sysfs: simplify sysfs_rename_dir()

With the shadow directories gone, sysfs_rename_dir() can be simplified.

* parent doesn't need to be grabbed separately.  Just access
  old_dentry->d_parent.

* parent sd can never change.  Remove code to move under the new
  parent.

* Massage comments a bit.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 4 insertions, 22 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 5da8da806660..9504d4cb63eb 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -883,14 +883,10 @@ int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
         struct sysfs_dirent *sd;
         struct dentry *parent = NULL;
         struct dentry *old_dentry = NULL, *new_dentry = NULL;
-        struct sysfs_dirent *parent_sd;
         const char *dup_name = NULL;
         int error;
 
-        if (!kobj->parent)
-                return -EINVAL;
-
-        /* get dentries */
+        /* get the original dentry */
         sd = kobj->sd;
         old_dentry = sysfs_get_dentry(sd);
         if (IS_ERR(old_dentry)) {
@@ -898,12 +894,7 @@ int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
                 goto out_dput;
         }
 
-        parent_sd = kobj->parent->sd;
-        parent = sysfs_get_dentry(parent_sd);
-        if (IS_ERR(parent)) {
-                error = PTR_ERR(parent);
-                goto out_dput;
-        }
+        parent = old_dentry->d_parent;
 
         /* lock parent and get dentry for new name */
         mutex_lock(&parent->d_inode->i_mutex);
@@ -933,22 +924,14 @@ int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
                 goto out_drop;
 
         mutex_lock(&sysfs_mutex);
-
         dup_name = sd->s_name;
         sd->s_name = new_name;
+        mutex_unlock(&sysfs_mutex);
 
-        /* move under the new parent */
+        /* rename */
         d_add(new_dentry, NULL);
         d_move(sd->s_dentry, new_dentry);
 
-        sysfs_unlink_sibling(sd);
-        sysfs_get(parent_sd);
-        sysfs_put(sd->s_parent);
-        sd->s_parent = parent_sd;
-        sysfs_link_sibling(sd);
-
-        mutex_unlock(&sysfs_mutex);
-
         error = 0;
         goto out_unlock;
 
@@ -958,7 +941,6 @@ int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
         mutex_unlock(&parent->d_inode->i_mutex);
  out_dput:
         kfree(dup_name);
-        dput(parent);
         dput(old_dentry);
         dput(new_dentry);
         return error;