sysfs: Rewrite rename in terms of sysfs dirents

This patch rewrites sysfs_rename_dir to perform it's checks
as much as possible on the underlying sysfs_dirents instead
of the contents of the dcache.  It turns out that this version
is a little simpler, and a little more like the rest of
the sysfs directory modification code.

tj: fixed double locking of sysfs_mutex

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 16 insertions, 22 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 36b6c796d4d5..463c5e3ccf1f 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -770,7 +770,7 @@ void sysfs_remove_dir(struct kobject * kobj)
 
 int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
 {
-        struct sysfs_dirent *sd;
+        struct sysfs_dirent *sd = kobj->sd;
         struct dentry *parent = NULL;
         struct dentry *old_dentry = NULL, *new_dentry = NULL;
         const char *dup_name = NULL;
@@ -778,63 +778,57 @@ int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
 
         mutex_lock(&sysfs_rename_mutex);
 
+        error = 0;
+        if (strcmp(sd->s_name, new_name) == 0)
+                goto out;       /* nothing to rename */
+
         /* get the original dentry */
-        sd = kobj->sd;
         old_dentry = sysfs_get_dentry(sd);
         if (IS_ERR(old_dentry)) {
                 error = PTR_ERR(old_dentry);
-                goto out_dput;
+                goto out;
         }
 
         parent = old_dentry->d_parent;
 
         /* lock parent and get dentry for new name */
         mutex_lock(&parent->d_inode->i_mutex);
+        mutex_lock(&sysfs_mutex);
 
-        new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
-        if (IS_ERR(new_dentry)) {
-                error = PTR_ERR(new_dentry);
-                goto out_unlock;
-        }
-
-        error = -EINVAL;
-        if (old_dentry == new_dentry)
+        error = -EEXIST;
+        if (sysfs_find_dirent(sd->s_parent, new_name))
                 goto out_unlock;
 
-        error = -EEXIST;
-        if (new_dentry->d_inode)
+        error = -ENOMEM;
+        new_dentry = d_alloc_name(parent, new_name);
+        if (!new_dentry)
                 goto out_unlock;
 
         /* rename kobject and sysfs_dirent */
         error = -ENOMEM;
         new_name = dup_name = kstrdup(new_name, GFP_KERNEL);
         if (!new_name)
-                goto out_drop;
+                goto out_unlock;
 
         error = kobject_set_name(kobj, "%s", new_name);
         if (error)
-                goto out_drop;
+                goto out_unlock;
 
-        mutex_lock(&sysfs_mutex);
         dup_name = sd->s_name;
         sd->s_name = new_name;
-        mutex_unlock(&sysfs_mutex);
 
         /* rename */
         d_add(new_dentry, NULL);
         d_move(old_dentry, new_dentry);
 
         error = 0;
-        goto out_unlock;
-
- out_drop:
-        d_drop(new_dentry);
  out_unlock:
+        mutex_unlock(&sysfs_mutex);
         mutex_unlock(&parent->d_inode->i_mutex);
- out_dput:
         kfree(dup_name);
         dput(old_dentry);
         dput(new_dentry);
+ out:
         mutex_unlock(&sysfs_rename_mutex);
         return error;
 }