From a7c3e62bdc71d33f75803115d44e3ee7dab3d811 Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@redhat.com>
Date: Wed, 19 Jul 2017 11:24:08 -0400
Subject: [PATCH] dm integrity: use plugging when writing the journal
Git-commit: a7c3e62bdc71d33f75803115d44e3ee7dab3d811
Patch-mainline: v4.13-rc3
References: fate#322738,fate#322919,fate#322950,fate#323773

When copying data from the journal to the appropriate place, we submit
many IOs.  Some of these IOs could go to adjacent areas.  Use on-stack
plugging so that adjacent IOs get merged during submission.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Coly Li <colyli@suse.de>

---
 drivers/md/dm-integrity.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
index 4b2fd524e38d..be3b6f42095c 100644
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -1823,6 +1823,9 @@ static void do_journal_write(struct dm_integrity_c *ic, unsigned write_start,
 {
 	unsigned i, j, n;
 	struct journal_completion comp;
+	struct blk_plug plug;
+
+	blk_start_plug(&plug);
 
 	comp.ic = ic;
 	comp.in_flight = (atomic_t)ATOMIC_INIT(1);
@@ -1947,6 +1950,8 @@ static void do_journal_write(struct dm_integrity_c *ic, unsigned write_start,
 
 	dm_bufio_write_dirty_buffers_async(ic->bufio);
 
+	blk_finish_plug(&plug);
+
 	complete_journal_op(&comp);
 	wait_for_completion_io(&comp.comp);
 
-- 
2.13.1