+ /*
+ * How do we know the locking is safe from deadlocks?
+ * The vfs does the hard part for us. Any time we are taking nested
+ * commit_mutexes, the vfs already has i_mutex held on the parent.
+ * Here, the vfs has already taken i_mutex on both old_dir and new_dir.
+ */
+ mutex_lock_nested(&JFS_IP(new_dir)->commit_mutex, COMMIT_MUTEX_PARENT);
+ mutex_lock_nested(&JFS_IP(old_ip)->commit_mutex, COMMIT_MUTEX_CHILD);