Commit 44f705e9 authored Mar 06, 2019 by Josef Bacik Committed by Greg Kroah-Hartman Apr 03, 2019

btrfs: remove WARN_ON in log_dir_items



commit 2cc8334270e281815c3850c3adea363c51f21e0d upstream.

When Filipe added the recursive directory logging stuff in
2f2ff0ee ("Btrfs: fix metadata inconsistencies after directory
fsync") he specifically didn't take the directory i_mutex for the
children directories that we need to log because of lockdep.  This is
generally fine, but can lead to this WARN_ON() tripping if we happen to
run delayed deletion's in between our first search and our second search
of dir_item/dir_indexes for this directory.  We expect this to happen,
so the WARN_ON() isn't necessary.  Drop the WARN_ON() and add a comment
so we know why this case can happen.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 7b5f260f

fs/btrfs/tree-log.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -3343,9 +3343,16 @@ static noinline int log_dir_items(struct btrfs_trans_handle *trans,
		}
		btrfs_release_path(path);

		/* find the first key from this transaction again */
		/*
		* Find the first key from this transaction again. See the note for
		* log_new_dir_dentries, if we're logging a directory recursively we
		* won't be holding its i_mutex, which means we can modify the directory
		* while we're logging it. If we remove an entry between our first
		* search and this search we'll not find the key again and can just
		* bail.
		*/
		ret = btrfs_search_slot(NULL, root, &min_key, path, 0, 0);
		if (WARN_ON(ret != 0))
		if (ret != 0)
		goto done;

		/*