From f21c601a2bb319ec19eb4562eadc7797d90fd90e Mon Sep 17 00:00:00 2001

From: Mike Snitzer <snitzer@redhat.com>

Date: Fri, 15 Jun 2018 09:35:33 -0400

Subject: [PATCH] dm: use bio_split() when splitting out the already processed

 bio

Git-commit: f21c601a2bb319ec19eb4562eadc7797d90fd90e

Patch-mainline: v4.18-rc3

References: bsc#1099918

Use of bio_clone_bioset() is inefficient if there is no need to clone

the original bio's bio_vec array.  Best to use the bio_clone_fast()

variant.  Also, just using bio_advance() is only part of what is needed

to properly setup the clone -- it doesn't account for the various

bio_integrity() related work that also needs to be performed (see

bio_split).

Address both of these issues by switching from bio_clone_bioset() to

bio_split().

(Coly Li: rebase for SLE15 kernel)

Fixes: 18a25da8 ("dm: ensure bio submission follows a depth-first tree walk")

Cc: stable@vger.kernel.org # 4.15+, requires removal of '&' before md->queue->bio_split

Reported-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: NeilBrown <neilb@suse.com>

Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Signed-off-by: Coly Li <colyli@suse.de>

---

 drivers/md/dm.c |    5 ++---

 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/drivers/md/dm.c

+++ b/drivers/md/dm.c

@@ -1481,10 +1481,9 @@ static void __split_and_process_bio(stru

 				 * the usage of io->orig_bio in dm_remap_zone_report()

 				 * won't be affected by this reassignment.

 				 */

-				struct bio *b = bio_clone_bioset(bio, GFP_NOIO,

-								 md->queue->bio_split);

+				struct bio *b = bio_split(bio, bio_sectors(bio) - ci.sector_count,

+							  GFP_NOIO, md->queue->bio_split);

 				ci.io->orig_bio = b;

-				bio_advance(bio, (bio_sectors(bio) - ci.sector_count) << 9);

 				bio_chain(b, bio);

 				generic_make_request(bio);

 				break;