From: Li Nan linan122@huawei.com
[ Upstream commit 125bfc7cd750e68c99f1d446e2c22abea08c237f ]
/sys/block/[device]/queue/iostats is used to control whether to count io stat. Write 0 to it will clear queue_flags QUEUE_FLAG_IO_STAT which means iostats is disabled. If we disable iostats and later endable it, the io issued during this period will be counted incorrectly, inflight will be decreased to -1.
//T1 set iostats echo 0 > /sys/block/md0/queue/iostats clear QUEUE_FLAG_IO_STAT
//T2 issue io if (QUEUE_FLAG_IO_STAT) -> false bio_start_io_acct inflight++
echo 1 > /sys/block/md0/queue/iostats set QUEUE_FLAG_IO_STAT
//T3 io end if (QUEUE_FLAG_IO_STAT) -> true bio_end_io_acct inflight-- -> -1
Also, if iostats is enabled while issuing io but disabled while io end, inflight will never be decreased.
Fix it by checking start_time when io end. If start_time is not 0, call bio_end_io_acct().
Fixes: 528bc2cf2fcc ("md/raid10: enable io accounting") Signed-off-by: Li Nan linan122@huawei.com Signed-off-by: Song Liu song@kernel.org Link: https://lore.kernel.org/r/20230609094320.2397604-1-linan666@huaweicloud.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/md/raid10.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index 99607d51d128d..edd3b65c447db 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -297,7 +297,7 @@ static void raid_end_bio_io(struct r10bio *r10_bio) if (!test_bit(R10BIO_Uptodate, &r10_bio->state)) bio->bi_status = BLK_STS_IOERR;
- if (blk_queue_io_stat(bio->bi_bdev->bd_disk->queue)) + if (r10_bio->start_time) bio_end_io_acct(bio, r10_bio->start_time); bio_endio(bio); /*