---
+ **mandatory**
+
+ If ->rename() update of .. on cross-directory move needs an exclusion with
+ directory modifications, do *not* lock the subdirectory in question in your
+ ->rename() - it's done by the caller now [that item should've been added in
+ 28eceeda130f "fs: Lock moved directories"].
+
+ ---
+
+ **mandatory**
+
+ On same-directory ->rename() the (tautological) update of .. is not protected
+ by any locks; just don't do it if the old parent is the same as the new one.
+ We really can't lock two subdirectories in same-directory rename - not without
+ deadlocks.
+
+ ---
+
+ **mandatory**
+
+ lock_rename() and lock_rename_child() may fail in cross-directory case, if
+ their arguments do not have a common ancestor. In that case ERR_PTR(-EXDEV)
+ is returned, with no locks taken. In-tree users updated; out-of-tree ones
+ would need to do so.
++
++---
++
+**recommended**
+
+Block device freezing and thawing have been moved to holder operations.
+
+Before this change, get_active_super() would only be able to find the
+superblock of the main block device, i.e., the one stored in sb->s_bdev. Block
+device freezing now works for any block device owned by a given superblock, not
+just the main block device. The get_active_super() helper and bd_fsfreeze_sb
+pointer are gone.
* lock ordering with sb_writers, which shouldn't be held when calling
* ovl_copy_up_data(), so lock workdir and destdir and make sure that
* temp wasn't moved before copy up completion or cleanup.
- * If temp was moved, abort without the cleanup.
*/
ovl_start_write(c->dentry);
- if (lock_rename(c->workdir, c->destdir) != NULL ||
- temp->d_parent != c->workdir) {
+ trap = lock_rename(c->workdir, c->destdir);
+ if (trap || temp->d_parent != c->workdir) {
+ /* temp or workdir moved underneath us? abort without cleanup */
+ dput(temp);
err = -EIO;
+ if (IS_ERR(trap))
+ goto out;
goto unlock;
} else if (err) {
goto cleanup;