[PATCH v2 0/7] libfs: group and simplify linux fs code

[PATCH v2 0/7] libfs: group and simplify linux fs code

[Emanuele Giuseppe Esposito]

libfs.c has many functions that are useful to implement dentry and inode
operations, but not many at the filesystem level.  As a result, code to
create files and inodes has a lot of duplication, to the point that
tracefs has copied several hundred lines from debugfs.

The main two libfs.c functions for filesystems are simple_pin_fs and
simple_release_fs, which hide a somewhat complicated locking sequence
that is needed to serialize vfs_kern_mount and mntget.  In this series,
my aim is to add functions that create dentries and inodes of various
kinds (either anonymous inodes, or directory/file/symlink).  These
functions take the code that was duplicated across debugfs and tracefs
and move it to libfs.c.

In order to limit the number of arguments to the new functions, the
series first creates a data type that is passed to both
simple_pin_fs/simple_release_fs and the new creation functions.  The new
struct, introduced in patch 2, simply groups the "mount" and "count"
arguments to simple_pin_fs and simple_release_fs.

Patches 1-4 are preparations to introduce the new simple_fs struct and
new functions that are useful in the remainder of the series.  Patch 5
introduces the dentry and inode creation functions.  Patch 6-7 can then
adopt them in debugfs and tracefs.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>

v1->v2: rename simple_new_inode in new_inode_current_time,
more detailed explanations, put all common code in fs/libfs.c

Emanuele Giuseppe Esposito (7):
  apparmor: just use vfs_kern_mount to make .null
  libfs: wrap simple_pin_fs/simple_release_fs arguments in a struct
  libfs: introduce new_inode_current_time
  libfs: add alloc_anon_inode wrapper
  libfs: add file creation functions
  debugfs: switch to simplefs inode creation API
  tracefs: switch to simplefs inode creation API

 drivers/gpu/drm/drm_drv.c       |  11 +-
 drivers/misc/cxl/api.c          |  13 +-
 drivers/scsi/cxlflash/ocxl_hw.c |  14 +-
 fs/binfmt_misc.c                |   9 +-
 fs/configfs/mount.c             |  10 +-
 fs/debugfs/inode.c              | 158 +++--------------
 fs/libfs.c                      | 299 ++++++++++++++++++++++++++++++--
 fs/tracefs/inode.c              |  96 ++--------
 include/linux/fs.h              |  31 +++-
 security/apparmor/apparmorfs.c  |  38 ++--
 security/inode.c                |  11 +-
 11 files changed, 399 insertions(+), 291 deletions(-)

-- 
2.25.2

[PATCH v2 1/7] apparmor: just use vfs_kern_mount to make .null

[Emanuele Giuseppe Esposito]

aa_mk_null_file is using simple_pin_fs/simple_release_fs with local
variables as arguments, for what would amount to a simple
vfs_kern_mount/mntput pair if everything was inlined.  Just use
the normal filesystem API since the reference counting is not needed
here (it is a local variable and always 0 on entry and on exit).

There is no functional change intended.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
 security/apparmor/apparmorfs.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index 280741fc0f5f..36f848734902 100644
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -2525,14 +2525,15 @@ struct path aa_null;
 
 static int aa_mk_null_file(struct dentry *parent)
 {
-	struct vfsmount *mount = NULL;
+	struct file_system_type *type = parent->d_sb->s_type;
+	struct vfsmount *mount;
 	struct dentry *dentry;
 	struct inode *inode;
-	int count = 0;
-	int error = simple_pin_fs(parent->d_sb->s_type, &mount, &count);
+	int error;
 
-	if (error)
-		return error;
+	mount = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL);
+	if (IS_ERR(mount))
+		return PTR_ERR(mount);
 
 	inode_lock(d_inode(parent));
 	dentry = lookup_one_len(NULL_FILE_NAME, parent, strlen(NULL_FILE_NAME));
@@ -2561,7 +2562,7 @@ static int aa_mk_null_file(struct dentry *parent)
 	dput(dentry);
 out:
 	inode_unlock(d_inode(parent));
-	simple_release_fs(&mount, &count);
+	mntput(mount);
 	return error;
 }
 
-- 
2.25.2

[PATCH v2 2/7] libfs: wrap simple_pin_fs/simple_release_fs arguments in a struct

[Emanuele Giuseppe Esposito]

Simplify passing the count and mount to simple_pin_fs and
simple_release_fs by wrapping them in the simple_fs struct,
in preparation for adding more high level operations to
fs/libfs.c

There is no functional change intended.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
 drivers/gpu/drm/drm_drv.c       | 11 ++++----
 drivers/misc/cxl/api.c          | 13 +++++-----
 drivers/scsi/cxlflash/ocxl_hw.c | 14 +++++-----
 fs/binfmt_misc.c                |  9 +++----
 fs/configfs/mount.c             | 10 +++-----
 fs/debugfs/inode.c              | 22 ++++++++--------
 fs/libfs.c                      | 45 +++++++++++++++++++++++++--------
 fs/tracefs/inode.c              | 18 ++++++-------
 include/linux/fs.h              | 10 ++++++--
 security/apparmor/apparmorfs.c  | 25 +++++++++---------
 security/inode.c                | 11 ++++----
 11 files changed, 103 insertions(+), 85 deletions(-)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 7b1a628d1f6e..e29424d64874 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -514,8 +514,7 @@ EXPORT_SYMBOL(drm_dev_unplug);
  * iput(), but this way you'd end up with a new vfsmount for each inode.
  */
 
-static int drm_fs_cnt;
-static struct vfsmount *drm_fs_mnt;
+static struct simple_fs drm_fs;
 
 static int drm_fs_init_fs_context(struct fs_context *fc)
 {
@@ -534,15 +533,15 @@ static struct inode *drm_fs_inode_new(void)
 	struct inode *inode;
 	int r;
 
-	r = simple_pin_fs(&drm_fs_type, &drm_fs_mnt, &drm_fs_cnt);
+	r = simple_pin_fs(&drm_fs, &drm_fs_type);
 	if (r < 0) {
 		DRM_ERROR("Cannot mount pseudo fs: %d\n", r);
 		return ERR_PTR(r);
 	}
 
-	inode = alloc_anon_inode(drm_fs_mnt->mnt_sb);
+	inode = alloc_anon_inode(drm_fs.mount->mnt_sb);
 	if (IS_ERR(inode))
-		simple_release_fs(&drm_fs_mnt, &drm_fs_cnt);
+		simple_release_fs(&drm_fs);
 
 	return inode;
 }
@@ -551,7 +550,7 @@ static void drm_fs_inode_free(struct inode *inode)
 {
 	if (inode) {
 		iput(inode);
-		simple_release_fs(&drm_fs_mnt, &drm_fs_cnt);
+		simple_release_fs(&drm_fs);
 	}
 }
 
diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c
index b493de962153..67e4808bce49 100644
--- a/drivers/misc/cxl/api.c
+++ b/drivers/misc/cxl/api.c
@@ -31,8 +31,7 @@
 
