_open_file *of = sysfs_of(filp);
-
-	sysfs_put_open_dirent(sd, of);
-	seq_release(inode, filp);
-	kfree(of);
-
-	return 0;
-}
-
-void sysfs_unmap_bin_file(struct sysfs_dirent *sd)
-{
-	struct sysfs_open_dirent *od;
-	struct sysfs_open_file *of;
-
-	if (!(sd->s_flags & SYSFS_FLAG_HAS_MMAP))
-		return;
-
-	spin_lock_irq(&sysfs_open_dirent_lock);
-	od = sd->s_attr.open;
-	if (od)
-		atomic_inc(&od->refcnt);
-	spin_unlock_irq(&sysfs_open_dirent_lock);
-	if (!od)
-		return;
-
-	mutex_lock(&sysfs_open_file_mutex);
-	list_for_each_entry(of, &od->files, list) {
-		struct inode *inode = file_inode(of->file);
-		unmap_mapping_range(inode->i_mapping, 0, 0, 1);
-	}
-	mutex_unlock(&sysfs_open_file_mutex);
-
-	sysfs_put_open_dirent(sd, NULL);
-}
-
-/* Sysfs attribute files are pollable.  The idea is that you read
- * the content and then you use 'poll' or 'select' to wait for
- * the content to change.  When the content changes (assuming the
- * manager for the kobject supports notification), poll will
- * return POLLERR|POLLPRI, and select will return the fd whether
- * it is waiting for read, write, or exceptions.
- * Once poll/select indicates that the value has changed, you
- * need to close and re-open the file, or seek to 0 and read again.
- * Reminder: this only works for attributes which actively support
- * it, and it is not possible to test an attribute from userspace
- * to see if it supports poll (Neither 'poll' nor 'select' return
- * an appropriate error code).  When in doubt, set a suitable timeout value.
- */
-static unsigned int kernfs_file_poll(struct file *filp, poll_table *wait)
-{
-	struct sysfs_open_file *of = sysfs_of(filp);
-	struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
-	struct sysfs_open_dirent *od = attr_sd->s_attr.open;
-
-	/* need parent for the kobj, grab both */
-	if (!sysfs_get_active(attr_sd))
-		goto trigger;
-
-	poll_wait(filp, &od->poll, wait);
-
-	sysfs_put_active(attr_sd);
-
-	if (of->event != atomic_read(&od->event))
-		goto trigger;
-
-	return DEFAULT_POLLMASK;
-
- trigger:
-	return DEFAULT_POLLMASK|POLLERR|POLLPRI;
-}
-
-/**
- * kernfs_notify - notify a kernfs file
- * @sd: file to notify
- *
- * Notify @sd such that poll(2) on @sd wakes up.
- */
-void kernfs_notify(struct sysfs_dirent *sd)
-{
-	struct sysfs_open_dirent *od;
-	unsigned long flags;
-
-	spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
-
-	if (!WARN_ON(sysfs_type(sd) != SYSFS_KOBJ_ATTR)) {
-		od = sd->s_attr.open;
-		if (od) {
-			atomic_inc(&od->event);
-			wake_up_interruptible(&od->poll);
-		}
-	}
-
-	spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
-}
-EXPORT_SYMBOL_GPL(kernfs_notify);
-
 void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
 {
 	struct sysfs_dirent *sd = k->sd, *tmp;
@@ -898,16 +170,6 @@ void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
 }
 EXPORT_SYMBOL_GPL(sysfs_notify);
 
-const struct file_operations kernfs_file_operations = {
-	.read		= kernfs_file_read,
-	.write		= kernfs_file_write,
-	.llseek		= generic_file_llseek,
-	.mmap		= kernfs_file_mmap,
-	.open		= kernfs_file_open,
-	.release	= kernfs_file_release,
-	.poll		= kernfs_file_poll,
-};
-
 static const struct kernfs_ops sysfs_file_kfops_empty = {
 };
 
@@ -996,68 +258,6 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 	return 0;
 }
 
-/**
- * kernfs_create_file_ns_key - create a file
- * @parent: directory to create the file in
- * @name: name of the file
- * @mode: mode of the file
- * @size: size of the file
- * @ops: kernfs operations for the file
- * @priv: private data for the file
- * @ns: optional namespace tag of the file
- * @key: lockdep key for the file's active_ref, %NULL to disable lockdep
- *
- * Returns the created node on success, ERR_PTR() value on error.
- */
-struct sysfs_dirent *kernfs_create_file_ns_key(struct sysfs_dirent *parent,
-					       const char *name,
-					       umode_t mode, loff_t size,
-					       const struct kernfs_ops *ops,
-					       void *priv, const void *ns,
-					       struct lock_class_key *key)
-{
-	struct sysfs_addrm_cxt acxt;
-	struct sysfs_dirent *sd;
-	int rc;
-
-	sd = sysfs_new_dirent(name, (mode & S_IALLUGO) | S_IFREG,
-			      SYSFS_KOBJ_ATTR);
-	if (!sd)
-		return ERR_PTR(-ENOMEM);
-
-	sd->s_attr.ops = ops;
-	sd->s_attr.size = size;
-	sd->s_ns = ns;
-	sd->priv = priv;
-
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-	if (key) {
-		lockdep_init_map(&sd->dep_map, "s_active", key, 0);
-		sd->s_flags |= SYSFS_FLAG_LOCKDEP;
-	}
-#endif
-
-	/*
-	 * sd->s_attr.ops is accesible only while holding active ref.  We
-	 * need to know whether some ops are implemented outside active
-	 * ref.  Cache their existence in flags.
-	 */
-	if (ops->seq_show)
-		sd->s_flags |= SYSFS_FLAG_HAS_SEQ_SHOW;
-	if (ops->mmap)
-		sd->s_flags |= SYSFS_FLAG_HAS_MMAP;
-
-	sysfs_addrm_start(&acxt);
-	rc = sysfs_add_one(&acxt, sd, parent);
-	sysfs_addrm_finish(&acxt);
-
-	if (rc) {
-		kernfs_put(sd);
-		return ERR_PTR(rc);
-	}
-	return sd;
-}
-
 int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
 		   bool is_bin)
 {
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 972b4a4..4b8b60d 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -41,15 +41,11 @@ void sysfs_warn_dup(struct sysfs_dirent *parent, const char *name);
 /*
  * file.c
  */
-extern const struct file_operations kernfs_file_operations;
-
 int sysfs_add_file(struct sysfs_dirent *dir_sd,
 		   const struct attribute *attr, bool is_bin);
-
 int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 			   const struct attribute *attr, bool is_bin,
 			   umode_t amode, const void *ns);
-void sysfs_unmap_bin_file(struct sysfs_dirent *sd);
 
 /*
  * symlink.c
-- 
1.8.4.2

[PATCH 22/34] sysfs, kernfs: move symlink core code to fs/kernfs/symlink.c

[Tejun Heo]

Move core symlink code to fs/kernfs/symlink.c.  fs/sysfs/symlink.c now
only contains sysfs wrappers around kernfs interfaces.  The respective
declarations in fs/sysfs/sysfs.h are moved to
fs/kernfs/kernfs-internal.h.

This is pure relocation.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/kernfs-internal.h |   5 ++
 fs/kernfs/symlink.c         | 139 ++++++++++++++++++++++++++++++++++++++++++++
 fs/sysfs/symlink.c          | 137 -------------------------------------------
 fs/sysfs/sysfs.h            |   1 -
 4 files changed, 144 insertions(+), 138 deletions(-)

diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 38e3a16..62ae35f 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -149,4 +149,9 @@ extern const struct file_operations kernfs_file_operations;
 
 void sysfs_unmap_bin_file(struct sysfs_dirent *sd);
 
+/*
+ * symlink.c
+ */
+extern const struct inode_operations sysfs_symlink_inode_operations;
+
 #endif	/* __KERNFS_INTERNAL_H */
diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c
index 2578715..af3570b 100644
--- a/fs/kernfs/symlink.c
+++ b/fs/kernfs/symlink.c
@@ -7,3 +7,142 @@
  *
  * This file is released under the GPLv2.
  */
+
+#include <linux/fs.h>
+#include <linux/gfp.h>
+#include <linux/namei.h>
+
+#include "kernfs-internal.h"
+
+/**
+ * kernfs_create_link - create a symlink
+ * @parent: directory to create the symlink in
+ * @name: name of the symlink
+ * @target: target node for the symlink to point to
+ *
+ * Returns the created node on success, ERR_PTR() value on error.
+ */
+struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
+					const char *name,
+					struct sysfs_dirent *target)
+{
+	struct sysfs_dirent *sd;
+	struct sysfs_addrm_cxt acxt;
+	int error;
+
+	sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
+	if (!sd)
+		return ERR_PTR(-ENOMEM);
+
+	if (parent->s_flags & SYSFS_FLAG_NS)
+		sd->s_ns = target->s_ns;
+	sd->s_symlink.target_sd = target;
+	kernfs_get(target);	/* ref owned by symlink */
+
+	sysfs_addrm_start(&acxt);
+	error = sysfs_add_one(&acxt, sd, parent);
+	sysfs_addrm_finish(&acxt);
+
+	if (!error)
+		return sd;
+
+	kernfs_put(sd);
+	return ERR_PTR(error);
+}
+
+static int sysfs_get_target_path(struct sysfs_dirent *parent_sd,
+				 struct sysfs_dirent *target_sd, char *path)
+{
+	struct sysfs_dirent *base, *sd;
+	char *s = path;
+	int len = 0;
+
+	/* go up to the root, stop at the base */
+	base = parent_sd;
+	while (base->s_parent) {
+		sd = target_sd->s_parent;
+		while (sd->s_parent && base != sd)
+			sd = sd->s_parent;
+
+		if (base == sd)
+			break;
+
+		strcpy(s, "../");
+		s += 3;
+		base = base->s_parent;
+	}
+
+	/* determine end of target string for reverse fillup */
+	sd = target_sd;
+	while (sd->s_parent && sd != base) {
+		len += strlen(sd->s_name) + 1;
+		sd = sd->s_parent;
+	}
+
+	/* check limits */
+	if (len < 2)
+		return -EINVAL;
+	len--;
+	if ((s - path) + len > PATH_MAX)
+		return -ENAMETOOLONG;
+
+	/* reverse fillup of target string from target to base */
+	sd = target_sd;
+	while (sd->s_parent && sd != base) {
+		int slen = strlen(sd->s_name);
+
+		len -= slen;
+		strncpy(s + len, sd->s_name, slen);
+		if (len)
+			s[--len] = '/';
+
+		sd = sd->s_parent;
+	}
+
+	return 0;
+}
+
+static int sysfs_getlink(struct dentry *dentry, char *path)
+{
+	struct sysfs_dirent *sd = dentry->d_fsdata;
+	struct sysfs_dirent *parent_sd = sd->s_parent;
+	struct sysfs_dirent *target_sd = sd->s_symlink.target_sd;
+	int error;
+
+	mutex_lock(&sysfs_mutex);
+	error = sysfs_get_target_path(parent_sd, target_sd, path);
+	mutex_unlock(&sysfs_mutex);
+
+	return error;
+}
+
+static void *sysfs_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+	int error = -ENOMEM;
+	unsigned long page = get_zeroed_page(GFP_KERNEL);
+	if (page) {
+		error = sysfs_getlink(dentry, (char *) page);
+		if (error < 0)
+			free_page((unsigned long)page);
+	}
+	nd_set_link(nd, error ? ERR_PTR(error) : (char *)page);
+	return NULL;
+}
+
+static void sysfs_put_link(struct dentry *dentry, struct nameidata *nd,
+			   void *cookie)
+{
+	char *page = nd_get_link(nd);
+	if (!IS_ERR(page))
+		free_page((unsigned long)page);
+}
+
+const struct inode_operations sysfs_symlink_inode_operations = {
+	.setxattr	= sysfs_setxattr,
+	.readlink	= generic_readlink,
+	.follow_link	= sysfs_follow_link,
+	.put_link	= sysfs_put_link,
+	.setattr	= sysfs_setattr,
+	.getattr	= sysfs_getattr,
+	.permission	= sysfs_permission,
+};
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index b137aa3..6797c9c 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -11,53 +11,13 @@
  */
 
 #include <linux/fs.h>
-#include <linux/gfp.h>
-#include <linux/mount.h>
 #include <linux/module.h>
 #include <linux/kobject.h>
-#include <linux/namei.h>
 #include <linux/mutex.h>
 #include <linux/security.h>
 
 #include "sysfs.h"
 
