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From: Shaohua Li <shli@fb.com>
To: <linux-kernel@vger.kernel.org>
Cc: <tj@kernel.org>, <gregkh@linuxfoundation.org>,
	<viro@zeniv.linux.org.uk>, <Kernel-team@fb.com>
Subject: [PATCH 4/5] kernfs: don't set dentry->d_fsdata
Date: Mon, 22 May 2017 15:53:08 -0700	[thread overview]
Message-ID: <569790908deae2d9f32165b8844ad9f3c0f38589.1495490800.git.shli@fb.com> (raw)
In-Reply-To: <cover.1495490800.git.shli@fb.com>

When working on adding exportfs operations in kernfs, I found it's hard
to initialize dentry->d_fsdata in the exportfs operations. Looks there
is no way to do it without race condition. Look at the kernfs code
closely, there is no point to set dentry->d_fsdata. inode->i_private
already points to kernfs_node, and we can get inode from a dentry. So
this patch just delete the d_fsdata usage.

Signed-off-by: Shaohua Li <shli@fb.com>
---
 fs/kernfs/dir.c             | 22 +++++++---------------
 fs/kernfs/file.c            |  6 +++---
 fs/kernfs/inode.c           |  6 +++---
 fs/kernfs/kernfs-internal.h |  2 ++
 fs/kernfs/mount.c           |  8 ++------
 fs/kernfs/symlink.c         |  2 +-
 6 files changed, 18 insertions(+), 28 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 4c86e4c..d5721c8 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -562,7 +562,7 @@ static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
 	if (d_really_is_negative(dentry))
 		goto out_bad_unlocked;
 
-	kn = dentry->d_fsdata;
+	kn = kernfs_dentry_node(dentry);
 	mutex_lock(&kernfs_mutex);
 
 	/* The kernfs node has been deactivated */
@@ -570,7 +570,7 @@ static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
 		goto out_bad;
 
 	/* The kernfs node has been moved? */
-	if (dentry->d_parent->d_fsdata != kn->parent)
+	if (kernfs_dentry_node(dentry->d_parent) != kn->parent)
 		goto out_bad;
 
 	/* The kernfs node has been renamed */
@@ -590,14 +590,8 @@ static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
 	return 0;
 }
 
-static void kernfs_dop_release(struct dentry *dentry)
-{
-	kernfs_put(dentry->d_fsdata);
-}
-
 const struct dentry_operations kernfs_dops = {
 	.d_revalidate	= kernfs_dop_revalidate,
-	.d_release	= kernfs_dop_release,
 };
 
 /**
@@ -614,7 +608,7 @@ const struct dentry_operations kernfs_dops = {
 struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry)
 {
 	if (dentry->d_sb->s_op == &kernfs_sops)
-		return dentry->d_fsdata;
+		return kernfs_dentry_node(dentry);
 	return NULL;
 }
 
@@ -1028,7 +1022,7 @@ static struct dentry *kernfs_iop_lookup(struct inode *dir,
 					unsigned int flags)
 {
 	struct dentry *ret;
-	struct kernfs_node *parent = dentry->d_parent->d_fsdata;
+	struct kernfs_node *parent = kernfs_dentry_node(dentry->d_parent);
 	struct kernfs_node *kn;
 	struct inode *inode;
 	const void *ns = NULL;
@@ -1045,8 +1039,6 @@ static struct dentry *kernfs_iop_lookup(struct inode *dir,
 		ret = NULL;
 		goto out_unlock;
 	}
-	kernfs_get(kn);
-	dentry->d_fsdata = kn;
 
 	/* attach dentry and inode */
 	inode = kernfs_get_inode(dir->i_sb, kn);
@@ -1083,7 +1075,7 @@ static int kernfs_iop_mkdir(struct inode *dir, struct dentry *dentry,
 
 static int kernfs_iop_rmdir(struct inode *dir, struct dentry *dentry)
 {
-	struct kernfs_node *kn  = dentry->d_fsdata;
+	struct kernfs_node *kn  = kernfs_dentry_node(dentry);
 	struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops;
 	int ret;
 
