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>

5 files changed, 9 insertions, 8 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;
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 93ada214b50e..af443ab868db 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -282,7 +282,7 @@ struct mddev {
 
         sector_t                        resync_max_sectors; /* may be set by personality */
 
-        sector_t                        resync_mismatches; /* count of sectors where
+        atomic64_t                      resync_mismatches; /* count of sectors where
                                                             * parity/replica mismatch found
                                                             */
 
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index e913356b257e..8034fbd6190c 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1876,7 +1876,7 @@ static int process_checks(struct r1bio *r1_bio)
                 } else
                         j = 0;
                 if (j >= 0)
-                        mddev->resync_mismatches += r1_bio->sectors;
+                        atomic64_add(r1_bio->sectors, &mddev->resync_mismatches);
                 if (j < 0 || (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)
                               && test_bit(BIO_UPTODATE, &sbio->bi_flags))) {
                         /* No need to write to this device. */
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index fb5bd607e15c..146749b277c6 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -2011,7 +2011,7 @@ static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
                                         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;
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index ab613efbbead..4cc6b0e398bc 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2973,7 +2973,7 @@ static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
                          */
                         set_bit(STRIPE_INSYNC, &sh->state);
                 else {
-                        conf->mddev->resync_mismatches += STRIPE_SECTORS;
+                        atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
                                 /* don't try to repair!! */
                                 set_bit(STRIPE_INSYNC, &sh->state);
@@ -3125,7 +3125,7 @@ static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
                                  */
                         }
                 } else {
-                        conf->mddev->resync_mismatches += STRIPE_SECTORS;
+                        atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
                                 /* don't try to repair!! */
                                 set_bit(STRIPE_INSYNC, &sh->state);