-/**
- * kernfs_create_link - create a symlink
- * @parent: directory to create the symlink in
- * @name: name of the symlink
- * @target: target node for the symlink to point to
- *
- * Returns the created node on success, ERR_PTR() value on error.
- */
-struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
-					const char *name,
-					struct sysfs_dirent *target)
-{
-	struct sysfs_dirent *sd;
-	struct sysfs_addrm_cxt acxt;
-	int error;
-
-	sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
-	if (!sd)
-		return ERR_PTR(-ENOMEM);
-
-	if (parent->s_flags & SYSFS_FLAG_NS)
-		sd->s_ns = target->s_ns;
-	sd->s_symlink.target_sd = target;
-	kernfs_get(target);	/* ref owned by symlink */
-
-	sysfs_addrm_start(&acxt);
-	error = sysfs_add_one(&acxt, sd, parent);
-	sysfs_addrm_finish(&acxt);
-
-	if (!error)
-		return sd;
-
-	kernfs_put(sd);
-	return ERR_PTR(error);
-}
-
-
 static int sysfs_do_create_link_sd(struct sysfs_dirent *parent_sd,
 				   struct kobject *target,
 				   const char *name, int warn)
@@ -235,100 +195,3 @@ out:
 	return result;
 }
 EXPORT_SYMBOL_GPL(sysfs_rename_link_ns);
-
-static int sysfs_get_target_path(struct sysfs_dirent *parent_sd,
-				 struct sysfs_dirent *target_sd, char *path)
-{
-	struct sysfs_dirent *base, *sd;
-	char *s = path;
-	int len = 0;
-
-	/* go up to the root, stop at the base */
-	base = parent_sd;
-	while (base->s_parent) {
-		sd = target_sd->s_parent;
-		while (sd->s_parent && base != sd)
-			sd = sd->s_parent;
-
-		if (base == sd)
-			break;
-
-		strcpy(s, "../");
-		s += 3;
-		base = base->s_parent;
-	}
-
-	/* determine end of target string for reverse fillup */
-	sd = target_sd;
-	while (sd->s_parent && sd != base) {
-		len += strlen(sd->s_name) + 1;
-		sd = sd->s_parent;
-	}
-
-	/* check limits */
-	if (len < 2)
-		return -EINVAL;
-	len--;
-	if ((s - path) + len > PATH_MAX)
-		return -ENAMETOOLONG;
-
-	/* reverse fillup of target string from target to base */
-	sd = target_sd;
-	while (sd->s_parent && sd != base) {
-		int slen = strlen(sd->s_name);
-
-		len -= slen;
-		strncpy(s + len, sd->s_name, slen);
-		if (len)
-			s[--len] = '/';
-
-		sd = sd->s_parent;
-	}
-
-	return 0;
-}
-
-static int sysfs_getlink(struct dentry *dentry, char *path)
-{
-	struct sysfs_dirent *sd = dentry->d_fsdata;
-	struct sysfs_dirent *parent_sd = sd->s_parent;
-	struct sysfs_dirent *target_sd = sd->s_symlink.target_sd;
-	int error;
-
-	mutex_lock(&sysfs_mutex);
-	error = sysfs_get_target_path(parent_sd, target_sd, path);
-	mutex_unlock(&sysfs_mutex);
-
-	return error;
-}
-
-static void *sysfs_follow_link(struct dentry *dentry, struct nameidata *nd)
-{
-	int error = -ENOMEM;
-	unsigned long page = get_zeroed_page(GFP_KERNEL);
-	if (page) {
-		error = sysfs_getlink(dentry, (char *) page);
-		if (error < 0)
-			free_page((unsigned long)page);
-	}
-	nd_set_link(nd, error ? ERR_PTR(error) : (char *)page);
-	return NULL;
-}
-
-static void sysfs_put_link(struct dentry *dentry, struct nameidata *nd,
-			   void *cookie)
-{
-	char *page = nd_get_link(nd);
-	if (!IS_ERR(page))
-		free_page((unsigned long)page);
-}
-
-const struct inode_operations sysfs_symlink_inode_operations = {
-	.setxattr	= sysfs_setxattr,
-	.readlink	= generic_readlink,
-	.follow_link	= sysfs_follow_link,
-	.put_link	= sysfs_put_link,
-	.setattr	= sysfs_setattr,
-	.getattr	= sysfs_getattr,
-	.permission	= sysfs_permission,
-};
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 4b8b60d..6d0dcea 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -50,7 +50,6 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 /*
  * symlink.c
  */
-extern const struct inode_operations sysfs_symlink_inode_operations;
 int sysfs_create_link_sd(struct sysfs_dirent *sd, struct kobject *target,
 			 const char *name);
 
-- 
1.8.4.2

[PATCH 23/34] sysfs, kernfs: drop unused params from sysfs_fill_super()

[Tejun Heo]

sysfs_fill_super() takes three params - @sb, @data and @silent - but
uses only @sb.  Drop the latter two.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/mount.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 852d115..21070c2 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -41,7 +41,7 @@ struct sysfs_dirent sysfs_root = {
 	.s_ino		= 1,
 };
 
-static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
+static int sysfs_fill_super(struct super_block *sb)
 {
 	struct inode *inode;
 	struct dentry *root;
@@ -123,7 +123,7 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 	if (IS_ERR(sb))
 		return ERR_CAST(sb);
 	if (!sb->s_root) {
-		error = sysfs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
+		error = sysfs_fill_super(sb);
 		if (error) {
 			deactivate_locked_super(sb);
 			return ERR_PTR(error);
-- 
1.8.4.2

[PATCH 24/34] sysfs, kernfs: make sysfs_super_info->ns const

[Tejun Heo]

Add const qualifier to sysfs_super_info->ns so that it's consistent
with other namespace tag usages in sysfs.  Because kobject doesn't use
const qualifier for namespace tags, this ends up requiring an explicit
cast to drop const qualifier in free_sysfs_super_info().

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/mount.c |  2 +-
 fs/sysfs/sysfs.h | 14 +++++++-------
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 21070c2..fcbe5e8 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -92,7 +92,7 @@ static int sysfs_set_super(struct super_block *sb, void *data)
 
 static void free_sysfs_super_info(struct sysfs_super_info *info)
 {
-	kobj_ns_drop(KOBJ_NS_TYPE_NET, info->ns);
+	kobj_ns_drop(KOBJ_NS_TYPE_NET, (void *)info->ns);
 	kfree(info);
 }
 
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 6d0dcea..ce97907 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -18,14 +18,14 @@
  * mount.c
  */
 
-/*
- * Each sb is associated with one namespace tag, currently the network
- * namespace of the task which mounted this sysfs instance.  If multiple
- * tags become necessary, make the following an array and compare
- * sysfs_dirent tag against every entry.
- */
 struct sysfs_super_info {
-	void *ns;
+	/*
+	 * Each sb is associated with one namespace tag, currently the network
+	 * namespace of the task which mounted this sysfs instance.  If multiple
+	 * tags become necessary, make the following an array and compare
+	 * sysfs_dirent tag against every entry.
+	 */
+	const void		*ns;
 };
 #define sysfs_info(SB) ((struct sysfs_super_info *)(SB->s_fs_info))
 extern struct sysfs_dirent sysfs_root;
-- 
1.8.4.2

[PATCH 25/34] sysfs, kernfs: no need to kern_mount() sysfs from sysfs_init()

[Tejun Heo]

It has been very long since sysfs depended on vfs to keep track of
internal states and whether sysfs is mounted or not doesn't make any
difference to sysfs's internal operation.

In addition to init and filesystem type registration, sysfs_init()
invokes kern_mount() to create in-kernel mount of sysfs.  This
internal mounting doesn't server any purpose anymore.  Remove it.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/mount.c | 23 +++++++----------------
 1 file changed, 7 insertions(+), 16 deletions(-)

diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index fcbe5e8..0c80f03 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -24,7 +24,6 @@
 #include "sysfs.h"
 
 
-static struct vfsmount *sysfs_mnt;
 struct kmem_cache *sysfs_dir_cachep;
 
 static const struct super_operations sysfs_ops = {
@@ -153,34 +152,26 @@ static struct file_system_type sysfs_fs_type = {
 
 int __init sysfs_init(void)
 {
-	int err = -ENOMEM;
+	int err;
 
 	sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
 					      sizeof(struct sysfs_dirent),
 					      0, 0, NULL);
 	if (!sysfs_dir_cachep)
-		goto out;
+		return -ENOMEM;
 
 	err = sysfs_inode_init();
 	if (err)
 		goto out_err;
 
 	err = register_filesystem(&sysfs_fs_type);
-	if (!err) {
-		sysfs_mnt = kern_mount(&sysfs_fs_type);
-		if (IS_ERR(sysfs_mnt)) {
-			printk(KERN_ERR "sysfs: could not mount!\n");
-			err = PTR_ERR(sysfs_mnt);
-			sysfs_mnt = NULL;
-			unregister_filesystem(&sysfs_fs_type);
-			goto out_err;
-		}
-	} else
+	if (err)
 		goto out_err;
-out:
-	return err;
+
+	return 0;
+
 out_err:
 	kmem_cache_destroy(sysfs_dir_cachep);
 	sysfs_dir_cachep = NULL;
-	goto out;
+	return err;
 }
-- 
1.8.4.2

[PATCH 26/34] sysfs, kernfs: introduce sysfs_root_sd

[Tejun Heo]

Currently, it's assumed that there's a single kernfs hierarchy in the
system anchored at sysfs_root which is defined as a global struct.  To
allow other users of kernfs, this will be made dynamic.  Introduce a
new global variable sysfs_root_sd which points to &sysfs_root and
convert all &sysfs_root users.

This patch doesn't introduce any behavior difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/dir.c     | 4 ++--
 fs/sysfs/mount.c   | 8 +++++---
 fs/sysfs/symlink.c | 6 +++---
 fs/sysfs/sysfs.h   | 2 +-
 4 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index e5c4e71..2fea501 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -68,7 +68,7 @@ int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
 	if (kobj->parent)
 		parent_sd = kobj->parent->sd;
 	else
-		parent_sd = &sysfs_root;
+		parent_sd = sysfs_root_sd;
 
 	if (!parent_sd)
 		return -ENOENT;
@@ -134,7 +134,7 @@ int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
 
 	BUG_ON(!sd->s_parent);
 	new_parent_sd = new_parent_kobj && new_parent_kobj->sd ?
-		new_parent_kobj->sd : &sysfs_root;
+		new_parent_kobj->sd : sysfs_root_sd;
 
 	return kernfs_rename_ns(sd, new_parent_sd, sd->s_name, new_ns);
 }
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 0c80f03..7cbd1fc 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -32,7 +32,7 @@ static const struct super_operations sysfs_ops = {
 	.evict_inode	= sysfs_evict_inode,
 };
 
-struct sysfs_dirent sysfs_root = {
+static struct sysfs_dirent sysfs_root = {
 	.s_name		= "",
 	.s_count	= ATOMIC_INIT(1),
 	.s_flags	= SYSFS_DIR,
@@ -40,6 +40,8 @@ struct sysfs_dirent sysfs_root = {
 	.s_ino		= 1,
 };
 
+struct sysfs_dirent *sysfs_root_sd = &sysfs_root;
+
 static int sysfs_fill_super(struct super_block *sb)
 {
 	struct inode *inode;
@@ -53,7 +55,7 @@ static int sysfs_fill_super(struct super_block *sb)
 
 	/* get root inode, initialize and unlock it */
 	mutex_lock(&sysfs_mutex);
-	inode = sysfs_get_inode(sb, &sysfs_root);
+	inode = sysfs_get_inode(sb, sysfs_root_sd);
 	mutex_unlock(&sysfs_mutex);
 	if (!inode) {
 		pr_debug("sysfs: could not get root inode\n");
@@ -66,7 +68,7 @@ static int sysfs_fill_super(struct super_block *sb)
 		pr_debug("%s: could not get root dentry!\n", __func__);
 		return -ENOMEM;
 	}
-	root->d_fsdata = &sysfs_root;
+	root->d_fsdata = sysfs_root_sd;
 	sb->s_root = root;
 	sb->s_d_op = &sysfs_dentry_ops;
 	return 0;
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 6797c9c..62f0e01 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -70,7 +70,7 @@ static int sysfs_do_create_link(struct kobject *kobj, struct kobject *target,
 	struct sysfs_dirent *parent_sd = NULL;
 
 	if (!kobj)
-		parent_sd = &sysfs_root;
+		parent_sd = sysfs_root_sd;
 	else
 		parent_sd = kobj->sd;
 
@@ -144,7 +144,7 @@ void sysfs_remove_link(struct kobject *kobj, const char *name)
 	struct sysfs_dirent *parent_sd = NULL;
 
 	if (!kobj)
-		parent_sd = &sysfs_root;
+		parent_sd = sysfs_root_sd;
 	else
 		parent_sd = kobj->sd;
 
@@ -170,7 +170,7 @@ int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *targ,
 	int result;
 
 	if (!kobj)
-		parent_sd = &sysfs_root;
+		parent_sd = sysfs_root_sd;
 	else
 		parent_sd = kobj->sd;
 
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index ce97907..2b217ce 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -28,7 +28,7 @@ struct sysfs_super_info {
 	const void		*ns;
 };
 #define sysfs_info(SB) ((struct sysfs_super_info *)(SB->s_fs_info))
-extern struct sysfs_dirent sysfs_root;
+extern struct sysfs_dirent *sysfs_root_sd;
 extern struct kmem_cache *sysfs_dir_cachep;
 
 /*
-- 
1.8.4.2

[PATCH 27/34] sysfs, kernfs: implement kernfs_create/destroy_root()

[Tejun Heo]

There currently is single kernfs hierarchy in the whole system which
is used for sysfs.  kernfs needs to support multiple hierarchies to
allow other users.  This patch introduces struct kernfs_root which
serves as the root of each kernfs hierarchy and implements
kernfs_create/destroy_root().

