We use the async_delalloc_pages mechanism to make sure that we've completed our async work before trying to continue our delalloc flushing. The reason for this is we need to see any ordered extents that were created by our delalloc flushing. However we're waking up before we do the submit work, which is before we create the ordered extents. This is a pretty wide race window where we could potentially think there are no ordered extents and thus exit shrink_delalloc prematurely. Fix this by waking us up after we've done the work to create ordered extents.

cc: stable@vger.kernel.org Signed-off-by: Josef Bacik josef@toxicpanda.com --- fs/btrfs/inode.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index b1f02e3fea5d..e388153c4ae4 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1290,11 +1290,6 @@ static noinline void async_cow_submit(struct btrfs_work *work) nr_pages = (async_chunk->end - async_chunk->start + PAGE_SIZE) >> PAGE_SHIFT;

- /* atomic_sub_return implies a barrier */ - if (atomic_sub_return(nr_pages, &fs_info->async_delalloc_pages) < - 5 * SZ_1M) - cond_wake_up_nomb(&fs_info->async_submit_wait); - /* * ->inode could be NULL if async_chunk_start has failed to compress, * in which case we don't have anything to submit, yet we need to @@ -1303,6 +1298,11 @@ static noinline void async_cow_submit(struct btrfs_work *work) */ if (async_chunk->inode) submit_compressed_extents(async_chunk); + + /* atomic_sub_return implies a barrier */ + if (atomic_sub_return(nr_pages, &fs_info->async_delalloc_pages) < + 5 * SZ_1M) + cond_wake_up_nomb(&fs_info->async_submit_wait); }

static noinline void async_cow_free(struct btrfs_work *work)