Add missing unlocks to error paths of mountpoint_last.

Signed-off-by: Dave Jones <davej@fedoraproject.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namei.c

@@ -2261,12 +2261,15 @@ mountpoint_last(struct nameidata *nd, struct path *path)
 		dentry = d_alloc(dir, &nd->last);
 		if (!dentry) {
 			error = -ENOMEM;
+			mutex_unlock(&dir->d_inode->i_mutex);
 			goto out;
 		}
 		dentry = lookup_real(dir->d_inode, dentry, nd->flags);
 		error = PTR_ERR(dentry);
-		if (IS_ERR(dentry))
+		if (IS_ERR(dentry)) {
+			mutex_unlock(&dir->d_inode->i_mutex);
 			goto out;
+		}
 	}
 	mutex_unlock(&dir->d_inode->i_mutex);