 #define CXL_PSEUDO_FS_MAGIC	0x1697697f
 
-static int cxl_fs_cnt;
-static struct vfsmount *cxl_vfs_mount;
+static struct simple_fs cxl_fs;
 
 static int cxl_fs_init_fs_context(struct fs_context *fc)
 {
@@ -50,7 +49,7 @@ static struct file_system_type cxl_fs_type = {
 void cxl_release_mapping(struct cxl_context *ctx)
 {
 	if (ctx->kernelapi && ctx->mapping)
-		simple_release_fs(&cxl_vfs_mount, &cxl_fs_cnt);
+		simple_release_fs(&cxl_fs);
 }
 
 static struct file *cxl_getfile(const char *name,
@@ -66,20 +65,20 @@ static struct file *cxl_getfile(const char *name,
 	if (fops->owner && !try_module_get(fops->owner))
 		return ERR_PTR(-ENOENT);
 
-	rc = simple_pin_fs(&cxl_fs_type, &cxl_vfs_mount, &cxl_fs_cnt);
+	rc = simple_pin_fs(&cxl_fs, &cxl_fs_type);
 	if (rc < 0) {
 		pr_err("Cannot mount cxl pseudo filesystem: %d\n", rc);
 		file = ERR_PTR(rc);
 		goto err_module;
 	}
 
-	inode = alloc_anon_inode(cxl_vfs_mount->mnt_sb);
+	inode = alloc_anon_inode(cxl_fs.mount->mnt_sb);
 	if (IS_ERR(inode)) {
 		file = ERR_CAST(inode);
 		goto err_fs;
 	}
 
-	file = alloc_file_pseudo(inode, cxl_vfs_mount, name,
+	file = alloc_file_pseudo(inode, cxl_fs.mount, name,
 				 flags & (O_ACCMODE | O_NONBLOCK), fops);
 	if (IS_ERR(file))
 		goto err_inode;
@@ -91,7 +90,7 @@ static struct file *cxl_getfile(const char *name,
 err_inode:
 	iput(inode);
 err_fs:
-	simple_release_fs(&cxl_vfs_mount, &cxl_fs_cnt);
+	simple_release_fs(&cxl_fs);
 err_module:
 	module_put(fops->owner);
 	return file;
diff --git a/drivers/scsi/cxlflash/ocxl_hw.c b/drivers/scsi/cxlflash/ocxl_hw.c
index 7018cd802569..7fa98dd4fa28 100644
--- a/drivers/scsi/cxlflash/ocxl_hw.c
+++ b/drivers/scsi/cxlflash/ocxl_hw.c
@@ -29,8 +29,7 @@
 
 #define OCXLFLASH_FS_MAGIC      0x1697698f
 
-static int ocxlflash_fs_cnt;
-static struct vfsmount *ocxlflash_vfs_mount;
+static struct simple_fs ocxlflash_fs;
 
 static int ocxlflash_fs_init_fs_context(struct fs_context *fc)
 {
@@ -51,7 +50,7 @@ static struct file_system_type ocxlflash_fs_type = {
 static void ocxlflash_release_mapping(struct ocxlflash_context *ctx)
 {
 	if (ctx->mapping)
-		simple_release_fs(&ocxlflash_vfs_mount, &ocxlflash_fs_cnt);
+		simple_release_fs(&ocxlflash_fs);
 	ctx->mapping = NULL;
 }
 
@@ -79,15 +78,14 @@ static struct file *ocxlflash_getfile(struct device *dev, const char *name,
 		goto err1;
 	}
 
-	rc = simple_pin_fs(&ocxlflash_fs_type, &ocxlflash_vfs_mount,
-			   &ocxlflash_fs_cnt);
+	rc = simple_pin_fs(&ocxlflash_fs, &ocxlflash_fs_type);
 	if (unlikely(rc < 0)) {
 		dev_err(dev, "%s: Cannot mount ocxlflash pseudofs rc=%d\n",
 			__func__, rc);
 		goto err2;
 	}
 
-	inode = alloc_anon_inode(ocxlflash_vfs_mount->mnt_sb);
+	inode = alloc_anon_inode(ocxlflash_fs.mount->mnt_sb);
 	if (IS_ERR(inode)) {
 		rc = PTR_ERR(inode);
 		dev_err(dev, "%s: alloc_anon_inode failed rc=%d\n",
@@ -95,7 +93,7 @@ static struct file *ocxlflash_getfile(struct device *dev, const char *name,
 		goto err3;
 	}
 
-	file = alloc_file_pseudo(inode, ocxlflash_vfs_mount, name,
+	file = alloc_file_pseudo(inode, ocxlflash_fs.mount, name,
 				 flags & (O_ACCMODE | O_NONBLOCK), fops);
 	if (IS_ERR(file)) {
 		rc = PTR_ERR(file);
@@ -110,7 +108,7 @@ static struct file *ocxlflash_getfile(struct device *dev, const char *name,
 err4:
 	iput(inode);
 err3:
-	simple_release_fs(&ocxlflash_vfs_mount, &ocxlflash_fs_cnt);
+	simple_release_fs(&ocxlflash_fs);
 err2:
 	module_put(fops->owner);
 err1:
diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index cdb45829354d..3cff446f222b 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -64,8 +64,7 @@ typedef struct {
 
 static DEFINE_RWLOCK(entries_lock);
 static struct file_system_type bm_fs_type;
-static struct vfsmount *bm_mnt;
-static int entry_count;
+static struct simple_fs bm_fs;
 
 /*
  * Max length of the register string.  Determined by:
@@ -623,7 +622,7 @@ static void kill_node(Node *e)
 	drop_nlink(d_inode(dentry));
 	d_drop(dentry);
 	dput(dentry);
-	simple_release_fs(&bm_mnt, &entry_count);
+	simple_release_fs(&bm_fs);
 }
 
 /* /<entry> */
@@ -718,7 +717,7 @@ static ssize_t bm_register_write(struct file *file, const char __user *buffer,
 	if (!inode)
 		goto out2;
 
-	err = simple_pin_fs(&bm_fs_type, &bm_mnt, &entry_count);
+	err = simple_pin_fs(&bm_fs, &bm_fs_type);
 	if (err) {
 		iput(inode);
 		inode = NULL;
@@ -732,7 +731,7 @@ static ssize_t bm_register_write(struct file *file, const char __user *buffer,
 		if (IS_ERR(f)) {
 			err = PTR_ERR(f);
 			pr_notice("register: failed to install interpreter file %s\n", e->interpreter);
-			simple_release_fs(&bm_mnt, &entry_count);
+			simple_release_fs(&bm_fs);
 			iput(inode);
 			inode = NULL;
 			goto out2;
diff --git a/fs/configfs/mount.c b/fs/configfs/mount.c
index 0c6e8cf61953..9fb2791e5eed 100644
--- a/fs/configfs/mount.c
+++ b/fs/configfs/mount.c
@@ -24,9 +24,8 @@
 /* Random magic number */
 #define CONFIGFS_MAGIC 0x62656570
 
-static struct vfsmount *configfs_mount = NULL;
+static struct simple_fs configfs_fs;
 struct kmem_cache *configfs_dir_cachep;
-static int configfs_mnt_count = 0;
 
 
 static void configfs_free_inode(struct inode *inode)
@@ -123,14 +122,13 @@ MODULE_ALIAS_FS("configfs");
 
 struct dentry *configfs_pin_fs(void)
 {
-	int err = simple_pin_fs(&configfs_fs_type, &configfs_mount,
-			     &configfs_mnt_count);
-	return err ? ERR_PTR(err) : configfs_mount->mnt_root;
+	int err = simple_pin_fs(&configfs_fs, &configfs_fs_type);
+	return err ? ERR_PTR(err) : configfs_fs.mount->mnt_root;
 }
 
 void configfs_release_fs(void)
 {
-	simple_release_fs(&configfs_mount, &configfs_mnt_count);
+	simple_release_fs(&configfs_fs);
 }
 