* Each kernfs_root is associated with a root sd (sysfs_dentry).  The
  root is freed when the root sd is released and kernfs_destory_root()
  simply invokes kernfs_remove() on the root sd.  sysfs_remove_one()
  is updated to handle release of the root sd.  Note that ps_iattr
  update in sysfs_remove_one() is trivially updated for readability.

* Root sd's are now dynamically allocated using sysfs_new_dirent().
  Update sysfs_alloc_ino() so that it gives out ino from 1 so that the
  root sd still gets ino 1.

* While kernfs currently only points to the root sd, it'll soon grow
  fields which are specific to each hierarchy.  As determining a given
  sd's root will be necessary, sd->s_dir.root is added.  This backlink
  fits better as a separate field in sd; however, sd->s_dir is inside
  union with space to spare, so use it to save space and provide
  kernfs_root() accessor to determine the root sd.

* As hierarchies may be destroyed now, each mount needs to hold onto
  the hierarchy it's attached to.  Update sysfs_fill_super() and
  sysfs_kill_sb() so that they get and put the kernfs_root
  respectively.

* sysfs_root is replaced with kernfs_root which is dynamically created
  by invoking kernfs_create_root() from sysfs_init().

This patch doesn't introduce any visible behavior changes.

v2: kernfs_create_root() forgot to set @sd->priv.  Fixed.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/dir.c             | 71 +++++++++++++++++++++++++++++++++++++++------
 fs/kernfs/kernfs-internal.h | 20 +++++++++++++
 fs/sysfs/mount.c            | 29 +++++++++++-------
 include/linux/kernfs.h      | 13 +++++++++
 4 files changed, 113 insertions(+), 20 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index a4ca4de..246740a 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -211,7 +211,7 @@ static int sysfs_alloc_ino(unsigned int *pino)
 
  retry:
 	spin_lock(&sysfs_ino_lock);
-	rc = ida_get_new_above(&sysfs_ino_ida, 2, &ino);
+	rc = ida_get_new_above(&sysfs_ino_ida, 1, &ino);
 	spin_unlock(&sysfs_ino_lock);
 
 	if (rc == -EAGAIN) {
@@ -253,9 +253,11 @@ EXPORT_SYMBOL_GPL(kernfs_get);
 void kernfs_put(struct sysfs_dirent *sd)
 {
 	struct sysfs_dirent *parent_sd;
+	struct kernfs_root *root;
 
 	if (!sd || !atomic_dec_and_test(&sd->s_count))
 		return;
+	root = kernfs_root(sd);
  repeat:
 	/* Moving/renaming is always done while holding reference.
 	 * sd->s_parent won't change beneath us.
@@ -278,8 +280,13 @@ void kernfs_put(struct sysfs_dirent *sd)
 	kmem_cache_free(sysfs_dir_cachep, sd);
 
 	sd = parent_sd;
-	if (sd && atomic_dec_and_test(&sd->s_count))
-		goto repeat;
+	if (sd) {
+		if (atomic_dec_and_test(&sd->s_count))
+			goto repeat;
+	} else {
+		/* just released the root sd, free @root too */
+		kfree(root);
+	}
 }
 EXPORT_SYMBOL_GPL(kernfs_put);
 
@@ -493,13 +500,15 @@ static void sysfs_remove_one(struct sysfs_addrm_cxt *acxt,
 	if (sd->s_flags & SYSFS_FLAG_REMOVED)
 		return;
 
-	sysfs_unlink_sibling(sd);
+	if (sd->s_parent) {
+		sysfs_unlink_sibling(sd);
 
-	/* Update timestamps on the parent */
-	ps_iattr = sd->s_parent->s_iattr;
-	if (ps_iattr) {
-		struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
-		ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
+		/* Update timestamps on the parent */
+		ps_iattr = sd->s_parent->s_iattr;
+		if (ps_iattr) {
+			ps_iattr->ia_iattr.ia_ctime = CURRENT_TIME;
+			ps_iattr->ia_iattr.ia_mtime = CURRENT_TIME;
+		}
 	}
 
 	sd->s_flags |= SYSFS_FLAG_REMOVED;
@@ -604,6 +613,49 @@ struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
 EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns);
 
 /**
+ * kernfs_create_root - create a new kernfs hierarchy
+ * @priv: opaque data associated with the new directory
+ *
+ * Returns the root of the new hierarchy on success, ERR_PTR() value on
+ * failure.
+ */
+struct kernfs_root *kernfs_create_root(void *priv)
+{
+	struct kernfs_root *root;
+	struct sysfs_dirent *sd;
+
+	root = kzalloc(sizeof(*root), GFP_KERNEL);
+	if (!root)
+		return ERR_PTR(-ENOMEM);
+
+	sd = sysfs_new_dirent("", S_IFDIR | S_IRUGO | S_IXUGO, SYSFS_DIR);
+	if (!sd) {
+		kfree(root);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	sd->s_flags &= ~SYSFS_FLAG_REMOVED;
+	sd->priv = priv;
+	sd->s_dir.root = root;
+
+	root->sd = sd;
+
+	return root;
+}
+
+/**
+ * kernfs_destroy_root - destroy a kernfs hierarchy
+ * @root: root of the hierarchy to destroy
+ *
+ * Destroy the hierarchy anchored at @root by removing all existing
+ * directories and destroying @root.
+ */
+void kernfs_destroy_root(struct kernfs_root *root)
+{
+	kernfs_remove(root->sd);	/* will also free @root */
+}
+
+/**
  * kernfs_create_dir_ns - create a directory
  * @parent: parent in which to create a new directory
  * @name: name of the new directory
@@ -626,6 +678,7 @@ struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
 	if (!sd)
 		return ERR_PTR(-ENOMEM);
 
+	sd->s_dir.root = parent->s_dir.root;
 	sd->s_ns = ns;
 	sd->priv = priv;
 
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 62ae35f..7dfe062 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -25,6 +25,12 @@ struct sysfs_elem_dir {
 	unsigned long		subdirs;
 	/* children rbtree starts here and goes through sd->s_rb */
 	struct rb_root		children;
+
+	/*
+	 * The kernfs hierarchy this directory belongs to.  This fits
+	 * better directly in sysfs_dirent but is here to save space.
+	 */
+	struct kernfs_root	*root;
 };
 
 struct sysfs_elem_symlink {
@@ -104,6 +110,20 @@ static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
 	return sd->s_flags & SYSFS_TYPE_MASK;
 }
 
+/**
+ * kernfs_root - find out the kernfs_root a sysfs_dirent belongs to
+ * @sd: sysfs_dirent of interest
+ *
+ * Return the kernfs_root @sd belongs to.
+ */
+static inline struct kernfs_root *kernfs_root(struct sysfs_dirent *sd)
+{
+	/* if parent exists, it's always a dir; otherwise, @sd is a dir */
+	if (sd->s_parent)
+		sd = sd->s_parent;
+	return sd->s_dir.root;
+}
+
 /*
  * Context structure to be used while adding/removing nodes.
  */
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 7cbd1fc..0b5661b 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -32,15 +32,8 @@ static const struct super_operations sysfs_ops = {
 	.evict_inode	= sysfs_evict_inode,
 };
 
-static struct sysfs_dirent sysfs_root = {
-	.s_name		= "",
-	.s_count	= ATOMIC_INIT(1),
-	.s_flags	= SYSFS_DIR,
-	.s_mode		= S_IFDIR | S_IRUGO | S_IXUGO,
-	.s_ino		= 1,
-};
-
-struct sysfs_dirent *sysfs_root_sd = &sysfs_root;
+static struct kernfs_root *sysfs_root;
+struct sysfs_dirent *sysfs_root_sd;
 
 static int sysfs_fill_super(struct super_block *sb)
 {
@@ -68,6 +61,7 @@ static int sysfs_fill_super(struct super_block *sb)
 		pr_debug("%s: could not get root dentry!\n", __func__);
 		return -ENOMEM;
 	}
+	kernfs_get(sysfs_root_sd);
 	root->d_fsdata = sysfs_root_sd;
 	sb->s_root = root;
 	sb->s_d_op = &sysfs_dentry_ops;
@@ -138,11 +132,15 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 static void sysfs_kill_sb(struct super_block *sb)
 {
 	struct sysfs_super_info *info = sysfs_info(sb);
-	/* Remove the superblock from fs_supers/s_instances
+	struct sysfs_dirent *root_sd = sb->s_root->d_fsdata;
+
+	/*
+	 * Remove the superblock from fs_supers/s_instances
 	 * so we can't find it, before freeing sysfs_super_info.
 	 */
 	kill_anon_super(sb);
 	free_sysfs_super_info(info);
+	kernfs_put(root_sd);
 }
 
 static struct file_system_type sysfs_fs_type = {
@@ -166,12 +164,21 @@ int __init sysfs_init(void)
 	if (err)
 		goto out_err;
 
+	sysfs_root = kernfs_create_root(NULL);
+	if (IS_ERR(sysfs_root)) {
+		err = PTR_ERR(sysfs_root);
+		goto out_err;
+	}
+	sysfs_root_sd = sysfs_root->sd;
+
 	err = register_filesystem(&sysfs_fs_type);
 	if (err)
-		goto out_err;
+		goto out_destroy_root;
 
 	return 0;
 
+out_destroy_root:
+	kernfs_destroy_root(sysfs_root);
 out_err:
 	kmem_cache_destroy(sysfs_dir_cachep);
 	sysfs_dir_cachep = NULL;
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index fd8f574..f75548b 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -20,6 +20,11 @@ struct vm_area_struct;
 
 struct sysfs_dirent;
 
+struct kernfs_root {
+	/* published fields */
+	struct sysfs_dirent	*sd;
+};
+
 struct sysfs_open_file {
 	/* published fields */
 	struct sysfs_dirent	*sd;
@@ -76,6 +81,9 @@ struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
 void kernfs_get(struct sysfs_dirent *sd);
 void kernfs_put(struct sysfs_dirent *sd);
 
+struct kernfs_root *kernfs_create_root(void *priv);
+void kernfs_destroy_root(struct kernfs_root *root);
+
 struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
 					  const char *name, void *priv,
 					  const void *ns);
@@ -107,6 +115,11 @@ kernfs_find_and_get_ns(struct sysfs_dirent *parent, const char *name,
 static inline void kernfs_get(struct sysfs_dirent *sd) { }
 static inline void kernfs_put(struct sysfs_dirent *sd) { }
 
+static inline struct kernfs_root *kernfs_create_root(void *priv)
+{ return ERR_PTR(-ENOSYS); }
+
+static inline void kernfs_destroy_root(struct kernfs_root *root) { }
+
 static inline struct sysfs_dirent *
 kernfs_create_dir_ns(struct sysfs_dirent *parent, const char *name, void *priv,
 		     const void *ns)
-- 
1.8.4.2

[PATCH 28/34] sysfs, kernfs: make inode number ida per kernfs_root

[Tejun Heo]

kernfs is being updated to allow multiple sysfs_dirent hierarchies so
that it can also be used by other users.  Currently, inode number is
allocated using a global ida, sysfs_ino_ida; however, inos for
different hierarchies should be handled separately.

This patch makes ino allocation per kernfs_root.  sysfs_ino_ida is
replaced by kernfs_root->ino_ida and sysfs_new_dirent() is updated to
take @root and allocate ino from it.  ida_simple_get/remove() are used
instead of sysfs_ino_lock and sysfs_alloc/free_ino().

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/dir.c             | 47 +++++++++++++--------------------------------
 fs/kernfs/file.c            |  4 ++--
 fs/kernfs/kernfs-internal.h |  3 ++-
 fs/kernfs/symlink.c         |  3 ++-
 include/linux/kernfs.h      |  4 ++++
 5 files changed, 23 insertions(+), 38 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 246740a..eaffa83 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -21,9 +21,6 @@ DEFINE_MUTEX(sysfs_mutex);
 
 #define to_sysfs_dirent(X) rb_entry((X), struct sysfs_dirent, s_rb)
 
-static DEFINE_SPINLOCK(sysfs_ino_lock);
-static DEFINE_IDA(sysfs_ino_ida);
-
 /**
  *	sysfs_name_hash
  *	@name: Null terminated string to hash
@@ -205,32 +202,6 @@ static void sysfs_deactivate(struct sysfs_dirent *sd)
 	rwsem_release(&sd->dep_map, 1, _RET_IP_);
 }
 
-static int sysfs_alloc_ino(unsigned int *pino)
-{
-	int ino, rc;
-
- retry:
-	spin_lock(&sysfs_ino_lock);
-	rc = ida_get_new_above(&sysfs_ino_ida, 1, &ino);
-	spin_unlock(&sysfs_ino_lock);
-
-	if (rc == -EAGAIN) {
-		if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL))
-			goto retry;
-		rc = -ENOMEM;
-	}
-
-	*pino = ino;
-	return rc;
-}
-
-static void sysfs_free_ino(unsigned int ino)
-{
-	spin_lock(&sysfs_ino_lock);
-	ida_remove(&sysfs_ino_ida, ino);
-	spin_unlock(&sysfs_ino_lock);
-}
-
 /**
  * kernfs_get - get a reference count on a sysfs_dirent
  * @sd: the target sysfs_dirent
@@ -276,7 +247,7 @@ void kernfs_put(struct sysfs_dirent *sd)
 		security_release_secctx(sd->s_iattr->ia_secdata,
 					sd->s_iattr->ia_secdata_len);
 	kfree(sd->s_iattr);
-	sysfs_free_ino(sd->s_ino);
+	ida_simple_remove(&root->ino_ida, sd->s_ino);
 	kmem_cache_free(sysfs_dir_cachep, sd);
 
 	sd = parent_sd;
@@ -285,6 +256,7 @@ void kernfs_put(struct sysfs_dirent *sd)
 			goto repeat;
 	} else {
 		/* just released the root sd, free @root too */
+		ida_destroy(&root->ino_ida);
 		kfree(root);
 	}
 }
@@ -360,10 +332,12 @@ const struct dentry_operations sysfs_dentry_ops = {
 	.d_release	= sysfs_dentry_release,
 };
 
-struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
+struct sysfs_dirent *sysfs_new_dirent(struct kernfs_root *root,
+				      const char *name, umode_t mode, int type)
 {
 	char *dup_name = NULL;
 	struct sysfs_dirent *sd;
+	int ret;
 
 	if (type & SYSFS_COPY_NAME) {
 		name = dup_name = kstrdup(name, GFP_KERNEL);
@@ -375,8 +349,10 @@ struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
 	if (!sd)
 		goto err_out1;
 
-	if (sysfs_alloc_ino(&sd->s_ino))
+	ret = ida_simple_get(&root->ino_ida, 1, 0, GFP_KERNEL);
+	if (ret < 0)
 		goto err_out2;
+	sd->s_ino = ret;
 
 	atomic_set(&sd->s_count, 1);
 	atomic_set(&sd->s_active, 0);
@@ -628,8 +604,11 @@ struct kernfs_root *kernfs_create_root(void *priv)
 	if (!root)
 		return ERR_PTR(-ENOMEM);
 
-	sd = sysfs_new_dirent("", S_IFDIR | S_IRUGO | S_IXUGO, SYSFS_DIR);
+	ida_init(&root->ino_ida);
+
+	sd = sysfs_new_dirent(root, "", S_IFDIR | S_IRUGO | S_IXUGO, SYSFS_DIR);
 	if (!sd) {
+		ida_destroy(&root->ino_ida);
 		kfree(root);
 		return ERR_PTR(-ENOMEM);
 	}
@@ -674,7 +653,7 @@ struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
 	int rc;
 
 	/* allocate */
-	sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
+	sd = sysfs_new_dirent(kernfs_root(parent), name, mode, SYSFS_DIR);
 	if (!sd)
 		return ERR_PTR(-ENOMEM);
 
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index fa172e8..990c97f 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -775,8 +775,8 @@ struct sysfs_dirent *kernfs_create_file_ns_key(struct sysfs_dirent *parent,
 	struct sysfs_dirent *sd;
 	int rc;
 
-	sd = sysfs_new_dirent(name, (mode & S_IALLUGO) | S_IFREG,
-			      SYSFS_KOBJ_ATTR);
+	sd = sysfs_new_dirent(kernfs_root(parent), name,
+			      (mode & S_IALLUGO) | S_IFREG, SYSFS_KOBJ_ATTR);
 	if (!sd)
 		return ERR_PTR(-ENOMEM);
 
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 7dfe062..466943d 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -160,7 +160,8 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt);
 int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
 		  struct sysfs_dirent *parent_sd);
 void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
-struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);
+struct sysfs_dirent *sysfs_new_dirent(struct kernfs_root *root,
+				      const char *name, umode_t mode, int type);
 
 /*
  * file.c
diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c
index af3570b..004c164 100644
--- a/fs/kernfs/symlink.c
+++ b/fs/kernfs/symlink.c
@@ -30,7 +30,8 @@ struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
 	struct sysfs_addrm_cxt acxt;
 	int error;
 
-	sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
+	sd = sysfs_new_dirent(kernfs_root(parent), name, S_IFLNK|S_IRWXUGO,
+			      SYSFS_KOBJ_LINK);
 	if (!sd)
 		return ERR_PTR(-ENOMEM);
 
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index f75548b..fad8b98 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -11,6 +11,7 @@
 #include <linux/err.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
+#include <linux/idr.h>
 #include <linux/lockdep.h>
 
 struct file;
@@ -23,6 +24,9 @@ struct sysfs_dirent;
 struct kernfs_root {
 	/* published fields */
 	struct sysfs_dirent	*sd;
+
+	/* private fields, do not use outside kernfs proper */
+	struct ida		ino_ida;
 };
 
 struct sysfs_open_file {
-- 
1.8.4.2

[PATCH 29/34] sysfs, kernfs: make super_blocks bind to different kernfs_roots

[Tejun Heo]

kernfs is being updated to allow multiple sysfs_dirent hierarchies so
that it can also be used by other users.  Currently, sysfs
super_blocks are always attached to one kernfs_root - sysfs_root - and
distinguished only by their namespace tags.

This patch adds sysfs_super_info->root and update
sysfs_fill/test_super() so that super_blocks are identified by the
combination of both the associated kernfs_root and namespace tag.
This allows mounting different kernfs hierarchies.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/sysfs/mount.c | 10 ++++++----
 fs/sysfs/sysfs.h |  6 ++++++
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 0b5661b..f143b20 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -37,6 +37,7 @@ struct sysfs_dirent *sysfs_root_sd;
 
 static int sysfs_fill_super(struct super_block *sb)
 {
+	struct sysfs_super_info *info = sysfs_info(sb);
 	struct inode *inode;
 	struct dentry *root;
 
@@ -48,7 +49,7 @@ static int sysfs_fill_super(struct super_block *sb)
 
 	/* get root inode, initialize and unlock it */
 	mutex_lock(&sysfs_mutex);
-	inode = sysfs_get_inode(sb, sysfs_root_sd);
+	inode = sysfs_get_inode(sb, info->root->sd);
 	mutex_unlock(&sysfs_mutex);
 	if (!inode) {
 		pr_debug("sysfs: could not get root inode\n");
@@ -61,8 +62,8 @@ static int sysfs_fill_super(struct super_block *sb)
 		pr_debug("%s: could not get root dentry!\n", __func__);
 		return -ENOMEM;
 	}
-	kernfs_get(sysfs_root_sd);
-	root->d_fsdata = sysfs_root_sd;
+	kernfs_get(info->root->sd);
+	root->d_fsdata = info->root->sd;
 	sb->s_root = root;
 	sb->s_d_op = &sysfs_dentry_ops;
 	return 0;
@@ -73,7 +74,7 @@ static int sysfs_test_super(struct super_block *sb, void *data)
 	struct sysfs_super_info *sb_info = sysfs_info(sb);
 	struct sysfs_super_info *info = data;
 
-	return sb_info->ns == info->ns;
+	return sb_info->root == info->root && sb_info->ns == info->ns;
 }
 
 static int sysfs_set_super(struct super_block *sb, void *data)
@@ -110,6 +111,7 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 	if (!info)
 		return ERR_PTR(-ENOMEM);
 
+	info->root = sysfs_root;
 	info->ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
 
 	sb = sget(fs_type, sysfs_test_super, sysfs_set_super, flags, info);
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 2b217ce..93b4b68 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -20,6 +20,12 @@
 
 struct sysfs_super_info {
 	/*
+	 * The root associated with this super_block.  Each super_block is
+	 * identified by the root and ns it's associated with.
+	 */
+	struct kernfs_root	*root;
+
+	/*
 	 * Each sb is associated with one namespace tag, currently the network
 	 * namespace of the task which mounted this sysfs instance.  If multiple
 	 * tags become necessary, make the following an array and compare
-- 
1.8.4.2

[PATCH 30/34] sysfs, kernfs: prepare mount path for kernfs

[Tejun Heo]

We're in the process of separating out core sysfs functionality into
kernfs which will deal with sysfs_dirents directly.  This patch
rearranges mount path so that the kernfs and sysfs parts are separate.

* As sysfs_super_info won't be visible outside kernfs proper,
  kernfs_super_ns() is added to allow kernfs users to access a
  super_block's namespace tag.

* Generic mount operation is separated out into kernfs_mount_ns().
  sysfs_mount() now just performs sysfs-specific permission check,
  acquires namespace tag, and invokes kernfs_mount_ns().

* Generic superblock release is separated out into kernfs_kill_sb()
  which can be used directly as file_system_type->kill_sb().  As sysfs
  needs to put the namespace tag, sysfs_kill_sb() wraps
  kernfs_kill_sb() with ns tag put.

* sysfs_dir_cachep init and sysfs_inode_init() are separated out into
  kernfs_init().  kernfs_init() uses only small amount of memory and
  trying to handle and propagate kernfs_init() failure doesn't make
  much sense.  Use SLAB_PANIC for sysfs_dir_cachep and make
  sysfs_inode_init() panic on failure.

  After this change, kernfs_init() should be called before
  sysfs_init(), fs/namespace.c::mnt_init() modified accordingly.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: Christoph Hellwig <hch@infradead.org>
---
 fs/kernfs/inode.c           |   5 ++-
 fs/kernfs/kernfs-internal.h |   2 +-
 fs/namespace.c              |   2 +
 fs/sysfs/mount.c            | 104 ++++++++++++++++++++++++++++++--------------
 include/linux/kernfs.h      |  28 ++++++++++++
 5 files changed, 106 insertions(+), 35 deletions(-)

diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 9d4fab4..b4cae6f 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -37,9 +37,10 @@ static const struct inode_operations sysfs_inode_operations = {
 	.setxattr	= sysfs_setxattr,
 };
 
-int __init sysfs_inode_init(void)
+void __init sysfs_inode_init(void)
 {
-	return bdi_init(&sysfs_backing_dev_info);
+	if (bdi_init(&sysfs_backing_dev_info))
+		panic("failed to init sysfs_backing_dev_info");
 }
 
 static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 466943d..0d94988 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -144,7 +144,7 @@ int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
 		  struct kstat *stat);
 int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
 		   size_t size, int flags);
-int sysfs_inode_init(void);
+void sysfs_inode_init(void);
 
 /*
  * dir.c
diff --git a/fs/namespace.c b/fs/namespace.c
index ac2ce8a..a511ea0 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2790,6 +2790,8 @@ void __init mnt_init(void)
 	for (u = 0; u < HASH_SIZE; u++)
 		INIT_LIST_HEAD(&mountpoint_hashtable[u]);
 
+	kernfs_init();
+
 	err = sysfs_init();
 	if (err)
 		printk(KERN_WARNING "%s: sysfs_init error: %d\n",
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index f143b20..5384732 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -86,18 +86,24 @@ static int sysfs_set_super(struct super_block *sb, void *data)
 	return error;
 }
 
-static void free_sysfs_super_info(struct sysfs_super_info *info)
+/**
+ * kernfs_super_ns - determine the namespace tag of a kernfs super_block
+ * @sb: super_block of interest
+ *
+ * Return the namespace tag associated with kernfs super_block @sb.
+ */
+const void *kernfs_super_ns(struct super_block *sb)
 {
-	kobj_ns_drop(KOBJ_NS_TYPE_NET, (void *)info->ns);
-	kfree(info);
+	struct sysfs_super_info *info = sysfs_info(sb);
+
+	return info->ns;
 }
 
 static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data)
 {
-	struct sysfs_super_info *info;
-	struct super_block *sb;
-	int error;
+	struct dentry *root;
+	void *ns;
 
 	if (!(flags & MS_KERNMOUNT)) {
 		if (!capable(CAP_SYS_ADMIN) && !fs_fully_visible(fs_type))
@@ -107,16 +113,44 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 			return ERR_PTR(-EPERM);
 	}
 
+	ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
+	root = kernfs_mount_ns(fs_type, flags, sysfs_root, ns);
+	if (IS_ERR(root))
+		kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
+	return root;
+}
+
+/**
+ * kernfs_mount_ns - kernfs mount helper
+ * @fs_type: file_system_type of the fs being mounted
+ * @flags: mount flags specified for the mount
+ * @root: kernfs_root of the hierarchy being mounted
+ * @ns: optional namespace tag of the mount
+ *
+ * This is to be called from each kernfs user's file_system_type->mount()
+ * implementation, which should pass through the specified @fs_type and
+ * @flags, and specify the hierarchy and namespace tag to mount via @root
+ * and @ns, respectively.
+ *
+ * The return value can be passed to the vfs layer verbatim.
+ */
+struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
+			       struct kernfs_root *root, const void *ns)
+{
+	struct super_block *sb;
+	struct sysfs_super_info *info;
+	int error;
+
 	info = kzalloc(sizeof(*info), GFP_KERNEL);
 	if (!info)
 		return ERR_PTR(-ENOMEM);
 
-	info->root = sysfs_root;
-	info->ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
+	info->root = root;
+	info->ns = ns;
 
 	sb = sget(fs_type, sysfs_test_super, sysfs_set_super, flags, info);
 	if (IS_ERR(sb) || sb->s_fs_info != info)
-		free_sysfs_super_info(info);
+		kfree(info);
 	if (IS_ERR(sb))
 		return ERR_CAST(sb);
 	if (!sb->s_root) {
@@ -133,6 +167,20 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 
 static void sysfs_kill_sb(struct super_block *sb)
 {
+	kernfs_kill_sb(sb);
+	kobj_ns_drop(KOBJ_NS_TYPE_NET, (void *)kernfs_super_ns(sb));
+}
+
+/**
+ * kernfs_kill_sb - kill_sb for kernfs
+ * @sb: super_block being killed
+ *
+ * This can be used directly for file_system_type->kill_sb().  If a kernfs
+ * user needs extra cleanup, it can implement its own kill_sb() and call
+ * this function at the end.
+ */
+void kernfs_kill_sb(struct super_block *sb)
+{
 	struct sysfs_super_info *info = sysfs_info(sb);
 	struct sysfs_dirent *root_sd = sb->s_root->d_fsdata;
 
@@ -141,7 +189,7 @@ static void sysfs_kill_sb(struct super_block *sb)
 	 * so we can't find it, before freeing sysfs_super_info.
 	 */
 	kill_anon_super(sb);
-	free_sysfs_super_info(info);
+	kfree(info);
 	kernfs_put(root_sd);
 }
 
@@ -152,37 +200,29 @@ static struct file_system_type sysfs_fs_type = {
 	.fs_flags	= FS_USERNS_MOUNT,
 };
 
-int __init sysfs_init(void)
+void __init kernfs_init(void)
 {
-	int err;
-
 	sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
 					      sizeof(struct sysfs_dirent),
-					      0, 0, NULL);
-	if (!sysfs_dir_cachep)
-		return -ENOMEM;
+					      0, SLAB_PANIC, NULL);
+	sysfs_inode_init();
+}
 
-	err = sysfs_inode_init();
-	if (err)
-		goto out_err;
+int __init sysfs_init(void)
+{
+	int err;
 
 	sysfs_root = kernfs_create_root(NULL);
-	if (IS_ERR(sysfs_root)) {
-		err = PTR_ERR(sysfs_root);
-		goto out_err;
-	}
+	if (IS_ERR(sysfs_root))
+		return PTR_ERR(sysfs_root);
+
 	sysfs_root_sd = sysfs_root->sd;
 
 	err = register_filesystem(&sysfs_fs_type);
-	if (err)
-		goto out_destroy_root;
+	if (err) {
+		kernfs_destroy_root(sysfs_root);
+		return err;
+	}
 
 	return 0;
-
-out_destroy_root:
-	kernfs_destroy_root(sysfs_root);
-out_err:
-	kmem_cache_destroy(sysfs_dir_cachep);
-	sysfs_dir_cachep = NULL;
-	return err;
 }
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index fad8b98..75fcbe5 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -18,6 +18,8 @@ struct file;
 struct iattr;
 struct seq_file;
 struct vm_area_struct;
+struct super_block;
+struct file_system_type;
 
 struct sysfs_dirent;
 
@@ -109,6 +111,13 @@ void kernfs_enable_ns(struct sysfs_dirent *sd);
 int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr);
 void kernfs_notify(struct sysfs_dirent *sd);
 
+const void *kernfs_super_ns(struct super_block *sb);
+struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
+			       struct kernfs_root *root, const void *ns);
+void kernfs_kill_sb(struct super_block *sb);
+
+void kernfs_init(void);
+
 #else	/* CONFIG_SYSFS */
 
 static inline struct sysfs_dirent *
@@ -160,6 +169,18 @@ static inline int kernfs_setattr(struct sysfs_dirent *sd,
 
 static inline void kernfs_notify(struct sysfs_dirent *sd) { }
 
+static inline const void *kernfs_super_ns(struct super_block *sb)
+{ return NULL; }
+
+static inline struct dentry *
+kernfs_mount_ns(struct file_system_type *fs_type, int flags,
+		struct kernfs_root *root, const void *ns)
+{ return ERR_PTR(-ENOSYS); }
+
+static inline void kernfs_kill_sb(struct super_block *sb) { }
+
+static inline void kernfs_init(void) { }
+
 #endif	/* CONFIG_SYSFS */
 
 static inline struct sysfs_dirent *
@@ -201,4 +222,11 @@ static inline int kernfs_remove_by_name(struct sysfs_dirent *parent,
 	return kernfs_remove_by_name_ns(parent, name, NULL);
 }
 
+static inline struct dentry *
+kernfs_mount(struct file_system_type *fs_type, int flags,
+	     struct kernfs_root *root)
+{
+	return kernfs_mount_ns(fs_type, flags, root, NULL);
+}
+
 #endif	/* __LINUX_KERNFS_H */
-- 
1.8.4.2

[PATCH 31/34] sysfs, kernfs: move mount core code to fs/kernfs/mount.c

[Tejun Heo]

Move core mount code to fs/kernfs/mount.c.  The respective
declarations in fs/sysfs/sysfs.h are moved to
fs/kernfs/kernfs-internal.h.

This is pure relocation.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/kernfs-internal.h |  22 +++++++
 fs/kernfs/mount.c           | 156 ++++++++++++++++++++++++++++++++++++++++++++
 fs/sysfs/mount.c            | 152 ------------------------------------------
 fs/sysfs/sysfs.h            |  18 -----
 4 files changed, 178 insertions(+), 170 deletions(-)

diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 0d94988..ced0d6d 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -134,6 +134,28 @@ struct sysfs_addrm_cxt {
 #include "../sysfs/sysfs.h"
 
 /*
+ * mount.c
+ */
+struct sysfs_super_info {
+	/*
+	 * The root associated with this super_block.  Each super_block is
+	 * identified by the root and ns it's associated with.
+	 */
+	struct kernfs_root	*root;
+
+	/*
+	 * Each sb is associated with one namespace tag, currently the network
+	 * namespace of the task which mounted this sysfs instance.  If multiple
+	 * tags become necessary, make the following an array and compare
+	 * sysfs_dirent tag against every entry.
+	 */
+	const void		*ns;
+};
+#define sysfs_info(SB) ((struct sysfs_super_info *)(SB->s_fs_info))
+
+extern struct kmem_cache *sysfs_dir_cachep;
+
+/*
  * inode.c
  */
 struct inode *sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd);
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 872e262..84c83e2 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -7,3 +7,159 @@
  *
  * This file is released under the GPLv2.
  */
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/init.h>
+#include <linux/magic.h>
+#include <linux/slab.h>
+#include <linux/pagemap.h>
+
+#include "kernfs-internal.h"
+
+struct kmem_cache *sysfs_dir_cachep;
+
+static const struct super_operations sysfs_ops = {
+	.statfs		= simple_statfs,
+	.drop_inode	= generic_delete_inode,
+	.evict_inode	= sysfs_evict_inode,
+};
+
+static int sysfs_fill_super(struct super_block *sb)
+{
+	struct sysfs_super_info *info = sysfs_info(sb);
+	struct inode *inode;
+	struct dentry *root;
+
+	sb->s_blocksize = PAGE_CACHE_SIZE;
+	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+	sb->s_magic = SYSFS_MAGIC;
+	sb->s_op = &sysfs_ops;
+	sb->s_time_gran = 1;
+
+	/* get root inode, initialize and unlock it */
+	mutex_lock(&sysfs_mutex);
+	inode = sysfs_get_inode(sb, info->root->sd);
+	mutex_unlock(&sysfs_mutex);
+	if (!inode) {
+		pr_debug("sysfs: could not get root inode\n");
+		return -ENOMEM;
+	}
+
+	/* instantiate and link root dentry */
+	root = d_make_root(inode);
+	if (!root) {
+		pr_debug("%s: could not get root dentry!\n", __func__);
+		return -ENOMEM;
+	}
+	kernfs_get(info->root->sd);
+	root->d_fsdata = info->root->sd;
+	sb->s_root = root;
+	sb->s_d_op = &sysfs_dentry_ops;
+	return 0;
+}
+
+static int sysfs_test_super(struct super_block *sb, void *data)
+{
+	struct sysfs_super_info *sb_info = sysfs_info(sb);
+	struct sysfs_super_info *info = data;
+
+	return sb_info->root == info->root && sb_info->ns == info->ns;
+}
+
+static int sysfs_set_super(struct super_block *sb, void *data)
+{
+	int error;
+	error = set_anon_super(sb, data);
+	if (!error)
+		sb->s_fs_info = data;
+	return error;
+}
+
+/**
+ * kernfs_super_ns - determine the namespace tag of a kernfs super_block
+ * @sb: super_block of interest
+ *
+ * Return the namespace tag associated with kernfs super_block @sb.
+ */
+const void *kernfs_super_ns(struct super_block *sb)
+{
+	struct sysfs_super_info *info = sysfs_info(sb);
+
+	return info->ns;
+}
+
+/**
+ * kernfs_mount_ns - kernfs mount helper
+ * @fs_type: file_system_type of the fs being mounted
+ * @flags: mount flags specified for the mount
+ * @root: kernfs_root of the hierarchy being mounted
+ * @ns: optional namespace tag of the mount
+ *
+ * This is to be called from each kernfs user's file_system_type->mount()
+ * implementation, which should pass through the specified @fs_type and
+ * @flags, and specify the hierarchy and namespace tag to mount via @root
+ * and @ns, respectively.
+ *
+ * The return value can be passed to the vfs layer verbatim.
+ */
+struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
+			       struct kernfs_root *root, const void *ns)
+{
+	struct super_block *sb;
+	struct sysfs_super_info *info;
+	int error;
+
+	info = kzalloc(sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return ERR_PTR(-ENOMEM);
+
+	info->root = root;
+	info->ns = ns;
+
+	sb = sget(fs_type, sysfs_test_super, sysfs_set_super, flags, info);
+	if (IS_ERR(sb) || sb->s_fs_info != info)
+		kfree(info);
+	if (IS_ERR(sb))
+		return ERR_CAST(sb);
+	if (!sb->s_root) {
+		error = sysfs_fill_super(sb);
+		if (error) {
+			deactivate_locked_super(sb);
+			return ERR_PTR(error);
+		}
+		sb->s_flags |= MS_ACTIVE;
+	}
+
+	return dget(sb->s_root);
+}
+
+/**
+ * kernfs_kill_sb - kill_sb for kernfs
+ * @sb: super_block being killed
+ *
+ * This can be used directly for file_system_type->kill_sb().  If a kernfs
+ * user needs extra cleanup, it can implement its own kill_sb() and call
+ * this function at the end.
+ */
+void kernfs_kill_sb(struct super_block *sb)
+{
+	struct sysfs_super_info *info = sysfs_info(sb);
+	struct sysfs_dirent *root_sd = sb->s_root->d_fsdata;
+
+	/*
+	 * Remove the superblock from fs_supers/s_instances
+	 * so we can't find it, before freeing sysfs_super_info.
+	 */
+	kill_anon_super(sb);
+	kfree(info);
+	kernfs_put(root_sd);
+}
+
+void __init kernfs_init(void)
+{
+	sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
+					      sizeof(struct sysfs_dirent),
+					      0, SLAB_PANIC, NULL);
+	sysfs_inode_init();
+}
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 5384732..e7e3aa8 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -14,91 +14,14 @@
 
 #include <linux/fs.h>
 #include <linux/mount.h>
-#include <linux/pagemap.h>
 #include <linux/init.h>
-#include <linux/module.h>
-#include <linux/magic.h>
-#include <linux/slab.h>
 #include <linux/user_namespace.h>
 
 #include "sysfs.h"
 
-
-struct kmem_cache *sysfs_dir_cachep;
-
-static const struct super_operations sysfs_ops = {
-	.statfs		= simple_statfs,
-	.drop_inode	= generic_delete_inode,
-	.evict_inode	= sysfs_evict_inode,
-};
-
 static struct kernfs_root *sysfs_root;
 struct sysfs_dirent *sysfs_root_sd;
 
-static int sysfs_fill_super(struct super_block *sb)
-{
-	struct sysfs_super_info *info = sysfs_info(sb);
-	struct inode *inode;
-	struct dentry *root;
-
-	sb->s_blocksize = PAGE_CACHE_SIZE;
-	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
-	sb->s_magic = SYSFS_MAGIC;
-	sb->s_op = &sysfs_ops;
-	sb->s_time_gran = 1;
-
-	/* get root inode, initialize and unlock it */
-	mutex_lock(&sysfs_mutex);
-	inode = sysfs_get_inode(sb, info->root->sd);
-	mutex_unlock(&sysfs_mutex);
-	if (!inode) {
-		pr_debug("sysfs: could not get root inode\n");
-		return -ENOMEM;
-	}
-
-	/* instantiate and link root dentry */
-	root = d_make_root(inode);
-	if (!root) {
-		pr_debug("%s: could not get root dentry!\n", __func__);
-		return -ENOMEM;
-	}
-	kernfs_get(info->root->sd);
-	root->d_fsdata = info->root->sd;
-	sb->s_root = root;
-	sb->s_d_op = &sysfs_dentry_ops;
-	return 0;
-}
-
-static int sysfs_test_super(struct super_block *sb, void *data)
-{
-	struct sysfs_super_info *sb_info = sysfs_info(sb);
-	struct sysfs_super_info *info = data;
-
-	return sb_info->root == info->root && sb_info->ns == info->ns;
-}
-
-static int sysfs_set_super(struct super_block *sb, void *data)
-{
-	int error;
-	error = set_anon_super(sb, data);
-	if (!error)
-		sb->s_fs_info = data;
-	return error;
-}
-
-/**
- * kernfs_super_ns - determine the namespace tag of a kernfs super_block
- * @sb: super_block of interest
- *
- * Return the namespace tag associated with kernfs super_block @sb.
- */
-const void *kernfs_super_ns(struct super_block *sb)
-{
-	struct sysfs_super_info *info = sysfs_info(sb);
-
-	return info->ns;
-}
-
 static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data)
 {
@@ -120,79 +43,12 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
 	return root;
 }
 
