4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Josef Bacik josef@toxicpanda.com
commit 2cc8334270e281815c3850c3adea363c51f21e0d upstream.
When Filipe added the recursive directory logging stuff in 2f2ff0ee5e430 ("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
--- fs/btrfs/tree-log.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
--- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -3343,9 +3343,16 @@ static noinline int log_dir_items(struct } 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;
/*