 
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index b7f2e971ecbc..5dbb74a23e7c 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -32,8 +32,7 @@
 
 #define DEBUGFS_DEFAULT_MODE	0700
 
-static struct vfsmount *debugfs_mount;
-static int debugfs_mount_count;
+static struct simple_fs debugfs;
 static bool debugfs_registered;
 
 /*
@@ -297,7 +296,7 @@ struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
 		return NULL;
 
 	if (!parent)
-		parent = debugfs_mount->mnt_root;
+		parent = debugfs.mount->mnt_root;
 
 	dentry = lookup_positive_unlocked(name, parent, strlen(name));
 	if (IS_ERR(dentry))
@@ -316,8 +315,7 @@ static struct dentry *start_creating(const char *name, struct dentry *parent)
 	if (IS_ERR(parent))
 		return parent;
 
-	error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
-			      &debugfs_mount_count);
+	error = simple_pin_fs(&debugfs, &debug_fs_type);
 	if (error) {
 		pr_err("Unable to pin filesystem for file '%s'\n", name);
 		return ERR_PTR(error);
@@ -329,7 +327,7 @@ static struct dentry *start_creating(const char *name, struct dentry *parent)
 	 * have around.
 	 */
 	if (!parent)
-		parent = debugfs_mount->mnt_root;
+		parent = debugfs.mount->mnt_root;
 
 	inode_lock(d_inode(parent));
 	if (unlikely(IS_DEADDIR(d_inode(parent))))
@@ -349,7 +347,7 @@ static struct dentry *start_creating(const char *name, struct dentry *parent)
 
 	if (IS_ERR(dentry)) {
 		inode_unlock(d_inode(parent));
-		simple_release_fs(&debugfs_mount, &debugfs_mount_count);
+		simple_release_fs(&debugfs);
 	}
 
 	return dentry;
@@ -359,7 +357,7 @@ static struct dentry *failed_creating(struct dentry *dentry)
 {
 	inode_unlock(d_inode(dentry->d_parent));
 	dput(dentry);
-	simple_release_fs(&debugfs_mount, &debugfs_mount_count);
+	simple_release_fs(&debugfs);
 	return ERR_PTR(-ENOMEM);
 }
 
@@ -676,9 +674,9 @@ static void __debugfs_file_removed(struct dentry *dentry)
 
 static void remove_one(struct dentry *victim)
 {
-        if (d_is_reg(victim))
+	if (d_is_reg(victim))
 		__debugfs_file_removed(victim);
-	simple_release_fs(&debugfs_mount, &debugfs_mount_count);
+	simple_release_fs(&debugfs);
 }
 
 /**
@@ -699,9 +697,9 @@ void debugfs_remove(struct dentry *dentry)
 	if (IS_ERR_OR_NULL(dentry))
 		return;
 
-	simple_pin_fs(&debug_fs_type, &debugfs_mount, &debugfs_mount_count);
+	simple_pin_fs(&debugfs, &debug_fs_type);
 	simple_recursive_removal(dentry, remove_one);
-	simple_release_fs(&debugfs_mount, &debugfs_mount_count);
+	simple_release_fs(&debugfs);
 }
 EXPORT_SYMBOL_GPL(debugfs_remove);
 
diff --git a/fs/libfs.c b/fs/libfs.c
index 3759fbacf522..54e07ae986ca 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -665,39 +665,64 @@ EXPORT_SYMBOL(simple_fill_super);
 
 static DEFINE_SPINLOCK(pin_fs_lock);
 
-int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
+/**
+ * simple_pin_fs - generic function to pin (mount if needed,
+ *                otherwise add a reference to the mount) a filesystem
+ * @fs: a pointer to a the simple_fs struct containing a struct vfs_mount
+ *      pointer (that can be NULL) and a counter.
+ * @type: a pointer to the file system type used by vfs_kern_mount.
+ *
+ * This function sets fs->mount if NULL, by calling vfs_kern_mount
+ * on @type.
+ * It also takes care of incrementing the reference counter.
+ *
+ * This function will return 0 in case of success, and PTR_ERR(-ERROR)
+ * if vfs_kern_mount fails.
+ **/
+int simple_pin_fs(struct simple_fs *fs, struct file_system_type *type)
 {
 	struct vfsmount *mnt = NULL;
 	spin_lock(&pin_fs_lock);
-	if (unlikely(!*mount)) {
+	if (unlikely(!fs->mount)) {
 		spin_unlock(&pin_fs_lock);
 		mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL);
 		if (IS_ERR(mnt))
 			return PTR_ERR(mnt);
 		spin_lock(&pin_fs_lock);
-		if (!*mount)
-			*mount = mnt;
+		if (!fs->mount)
+			fs->mount = mnt;
 	}
-	mntget(*mount);
-	++*count;
+	mntget(fs->mount);
+	++fs->count;
 	spin_unlock(&pin_fs_lock);
 	mntput(mnt);
 	return 0;
 }
 EXPORT_SYMBOL(simple_pin_fs);
 
-void simple_release_fs(struct vfsmount **mount, int *count)
+/**
+ * simple_release_fs - decrements the reference counter and unmounts the
+ *                    file system.
+ * @fs: a pointer to a struct simple_fs containing the reference counter
+ *      and vfs_mount pointer
+ *
+ * This function decrements the refcount of the given file system and
+ * if 0 sets the mount pointer to NULL.
+ **/
+void simple_release_fs(struct simple_fs *fs)
 {
 	struct vfsmount *mnt;
 	spin_lock(&pin_fs_lock);
-	mnt = *mount;
-	if (!--*count)
-		*mount = NULL;
+	mnt = fs->mount;
+	if (!--fs->count)
+		fs->mount = NULL;
 	spin_unlock(&pin_fs_lock);
 	mntput(mnt);
 }
 EXPORT_SYMBOL(simple_release_fs);
 
+
+
 /**
  * simple_read_from_buffer - copy data from the buffer to user space
  * @to: the user space buffer to read to
diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index 0ee8c6dfb036..370eb38ff1ad 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -24,8 +24,7 @@
 
 #define TRACEFS_DEFAULT_MODE	0700
 
-static struct vfsmount *tracefs_mount;
-static int tracefs_mount_count;
+static struct simple_fs tracefs;
 static bool tracefs_registered;
 
 static ssize_t default_read_file(struct file *file, char __user *buf,
@@ -316,8 +315,7 @@ static struct dentry *start_creating(const char *name, struct dentry *parent)
 
 	pr_debug("tracefs: creating file '%s'\n",name);
 
-	error = simple_pin_fs(&trace_fs_type, &tracefs_mount,
-			      &tracefs_mount_count);
+	error = simple_pin_fs(&tracefs, &trace_fs_type);
 	if (error)
 		return ERR_PTR(error);
 
@@ -327,7 +325,7 @@ static struct dentry *start_creating(const char *name, struct dentry *parent)
 	 * have around.
 	 */
 	if (!parent)
-		parent = tracefs_mount->mnt_root;
+		parent = tracefs.mount->mnt_root;
 
 	inode_lock(parent->d_inode);
 	if (unlikely(IS_DEADDIR(parent->d_inode)))
@@ -341,7 +339,7 @@ static struct dentry *start_creating(const char *name, struct dentry *parent)
 
 	if (IS_ERR(dentry)) {
 		inode_unlock(parent->d_inode);
-		simple_release_fs(&tracefs_mount, &tracefs_mount_count);
+		simple_release_fs(&tracefs);
 	}
 
 	return dentry;
@@ -351,7 +349,7 @@ static struct dentry *failed_creating(struct dentry *dentry)
 {
 	inode_unlock(dentry->d_parent->d_inode);
 	dput(dentry);
-	simple_release_fs(&tracefs_mount, &tracefs_mount_count);
+	simple_release_fs(&tracefs);
 	return NULL;
 }
 
