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md/raid10: factor out dereference_rdev_and_rrdev()
authorLi Nan <linan122@huawei.com>
Sat, 1 Jul 2023 08:05:28 +0000 (16:05 +0800)
committerSong Liu <song@kernel.org>
Thu, 27 Jul 2023 07:13:30 +0000 (00:13 -0700)
Factor out a helper to get 'rdev' and 'replacement' from config->mirrors.
Just to make code cleaner and prepare to fix the bug of io loss while
'replacement' replace 'rdev'.

There is no functional change.

Signed-off-by: Li Nan <linan122@huawei.com>
Link: https://lore.kernel.org/r/20230701080529.2684932-3-linan666@huaweicloud.com
Signed-off-by: Song Liu <song@kernel.org>
drivers/md/raid10.c

index 6096344..d21aeb9 100644 (file)
@@ -1321,6 +1321,25 @@ static void raid10_write_one_disk(struct mddev *mddev, struct r10bio *r10_bio,
        }
 }
 
+static struct md_rdev *dereference_rdev_and_rrdev(struct raid10_info *mirror,
+                                                 struct md_rdev **prrdev)
+{
+       struct md_rdev *rdev, *rrdev;
+
+       rrdev = rcu_dereference(mirror->replacement);
+       /*
+        * Read replacement first to prevent reading both rdev and
+        * replacement as NULL during replacement replace rdev.
+        */
+       smp_mb();
+       rdev = rcu_dereference(mirror->rdev);
+       if (rdev == rrdev)
+               rrdev = NULL;
+
+       *prrdev = rrdev;
+       return rdev;
+}
+
 static void wait_blocked_dev(struct mddev *mddev, struct r10bio *r10_bio)
 {
        int i;
@@ -1464,15 +1483,7 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio,
                int d = r10_bio->devs[i].devnum;
                struct md_rdev *rdev, *rrdev;
 
-               rrdev = rcu_dereference(conf->mirrors[d].replacement);
-               /*
-                * Read replacement first to prevent reading both rdev and
-                * replacement as NULL during replacement replace rdev.
-                */
-               smp_mb();
-               rdev = rcu_dereference(conf->mirrors[d].rdev);
-               if (rdev == rrdev)
-                       rrdev = NULL;
+               rdev = dereference_rdev_and_rrdev(&conf->mirrors[d], &rrdev);
                if (rdev && (test_bit(Faulty, &rdev->flags)))
                        rdev = NULL;
                if (rrdev && (test_bit(Faulty, &rrdev->flags)))