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md/raid10: fix the condition to call bio_end_io_acct() 

/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: 528bc2cf2f ("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
This commit is contained in:
Li Nan 2023-06-09 17:43:20 +08:00 committed by Song Liu
parent fcaa174a9c
commit 125bfc7cd7
1 changed files with 1 additions and 1 deletions
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2
drivers/md/raid10.c
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@ -325,7 +325,7 @@ 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);
/*