@@ -504,7 +502,7 @@ __init struct dentry *tracefs_create_instance_dir(const char *name,
 
 static void remove_one(struct dentry *victim)
 {
-	simple_release_fs(&tracefs_mount, &tracefs_mount_count);
+	simple_release_fs(&tracefs);
 }
 
 /**
@@ -520,9 +518,9 @@ void tracefs_remove(struct dentry *dentry)
 	if (IS_ERR_OR_NULL(dentry))
 		return;
 
-	simple_pin_fs(&trace_fs_type, &tracefs_mount, &tracefs_mount_count);
+	simple_pin_fs(&tracefs, &trace_fs_type);
 	simple_recursive_removal(dentry, remove_one);
-	simple_release_fs(&tracefs_mount, &tracefs_mount_count);
+	simple_release_fs(&tracefs);
 }
 
 /**
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 4f6f59b4f22a..a3691c132b3a 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3363,8 +3363,14 @@ struct tree_descr { const char *name; const struct file_operations *ops; int mod
 struct dentry *d_alloc_name(struct dentry *, const char *);
 extern int simple_fill_super(struct super_block *, unsigned long,
 			     const struct tree_descr *);
-extern int simple_pin_fs(struct file_system_type *, struct vfsmount **mount, int *count);
-extern void simple_release_fs(struct vfsmount **mount, int *count);
+
+struct simple_fs {
+	struct vfsmount *mount;
+	int count;
+};
+
+extern int simple_pin_fs(struct simple_fs *, struct file_system_type *);
+extern void simple_release_fs(struct simple_fs *);
 
 extern ssize_t simple_read_from_buffer(void __user *to, size_t count,
 			loff_t *ppos, const void *from, size_t available);
diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index 36f848734902..00f0158fb1e1 100644
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -140,8 +140,7 @@ static int mangle_name(const char *name, char *target)
  */
 
 #define AAFS_NAME		"apparmorfs"
-static struct vfsmount *aafs_mnt;
-static int aafs_count;
+static struct simple_fs aafs;
 
 
 static int aafs_show_path(struct seq_file *seq, struct dentry *dentry)
@@ -273,7 +272,7 @@ static struct dentry *aafs_create(const char *name, umode_t mode,
 	if (!(mode & S_IFMT))
 		mode = (mode & S_IALLUGO) | S_IFREG;
 
-	error = simple_pin_fs(&aafs_ops, &aafs_mnt, &aafs_count);
+	error = simple_pin_fs(&aafs, &aafs_ops);
 	if (error)
 		return ERR_PTR(error);
 
@@ -303,7 +302,7 @@ static struct dentry *aafs_create(const char *name, umode_t mode,
 
 fail_lock:
 	inode_unlock(dir);
-	simple_release_fs(&aafs_mnt, &aafs_count);
+	simple_release_fs(&aafs);
 
 	return ERR_PTR(error);
 }
@@ -395,7 +394,7 @@ static void aafs_remove(struct dentry *dentry)
 		dput(dentry);
 	}
 	inode_unlock(dir);
-	simple_release_fs(&aafs_mnt, &aafs_count);
+	simple_release_fs(&aafs);
 }
 
 
@@ -1824,7 +1823,7 @@ static int ns_mkdir_op(struct inode *dir, struct dentry *dentry, umode_t mode)
 	 * for pin_fs
 	 */
 	inode_unlock(dir);
-	error = simple_pin_fs(&aafs_ops, &aafs_mnt, &aafs_count);
+	error = simple_pin_fs(&aafs, &aafs_ops);
 	mutex_lock_nested(&parent->lock, parent->level);
 	inode_lock_nested(dir, I_MUTEX_PARENT);
 	if (error)
@@ -1845,7 +1844,7 @@ static int ns_mkdir_op(struct inode *dir, struct dentry *dentry, umode_t mode)
 	aa_put_ns(ns);		/* list ref remains */
 out_pin:
 	if (error)
-		simple_release_fs(&aafs_mnt, &aafs_count);
+		simple_release_fs(&aafs);
 out:
 	mutex_unlock(&parent->lock);
 	aa_put_ns(parent);
@@ -2580,7 +2579,7 @@ static const char *policy_get_link(struct dentry *dentry,
 		return ERR_PTR(-ECHILD);
 
 	ns = aa_get_current_ns();
-	path.mnt = mntget(aafs_mnt);
+	path.mnt = mntget(aafs.mount);
 	path.dentry = dget(ns_dir(ns));
 	error = nd_jump_link(&path);
 	aa_put_ns(ns);
@@ -2631,10 +2630,10 @@ static int __init aa_create_aafs(void)
 	}
 
 	/* setup apparmorfs used to virtualize policy/ */
-	aafs_mnt = kern_mount(&aafs_ops);
-	if (IS_ERR(aafs_mnt))
+	aafs.mount = kern_mount(&aafs_ops);
+	if (IS_ERR(aafs.mount))
 		panic("can't set apparmorfs up\n");
-	aafs_mnt->mnt_sb->s_flags &= ~SB_NOUSER;
+	aafs.mount->mnt_sb->s_flags &= ~SB_NOUSER;
 
 	/* Populate fs tree. */
 	error = entry_create_dir(&aa_sfs_entry, NULL);
@@ -2667,8 +2666,8 @@ static int __init aa_create_aafs(void)
 
 	/* policy tree referenced by magic policy symlink */
 	mutex_lock_nested(&root_ns->lock, root_ns->level);
-	error = __aafs_ns_mkdir(root_ns, aafs_mnt->mnt_root, ".policy",
-				aafs_mnt->mnt_root);
+	error = __aafs_ns_mkdir(root_ns, aafs.mount->mnt_root, ".policy",
+				aafs.mount->mnt_root);
 	mutex_unlock(&root_ns->lock);
 	if (error)
 		goto error;
diff --git a/security/inode.c b/security/inode.c
index 6c326939750d..8a1bee35470a 100644
--- a/security/inode.c
+++ b/security/inode.c
@@ -22,8 +22,7 @@
 #include <linux/lsm_hooks.h>
 #include <linux/magic.h>
 
-static struct vfsmount *mount;
-static int mount_count;
+static struct simple_fs securityfs;
 
 static void securityfs_free_inode(struct inode *inode)
 {
@@ -118,12 +117,12 @@ static struct dentry *securityfs_create_dentry(const char *name, umode_t mode,
 
 	pr_debug("securityfs: creating file '%s'\n",name);
 
-	error = simple_pin_fs(&fs_type, &mount, &mount_count);
+	error = simple_pin_fs(&securityfs, &fs_type);
 	if (error)
 		return ERR_PTR(error);
 
 	if (!parent)
-		parent = mount->mnt_root;
+		parent = securityfs.mount->mnt_root;
 
 	dir = d_inode(parent);
 
@@ -168,7 +167,7 @@ static struct dentry *securityfs_create_dentry(const char *name, umode_t mode,
 	dentry = ERR_PTR(error);
 out:
 	inode_unlock(dir);
-	simple_release_fs(&mount, &mount_count);
+	simple_release_fs(&securityfs);
 	return dentry;
 }
 
