diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 10c3865e118674007ee099a1106effd736227b49..c33e96e33b8e2b9b73579ff8e25c7a4ee4fa426b 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -1587,9 +1587,30 @@ static void raid1_make_request(struct mddev *mddev, struct bio *bio) split = bio; } - if (bio_data_dir(split) == READ) + if (bio_data_dir(split) == READ) { raid1_read_request(mddev, split); - else + + /* + * If a bio is splitted, the first part of bio will + * pass barrier but the bio is queued in + * current->bio_list (see generic_make_request). If + * there is a raise_barrier() called here, the second + * part of bio can't pass barrier. But since the first + * part bio isn't dispatched to underlaying disks yet, + * the barrier is never released, hence raise_barrier + * will alays wait. We have a deadlock. + * Note, this only happens in read path. For write + * path, the first part of bio is dispatched in a + * schedule() call (because of blk plug) or offloaded + * to raid10d. + * Quitting from the function immediately can change + * the bio order queued in bio_list and avoid the deadlock. + */ + if (split != bio) { + generic_make_request(bio); + break; + } + } else raid1_write_request(mddev, split); } while (split != bio); } diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index c4db6d1fb6a2389ad416e055836e4a21e386c4c2..b1b1f982a722be3210f55bbcc521a9481871c959 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -1584,7 +1584,25 @@ static void raid10_make_request(struct mddev *mddev, struct bio *bio) split = bio; } + /* + * If a bio is splitted, the first part of bio will pass + * barrier but the bio is queued in current->bio_list (see + * generic_make_request). If there is a raise_barrier() called + * here, the second part of bio can't pass barrier. But since + * the first part bio isn't dispatched to underlaying disks + * yet, the barrier is never released, hence raise_barrier will + * alays wait. We have a deadlock. + * Note, this only happens in read path. For write path, the + * first part of bio is dispatched in a schedule() call + * (because of blk plug) or offloaded to raid10d. + * Quitting from the function immediately can change the bio + * order queued in bio_list and avoid the deadlock. + */ __make_request(mddev, split); + if (split != bio && bio_data_dir(bio) == READ) { + generic_make_request(bio); + break; + } } while (split != bio); /* In case raid10d snuck in to freeze_array */