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

[linan666]

From: Li Nan <linan122@xxxxxxxxxx>

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@xxxxxxxxxx>
---
 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..d57e765b4ec2 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -589,7 +589,8 @@ static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sect
 
 static inline void md_sync_acct_bio(struct bio *bio, unsigned long nr_sectors)
 {
-	md_sync_acct(bio->bi_bdev, nr_sectors);
+	if (blk_queue_io_stat(disk—>queue))
+		md_sync_acct(bio->bi_bdev, nr_sectors);
 }
 
 struct md_personality
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 1d71b2a9af03..9a3610bcc75f 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