@@ -309,7 +308,7 @@ void securityfs_remove(struct dentry *dentry)
 		dput(dentry);
 	}
 	inode_unlock(dir);
-	simple_release_fs(&mount, &mount_count);
+	simple_release_fs(&securityfs);
 }
 EXPORT_SYMBOL_GPL(securityfs_remove);
 
-- 
2.25.2

[PATCH v2 3/7] libfs: introduce new_inode_current_time

[Emanuele Giuseppe Esposito]

It is a common special case for new_inode to initialize the
time to the current time and the inode to get_next_ino().
Introduce a core function that does it.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
 fs/libfs.c         | 20 ++++++++++++++++++++
 include/linux/fs.h |  1 +
 2 files changed, 21 insertions(+)

diff --git a/fs/libfs.c b/fs/libfs.c
index 54e07ae986ca..3fa0cd27ab06 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -594,6 +594,26 @@ int simple_write_end(struct file *file, struct address_space *mapping,
 }
 EXPORT_SYMBOL(simple_write_end);
 
+/**
+ * new_inode_current_time - create new inode by initializing the
+ * time to the current time and the inode to get_next_ino()
+ * @sb: pointer to super block of the file system
+ *
+ * Returns an inode pointer on success, NULL on failure.
+ */
+struct inode *new_inode_current_time(struct super_block *sb)
+{
+	struct inode *inode = new_inode(sb);
+
+	if (inode) {
+		inode->i_ino = get_next_ino();
+		inode->i_atime = inode->i_mtime =
+			inode->i_ctime = current_time(inode);
+	}
+	return inode;
+}
+EXPORT_SYMBOL(new_inode_current_time);
+
 /*
  * the inodes created here are not hashed. If you use iunique to generate
  * unique inode values later for this filesystem, then you must take care
diff --git a/include/linux/fs.h b/include/linux/fs.h
index a3691c132b3a..de2577df30ae 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3088,6 +3088,7 @@ extern void clear_inode(struct inode *);
 extern void __destroy_inode(struct inode *);
 extern struct inode *new_inode_pseudo(struct super_block *sb);
 extern struct inode *new_inode(struct super_block *sb);
+extern struct inode *new_inode_current_time(struct super_block *sb);
 extern void free_inode_nonrcu(struct inode *inode);
 extern int should_remove_suid(struct dentry *);
 extern int file_remove_privs(struct file *);
-- 
2.25.2

[PATCH v2 4/7] libfs: add alloc_anon_inode wrapper

[Emanuele Giuseppe Esposito]

libfs.c has many functions that are useful to implement dentry and inode
operations, but not many at the filesystem level. Start adding file
creation wrappers, the simplest returns an anonymous inode.

There is no functional change intended.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
 drivers/gpu/drm/drm_drv.c       |  2 +-
 drivers/misc/cxl/api.c          |  2 +-
 drivers/scsi/cxlflash/ocxl_hw.c |  2 +-
 fs/libfs.c                      | 10 +++++++++-
 include/linux/fs.h              |  2 ++
 5 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index e29424d64874..1854f760ad39 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -539,7 +539,7 @@ static struct inode *drm_fs_inode_new(void)
 		return ERR_PTR(r);
 	}
 
-	inode = alloc_anon_inode(drm_fs.mount->mnt_sb);
+	inode = simple_alloc_anon_inode(&drm_fs);
 	if (IS_ERR(inode))
 		simple_release_fs(&drm_fs);
 
diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c
index 67e4808bce49..57672abb6223 100644
--- a/drivers/misc/cxl/api.c
+++ b/drivers/misc/cxl/api.c
@@ -72,7 +72,7 @@ static struct file *cxl_getfile(const char *name,
 		goto err_module;
 	}
 
-	inode = alloc_anon_inode(cxl_fs.mount->mnt_sb);
+	inode = simple_alloc_anon_inode(&cxl_fs);
 	if (IS_ERR(inode)) {
 		file = ERR_CAST(inode);
 		goto err_fs;
diff --git a/drivers/scsi/cxlflash/ocxl_hw.c b/drivers/scsi/cxlflash/ocxl_hw.c
index 7fa98dd4fa28..0e9f2ae7eebf 100644
--- a/drivers/scsi/cxlflash/ocxl_hw.c
+++ b/drivers/scsi/cxlflash/ocxl_hw.c
@@ -85,7 +85,7 @@ static struct file *ocxlflash_getfile(struct device *dev, const char *name,
 		goto err2;
 	}
 
-	inode = alloc_anon_inode(ocxlflash_fs.mount->mnt_sb);
+	inode = simple_alloc_anon_inode(&ocxlflash_fs);
 	if (IS_ERR(inode)) {
 		rc = PTR_ERR(inode);
 		dev_err(dev, "%s: alloc_anon_inode failed rc=%d\n",
diff --git a/fs/libfs.c b/fs/libfs.c
index 3fa0cd27ab06..5c76e4c648dc 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -741,7 +741,15 @@ void simple_release_fs(struct simple_fs *fs)
 }
 EXPORT_SYMBOL(simple_release_fs);
 
-
+/**
+ * simple_alloc_anon_inode - wrapper for alloc_anon_inode
+ * @fs: a pointer to a struct simple_fs containing a valid vfs_mount pointer
+ **/
+struct inode *simple_alloc_anon_inode(struct simple_fs *fs)
+{
+	return alloc_anon_inode(fs->mount->mnt_sb);
+}
+EXPORT_SYMBOL(simple_alloc_anon_inode);
 
 /**
  * simple_read_from_buffer - copy data from the buffer to user space
diff --git a/include/linux/fs.h b/include/linux/fs.h
index de2577df30ae..5e93de72118b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3373,6 +3373,8 @@ struct simple_fs {
 extern int simple_pin_fs(struct simple_fs *, struct file_system_type *);
 extern void simple_release_fs(struct simple_fs *);
 
+extern struct inode *simple_alloc_anon_inode(struct simple_fs *fs);
+
 extern ssize_t simple_read_from_buffer(void __user *to, size_t count,
 			loff_t *ppos, const void *from, size_t available);
 extern ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
-- 
2.25.2

[PATCH v2 5/7] libfs: add file creation functions

[Emanuele Giuseppe Esposito]

A bunch of code is duplicated between debugfs and tracefs, unify it to the
libfs library.

The code is very similar, except that dentry and inode creation are unified
into a single function (unlike start_creating in debugfs and tracefs, which
only takes care of dentries).  This adds an output parameter to the
creation functions, but pushes all error recovery into fs/libfs.c.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
 fs/libfs.c         | 226 +++++++++++++++++++++++++++++++++++++++++++++
 include/linux/fs.h |  18 ++++
 2 files changed, 244 insertions(+)

diff --git a/fs/libfs.c b/fs/libfs.c
index 5c76e4c648dc..90b0c221d9a2 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -751,6 +751,232 @@ struct inode *simple_alloc_anon_inode(struct simple_fs *fs)
 }
 EXPORT_SYMBOL(simple_alloc_anon_inode);
 
+static struct dentry *failed_creating(struct simple_fs *fs, struct dentry *dentry)
+{
+	inode_unlock(d_inode(dentry->d_parent));
+	dput(dentry);
+	simple_release_fs(fs);
+	return ERR_PTR(-ENOMEM);
+}
+
+/**
+ * simplefs_create_dentry - creates a new dentry and inode
+ * @fs: a pointer to a struct simple_fs containing the reference counter
+ *      and vfs_mount pointer
+ * @type: the fs type
+ * @name: dentry name
+ * @parent: parent dentry. If this parameter is NULL,
+ *          then the dentry will be created in the root of the
+ *          filesystem.
+ * @inode: pointer that will contain a newly created inode
+ *
+ * This function returns a new dentry, or NULL on error.  On success, a
+ * new inode is created and stored into @inode.  Also note that the inode
+ * for the parent directory is locked by simplefs_create_dentry(),
+ * and will be unlocked by simple_finish_dentry().
+ **/
+struct dentry *simplefs_create_dentry(struct simple_fs *fs, struct file_system_type *type,
+				      const char *name, struct dentry *parent,
+				      struct inode **inode)
+{
+	struct dentry *dentry;
+	int error;
+
+	pr_debug("creating file '%s'\n", name);
+
+	if (IS_ERR(parent))
+		return parent;
+
+	error = simple_pin_fs(fs, type);
+	if (error) {
+		pr_err("Unable to pin filesystem for file '%s'\n", name);
+		return ERR_PTR(error);
+	}
+
+	/* If the parent is not specified, we create it in the root.
+	 * We need the root dentry to do this, which is in the super
+	 * block. A pointer to that is in the struct vfsmount that we
+	 * have around.
+	 */
+	if (!parent)
+		parent = fs->mount->mnt_root;
+
+	inode_lock(d_inode(parent));
+	dentry = lookup_one_len(name, parent, strlen(name));
+	if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
+		if (d_is_dir(dentry))
+			pr_err("Directory '%s' with parent '%s' already present!\n",
+			       name, parent->d_name.name);
+		else
+			pr_err("File '%s' in directory '%s' already present!\n",
+			       name, parent->d_name.name);
+		dput(dentry);
+		dentry = ERR_PTR(-EEXIST);
+	}
+
+	if (IS_ERR(dentry)) {
+		inode_unlock(d_inode(parent));
+		simple_release_fs(fs);
+	}
+
+
+	if (IS_ERR(dentry))
+		return dentry;
+
+	*inode = new_inode_current_time(fs->mount->mnt_sb);
+	if (unlikely(!(*inode))) {
+		pr_err("out of free inodes, can not create file '%s'\n",
+		       name);
+		return failed_creating(fs, dentry);
+	}
+
+	return dentry;
+}
+EXPORT_SYMBOL(simplefs_create_dentry);
+
+/**
+ * simplefs_create_file - creates a new file dentry and inode
+ * @fs: a pointer to a struct simple_fs containing the reference counter
+ *      and vfs_mount pointer
+ * @type: the fs type
+ * @name: file name
+ * @mode: file mode
+ * @parent: parent dentry. If this parameter is NULL,
+ *          then the file will be created in the root of the
+ *          filesystem.
+ * @data: what will the file contain
+ * @inode: pointer that will contain a newly created inode
+ *
+ * This function returns a new dentry, or NULL on error.  On success, a
+ * new inode is created and stored into @inode.  Also note that the inode
+ * for the parent directory is locked by simplefs_create_dentry(),
+ * and will be unlocked by simple_finish_dentry().
+ **/
+struct dentry *simplefs_create_file(struct simple_fs *fs, struct file_system_type *type,
+				    const char *name, umode_t mode,
+				    struct dentry *parent, void *data,
+				    struct inode **inode)
+{
+	struct dentry *dentry;
+
+	WARN_ON((mode & S_IFMT) && !S_ISREG(mode));
+	mode |= S_IFREG;
+
+	dentry = simplefs_create_dentry(fs, type, name, parent, inode);
+
+	if (IS_ERR(dentry))
+		return dentry;
+
+	(*inode)->i_mode = mode;
+	(*inode)->i_private = data;
+
+	return dentry;
+}
+EXPORT_SYMBOL(simplefs_create_file);
+
+
+/**
+ * simplefs_finish_dentry- complete creation of a new dentry
+ * @dentry: the dentry being created
+ * @inode: the inode associated to the dentry
+ *
+ * This function completes the creation of a dentry.
+ * This includes associating @inode with the dentry, ensuring the link
+ * counts are consistent and informing fsnotify.
+ **/
+struct dentry *simplefs_finish_dentry(struct dentry *dentry, struct inode *inode)
+{
+	d_instantiate(dentry, inode);
+	if (S_ISDIR(inode->i_mode)) {
+		inc_nlink(d_inode(dentry->d_parent));
+		fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
+	} else {
+		fsnotify_create(d_inode(dentry->d_parent), dentry);
+	}
+	inode_unlock(d_inode(dentry->d_parent));
+	return dentry;
+}
+EXPORT_SYMBOL(simplefs_finish_dentry);
+
+/**
+ * simplefs_create_dir - creates a new directory dentry and inode
+ * @fs: a pointer to a struct simple_fs containing the reference counter
+ *      and vfs_mount pointer
+ * @type: the fs type
+ * @name: dir name
+ * @mode: dir mode
+ * @parent: parent dentry. If this parameter is NULL,
+ *          then the directory will be created in the root of the
+ *          filesystem.
+ * @inode: pointer that will contain a newly created inode
+ *
+ * This function returns a new dentry, or NULL on error.  On success, a
+ * new inode is created and stored into @inode.  Also note that the inode
+ * for the parent directory is locked by simplefs_create_dentry(),
+ * and will be unlocked by simple_finish_dentry().
+ **/
+struct dentry *simplefs_create_dir(struct simple_fs *fs, struct file_system_type *type,
+				   const char *name, umode_t mode, struct dentry *parent,
+				   struct inode **inode)
+{
+	struct dentry *dentry;
+
+	WARN_ON((mode & S_IFMT) && !S_ISDIR(mode));
+	mode |= S_IFDIR;
+
+	dentry = simplefs_create_dentry(fs, type, name, parent, inode);
+	if (IS_ERR(dentry))
+		return dentry;
+
+	(*inode)->i_mode = mode;
+	(*inode)->i_op = &simple_dir_inode_operations;
+	(*inode)->i_fop = &simple_dir_operations;
+
+	/* directory inodes start off with i_nlink == 2 (for "." entry) */
+	inc_nlink(*inode);
+	return dentry;
+}
+EXPORT_SYMBOL(simplefs_create_dir);
+
+/**
+ * simplefs_create_symlink - creates a new symlink dentry and inode
+ * @fs: a pointer to a struct simple_fs containing the reference counter
+ *      and vfs_mount pointer
+ * @type: the fs type
+ * @name: symlink name
+ * @parent: parent dentry. If this parameter is NULL,
+ *          then the symbolic link will be created in the root of the
+ *          filesystem.
+ * @inode: pointer that will contain a newly created inode
+ *
+ * This function returns a new dentry, or NULL on error.  On success, a
+ * new inode is created and stored into @inode.  Also note that the inode
+ * for the parent directory is locked by simplefs_create_dentry(),
+ * and will be unlocked by simple_finish_dentry().
+ **/
+struct dentry *simplefs_create_symlink(struct simple_fs *fs, struct file_system_type *type,
+				       const char *name, struct dentry *parent,
+				       const char *target, struct inode **inode)
+{
+	struct dentry *dentry;
+	char *link = kstrdup(target, GFP_KERNEL);
+
+	if (!link)
+		return ERR_PTR(-ENOMEM);
+
+	dentry = simplefs_create_dentry(fs, type, name, parent, inode);
+	if (IS_ERR(dentry)) {
+		kfree_link(link);
+		return dentry;
+	}
+
+	(*inode)->i_mode = S_IFLNK | S_IRWXUGO;
+	(*inode)->i_link = link;
+	(*inode)->i_op = &simple_symlink_inode_operations;
+	return dentry;
+}
+EXPORT_SYMBOL(simplefs_create_symlink);
+
 /**
  * simple_read_from_buffer - copy data from the buffer to user space
  * @to: the user space buffer to read to
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 5e93de72118b..0569540fbe61 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3375,6 +3375,24 @@ extern void simple_release_fs(struct simple_fs *);
 
 extern struct inode *simple_alloc_anon_inode(struct simple_fs *fs);
 
