+ * - Locking dependency order is, when multiple locks are to be acquired, to
+ * acquire locks on parents in the filesystem tree before children.
+ * (TODO: What about rename when we acquire locks in unrelated parts of the
+ * filesystem?)
+ * - An inode should not be locked while the filesystem lock is already held,
+ * since some code may do an inode lookup (which acquires the filesystem
+ * lock) while a different inode is locked.