sysfs: fix bugs in sysfs_rename/move_dir()

sysfs_rename/move_dir() have the following bugs.

 - On dentry lookup failure, kfree() is called on ERR_PTR() value.
 - sysfs_move_dir() has an extra dput() on success path.

Fix them.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/sysfs/dir.c

@@ -783,6 +783,7 @@ 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);
+		old_dentry = NULL;
 		goto out;
 	}
 
@@ -850,6 +851,7 @@ int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj)
 	old_dentry = sysfs_get_dentry(sd);
 	if (IS_ERR(old_dentry)) {
 		error = PTR_ERR(old_dentry);
+		old_dentry = NULL;
 		goto out;
 	}
 	old_parent = old_dentry->d_parent;
@@ -857,6 +859,7 @@ int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj)
 	new_parent = sysfs_get_dentry(new_parent_sd);
 	if (IS_ERR(new_parent)) {
 		error = PTR_ERR(new_parent);
+		new_parent = NULL;
 		goto out;
 	}
 
@@ -880,7 +883,6 @@ int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj)
 	error = 0;
 	d_add(new_dentry, NULL);
 	d_move(old_dentry, new_dentry);
-	dput(new_dentry);
 
 	/* Remove from old parent's list and insert into new parent's list. */
 	sysfs_unlink_sibling(sd);