Btrfs prioritize sync I/Os to be handled by async checksum worker earlier. As a result, checksumming sync I/Os to larger logical extent address can finish faster than checksumming non-sync I/Os to smaller logical extent address. Since we have upper limit of number of checksum worker, it is possible that sync I/Os to wait forever for non-starting checksum of I/Os for smaller address. This situation can be reproduced by e.g. fstests btrfs/073. To avoid such disordering, disable sync IO prioritization for now. Note that sync I/Os anyway must wait for I/Os to smaller address to finish. So, actually prioritization have no benefit in HMZONED mode. Signed-off-by: Naohiro Aota <naohiro.aota@xxxxxxx> --- fs/btrfs/disk-io.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 56a416902ce7..6651986da470 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -838,7 +838,7 @@ blk_status_t btrfs_wq_submit_bio(struct btrfs_fs_info *fs_info, struct bio *bio, async->status = 0; - if (op_is_sync(bio->bi_opf)) + if (op_is_sync(bio->bi_opf) && !btrfs_fs_incompat(fs_info, HMZONED)) btrfs_set_work_high_priority(&async->work); btrfs_queue_work(fs_info->workers, &async->work); -- 2.21.0
