This function was introduced by 247e743cbe6e ("Btrfs: Use async helpers to deal with pages that have been improperly dirtied") and it didn't do any error handling then. This function might very well fail in ENOMEM situation, yet it's not handled, this could lead to inconsistent state. So let's handle the failure by setting the mapping error bit.

Cc: stable@vger.kernel.org Signed-off-by: Nikolay Borisov nborisov@suse.com Reviewed-by: Qu Wenruo wqu@suse.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com ---

Here is the 4.9 backport of upstream commit f3038ee3a3f1017a1cbe9907e31fa12d366c5dcb

fs/btrfs/inode.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 894d56361ea9..a8a1fb40e258 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -2063,8 +2063,15 @@ static void btrfs_writepage_fixup_worker(struct btrfs_work *work) goto out; }

- btrfs_set_extent_delalloc(inode, page_start, page_end, &cached_state, - 0); + ret = btrfs_set_extent_delalloc(inode, page_start, page_end, + &cached_state, 0); + if (ret) { + mapping_set_error(page->mapping, ret); + end_extent_writepage(page, ret, page_start, page_end); + ClearPageChecked(page); + goto out; + } + ClearPageChecked(page); set_page_dirty(page); out: