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>

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 36b6c79..463c5e3 100644 (file)
--- 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;
 }