-/**
- * kernfs_mount_ns - kernfs mount helper
- * @fs_type: file_system_type of the fs being mounted
- * @flags: mount flags specified for the mount
- * @root: kernfs_root of the hierarchy being mounted
- * @ns: optional namespace tag of the mount
- *
- * This is to be called from each kernfs user's file_system_type->mount()
- * implementation, which should pass through the specified @fs_type and
- * @flags, and specify the hierarchy and namespace tag to mount via @root
- * and @ns, respectively.
- *
- * The return value can be passed to the vfs layer verbatim.
- */
-struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
-			       struct kernfs_root *root, const void *ns)
-{
-	struct super_block *sb;
-	struct sysfs_super_info *info;
-	int error;
-
-	info = kzalloc(sizeof(*info), GFP_KERNEL);
-	if (!info)
-		return ERR_PTR(-ENOMEM);
-
-	info->root = root;
-	info->ns = ns;
-
-	sb = sget(fs_type, sysfs_test_super, sysfs_set_super, flags, info);
-	if (IS_ERR(sb) || sb->s_fs_info != info)
-		kfree(info);
-	if (IS_ERR(sb))
-		return ERR_CAST(sb);
-	if (!sb->s_root) {
-		error = sysfs_fill_super(sb);
-		if (error) {
-			deactivate_locked_super(sb);
-			return ERR_PTR(error);
-		}
-		sb->s_flags |= MS_ACTIVE;
-	}
-
-	return dget(sb->s_root);
-}
-
 static void sysfs_kill_sb(struct super_block *sb)
 {
 	kernfs_kill_sb(sb);
 	kobj_ns_drop(KOBJ_NS_TYPE_NET, (void *)kernfs_super_ns(sb));
 }
 
-/**
- * kernfs_kill_sb - kill_sb for kernfs
- * @sb: super_block being killed
- *
- * This can be used directly for file_system_type->kill_sb().  If a kernfs
- * user needs extra cleanup, it can implement its own kill_sb() and call
- * this function at the end.
- */
-void kernfs_kill_sb(struct super_block *sb)
-{
-	struct sysfs_super_info *info = sysfs_info(sb);
-	struct sysfs_dirent *root_sd = sb->s_root->d_fsdata;
-
-	/*
-	 * Remove the superblock from fs_supers/s_instances
-	 * so we can't find it, before freeing sysfs_super_info.
-	 */
-	kill_anon_super(sb);
-	kfree(info);
-	kernfs_put(root_sd);
-}
-
 static struct file_system_type sysfs_fs_type = {
 	.name		= "sysfs",
 	.mount		= sysfs_mount,
@@ -200,14 +56,6 @@ static struct file_system_type sysfs_fs_type = {
 	.fs_flags	= FS_USERNS_MOUNT,
 };
 
-void __init kernfs_init(void)
-{
-	sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
-					      sizeof(struct sysfs_dirent),
-					      0, SLAB_PANIC, NULL);
-	sysfs_inode_init();
-}
-
 int __init sysfs_init(void)
 {
 	int err;
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 93b4b68..6a82311 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -17,25 +17,7 @@
 /*
  * mount.c
  */
-
-struct sysfs_super_info {
-	/*
-	 * The root associated with this super_block.  Each super_block is
-	 * identified by the root and ns it's associated with.
-	 */
-	struct kernfs_root	*root;
-
-	/*
-	 * Each sb is associated with one namespace tag, currently the network
-	 * namespace of the task which mounted this sysfs instance.  If multiple
-	 * tags become necessary, make the following an array and compare
-	 * sysfs_dirent tag against every entry.
-	 */
-	const void		*ns;
-};
-#define sysfs_info(SB) ((struct sysfs_super_info *)(SB->s_fs_info))
 extern struct sysfs_dirent *sysfs_root_sd;
-extern struct kmem_cache *sysfs_dir_cachep;
 
 /*
  * dir.c
-- 
1.8.4.2

[PATCH 32/34] sysfs, kernfs: make sysfs_dirent definition public

[Tejun Heo]

sysfs_dirent includes some information which should be available to
kernfs users - the type, flags, name and parent pointer.  This patch
moves sysfs_dirent definition from kernfs/kernfs-internal.h to
include/linux/kernfs.h so that kernfs users can access them.

The type part of flags is exported as enum kernfs_node_type, the flags
kernfs_node_flag, sysfs_type() and kernfs_enable_ns() are moved to
include/linux/kernfs.h and the former is updated to return the enum
type.  sysfs_dirent->s_parent and ->s_name are marked explicitly as
public.

This patch doesn't introduce any functional changes.

v2: Flags exported too and kernfs_enable_ns() definition moved.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/dir.c             |  15 ------
 fs/kernfs/kernfs-internal.h |  85 +--------------------------------
 include/linux/kernfs.h      | 113 ++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 110 insertions(+), 103 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index eaffa83..7c5b517 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -895,21 +895,6 @@ int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
 	return error;
 }
 
-/**
- * kernfs_enable_ns - enable namespace under a directory
- * @sd: directory of interest, should be empty
- *
- * This is to be called right after @sd is created to enable namespace
- * under it.  All children of @sd must have non-NULL namespace tags and
- * only the ones which match the super_block's tag will be visible.
- */
-void kernfs_enable_ns(struct sysfs_dirent *sd)
-{
-	WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
-	WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));
-	sd->s_flags |= SYSFS_FLAG_NS;
-}
-
 /* Relationship between s_mode and the DT_xxx types */
 static inline unsigned char dt_type(struct sysfs_dirent *sd)
 {
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index ced0d6d..f33a784 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -13,102 +13,19 @@
 
 #include <linux/lockdep.h>
 #include <linux/fs.h>
-#include <linux/rbtree.h>
 #include <linux/mutex.h>
 
 #include <linux/kernfs.h>
 
-struct sysfs_open_dirent;
-
-/* type-specific structures for sysfs_dirent->s_* union members */
-struct sysfs_elem_dir {
-	unsigned long		subdirs;
-	/* children rbtree starts here and goes through sd->s_rb */
-	struct rb_root		children;
-
-	/*
-	 * The kernfs hierarchy this directory belongs to.  This fits
-	 * better directly in sysfs_dirent but is here to save space.
-	 */
-	struct kernfs_root	*root;
-};
-
-struct sysfs_elem_symlink {
-	struct sysfs_dirent	*target_sd;
-};
-
-struct sysfs_elem_attr {
-	const struct kernfs_ops	*ops;
-	struct sysfs_open_dirent *open;
-	loff_t			size;
-};
-
 struct sysfs_inode_attrs {
 	struct iattr	ia_iattr;
 	void		*ia_secdata;
 	u32		ia_secdata_len;
 };
 
-/*
- * sysfs_dirent - the building block of sysfs hierarchy.  Each and
- * every sysfs node is represented by single sysfs_dirent.
- *
- * As long as s_count reference is held, the sysfs_dirent itself is
- * accessible.  Dereferencing s_elem or any other outer entity
- * requires s_active reference.
- */
-struct sysfs_dirent {
-	atomic_t		s_count;
-	atomic_t		s_active;
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-	struct lockdep_map	dep_map;
-#endif
-	struct sysfs_dirent	*s_parent;
-	const char		*s_name;
-
-	struct rb_node		s_rb;
-
-	union {
-		struct completion	*completion;
-		struct sysfs_dirent	*removed_list;
-	} u;
-
-	const void		*s_ns; /* namespace tag */
-	unsigned int		s_hash; /* ns + name hash */
-	union {
-		struct sysfs_elem_dir		s_dir;
-		struct sysfs_elem_symlink	s_symlink;
-		struct sysfs_elem_attr		s_attr;
-	};
-
-	void			*priv;
-
-	unsigned short		s_flags;
-	umode_t			s_mode;
-	unsigned int		s_ino;
-	struct sysfs_inode_attrs *s_iattr;
-};
-
 #define SD_DEACTIVATED_BIAS		INT_MIN
 
-#define SYSFS_TYPE_MASK			0x000f
-#define SYSFS_DIR			0x0001
-#define SYSFS_KOBJ_ATTR			0x0002
-#define SYSFS_KOBJ_LINK			0x0004
-#define SYSFS_COPY_NAME			(SYSFS_DIR | SYSFS_KOBJ_LINK)
-#define SYSFS_ACTIVE_REF		SYSFS_KOBJ_ATTR
-
-#define SYSFS_FLAG_MASK			~SYSFS_TYPE_MASK
-#define SYSFS_FLAG_REMOVED		0x0010
-#define SYSFS_FLAG_NS			0x0020
-#define SYSFS_FLAG_HAS_SEQ_SHOW		0x0040
-#define SYSFS_FLAG_HAS_MMAP		0x0080
-#define SYSFS_FLAG_LOCKDEP		0x0100
-
-static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
-{
-	return sd->s_flags & SYSFS_TYPE_MASK;
-}
+/* SYSFS_TYPE_MASK and types are defined in include/linux/kernfs.h */
 
 /**
  * kernfs_root - find out the kernfs_root a sysfs_dirent belongs to
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 75fcbe5..f3f873e 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -13,6 +13,9 @@
 #include <linux/mutex.h>
 #include <linux/idr.h>
 #include <linux/lockdep.h>
+#include <linux/rbtree.h>
+#include <linux/atomic.h>
+#include <linux/completion.h>
 
 struct file;
 struct iattr;
@@ -21,7 +24,92 @@ struct vm_area_struct;
 struct super_block;
 struct file_system_type;
 
-struct sysfs_dirent;
+struct sysfs_open_dirent;
+struct sysfs_inode_attrs;
+
+enum kernfs_node_type {
+	SYSFS_DIR		= 0x0001,
+	SYSFS_KOBJ_ATTR		= 0x0002,
+	SYSFS_KOBJ_LINK		= 0x0004,
+};
+
+#define SYSFS_TYPE_MASK		0x000f
+#define SYSFS_COPY_NAME		(SYSFS_DIR | SYSFS_KOBJ_LINK)
+#define SYSFS_ACTIVE_REF	SYSFS_KOBJ_ATTR
+#define SYSFS_FLAG_MASK		~SYSFS_TYPE_MASK
+
+enum kernfs_node_flag {
+	SYSFS_FLAG_REMOVED	= 0x0010,
+	SYSFS_FLAG_NS		= 0x0020,
+	SYSFS_FLAG_HAS_SEQ_SHOW	= 0x0040,
+	SYSFS_FLAG_HAS_MMAP	= 0x0080,
+	SYSFS_FLAG_LOCKDEP	= 0x0100,
+};
+
+/* type-specific structures for sysfs_dirent->s_* union members */
+struct sysfs_elem_dir {
+	unsigned long		subdirs;
+	/* children rbtree starts here and goes through sd->s_rb */
+	struct rb_root		children;
+
+	/*
+	 * The kernfs hierarchy this directory belongs to.  This fits
+	 * better directly in sysfs_dirent but is here to save space.
+	 */
+	struct kernfs_root	*root;
+};
+
+struct sysfs_elem_symlink {
+	struct sysfs_dirent	*target_sd;
+};
+
+struct sysfs_elem_attr {
+	const struct kernfs_ops	*ops;
+	struct sysfs_open_dirent *open;
+	loff_t			size;
+};
+
+/*
+ * sysfs_dirent - the building block of sysfs hierarchy.  Each and every
+ * sysfs node is represented by single sysfs_dirent.  Most fields are
+ * private to kernfs and shouldn't be accessed directly by kernfs users.
+ *
+ * As long as s_count reference is held, the sysfs_dirent itself is
+ * accessible.  Dereferencing s_elem or any other outer entity
+ * requires s_active reference.
+ */
+struct sysfs_dirent {
+	atomic_t		s_count;
+	atomic_t		s_active;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lockdep_map	dep_map;
+#endif
+	/* the following two fields are published */
+	struct sysfs_dirent	*s_parent;
+	const char		*s_name;
+
+	struct rb_node		s_rb;
+
+	union {
+		struct completion	*completion;
+		struct sysfs_dirent	*removed_list;
+	} u;
+
+	const void		*s_ns; /* namespace tag */
+	unsigned int		s_hash; /* ns + name hash */
+	union {
+		struct sysfs_elem_dir		s_dir;
+		struct sysfs_elem_symlink	s_symlink;
+		struct sysfs_elem_attr		s_attr;
+	};
+
+	void			*priv;
+
+	unsigned short		s_flags;
+	umode_t			s_mode;
+	unsigned int		s_ino;
+	struct sysfs_inode_attrs *s_iattr;
+};
 
 struct kernfs_root {
 	/* published fields */
@@ -80,6 +168,26 @@ struct kernfs_ops {
 #endif
 };
 
+static inline enum kernfs_node_type sysfs_type(struct sysfs_dirent *sd)
+{
+	return sd->s_flags & SYSFS_TYPE_MASK;
+}
+
+/**
+ * kernfs_enable_ns - enable namespace under a directory
+ * @sd: directory of interest, should be empty
+ *
+ * This is to be called right after @sd is created to enable namespace
+ * under it.  All children of @sd must have non-NULL namespace tags and
+ * only the ones which match the super_block's tag will be visible.
+ */
+static inline void kernfs_enable_ns(struct sysfs_dirent *sd)
+{
+	WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
+	WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));
+	sd->s_flags |= SYSFS_FLAG_NS;
+}
+
 #ifdef CONFIG_SYSFS
 
 struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
@@ -107,7 +215,6 @@ int kernfs_remove_by_name_ns(struct sysfs_dirent *parent, const char *name,
 			     const void *ns);
 int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
 		     const char *new_name, const void *new_ns);
-void kernfs_enable_ns(struct sysfs_dirent *sd);
 int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr);
 void kernfs_notify(struct sysfs_dirent *sd);
 
@@ -161,8 +268,6 @@ static inline int kernfs_rename_ns(struct sysfs_dirent *sd,
 				   const char *new_name, const void *new_ns)
 { return -ENOSYS; }
 
-static inline void kernfs_enable_ns(struct sysfs_dirent *sd) { }
-
 static inline int kernfs_setattr(struct sysfs_dirent *sd,
 				 const struct iattr *iattr)
 { return -ENOSYS; }
-- 
1.8.4.2

[PATCH 33/34] sysfs, kernfs: implement kernfs_ns_enabled()

[Tejun Heo]

fs/sysfs/symlink.c::sysfs_delete_link() tests @sd->s_flags for
SYSFS_FLAG_NS.  Let's add kernfs_ns_enabled() so that sysfs doesn't
have to test sysfs_dirent flag directly.  This makes things tidier for
kernfs proper too.

