[Devel] [PATCH 08/14] sysfs: Perform renames under sysfs_mutex

[Eric W. Biederman]

This modifies sysfs_rename_dir to use sysfs_addrm_start/sysfs_addrm_finish
making it more like the rest of the sysfs directory manipulation functions.

This moves the entire rename operation inside of sysfs_mutex removing
the need to grab i_mutex, and incidentally this kills one s_dentry use.

Signed-off-by: Eric W. Biederman <ebiederm at xmission.com>
---
 fs/sysfs/dir.c |   46 +++++++++++++++++-----------------------------
 1 files changed, 17 insertions(+), 29 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index f22d60c..8e614d3 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -827,7 +827,7 @@ void sysfs_remove_dir(struct kobject * kobj)
 int sysfs_rename_dir(struct kobject *kobj, const char *new_name)
 {
 	struct sysfs_dirent *sd = kobj->sd;
-	struct dentry *new_parent = NULL;
+	struct sysfs_addrm_cxt acxt;
 	struct dentry *old_dentry = NULL, *new_dentry = NULL;
 	const char *dup_name = NULL;
 	int error;
@@ -836,59 +836,47 @@ int sysfs_rename_dir(struct kobject *kobj, const char *new_name)
 	old_dentry = sysfs_get_dentry(sd);
 	if (IS_ERR(old_dentry)) {
 		error = PTR_ERR(old_dentry);
-		goto out_dput;
+		goto out;
 	}
 
-	new_parent = dget(old_dentry->d_parent);
-
-	/* lock new_parent and get dentry for new name */
-	mutex_lock(&new_parent->d_inode->i_mutex);
-
-	new_dentry = lookup_one_len(new_name, new_parent, strlen(new_name));
-	if (IS_ERR(new_dentry)) {
-		error = PTR_ERR(new_dentry);
-		goto out_unlock;
-	}
+	sysfs_addrm_start(&acxt, sd->s_parent);
 
 	error = -EINVAL;
-	if (old_dentry == new_dentry)
-		goto out_unlock;
+	if (strcmp(new_name, sd->s_name) == 0)
+		goto addrm_finish;
 
 	error = -EEXIST;
-	if (new_dentry->d_inode)
-		goto out_unlock;
+	if (sysfs_find_dirent(acxt.parent_sd, new_name))
+		goto addrm_finish;
+
+	new_dentry = d_alloc_name(old_dentry->d_parent, new_name);
+	if (!new_dentry)
+		goto addrm_finish;
 
 	/* rename kobject and sysfs_dirent */
 	error = -ENOMEM;
 	new_name = dup_name = kstrdup(new_name, GFP_KERNEL);
 	if (!new_name)
-		goto out_drop;
+		goto addrm_finish;
 
 	error = kobject_set_name(kobj, "%s", new_name);
 	if (error)
-		goto out_drop;
+		goto addrm_finish;
 
-	mutex_lock(&sysfs_mutex);
 	dup_name = sd->s_name;
 	sd->s_name = new_name;
-	mutex_unlock(&sysfs_mutex);
 
 	/* move under the new parent */
 	d_add(new_dentry, NULL);
-	d_move(sd->s_dentry, new_dentry);
+	d_move(old_dentry, new_dentry);
 
 	error = 0;
-	goto out_unlock;
-
- out_drop:
-	d_drop(new_dentry);
- out_unlock:
-	mutex_unlock(&new_parent->d_inode->i_mutex);
- out_dput:
+addrm_finish:
+	sysfs_addrm_finish(&acxt);
 	kfree(dup_name);
-	dput(new_parent);
 	dput(old_dentry);
 	dput(new_dentry);
+out:
 	return error;
 }
 
-- 
1.5.1.1.181.g2de0

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