[PATCH v3] md/raid10: don't call bio_start_io_acct twice for bio which experienced read error

[Yu Kuai]

From: Yu Kuai <yukuai3@xxxxxxxxxx>

handle_read_error() will resumit r10_bio by raid10_read_request(), which
will call bio_start_io_acct() again, while bio_end_io_acct() will only
be called once.

Fix the problem by don't account io again from handle_read_error().

Fixes: 528bc2cf2fcc ("md/raid10: enable io accounting")
Suggested-by: Song Liu <song@xxxxxxxxxx>
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
Changes in v3:
 - use r10_bo->start_time instead of adding a new paramater.
Changes in v3:
 - Change the patch title

 drivers/md/raid10.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 6c66357f92f5..3483fdf796ec 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1244,7 +1244,8 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
 	}
 	slot = r10_bio->read_slot;
 
-	if (blk_queue_io_stat(bio->bi_bdev->bd_disk->queue))
+	if (!r10_bio->start_time &&
+	    blk_queue_io_stat(bio->bi_bdev->bd_disk->queue))
 		r10_bio->start_time = bio_start_io_acct(bio);
 	read_bio = bio_alloc_clone(rdev->bdev, bio, gfp, &mddev->bio_set);
 
@@ -1574,6 +1575,7 @@ static void __make_request(struct mddev *mddev, struct bio *bio, int sectors)
 	r10_bio->sector = bio->bi_iter.bi_sector;
 	r10_bio->state = 0;
 	r10_bio->read_slot = -1;
+	r10_bio->start_time = 0;
 	memset(r10_bio->devs, 0, sizeof(r10_bio->devs[0]) *
 			conf->geo.raid_disks);
 
-- 
2.31.1