- * Lock all moved children. Moved directories may need to change parent
- * pointer so they need the lock to prevent against concurrent
- * directory changes moving parent pointer. For regular files we've
- * historically always done this. The lockdep locking subclasses are
- * somewhat arbitrary but RENAME_EXCHANGE in particular can swap
- * regular files and directories so it's difficult to tell which
- * subclasses to use.
+ * Lock children.
+ * The source subdirectory needs to be locked on cross-directory
+ * rename or cross-directory exchange since its parent changes.
+ * The target subdirectory needs to be locked on cross-directory
+ * exchange due to parent change and on any rename due to becoming
+ * a victim.
+ * Non-directories need locking in all cases (for NFS reasons);
+ * they get locked after any subdirectories (in inode address order).
+ *
+ * NOTE: WE ONLY LOCK UNRELATED DIRECTORIES IN CROSS-DIRECTORY CASE.
+ * NEVER, EVER DO THAT WITHOUT ->s_vfs_rename_mutex.