md/raid10: improve code of mrdev in raid10_sync_request

commit 59f8f0b54c8ffb4521f6bbd1cb6f4dfa5022e75e upstream.

'need_recover' and 'mrdev' are equivalent in raid10_sync_request(), and
inc mrdev->nr_pending is unreasonable if don't need recovery. Replace
'need_recover' with 'mrdev', and only inc nr_pending when needed.

Signed-off-by: Li Nan <[email protected]>
Reviewed-by: Yu Kuai <[email protected]>
Signed-off-by: Song Liu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Cc: Hagar Gamal Halim <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Li Nan

drivers/md/raid10.c

@@ -3432,22 +3432,20 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 			sector_t sect;
 			int must_sync;
 			int any_working;
-			int need_recover = 0;
 			struct raid10_info *mirror = &conf->mirrors[i];
 			struct md_rdev *mrdev, *mreplace;
 
 			rcu_read_lock();
 			mrdev = rcu_dereference(mirror->rdev);
 			mreplace = rcu_dereference(mirror->replacement);
 
-			if (mrdev != NULL &&
-			    !test_bit(Faulty, &mrdev->flags) &&
-			    !test_bit(In_sync, &mrdev->flags))
-				need_recover = 1;
+			if (mrdev && (test_bit(Faulty, &mrdev->flags) ||
+			    test_bit(In_sync, &mrdev->flags)))
+				mrdev = NULL;
 			if (mreplace && test_bit(Faulty, &mreplace->flags))
 				mreplace = NULL;
 
-			if (!need_recover && !mreplace) {
+			if (!mrdev && !mreplace) {
 				rcu_read_unlock();
 				continue;
 			}
@@ -3481,7 +3479,8 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 				rcu_read_unlock();
 				continue;
 			}
-			atomic_inc(&mrdev->nr_pending);
+			if (mrdev)
+				atomic_inc(&mrdev->nr_pending);
 			if (mreplace)
 				atomic_inc(&mreplace->nr_pending);
 			rcu_read_unlock();
@@ -3568,7 +3567,7 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 				r10_bio->devs[1].devnum = i;
 				r10_bio->devs[1].addr = to_addr;
 
-				if (need_recover) {
+				if (mrdev) {
 					bio = r10_bio->devs[1].bio;
 					bio->bi_next = biolist;
 					biolist = bio;
@@ -3613,7 +3612,7 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 					for (k = 0; k < conf->copies; k++)
 						if (r10_bio->devs[k].devnum == i)
 							break;
-					if (!test_bit(In_sync,
+					if (mrdev && !test_bit(In_sync,
 						      &mrdev->flags)
 					    && !rdev_set_badblocks(
 						    mrdev,
@@ -3639,12 +3638,14 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 				if (rb2)
 					atomic_dec(&rb2->remaining);
 				r10_bio = rb2;
-				rdev_dec_pending(mrdev, mddev);
+				if (mrdev)
+					rdev_dec_pending(mrdev, mddev);
 				if (mreplace)
 					rdev_dec_pending(mreplace, mddev);
 				break;
 			}
-			rdev_dec_pending(mrdev, mddev);
+			if (mrdev)
+				rdev_dec_pending(mrdev, mddev);
 			if (mreplace)
 				rdev_dec_pending(mreplace, mddev);
 			if (r10_bio->devs[0].bio->bi_opf & MD_FAILFAST) {