Subject: [PATCH] md:change resync_mismatches to atomic64_t to avoid races

Now that multiple threads can handle stripes, it is safer to
use an atomic64_t for resync_mismatches, to avoid update races.

Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index fb5bd60..146749b 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -2011,7 +2011,7 @@
 					break;
 			if (j == vcnt)
 				continue;
-			mddev->resync_mismatches += r10_bio->sectors;
+			atomic64_add(r10_bio->sectors, &mddev->resync_mismatches);
 			if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
 				/* Don't fix anything. */
 				continue;