@@ -1103,7 +1095,7 @@ static int kernfs_iop_rename(struct inode *old_dir, struct dentry *old_dentry,
 			     struct inode *new_dir, struct dentry *new_dentry,
 			     unsigned int flags)
 {
-	struct kernfs_node *kn  = old_dentry->d_fsdata;
+	struct kernfs_node *kn = kernfs_dentry_node(old_dentry);
 	struct kernfs_node *new_parent = new_dir->i_private;
 	struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops;
 	int ret;
@@ -1616,7 +1608,7 @@ static struct kernfs_node *kernfs_dir_next_pos(const void *ns,
 static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx)
 {
 	struct dentry *dentry = file->f_path.dentry;
-	struct kernfs_node *parent = dentry->d_fsdata;
+	struct kernfs_node *parent = kernfs_dentry_node(dentry);
 	struct kernfs_node *pos = file->private_data;
 	const void *ns = NULL;
 
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index ac2dfe0..4a795ba 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -616,7 +616,7 @@ static void kernfs_put_open_node(struct kernfs_node *kn,
 
 static int kernfs_fop_open(struct inode *inode, struct file *file)
 {
-	struct kernfs_node *kn = file->f_path.dentry->d_fsdata;
+	struct kernfs_node *kn = kernfs_dentry_node(file->f_path.dentry);
 	struct kernfs_root *root = kernfs_root(kn);
 	const struct kernfs_ops *ops;
 	struct kernfs_open_file *of;
@@ -768,7 +768,7 @@ static void kernfs_release_file(struct kernfs_node *kn,
 
 static int kernfs_fop_release(struct inode *inode, struct file *filp)
 {
-	struct kernfs_node *kn = filp->f_path.dentry->d_fsdata;
+	struct kernfs_node *kn = kernfs_dentry_node(filp->f_path.dentry);
 	struct kernfs_open_file *of = kernfs_of(filp);
 
 	if (kn->flags & KERNFS_HAS_RELEASE) {
@@ -835,7 +835,7 @@ void kernfs_drain_open_files(struct kernfs_node *kn)
 static unsigned int kernfs_fop_poll(struct file *filp, poll_table *wait)
 {
 	struct kernfs_open_file *of = kernfs_of(filp);
-	struct kernfs_node *kn = filp->f_path.dentry->d_fsdata;
+	struct kernfs_node *kn = kernfs_dentry_node(filp->f_path.dentry);
 	struct kernfs_open_node *on = kn->attr.open;
 
 	if (!kernfs_get_active(kn))
diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 79cdae4..4c8b510 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -112,7 +112,7 @@ int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
 int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr)
 {
 	struct inode *inode = d_inode(dentry);
-	struct kernfs_node *kn = dentry->d_fsdata;
+	struct kernfs_node *kn = inode->i_private;
 	int error;
 
 	if (!kn)
@@ -154,7 +154,7 @@ static int kernfs_node_setsecdata(struct kernfs_iattrs *attrs, void **secdata,
 
 ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
 {
-	struct kernfs_node *kn = dentry->d_fsdata;
+	struct kernfs_node *kn = kernfs_dentry_node(dentry);
 	struct kernfs_iattrs *attrs;
 
 	attrs = kernfs_iattrs(kn);
@@ -203,8 +203,8 @@ static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
 int kernfs_iop_getattr(const struct path *path, struct kstat *stat,
 		       u32 request_mask, unsigned int query_flags)
 {
-	struct kernfs_node *kn = path->dentry->d_fsdata;
 	struct inode *inode = d_inode(path->dentry);
+	struct kernfs_node *kn = inode->i_private;
 
 	mutex_lock(&kernfs_mutex);
 	kernfs_refresh_inode(kn, inode);
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 3534cfe..82e11fa 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -70,6 +70,8 @@ struct kernfs_super_info {
 };
 #define kernfs_info(SB) ((struct kernfs_super_info *)(SB->s_fs_info))
 
+#define kernfs_dentry_node(d)  ((d_inode(d))->i_private)
+
 extern const struct super_operations kernfs_sops;
 extern struct kmem_cache *kernfs_node_cache;
 