+extern struct dentry *simplefs_create_dentry(struct simple_fs *fs,
+					     struct file_system_type *type,
+					     const char *name, struct dentry *parent,
+					     struct inode **inode);
+struct dentry *simplefs_finish_dentry(struct dentry *dentry, struct inode *inode);
+
+extern struct dentry *simplefs_create_file(struct simple_fs *fs,
+					   struct file_system_type *type,
+					   const char *name, umode_t mode,
+					   struct dentry *parent, void *data,
+					   struct inode **inode);
+extern struct dentry *simplefs_create_dir(struct simple_fs *fs, struct file_system_type *type,
+					  const char *name, umode_t mode, struct dentry *parent,
+					  struct inode **inode);
+extern struct dentry *simplefs_create_symlink(struct simple_fs *fs, struct file_system_type *type,
+					      const char *name, struct dentry *parent,
+					      const char *target, struct inode **inode);
+
 extern ssize_t simple_read_from_buffer(void __user *to, size_t count,
 			loff_t *ppos, const void *from, size_t available);
 extern ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
-- 
2.25.2

[PATCH v2 6/7] debugfs: switch to simplefs inode creation API

[Emanuele Giuseppe Esposito]

The only difference, compared to the pre-existing code, is that symlink
creation now triggers fsnotify_create.  This was a bug in the debugfs
code, since for example vfs_symlink does call fsnotify_create.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
 fs/debugfs/inode.c | 144 +++++----------------------------------------
 1 file changed, 15 insertions(+), 129 deletions(-)

diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 5dbb74a23e7c..ccbeea9e5f6c 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -305,68 +305,6 @@ struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
 }
 EXPORT_SYMBOL_GPL(debugfs_lookup);
 
-static struct dentry *start_creating(const char *name, struct dentry *parent)
-{
-	struct dentry *dentry;
-	int error;
-
-	pr_debug("creating file '%s'\n", name);
-
-	if (IS_ERR(parent))
-		return parent;
-
-	error = simple_pin_fs(&debugfs, &debug_fs_type);
-	if (error) {
-		pr_err("Unable to pin filesystem for file '%s'\n", name);
-		return ERR_PTR(error);
-	}
-
-	/* If the parent is not specified, we create it in the root.
-	 * We need the root dentry to do this, which is in the super
-	 * block. A pointer to that is in the struct vfsmount that we
-	 * have around.
-	 */
-	if (!parent)
-		parent = debugfs.mount->mnt_root;
-
-	inode_lock(d_inode(parent));
-	if (unlikely(IS_DEADDIR(d_inode(parent))))
-		dentry = ERR_PTR(-ENOENT);
-	else
-		dentry = lookup_one_len(name, parent, strlen(name));
-	if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
-		if (d_is_dir(dentry))
-			pr_err("Directory '%s' with parent '%s' already present!\n",
-			       name, parent->d_name.name);
-		else
-			pr_err("File '%s' in directory '%s' already present!\n",
-			       name, parent->d_name.name);
-		dput(dentry);
-		dentry = ERR_PTR(-EEXIST);
-	}
-
-	if (IS_ERR(dentry)) {
-		inode_unlock(d_inode(parent));
-		simple_release_fs(&debugfs);
-	}
-
-	return dentry;
-}
-
-static struct dentry *failed_creating(struct dentry *dentry)
-{
-	inode_unlock(d_inode(dentry->d_parent));
-	dput(dentry);
-	simple_release_fs(&debugfs);
-	return ERR_PTR(-ENOMEM);
-}
-
-static struct dentry *end_creating(struct dentry *dentry)
-{
-	inode_unlock(d_inode(dentry->d_parent));
-	return dentry;
-}
-
 static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
 				struct dentry *parent, void *data,
 				const struct file_operations *proxy_fops,
@@ -375,32 +313,17 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
 	struct dentry *dentry;
 	struct inode *inode;
 
-	if (!(mode & S_IFMT))
-		mode |= S_IFREG;
-	BUG_ON(!S_ISREG(mode));
-	dentry = start_creating(name, parent);
-
+	dentry = simplefs_create_file(&debugfs, &debug_fs_type,
+				      name, mode, parent, data, &inode);
 	if (IS_ERR(dentry))
 		return dentry;
 
-	inode = debugfs_get_inode(dentry->d_sb);
-	if (unlikely(!inode)) {
-		pr_err("out of free dentries, can not create file '%s'\n",
-		       name);
-		return failed_creating(dentry);
-	}
-
-	inode->i_mode = mode;
-	inode->i_private = data;
-
 	inode->i_op = &debugfs_file_inode_operations;
 	inode->i_fop = proxy_fops;
 	dentry->d_fsdata = (void *)((unsigned long)real_fops |
 				DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
 
-	d_instantiate(dentry, inode);
-	fsnotify_create(d_inode(dentry->d_parent), dentry);
-	return end_creating(dentry);
+	return simplefs_finish_dentry(dentry, inode);
 }
 
 /**
@@ -533,29 +456,16 @@ EXPORT_SYMBOL_GPL(debugfs_create_file_size);
  */
 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
 {
-	struct dentry *dentry = start_creating(name, parent);
+	struct dentry *dentry;
 	struct inode *inode;
 
+	dentry = simplefs_create_dir(&debugfs, &debug_fs_type,
+				     name, 0755, parent, &inode);
 	if (IS_ERR(dentry))
 		return dentry;
 
-	inode = debugfs_get_inode(dentry->d_sb);
-	if (unlikely(!inode)) {
-		pr_err("out of free dentries, can not create directory '%s'\n",
-		       name);
-		return failed_creating(dentry);
-	}
-
-	inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
 	inode->i_op = &debugfs_dir_inode_operations;
-	inode->i_fop = &simple_dir_operations;
-
-	/* directory inodes start off with i_nlink == 2 (for "." entry) */
-	inc_nlink(inode);
-	d_instantiate(dentry, inode);
-	inc_nlink(d_inode(dentry->d_parent));
-	fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
-	return end_creating(dentry);
+	return simplefs_finish_dentry(dentry, inode);
 }
 EXPORT_SYMBOL_GPL(debugfs_create_dir);
 
@@ -575,29 +485,19 @@ struct dentry *debugfs_create_automount(const char *name,
 					debugfs_automount_t f,
 					void *data)
 {
-	struct dentry *dentry = start_creating(name, parent);
+	struct dentry *dentry;
 	struct inode *inode;
 
+	dentry = simplefs_create_dentry(&debugfs, &debug_fs_type, name, parent,
+					&inode);
 	if (IS_ERR(dentry))
 		return dentry;
 
