From: Jan Kara <jack@suse.cz>
Date: Wed, 31 May 2017 07:44:32 +0000 (+0200)
Subject: dm: make flush bios explicitly sync
X-Git-Tag: v4.14-rc1~808^2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ff0361b34ac63ef80c785c32d62e0e9d89a2cf89;p=platform%2Fkernel%2Flinux-rpi3.git

dm: make flush bios explicitly sync

Commit b685d3d65ac7 ("block: treat REQ_FUA and REQ_PREFLUSH as
synchronous") removed REQ_SYNC flag from WRITE_{FUA|PREFLUSH|...}
definitions.  generic_make_request_checks() however strips REQ_FUA and
REQ_PREFLUSH flags from a bio when the storage doesn't report volatile
write cache and thus write effectively becomes asynchronous which can
lead to performance regressions.

Fix the problem by making sure all bios which are synchronous are
properly marked with REQ_SYNC.

Fixes: b685d3d65ac7 ("block: treat REQ_FUA and REQ_PREFLUSH as synchronous")
Cc: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
---

diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index cd81395..840c149 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -1334,7 +1334,7 @@ int dm_bufio_issue_flush(struct dm_bufio_client *c)
 {
 	struct dm_io_request io_req = {
 		.bi_op = REQ_OP_WRITE,
-		.bi_op_flags = REQ_PREFLUSH,
+		.bi_op_flags = REQ_PREFLUSH | REQ_SYNC,
 		.mem.type = DM_IO_KMEM,
 		.mem.ptr.addr = NULL,
 		.client = c->dm_io,
diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
index 1feeb2c..7910bfe 100644
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -783,7 +783,8 @@ static void write_journal(struct dm_integrity_c *ic, unsigned commit_start, unsi
 			for (i = 0; i < commit_sections; i++)
 				rw_section_mac(ic, commit_start + i, true);
 		}
-		rw_journal(ic, REQ_OP_WRITE, REQ_FUA, commit_start, commit_sections, &io_comp);
+		rw_journal(ic, REQ_OP_WRITE, REQ_FUA | REQ_SYNC, commit_start,
+			   commit_sections, &io_comp);
 	} else {
 		unsigned to_end;
 		io_comp.in_flight = (atomic_t)ATOMIC_INIT(2);
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index a95cbb8..e61c450 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -260,7 +260,7 @@ static int mirror_flush(struct dm_target *ti)
 	struct mirror *m;
 	struct dm_io_request io_req = {
 		.bi_op = REQ_OP_WRITE,
-		.bi_op_flags = REQ_PREFLUSH,
+		.bi_op_flags = REQ_PREFLUSH | REQ_SYNC,
 		.mem.type = DM_IO_KMEM,
 		.mem.ptr.addr = NULL,
 		.client = ms->io_client,
diff --git a/drivers/md/dm-snap-persistent.c b/drivers/md/dm-snap-persistent.c
index b93476c..c5534d2 100644
--- a/drivers/md/dm-snap-persistent.c
+++ b/drivers/md/dm-snap-persistent.c
@@ -741,7 +741,8 @@ static void persistent_commit_exception(struct dm_exception_store *store,
 	/*
 	 * Commit exceptions to disk.
 	 */
-	if (ps->valid && area_io(ps, REQ_OP_WRITE, REQ_PREFLUSH | REQ_FUA))
+	if (ps->valid && area_io(ps, REQ_OP_WRITE,
+				 REQ_PREFLUSH | REQ_FUA | REQ_SYNC))
 		ps->valid = 0;
 
 	/*
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 6ef9500..37ccd73 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1657,7 +1657,7 @@ static struct mapped_device *alloc_dev(int minor)
 
 	bio_init(&md->flush_bio, NULL, 0);
 	md->flush_bio.bi_bdev = md->bdev;
-	md->flush_bio.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH;
+	md->flush_bio.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC;
 
 	dm_stats_init(&md->stats);