MD: make bio mergeable
authorShaohua Li <shli@fb.com>
Mon, 25 Apr 2016 23:52:38 +0000 (16:52 -0700)
committerShaohua Li <shli@fb.com>
Tue, 26 Apr 2016 01:21:33 +0000 (18:21 -0700)
commit9c573de3283af007ea11c17bde1e4568d9417328
tree65df34db491d33e1432691b5ec69d53388df6f4f
parentb297874a2d5c5fcaeb5242a8b4708e54c5477d90
MD: make bio mergeable

blk_queue_split marks bio unmergeable, which makes sense for normal bio.
But if dispatching the bio to underlayer disk, the blk_queue_split
checks are invalid, hence it's possible the bio becomes mergeable.

In the reported bug, this bug causes trim against raid0 performance slash
https://bugzilla.kernel.org/show_bug.cgi?id=117051

Reported-and-tested-by: Park Ju Hyung <qkrwngud825@gmail.com>
Fixes: 6ac45aeb6bca(block: avoid to merge splitted bio)
Cc: stable@vger.kernel.org (v4.3+)
Cc: Ming Lei <ming.lei@canonical.com>
Cc: Neil Brown <neilb@suse.de>
Reviewed-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>
drivers/md/md.c