This is purely cosmetic.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/dir.c        | 10 +++++-----
 fs/kernfs/symlink.c    |  2 +-
 fs/sysfs/symlink.c     |  2 +-
 include/linux/kernfs.h | 11 +++++++++++
 4 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 7c5b517..f51e062 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -291,7 +291,7 @@ static int sysfs_dentry_revalidate(struct dentry *dentry, unsigned int flags)
 		goto out_bad;
 
 	/* The sysfs dirent has been moved to a different namespace */
-	if (sd->s_parent && (sd->s_parent->s_flags & SYSFS_FLAG_NS) &&
+	if (sd->s_parent && kernfs_ns_enabled(sd->s_parent) &&
 	    sysfs_info(dentry->d_sb)->ns != sd->s_ns)
 		goto out_bad;
 
@@ -414,7 +414,7 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt)
 int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
 		  struct sysfs_dirent *parent_sd)
 {
-	bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS;
+	bool has_ns = kernfs_ns_enabled(parent_sd);
 	struct sysfs_inode_attrs *ps_iattr;
 	int ret;
 
@@ -535,7 +535,7 @@ static struct sysfs_dirent *kernfs_find_ns(struct sysfs_dirent *parent,
 					   const void *ns)
 {
 	struct rb_node *node = parent->s_dir.children.rb_node;
-	bool has_ns = parent->s_flags & SYSFS_FLAG_NS;
+	bool has_ns = kernfs_ns_enabled(parent);
 	unsigned int hash;
 
 	lockdep_assert_held(&sysfs_mutex);
@@ -685,7 +685,7 @@ static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry,
 
 	mutex_lock(&sysfs_mutex);
 
-	if (parent_sd->s_flags & SYSFS_FLAG_NS)
+	if (kernfs_ns_enabled(parent_sd))
 		ns = sysfs_info(dir->i_sb)->ns;
 
 	sd = kernfs_find_ns(parent_sd, dentry->d_name.name, ns);
@@ -968,7 +968,7 @@ static int sysfs_readdir(struct file *file, struct dir_context *ctx)
 		return 0;
 	mutex_lock(&sysfs_mutex);
 
-	if (parent_sd->s_flags & SYSFS_FLAG_NS)
+	if (kernfs_ns_enabled(parent_sd))
 		ns = sysfs_info(dentry->d_sb)->ns;
 
 	for (pos = sysfs_dir_pos(ns, parent_sd, ctx->pos, pos);
diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c
index 004c164..12569a7 100644
--- a/fs/kernfs/symlink.c
+++ b/fs/kernfs/symlink.c
@@ -35,7 +35,7 @@ struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
 	if (!sd)
 		return ERR_PTR(-ENOMEM);
 
-	if (parent->s_flags & SYSFS_FLAG_NS)
+	if (kernfs_ns_enabled(parent))
 		sd->s_ns = target->s_ns;
 	sd->s_symlink.target_sd = target;
 	kernfs_get(target);	/* ref owned by symlink */
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 62f0e01..1b8c9ed 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -128,7 +128,7 @@ void sysfs_delete_link(struct kobject *kobj, struct kobject *targ,
 	 * sysfs_remove_dir() for details.
 	 */
 	spin_lock(&sysfs_symlink_target_lock);
-	if (targ->sd && (kobj->sd->s_flags & SYSFS_FLAG_NS))
+	if (targ->sd && kernfs_ns_enabled(kobj->sd))
 		ns = targ->sd->s_ns;
 	spin_unlock(&sysfs_symlink_target_lock);
 	kernfs_remove_by_name_ns(kobj->sd, name, ns);
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index f3f873e..7cb636c 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -188,6 +188,17 @@ static inline void kernfs_enable_ns(struct sysfs_dirent *sd)
 	sd->s_flags |= SYSFS_FLAG_NS;
 }
 
+/**
+ * kernfs_ns_enabled - test whether namespace is enabled
+ * @sd: the node to test
+ *
+ * Test whether namespace filtering is enabled for the children of @ns.
+ */
+static inline bool kernfs_ns_enabled(struct sysfs_dirent *sd)
+{
+	return sd->s_flags & SYSFS_FLAG_NS;
+}
+
 #ifdef CONFIG_SYSFS
 
 struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
-- 
1.8.4.2

[PATCH 34/34] sysfs, kernfs: remove cross inclusions of internal headers

[Tejun Heo]

fs/kernfs/kernfs-internal.h needed to include fs/sysfs/sysfs.h because
part of kernfs core implementation was living in sysfs.

fs/sysfs/sysfs.h needed to include fs/kernfs/kernfs-internal.h because
include/linux/kernfs.h didn't expose enough interface.

The separation is complete and neither is true anymore.  Remove the
cross inclusion and make sysfs a proper user of kernfs.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/kernfs-internal.h | 2 --
 fs/sysfs/sysfs.h            | 1 -
 2 files changed, 3 deletions(-)

diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index f33a784..d1ff591 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -48,8 +48,6 @@ struct sysfs_addrm_cxt {
 	struct sysfs_dirent	*removed;
 };
 
-#include "../sysfs/sysfs.h"
-
 /*
  * mount.c
  */
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 6a82311..c8e395b 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -11,7 +11,6 @@
 #ifndef __SYSFS_INTERNAL_H
 #define __SYSFS_INTERNAL_H
 
-#include "../kernfs/kernfs-internal.h"
 #include <linux/sysfs.h>
 
 /*
-- 
1.8.4.2

[PATCH 32/34] sysfs, kernfs: make sysfs_dirent definition public

[Tejun Heo]

sysfs_dirent includes some information which should be available to
kernfs users - the type, flags, name and parent pointer.  This patch
moves sysfs_dirent definition from kernfs/kernfs-internal.h to
include/linux/kernfs.h so that kernfs users can access them.

The type part of flags is exported as enum kernfs_node_type, the flags
kernfs_node_flag, sysfs_type() and kernfs_enable_ns() are moved to
include/linux/kernfs.h and the former is updated to return the enum
type.  sysfs_dirent->s_parent and ->s_name are marked explicitly as
public.

This patch doesn't introduce any functional changes.

v2: Flags exported too and kernfs_enable_ns() definition moved.

v3: While moving kernfs_enable_ns() to include/linux/kernfs.h, v1 and
    v2 put the definition outside CONFIG_SYSFS replacing the dummy
    implementation with the actual implementation too.  Unfortunately,
    this can lead to oops when !CONFIG_SYSFS because
    kernfs_enable_ns() may be called on a NULL @sd and now tries to
    dereference @sd instead of not doing anything.  This issue was
    reported by Yuanhan Liu.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
---
 fs/kernfs/dir.c             |  15 ------
 fs/kernfs/kernfs-internal.h |  85 +------------------------------
 include/linux/kernfs.h      | 118 ++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 115 insertions(+), 103 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index eaffa83..7c5b517 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -895,21 +895,6 @@ int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
 	return error;
 }
 
-/**
- * kernfs_enable_ns - enable namespace under a directory
- * @sd: directory of interest, should be empty
- *
- * This is to be called right after @sd is created to enable namespace
- * under it.  All children of @sd must have non-NULL namespace tags and
- * only the ones which match the super_block's tag will be visible.
- */
-void kernfs_enable_ns(struct sysfs_dirent *sd)
-{
-	WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
-	WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));
-	sd->s_flags |= SYSFS_FLAG_NS;
-}
-
 /* Relationship between s_mode and the DT_xxx types */
 static inline unsigned char dt_type(struct sysfs_dirent *sd)
 {
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index ced0d6d..f33a784 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -13,102 +13,19 @@
 
 #include <linux/lockdep.h>
 #include <linux/fs.h>
-#include <linux/rbtree.h>
 #include <linux/mutex.h>
 
 #include <linux/kernfs.h>
 
-struct sysfs_open_dirent;
-
-/* type-specific structures for sysfs_dirent->s_* union members */
-struct sysfs_elem_dir {
-	unsigned long		subdirs;
-	/* children rbtree starts here and goes through sd->s_rb */
-	struct rb_root		children;
-
-	/*
-	 * The kernfs hierarchy this directory belongs to.  This fits
-	 * better directly in sysfs_dirent but is here to save space.
-	 */
-	struct kernfs_root	*root;
-};
-
-struct sysfs_elem_symlink {
-	struct sysfs_dirent	*target_sd;
-};
-
-struct sysfs_elem_attr {
-	const struct kernfs_ops	*ops;
-	struct sysfs_open_dirent *open;
-	loff_t			size;
-};
-
 struct sysfs_inode_attrs {
 	struct iattr	ia_iattr;
 	void		*ia_secdata;
 	u32		ia_secdata_len;
 };
 
-/*
- * sysfs_dirent - the building block of sysfs hierarchy.  Each and
- * every sysfs node is represented by single sysfs_dirent.
- *
- * As long as s_count reference is held, the sysfs_dirent itself is
- * accessible.  Dereferencing s_elem or any other outer entity
- * requires s_active reference.
- */
-struct sysfs_dirent {
-	atomic_t		s_count;
-	atomic_t		s_active;
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-	struct lockdep_map	dep_map;
-#endif
-	struct sysfs_dirent	*s_parent;
-	const char		*s_name;
-
-	struct rb_node		s_rb;
-
-	union {
-		struct completion	*completion;
-		struct sysfs_dirent	*removed_list;
-	} u;
-
-	const void		*s_ns; /* namespace tag */
-	unsigned int		s_hash; /* ns + name hash */
-	union {
-		struct sysfs_elem_dir		s_dir;
-		struct sysfs_elem_symlink	s_symlink;
-		struct sysfs_elem_attr		s_attr;
-	};
-
-	void			*priv;
-
-	unsigned short		s_flags;
-	umode_t			s_mode;
-	unsigned int		s_ino;
-	struct sysfs_inode_attrs *s_iattr;
-};
-
 #define SD_DEACTIVATED_BIAS		INT_MIN
 
-#define SYSFS_TYPE_MASK			0x000f
-#define SYSFS_DIR			0x0001
-#define SYSFS_KOBJ_ATTR			0x0002
-#define SYSFS_KOBJ_LINK			0x0004
-#define SYSFS_COPY_NAME			(SYSFS_DIR | SYSFS_KOBJ_LINK)
-#define SYSFS_ACTIVE_REF		SYSFS_KOBJ_ATTR
-
-#define SYSFS_FLAG_MASK			~SYSFS_TYPE_MASK
-#define SYSFS_FLAG_REMOVED		0x0010
-#define SYSFS_FLAG_NS			0x0020
-#define SYSFS_FLAG_HAS_SEQ_SHOW		0x0040
-#define SYSFS_FLAG_HAS_MMAP		0x0080
-#define SYSFS_FLAG_LOCKDEP		0x0100
-
-static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
-{
-	return sd->s_flags & SYSFS_TYPE_MASK;
-}
+/* SYSFS_TYPE_MASK and types are defined in include/linux/kernfs.h */
 
 /**
  * kernfs_root - find out the kernfs_root a sysfs_dirent belongs to
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 75fcbe5..faaf4f2 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -13,6 +13,9 @@
 #include <linux/mutex.h>
 #include <linux/idr.h>
 #include <linux/lockdep.h>
+#include <linux/rbtree.h>
+#include <linux/atomic.h>
+#include <linux/completion.h>
 
 struct file;
 struct iattr;
@@ -21,7 +24,92 @@ struct vm_area_struct;
 struct super_block;
 struct file_system_type;
 
