From 2cc8334270e281815c3850c3adea363c51f21e0d Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Wed, 6 Mar 2019 17:13:04 -0500 Subject: [PATCH] btrfs: remove WARN_ON in log_dir_items 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 Signed-off-by: Josef Bacik Signed-off-by: David Sterba --- fs/btrfs/tree-log.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 5256cddf3a43..960ea49a7a0f 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -3578,9 +3578,16 @@ 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; /*