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 343dfeb..462a40c 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -33,7 +33,7 @@ static int kernfs_sop_remount_fs(struct super_block *sb, int *flags, char *data)
 
 static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry)
 {
-	struct kernfs_root *root = kernfs_root(dentry->d_fsdata);
+	struct kernfs_root *root = kernfs_root(kernfs_dentry_node(dentry));
 	struct kernfs_syscall_ops *scops = root->syscall_ops;
 
 	if (scops && scops->show_options)
@@ -43,7 +43,7 @@ static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry)
 
 static int kernfs_sop_show_path(struct seq_file *sf, struct dentry *dentry)
 {
-	struct kernfs_node *node = dentry->d_fsdata;
+	struct kernfs_node *node = kernfs_dentry_node(dentry);
 	struct kernfs_root *root = kernfs_root(node);
 	struct kernfs_syscall_ops *scops = root->syscall_ops;
 
@@ -176,8 +176,6 @@ static int kernfs_fill_super(struct super_block *sb, unsigned long magic)
 		pr_debug("%s: could not get root dentry!\n", __func__);
 		return -ENOMEM;
 	}
-	kernfs_get(info->root->kn);
-	root->d_fsdata = info->root->kn;
 	sb->s_root = root;
 	sb->s_d_op = &kernfs_dops;
 	return 0;
@@ -283,7 +281,6 @@ struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
 void kernfs_kill_sb(struct super_block *sb)
 {
 	struct kernfs_super_info *info = kernfs_info(sb);
-	struct kernfs_node *root_kn = sb->s_root->d_fsdata;
 
 	mutex_lock(&kernfs_mutex);
 	list_del(&info->node);
@@ -295,7 +292,6 @@ void kernfs_kill_sb(struct super_block *sb)
 	 */
 	kill_anon_super(sb);
 	kfree(info);
-	kernfs_put(root_kn);
 }
 
 /**
diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c
index 1684af4..efcfd7a 100644
--- a/fs/kernfs/symlink.c
+++ b/fs/kernfs/symlink.c
@@ -100,7 +100,7 @@ static int kernfs_get_target_path(struct kernfs_node *parent,
 
 static int kernfs_getlink(struct dentry *dentry, char *path)
 {
-	struct kernfs_node *kn = dentry->d_fsdata;
+	struct kernfs_node *kn = kernfs_dentry_node(dentry);
 	struct kernfs_node *parent = kn->parent;
 	struct kernfs_node *target = kn->symlink.target_kn;
 	int error;
-- 
2.9.3

  parent reply	other threads:[~2017-05-22 22:53 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-22 22:53 [PATCH 0/5] kernfs: add exportfs operations Shaohua Li
2017-05-22 22:53 ` [PATCH 1/5] kernfs: implement i_generation Shaohua Li
2017-05-23  7:41   ` Christoph Hellwig
2017-05-23 15:09     ` Shaohua Li
2017-05-23 19:20       ` Tejun Heo
2017-05-24 17:40       ` Christoph Hellwig
2017-05-22 22:53 ` [PATCH 2/5] kernfs: use idr instead of ida to manage inode number Shaohua Li
2017-05-22 22:53 ` [PATCH 3/5] kernfs: add an API to get kernfs node from " Shaohua Li
2017-05-22 22:53 ` Shaohua Li [this message]
2017-05-23 18:37   ` [PATCH 4/5] kernfs: don't set dentry->d_fsdata Tejun Heo
2017-05-22 22:53 ` [PATCH 5/5] kernfs: add exportfs operations Shaohua Li
2017-05-23  7:40   ` Christoph Hellwig
2017-05-23 18:57     ` Tejun Heo
2017-05-24 17:38       ` Christoph Hellwig
2017-05-24 17:39         ` Tejun Heo
2017-05-24 17:41           ` Christoph Hellwig
2017-05-24 17:46             ` Tejun Heo
2017-05-24 18:01               ` Shaohua Li
2017-05-23 18:59   ` Tejun Heo
2017-05-23  7:39 ` [PATCH 0/5] " Christoph Hellwig
2017-05-23 15:13   ` Shaohua Li
2017-05-23 19:06 ` Tejun Heo

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