-struct sysfs_dirent;
+struct sysfs_open_dirent;
+struct sysfs_inode_attrs;
+
+enum kernfs_node_type {
+	SYSFS_DIR		= 0x0001,
+	SYSFS_KOBJ_ATTR		= 0x0002,
+	SYSFS_KOBJ_LINK		= 0x0004,
+};
+
+#define SYSFS_TYPE_MASK		0x000f
+#define SYSFS_COPY_NAME		(SYSFS_DIR | SYSFS_KOBJ_LINK)
+#define SYSFS_ACTIVE_REF	SYSFS_KOBJ_ATTR
+#define SYSFS_FLAG_MASK		~SYSFS_TYPE_MASK
+
+enum kernfs_node_flag {
+	SYSFS_FLAG_REMOVED	= 0x0010,
+	SYSFS_FLAG_NS		= 0x0020,
+	SYSFS_FLAG_HAS_SEQ_SHOW	= 0x0040,
+	SYSFS_FLAG_HAS_MMAP	= 0x0080,
+	SYSFS_FLAG_LOCKDEP	= 0x0100,
+};
+
+/* type-specific structures for sysfs_dirent->s_* union members */
+struct sysfs_elem_dir {
+	unsigned long		subdirs;
+	/* children rbtree starts here and goes through sd->s_rb */
+	struct rb_root		children;
+
+	/*
+	 * The kernfs hierarchy this directory belongs to.  This fits
+	 * better directly in sysfs_dirent but is here to save space.
+	 */
+	struct kernfs_root	*root;
+};
+
+struct sysfs_elem_symlink {
+	struct sysfs_dirent	*target_sd;
+};
+
+struct sysfs_elem_attr {
+	const struct kernfs_ops	*ops;
+	struct sysfs_open_dirent *open;
+	loff_t			size;
+};
+
+/*
+ * sysfs_dirent - the building block of sysfs hierarchy.  Each and every
+ * sysfs node is represented by single sysfs_dirent.  Most fields are
+ * private to kernfs and shouldn't be accessed directly by kernfs users.
+ *
+ * As long as s_count reference is held, the sysfs_dirent itself is
+ * accessible.  Dereferencing s_elem or any other outer entity
+ * requires s_active reference.
+ */
+struct sysfs_dirent {
+	atomic_t		s_count;
+	atomic_t		s_active;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lockdep_map	dep_map;
+#endif
+	/* the following two fields are published */
+	struct sysfs_dirent	*s_parent;
+	const char		*s_name;
+
+	struct rb_node		s_rb;
+
+	union {
+		struct completion	*completion;
+		struct sysfs_dirent	*removed_list;
+	} u;
+
+	const void		*s_ns; /* namespace tag */
+	unsigned int		s_hash; /* ns + name hash */
+	union {
+		struct sysfs_elem_dir		s_dir;
+		struct sysfs_elem_symlink	s_symlink;
+		struct sysfs_elem_attr		s_attr;
+	};
+
+	void			*priv;
+
+	unsigned short		s_flags;
+	umode_t			s_mode;
+	unsigned int		s_ino;
+	struct sysfs_inode_attrs *s_iattr;
+};
 
 struct kernfs_root {
 	/* published fields */
@@ -82,6 +170,26 @@ struct kernfs_ops {
 
 #ifdef CONFIG_SYSFS
 
+static inline enum kernfs_node_type sysfs_type(struct sysfs_dirent *sd)
+{
+	return sd->s_flags & SYSFS_TYPE_MASK;
+}
+
+/**
+ * kernfs_enable_ns - enable namespace under a directory
+ * @sd: directory of interest, should be empty
+ *
+ * This is to be called right after @sd is created to enable namespace
+ * under it.  All children of @sd must have non-NULL namespace tags and
+ * only the ones which match the super_block's tag will be visible.
+ */
+static inline void kernfs_enable_ns(struct sysfs_dirent *sd)
+{
+	WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);
+	WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));
+	sd->s_flags |= SYSFS_FLAG_NS;
+}
+
 struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
 					    const char *name, const void *ns);
 void kernfs_get(struct sysfs_dirent *sd);
@@ -107,7 +215,6 @@ int kernfs_remove_by_name_ns(struct sysfs_dirent *parent, const char *name,
 			     const void *ns);
 int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
 		     const char *new_name, const void *new_ns);
-void kernfs_enable_ns(struct sysfs_dirent *sd);
 int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr);
 void kernfs_notify(struct sysfs_dirent *sd);
 
@@ -120,6 +227,11 @@ void kernfs_init(void);
 
 #else	/* CONFIG_SYSFS */
 
+static inline enum kernfs_node_type sysfs_type(struct sysfs_dirent *sd)
+{ return 0; }	/* whatever */
+
+static inline void kernfs_enable_ns(struct sysfs_dirent *sd) { }
+
 static inline struct sysfs_dirent *
 kernfs_find_and_get_ns(struct sysfs_dirent *parent, const char *name,
 		       const void *ns)
@@ -161,8 +273,6 @@ static inline int kernfs_rename_ns(struct sysfs_dirent *sd,
 				   const char *new_name, const void *new_ns)
 { return -ENOSYS; }
 
-static inline void kernfs_enable_ns(struct sysfs_dirent *sd) { }
-
 static inline int kernfs_setattr(struct sysfs_dirent *sd,
 				 const struct iattr *iattr)
 { return -ENOSYS; }
-- 
1.8.4.2

[PATCH v2 33/34] sysfs, kernfs: implement kernfs_ns_enabled()

[Tejun Heo]

fs/sysfs/symlink.c::sysfs_delete_link() tests @sd->s_flags for
SYSFS_FLAG_NS.  Let's add kernfs_ns_enabled() so that sysfs doesn't
have to test sysfs_dirent flag directly.  This makes things tidier for
kernfs proper too.

This is purely cosmetic.

v2: To avoid possible NULL deref, use noop dummy implementation which
    always returns false when !CONFIG_SYSFS.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/dir.c        | 10 +++++-----
 fs/kernfs/symlink.c    |  2 +-
 fs/sysfs/symlink.c     |  2 +-
 include/linux/kernfs.h | 14 ++++++++++++++
 4 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 7c5b517..f51e062 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -291,7 +291,7 @@ static int sysfs_dentry_revalidate(struct dentry *dentry, unsigned int flags)
 		goto out_bad;
 
 	/* The sysfs dirent has been moved to a different namespace */
-	if (sd->s_parent && (sd->s_parent->s_flags & SYSFS_FLAG_NS) &&
+	if (sd->s_parent && kernfs_ns_enabled(sd->s_parent) &&
 	    sysfs_info(dentry->d_sb)->ns != sd->s_ns)
 		goto out_bad;
 
@@ -414,7 +414,7 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt)
 int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
 		  struct sysfs_dirent *parent_sd)
 {
-	bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS;
+	bool has_ns = kernfs_ns_enabled(parent_sd);
 	struct sysfs_inode_attrs *ps_iattr;
 	int ret;
 
@@ -535,7 +535,7 @@ static struct sysfs_dirent *kernfs_find_ns(struct sysfs_dirent *parent,
 					   const void *ns)
 {
 	struct rb_node *node = parent->s_dir.children.rb_node;
-	bool has_ns = parent->s_flags & SYSFS_FLAG_NS;
+	bool has_ns = kernfs_ns_enabled(parent);
 	unsigned int hash;
 
 	lockdep_assert_held(&sysfs_mutex);
@@ -685,7 +685,7 @@ static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry,
 
 	mutex_lock(&sysfs_mutex);
 
-	if (parent_sd->s_flags & SYSFS_FLAG_NS)
+	if (kernfs_ns_enabled(parent_sd))
 		ns = sysfs_info(dir->i_sb)->ns;
 
 	sd = kernfs_find_ns(parent_sd, dentry->d_name.name, ns);
@@ -968,7 +968,7 @@ static int sysfs_readdir(struct file *file, struct dir_context *ctx)
 		return 0;
 	mutex_lock(&sysfs_mutex);
 
-	if (parent_sd->s_flags & SYSFS_FLAG_NS)
+	if (kernfs_ns_enabled(parent_sd))
 		ns = sysfs_info(dentry->d_sb)->ns;
 
 	for (pos = sysfs_dir_pos(ns, parent_sd, ctx->pos, pos);
diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c
index 004c164..12569a7 100644
--- a/fs/kernfs/symlink.c
+++ b/fs/kernfs/symlink.c
@@ -35,7 +35,7 @@ struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
 	if (!sd)
 		return ERR_PTR(-ENOMEM);
 
-	if (parent->s_flags & SYSFS_FLAG_NS)
+	if (kernfs_ns_enabled(parent))
 		sd->s_ns = target->s_ns;
 	sd->s_symlink.target_sd = target;
 	kernfs_get(target);	/* ref owned by symlink */
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 62f0e01..1b8c9ed 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -128,7 +128,7 @@ void sysfs_delete_link(struct kobject *kobj, struct kobject *targ,
 	 * sysfs_remove_dir() for details.
 	 */
 	spin_lock(&sysfs_symlink_target_lock);
-	if (targ->sd && (kobj->sd->s_flags & SYSFS_FLAG_NS))
+	if (targ->sd && kernfs_ns_enabled(kobj->sd))
 		ns = targ->sd->s_ns;
 	spin_unlock(&sysfs_symlink_target_lock);
 	kernfs_remove_by_name_ns(kobj->sd, name, ns);
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index faaf4f2..d655413 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -190,6 +190,17 @@ static inline void kernfs_enable_ns(struct sysfs_dirent *sd)
 	sd->s_flags |= SYSFS_FLAG_NS;
 }
 
+/**
+ * kernfs_ns_enabled - test whether namespace is enabled
+ * @sd: the node to test
+ *
+ * Test whether namespace filtering is enabled for the children of @ns.
+ */
+static inline bool kernfs_ns_enabled(struct sysfs_dirent *sd)
+{
+	return sd->s_flags & SYSFS_FLAG_NS;
+}
+
 struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,
 					    const char *name, const void *ns);
 void kernfs_get(struct sysfs_dirent *sd);
@@ -232,6 +243,9 @@ static inline enum kernfs_node_type sysfs_type(struct sysfs_dirent *sd)
 
 static inline void kernfs_enable_ns(struct sysfs_dirent *sd) { }
 
+static inline bool kernfs_ns_enabled(struct sysfs_dirent *sd)
+{ return false; }
+
 static inline struct sysfs_dirent *
 kernfs_find_and_get_ns(struct sysfs_dirent *parent, const char *name,
 		       const void *ns)
-- 
1.8.4.2

Re: [PATCH 32/34] sysfs, kernfs: make sysfs_dirent definition public

[Tejun Heo]

Oops, this was v3 posting.

Thanks.

-- 
tejun

Re: [PATCHSET PARTIAL REPOST driver-core-next] sysfs: separate out kernfs, take #3

[Tejun Heo]

On Thu, Nov 28, 2013 at 02:54:13PM -0500, Tejun Heo wrote:
> Hello, Greg.
> 
> For some reason, quilt can rebase the patches automatically here.  I'm
> reposting the rest of the series (patches 07-41) here just in case.
> git branches for both pending patchsets are updated accordingly.
> 
>  git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git review-separate-out-kernfs
>  git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git review-kernfs-xattr

Two patches updated - 0032 updated to v3 and 0033 updated to v2.  Both
add explicit noop implementation of inline functions for !CONFIG_SYSFS
cases.  git branches are updated.  If it's too confusing, pleaes let
me know.  I'll repost the whole series.

Thanks.

-- 
tejun

Re: [PATCHSET PARTIAL REPOST driver-core-next] sysfs: separate out kernfs, take #3

[Greg KH]

On Fri, Nov 29, 2013 at 05:21:12PM -0500, Tejun Heo wrote:
> On Thu, Nov 28, 2013 at 02:54:13PM -0500, Tejun Heo wrote:
> > Hello, Greg.
> > 
> > For some reason, quilt can rebase the patches automatically here.  I'm
> > reposting the rest of the series (patches 07-41) here just in case.
> > git branches for both pending patchsets are updated accordingly.
> > 
> >  git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git review-separate-out-kernfs
> >  git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git review-kernfs-xattr
> 
> Two patches updated - 0032 updated to v3 and 0033 updated to v2.  Both
> add explicit noop implementation of inline functions for !CONFIG_SYSFS
> cases.  git branches are updated.  If it's too confusing, pleaes let
> me know.  I'll repost the whole series.

No, I think I got it all right, I've applied the series to my tree, care
to check that I didn't mess anything up?

thanks,

greg k-h

Re: [PATCHSET PARTIAL REPOST driver-core-next] sysfs: separate out kernfs, take #3

[Tejun Heo]

On Fri, Nov 29, 2013 at 06:55:24PM -0800, Greg KH wrote:
> On Fri, Nov 29, 2013 at 05:21:12PM -0500, Tejun Heo wrote:
> > On Thu, Nov 28, 2013 at 02:54:13PM -0500, Tejun Heo wrote:
> > > Hello, Greg.
> > > 
> > > For some reason, quilt can rebase the patches automatically here.  I'm
> > > reposting the rest of the series (patches 07-41) here just in case.
> > > git branches for both pending patchsets are updated accordingly.
> > > 
> > >  git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git review-separate-out-kernfs
> > >  git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git review-kernfs-xattr
> > 
> > Two patches updated - 0032 updated to v3 and 0033 updated to v2.  Both
> > add explicit noop implementation of inline functions for !CONFIG_SYSFS
> > cases.  git branches are updated.  If it's too confusing, pleaes let
> > me know.  I'll repost the whole series.
> 
> No, I think I got it all right, I've applied the series to my tree, care
> to check that I didn't mess anything up?

Looks good to me.  Thanks!

-- 
tejun