diff options
Diffstat (limited to 'drivers/md/raid10.c')
| -rw-r--r-- | drivers/md/raid10.c | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index ebb0dd612ebd..a92979e704e3 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -1072,6 +1072,8 @@ static void __make_request(struct mddev *mddev, struct bio *bio) int max_sectors; int sectors; + md_write_start(mddev, bio); + /* * Register the new request and wait if the reconstruction * thread has put up a bar for new requests. @@ -1455,8 +1457,6 @@ static void make_request(struct mddev *mddev, struct bio *bio) return; } - md_write_start(mddev, bio); - do { /* @@ -1477,7 +1477,25 @@ static void 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 */ |