-	inode = debugfs_get_inode(dentry->d_sb);
-	if (unlikely(!inode)) {
-		pr_err("out of free dentries, can not create automount '%s'\n",
-		       name);
-		return failed_creating(dentry);
-	}
-
 	make_empty_dir_inode(inode);
 	inode->i_flags |= S_AUTOMOUNT;
 	inode->i_private = data;
 	dentry->d_fsdata = (void *)f;
-	/* directory inodes start off with i_nlink == 2 (for "." entry) */
-	inc_nlink(inode);
-	d_instantiate(dentry, inode);
-	inc_nlink(d_inode(dentry->d_parent));
-	fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
-	return end_creating(dentry);
+	return simplefs_finish_dentry(dentry, inode);
 }
 EXPORT_SYMBOL(debugfs_create_automount);
 
@@ -629,28 +529,14 @@ struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
 {
 	struct dentry *dentry;
 	struct inode *inode;
-	char *link = kstrdup(target, GFP_KERNEL);
-	if (!link)
-		return ERR_PTR(-ENOMEM);
 
-	dentry = start_creating(name, parent);
-	if (IS_ERR(dentry)) {
-		kfree(link);
+	dentry = simplefs_create_symlink(&debugfs, &debug_fs_type,
+					 name, parent, target, &inode);
+	if (IS_ERR(dentry))
 		return dentry;
-	}
 
-	inode = debugfs_get_inode(dentry->d_sb);
-	if (unlikely(!inode)) {
-		pr_err("out of free dentries, can not create symlink '%s'\n",
-		       name);
-		kfree(link);
-		return failed_creating(dentry);
-	}
-	inode->i_mode = S_IFLNK | S_IRWXUGO;
 	inode->i_op = &debugfs_symlink_inode_operations;
-	inode->i_link = link;
-	d_instantiate(dentry, inode);
-	return end_creating(dentry);
+	return simplefs_finish_dentry(dentry, inode);
 }
 EXPORT_SYMBOL_GPL(debugfs_create_symlink);
 
-- 
2.25.2

[PATCH v2 7/7] tracefs: switch to simplefs inode creation API

[Emanuele Giuseppe Esposito]

There is no semantic change intended; the code in the libfs.c
functions in fact was derived from debugfs and tracefs code.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
 fs/tracefs/inode.c | 86 ++++------------------------------------------
 1 file changed, 7 insertions(+), 79 deletions(-)

diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index 370eb38ff1ad..bceaa4f45da2 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -308,57 +308,6 @@ static struct file_system_type trace_fs_type = {
 };
 MODULE_ALIAS_FS("tracefs");
 
-static struct dentry *start_creating(const char *name, struct dentry *parent)
-{
-	struct dentry *dentry;
-	int error;
-
-	pr_debug("tracefs: creating file '%s'\n",name);
-
-	error = simple_pin_fs(&tracefs, &trace_fs_type);
-	if (error)
-		return ERR_PTR(error);
-
-	/* If the parent is not specified, we create it in the root.
-	 * We need the root dentry to do this, which is in the super
-	 * block. A pointer to that is in the struct vfsmount that we
-	 * have around.
-	 */
-	if (!parent)
-		parent = tracefs.mount->mnt_root;
-
-	inode_lock(parent->d_inode);
-	if (unlikely(IS_DEADDIR(parent->d_inode)))
-		dentry = ERR_PTR(-ENOENT);
-	else
-		dentry = lookup_one_len(name, parent, strlen(name));
-	if (!IS_ERR(dentry) && dentry->d_inode) {
-		dput(dentry);
-		dentry = ERR_PTR(-EEXIST);
-	}
-
-	if (IS_ERR(dentry)) {
-		inode_unlock(parent->d_inode);
-		simple_release_fs(&tracefs);
-	}
-
-	return dentry;
-}
-
-static struct dentry *failed_creating(struct dentry *dentry)
-{
-	inode_unlock(dentry->d_parent->d_inode);
-	dput(dentry);
-	simple_release_fs(&tracefs);
-	return NULL;
-}
-
-static struct dentry *end_creating(struct dentry *dentry)
-{
-	inode_unlock(dentry->d_parent->d_inode);
-	return dentry;
-}
-
 /**
  * tracefs_create_file - create a file in the tracefs filesystem
  * @name: a pointer to a string containing the name of the file to create.
@@ -395,49 +344,28 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode,
 	if (security_locked_down(LOCKDOWN_TRACEFS))
 		return NULL;
 
-	if (!(mode & S_IFMT))
-		mode |= S_IFREG;
-	BUG_ON(!S_ISREG(mode));
-	dentry = start_creating(name, parent);
-
+	dentry = simplefs_create_file(&tracefs, &trace_fs_type,
+				      name, mode, parent, data, &inode);
 	if (IS_ERR(dentry))
 		return NULL;
 
-	inode = tracefs_get_inode(dentry->d_sb);
-	if (unlikely(!inode))
-		return failed_creating(dentry);
-
-	inode->i_mode = mode;
 	inode->i_fop = fops ? fops : &tracefs_file_operations;
-	inode->i_private = data;
-	d_instantiate(dentry, inode);
-	fsnotify_create(dentry->d_parent->d_inode, dentry);
-	return end_creating(dentry);
+	return simplefs_finish_dentry(dentry, inode);
 }
 
 static struct dentry *__create_dir(const char *name, struct dentry *parent,
 				   const struct inode_operations *ops)
 {
-	struct dentry *dentry = start_creating(name, parent);
+	struct dentry *dentry;
 	struct inode *inode;
 
+	dentry = simplefs_create_dir(&tracefs, &trace_fs_type,
+				     name, 0755, parent, &inode);
 	if (IS_ERR(dentry))
 		return NULL;
 
-	inode = tracefs_get_inode(dentry->d_sb);
-	if (unlikely(!inode))
-		return failed_creating(dentry);
-
-	inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
 	inode->i_op = ops;
-	inode->i_fop = &simple_dir_operations;
-
-	/* directory inodes start off with i_nlink == 2 (for "." entry) */
-	inc_nlink(inode);
-	d_instantiate(dentry, inode);
-	inc_nlink(dentry->d_parent->d_inode);
-	fsnotify_mkdir(dentry->d_parent->d_inode, dentry);
-	return end_creating(dentry);
+	return simplefs_finish_dentry(dentry, inode);
 }
 
 /**
-- 
2.25.2

Re: [PATCH v2 2/7] libfs: wrap simple_pin_fs/simple_release_fs arguments in a struct

[James Morris]

On Tue, 21 Apr 2020, Emanuele Giuseppe Esposito wrote:

> Simplify passing the count and mount to simple_pin_fs and
> simple_release_fs by wrapping them in the simple_fs struct,
> in preparation for adding more high level operations to
> fs/libfs.c
> 
> There is no functional change intended.
> 
> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>


Reviewed-by: James Morris <jamorris@linux.microsoft.com>


-- 
James Morris
<jmorris@namei.org>

Re: [PATCH v2 6/7] debugfs: switch to simplefs inode creation API

[Paolo Bonzini]

On 21/04/20 15:57, Emanuele Giuseppe Esposito wrote:
> -	inode = debugfs_get_inode(dentry->d_sb);

You're not removing debugfs_get_inode so I think you're going to get a
warning (same in tracefs)?

You can wait a few more days for reviews and/or Acked-bys (especially
for patches 6 and 7) and then post v3.

Since the touch-everything patch (#2) has already been reviewed, and
it's mechanical and not introducing any semantic change, you can
probably reduce the To/Cc list to filesystem, debugfs and tracefs
maintainers.

Thanks,

Paolo