The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From f21c601a2bb319ec19eb4562eadc7797d90fd90e Mon Sep 17 00:00:00 2001
From: Mike Snitzer <snitzer@xxxxxxxxxx>
Date: Fri, 15 Jun 2018 09:35:33 -0400
Subject: [PATCH] dm: use bio_split() when splitting out the already processed
bio
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().
Fixes: 18a25da8 ("dm: ensure bio submission follows a depth-first tree walk")
Cc: stable@xxxxxxxxxxxxxxx # 4.15+, requires removal of '&' before md->queue->bio_split
Reported-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: NeilBrown <neilb@xxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index e65429a29c06..a3b103e8e3ce 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1606,10 +1606,9 @@ static blk_qc_t __split_and_process_bio(struct mapped_device *md,
* 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);
ret = generic_make_request(bio);
break;
