linux-kernel - [PATCH v4 1/2] md/raid10: improve code of mrdev in raid10_sync

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Message-Id: <20230531092812.694516-1-linan666@huaweicloud.com>
Date:   Wed, 31 May 2023 17:28:12 +0800
From:   linan666@...weicloud.com
To:     song@...nel.org
Cc:     linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
        linan122@...wei.com, yukuai3@...wei.com, yi.zhang@...wei.com,
        houtao1@...wei.com, yangerkun@...wei.com
Subject: [PATCH v4 1/2] md/raid10: improve code of mrdev in raid10_sync_request

From: Li Nan <linan122@...wei.com>

'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 <linan122@...wei.com>
Reviewed-by: Yu Kuai <yukuai3@...wei.com>
---
 drivers/md/raid10.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 0acb4c103c10..d93d8cb2b620 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -3437,7 +3437,6 @@ 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;
 
@@ -3445,14 +3444,13 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 			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;
 			}
@@ -3486,7 +3484,8 @@ 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();
@@ -3573,7 +3572,7 @@ 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;
@@ -3618,7 +3617,7 @@ 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,
@@ -3644,12 +3643,14 @@ 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) {
-- 
2.31.1