Patch "block: ensure to split after potentially bouncing a bio" has been added to the 4.3-stable tree

Patch "block: ensure to split after potentially bouncing a bio" has been added to the 4.3-stable tree

[gregkh]

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

    block: ensure to split after potentially bouncing a bio

to the 4.3-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:
     block-ensure-to-split-after-potentially-bouncing-a-bio.patch
and it can be found in the queue-4.3 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 23688bf4f830a89866fd0ed3501e342a7360fe4f Mon Sep 17 00:00:00 2001
From: Junichi Nomura <j-nomura@ce.jp.nec.com>
Date: Tue, 22 Dec 2015 10:23:44 -0700
Subject: block: ensure to split after potentially bouncing a bio

From: Junichi Nomura <j-nomura@ce.jp.nec.com>

commit 23688bf4f830a89866fd0ed3501e342a7360fe4f upstream.

blk_queue_bio() does split then bounce, which makes the segment
counting based on pages before bouncing and could go wrong. Move
the split to after bouncing, like we do for blk-mq, and the we
fix the issue of having the bio count for segments be wrong.

Fixes: 54efd50bfd87 ("block: make generic_make_request handle arbitrarily sized bios")
Tested-by: Artem S. Tashkinov <t.artem@lycos.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 block/blk-core.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1616,8 +1616,6 @@ static void blk_queue_bio(struct request
 	struct request *req;
 	unsigned int request_count = 0;
 
-	blk_queue_split(q, &bio, q->bio_split);
-
 	/*
 	 * low level driver can indicate that it wants pages above a
 	 * certain limit bounced to low memory (ie for highmem, or even
@@ -1625,6 +1623,8 @@ static void blk_queue_bio(struct request
 	 */
 	blk_queue_bounce(q, &bio);
 
+	blk_queue_split(q, &bio, q->bio_split);
+
 	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
 		bio->bi_error = -EIO;
 		bio_endio(bio);


Patches currently in stable-queue which might be from j-nomura@ce.jp.nec.com are

queue-4.3/block-ensure-to-split-after-potentially-bouncing-a-bio.patch