Patch "MD: make bio mergeable" has been added to the 4.5-stable tree

This is a note to let you know that I've just added the patch titled

MD: make bio mergeable

to the 4.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
md-make-bio-mergeable.patch
and it can be found in the queue-4.5 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Shaohua Li <[email protected]>
Date: Mon, 25 Apr 2016 16:52:38 -0700
Subject: MD: make bio mergeable

From: Shaohua Li <[email protected]>

commit 9c573de3283af007ea11c17bde1e4568d9417328 upstream.

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

---
 drivers/md/md.c |    2 ++
 1 file changed, 2 insertions(+)

@@ -284,6 +284,8 @@ static blk_qc_t md_make_request(struct r
 	 * go away inside make_request
 	 */
 	sectors = bio_sectors(bio);
+	/* bio could be mergeable after passing to underlayer */
+	bio->bi_rw &= ~REQ_NOMERGE;
 	mddev->pers->make_request(mddev, bio);
 
 	cpu = part_stat_lock();

Patches currently in stable-queue which might be from [email protected] are

queue-4.5/md-make-bio-mergeable.patch