Patch "ovl: don't remove non-empty opaque directory" has been added to the 4.0-stable tree

This is a note to let you know that I've just added the patch titled

ovl: don't remove non-empty opaque directory

to the 4.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ovl-don-t-remove-non-empty-opaque-directory.patch
and it can be found in the queue-4.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Miklos Szeredi <[email protected]>
Date: Thu, 14 May 2015 10:04:44 +0200
Subject: ovl: don't remove non-empty opaque directory

From: Miklos Szeredi <[email protected]>

commit d377c5eb54dd05aeb3094b7740252d19ba7791f7 upstream.

When removing an opaque directory we can't just call rmdir() to check for emptiness, because the directory will need to be replaced with a whiteout. The replacement is done with RENAME_EXCHANGE, which doesn't check emptiness.

Solution is just to check emptiness by reading the directory. In the future we could add a new rename flag to check for emptiness even for RENAME_EXCHANGE to optimize this case.

---
 fs/overlayfs/dir.c |   24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

@@ -506,11 +506,25 @@ static int ovl_remove_and_whiteout(struc
 	struct dentry *opaquedir = NULL;
 	int err;
 
-	if (is_dir && OVL_TYPE_MERGE_OR_LOWER(ovl_path_type(dentry))) {
-		opaquedir = ovl_check_empty_and_clear(dentry);
-		err = PTR_ERR(opaquedir);
-		if (IS_ERR(opaquedir))
-			goto out;
+	if (is_dir) {
+		if (OVL_TYPE_MERGE_OR_LOWER(ovl_path_type(dentry))) {
+			opaquedir = ovl_check_empty_and_clear(dentry);
+			err = PTR_ERR(opaquedir);
+			if (IS_ERR(opaquedir))
+				goto out;
+		} else {
+			LIST_HEAD(list);
+
+			/*
+			 * When removing an empty opaque directory, then it
+			 * makes no sense to replace it with an exact replica of
+			 * itself.  But emptiness still needs to be checked.
+			 */
+			err = ovl_check_empty_dir(dentry, &list);
+			ovl_cache_free(&list);
+			if (err)
+				goto out;
+		}
 	}
 
 	err = ovl_lock_rename_workdir(workdir, upperdir);

Patches currently in stable-queue which might be from [email protected] are

queue-4.0/ovl-don-t-remove-non-empty-opaque-directory.patch queue-4.0/ovl-mount-read-only-if-workdir-can-t-be-created.patch