FAILED: patch "[PATCH] md: Make flush bios explicitely sync" failed to apply to 4.11-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.11-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@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 5a8948f8a32ba56c17b3fb75d318ac98157f3ba5 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Wed, 31 May 2017 09:44:33 +0200
Subject: [PATCH] md: Make flush bios explicitely 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.

CC: linux-raid@vger.kernel.org
CC: Shaohua Li <shli@kernel.org>
Fixes: b685d3d65ac791406e0dfd8779cc9b3707fea5a3
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Shaohua Li <shli@fb.com>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 10367ffe92e3..212a6777ff31 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -765,7 +765,7 @@ void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
 	    test_bit(FailFast, &rdev->flags) &&
 	    !test_bit(LastDev, &rdev->flags))
 		ff = MD_FAILFAST;
-	bio->bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_FUA | ff;
+	bio->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_PREFLUSH | REQ_FUA | ff;
 
 	atomic_inc(&mddev->pending_writes);
 	submit_bio(bio);
diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 4c00bc248287..0a7af8b0a80a 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -1782,7 +1782,7 @@ static int r5l_log_write_empty_meta_block(struct r5l_log *log, sector_t pos,
 	mb->checksum = cpu_to_le32(crc32c_le(log->uuid_checksum,
 					     mb, PAGE_SIZE));
 	if (!sync_page_io(log->rdev, pos, PAGE_SIZE, page, REQ_OP_WRITE,
-			  REQ_FUA, false)) {
+			  REQ_SYNC | REQ_FUA, false)) {
 		__free_page(page);
 		return -EIO;
 	}
@@ -2388,7 +2388,7 @@ r5c_recovery_rewrite_data_only_stripes(struct r5l_log *log,
 		mb->checksum = cpu_to_le32(crc32c_le(log->uuid_checksum,
 						     mb, PAGE_SIZE));
 		sync_page_io(log->rdev, ctx->pos, PAGE_SIZE, page,
-			     REQ_OP_WRITE, REQ_FUA, false);
+			     REQ_OP_WRITE, REQ_SYNC | REQ_FUA, false);
 		sh->log_start = ctx->pos;
 		list_add_tail(&sh->r5c, &log->stripe_in_journal_list);
 		atomic_inc(&log->stripe_in_journal_count);
diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
index 5d25bebf3328..ccce92e68d7f 100644
--- a/drivers/md/raid5-ppl.c
+++ b/drivers/md/raid5-ppl.c
@@ -907,8 +907,8 @@ static int ppl_write_empty_header(struct ppl_log *log)
 	pplhdr->checksum = cpu_to_le32(~crc32c_le(~0, pplhdr, PAGE_SIZE));
 
 	if (!sync_page_io(rdev, rdev->ppl.sector - rdev->data_offset,
-			  PPL_HEADER_SIZE, page, REQ_OP_WRITE | REQ_FUA, 0,
-			  false)) {
+			  PPL_HEADER_SIZE, page, REQ_OP_WRITE | REQ_SYNC |
+			  REQ_FUA, 0, false)) {
 		md_error(rdev->mddev, rdev);
 		ret = -EIO;
 	}