Merge tag 'for-5.15/drivers-2021-08-30' of git://git.kernel.dk/linux-block

[linux-2.6-microblaze.git] / drivers / md / raid10.c

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 07119d7..aa26365 100644 (file)
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1712,6 +1712,11 @@ retry_discard:
        } else
                r10_bio->master_bio = (struct bio *)first_r10bio;
 
+       /*
+        * first select target devices under rcu_lock and
+        * inc refcount on their rdev.  Record them by setting
+        * bios[x] to bio
+        */
        rcu_read_lock();
        for (disk = 0; disk < geo->raid_disks; disk++) {
                struct md_rdev *rdev = rcu_dereference(conf->mirrors[disk].rdev);
@@ -1743,9 +1748,6 @@ retry_discard:
        for (disk = 0; disk < geo->raid_disks; disk++) {
                sector_t dev_start, dev_end;
                struct bio *mbio, *rbio = NULL;
-               struct md_rdev *rdev = rcu_dereference(conf->mirrors[disk].rdev);
-               struct md_rdev *rrdev = rcu_dereference(
-                       conf->mirrors[disk].replacement);
 
                /*
                 * Now start to calculate the start and end address for each disk.
@@ -1775,9 +1777,12 @@ retry_discard:
 
                /*
                 * It only handles discard bio which size is >= stripe size, so
-                * dev_end > dev_start all the time
+                * dev_end > dev_start all the time.
+                * It doesn't need to use rcu lock to get rdev here. We already
+                * add rdev->nr_pending in the first loop.
                 */
                if (r10_bio->devs[disk].bio) {
+                       struct md_rdev *rdev = conf->mirrors[disk].rdev;
                        mbio = bio_clone_fast(bio, GFP_NOIO, &mddev->bio_set);
                        mbio->bi_end_io = raid10_end_discard_request;
                        mbio->bi_private = r10_bio;
@@ -1790,6 +1795,7 @@ retry_discard:
                        bio_endio(mbio);
                }
                if (r10_bio->devs[disk].repl_bio) {
+                       struct md_rdev *rrdev = conf->mirrors[disk].replacement;
                        rbio = bio_clone_fast(bio, GFP_NOIO, &mddev->bio_set);
                        rbio->bi_end_io = raid10_end_discard_request;
                        rbio->bi_private = r10_bio;