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>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 85e6786653ea..7564c44b8045 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4269,7 +4269,8 @@ static ssize_t
 mismatch_cnt_show(struct mddev *mddev, char *page)
 {
         return sprintf(page, "%llu\n",
-                       (unsigned long long) mddev->resync_mismatches);
+                       (unsigned long long)
+                       atomic64_read(&mddev->resync_mismatches));
 }
 
 static struct md_sysfs_entry md_scan_mode =
@@ -5235,7 +5236,7 @@ static void md_clean(struct mddev *mddev)
         mddev->new_layout = 0;
         mddev->new_chunk_sectors = 0;
         mddev->curr_resync = 0;
-        mddev->resync_mismatches = 0;
+        atomic64_set(&mddev->resync_mismatches, 0);
         mddev->suspend_lo = mddev->suspend_hi = 0;
         mddev->sync_speed_min = mddev->sync_speed_max = 0;
         mddev->recovery = 0;
@@ -7357,7 +7358,7 @@ void md_do_sync(struct md_thread *thread)
                  * which defaults to physical size, but can be virtual size
                  */
                 max_sectors = mddev->resync_max_sectors;
-                mddev->resync_mismatches = 0;
+                atomic64_set(&mddev->resync_mismatches, 0);
                 /* we don't use the checkpoint if there's a bitmap */
                 if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
                         j = mddev->resync_min;