linux-kernel - [PATCH v3 2/2] md: don't account sync_io if iostats of the disk is disabled

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Message-Id: <20231223033703.2949831-3-linan666@huaweicloud.com>
Date: Sat, 23 Dec 2023 11:37:03 +0800
From: linan666@...weicloud.com
To: song@...nel.org,
	axboe@...nel.dk
Cc: linux-raid@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-block@...r.kernel.org,
	linan666@...weicloud.com,
	yukuai3@...wei.com,
	yi.zhang@...wei.com,
	houtao1@...wei.com,
	yangerkun@...wei.com
Subject: [PATCH v3 2/2] md: don't account sync_io if iostats of the disk is disabled

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

If iostats is disabled, disk_stats will not be updated and
part_stat_read_accum() only returns a constant value. In this case,
continuing to count sync_io and to check is_mddev_idle() is no longer
meaningful.

Signed-off-by: Li Nan <linan122@...wei.com>
---
 drivers/md/md.h | 3 ++-
 drivers/md/md.c | 4 ++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/md/md.h b/drivers/md/md.h
index 1a4f976951c1..e2d03a7a858c 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -584,7 +584,8 @@ extern void mddev_unlock(struct mddev *mddev);
 
 static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
 {
-	atomic64_add(nr_sectors, &bdev->bd_disk->sync_io);
+	if (blk_queue_io_stat(bdev->bd_disk->queue))
+		atomic64_add(nr_sectors, &bdev->bd_disk->sync_io);
 }
 
 static inline void md_sync_acct_bio(struct bio *bio, unsigned long nr_sectors)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index a6829ea5b560..b56614eae8dc 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8502,6 +8502,10 @@ static int is_mddev_idle(struct mddev *mddev, int init)
 	rcu_read_lock();
 	rdev_for_each_rcu(rdev, mddev) {
 		struct gendisk *disk = rdev->bdev->bd_disk;
+
+		if (!blk_queue_io_stat(disk->queue))
+			continue;
+
 		curr_events =
 			(long long)part_stat_read_accum(disk->part0, sectors) -
 			atomic64_read(&disk->sync_io);
-- 
2.39.2