From: Mikulas Patocka <mpatocka@redhat.com>
Date: Tue, 2 Aug 2011 11:32:00 +0000 (+0100)
Subject: dm snapshot: flush disk cache when merging
X-Git-Tag: firefly_0821_release~7541^2~3025
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=b41ed9c38a42daa4b474ebf18eb06ef1f17351f5;p=firefly-linux-kernel-4.4.55.git

dm snapshot: flush disk cache when merging

commit 762a80d9fc9f690a3a35983f3b4619a220650808 upstream.

This patch makes dm-snapshot flush disk cache when writing metadata for
merging snapshot.

Without cache flushing the disk may reorder metadata write and other
data writes and there is a possibility of data corruption in case of
power fault.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/drivers/md/dm-snap-persistent.c b/drivers/md/dm-snap-persistent.c
index 135c2f1fdbfc..e4ecadf0548a 100644
--- a/drivers/md/dm-snap-persistent.c
+++ b/drivers/md/dm-snap-persistent.c
@@ -753,7 +753,7 @@ static int persistent_commit_merge(struct dm_exception_store *store,
 	for (i = 0; i < nr_merged; i++)
 		clear_exception(ps, ps->current_committed - 1 - i);
 
-	r = area_io(ps, WRITE);
+	r = area_io(ps, WRITE_FLUSH_FUA);
 	if (r < 0)
 		return r;