From 83b2944fd2532b92db099cb3ada12df32a05b368 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@oracle.com>
Date: Mon, 30 Sep 2013 13:45:09 -0700
Subject: [PATCH] mm/bounce.c: fix a regression where MS_SNAP_STABLE (stable
 pages snapshotting) was ignored

The "force" parameter in __blk_queue_bounce was being ignored, which
means that stable page snapshots are not always happening (on ext3).
This of course leads to DIF disks reporting checksum errors, so fix this
regression.

The regression was introduced in commit 6bc454d15004 ("bounce: Refactor
__blk_queue_bounce to not use bi_io_vec")

Reported-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Kent Overstreet <koverstreet@google.com>
Cc: <stable@vger.kernel.org>	[3.10+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/bounce.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/bounce.c b/mm/bounce.c
index c9f0a4339a7d..5a7d58fb883b 100644
--- a/mm/bounce.c
+++ b/mm/bounce.c
@@ -204,6 +204,8 @@ static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
 	struct bio_vec *to, *from;
 	unsigned i;
 
+	if (force)
+		goto bounce;
 	bio_for_each_segment(from, *bio_orig, i)
 		if (page_to_pfn(from->bv_page) > queue_bounce_pfn(q))
 			goto bounce;
-- 
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