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dm: properly fix redundant bio-based IO accounting

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Record the start_time for a bio but defer the starting block core's IO
accounting until after IO is submitted using bio_start_io_acct_time().

This approach avoids the need to mess around with any of the
individual IO stats in response to a bio_split() that follows bio
submission.

Reported-by: Bud Brown <bubrown@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org
Depends-on: e45c47d1f9 ("block: add bio_start_io_acct_time() to control start_time")
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Link: https://lore.kernel.org/r/20220128155841.39644-4-snitzer@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Mike Snitzer 2022-01-28 10:58:41 -05:00 committed by Jens Axboe
parent f524d9c95f
commit b879f915bc
1 changed files with 3 additions and 2 deletions
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5
drivers/md/dm.c
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@ -489,7 +489,7 @@ static void start_io_acct(struct dm_io *io)
struct mapped_device *md = io->md;
struct bio *bio = io->orig_bio;
io->start_time = bio_start_io_acct(bio);
bio_start_io_acct_time(bio, io->start_time);
if (unlikely(dm_stats_used(&md->stats)))
dm_stats_account_io(&md->stats, bio_data_dir(bio),
bio->bi_iter.bi_sector, bio_sectors(bio),
@ -535,7 +535,7 @@ static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio)
io->md = md;
spin_lock_init(&io->endio_lock);
start_io_acct(io);
io->start_time = jiffies;
return io;
}
@ -1482,6 +1482,7 @@ static void __split_and_process_bio(struct mapped_device *md,
submit_bio_noacct(bio);
}
}
start_io_acct(ci.io);
/* drop the extra reference count */
dm_io_dec_pending(ci.io, errno_to_blk_status(error));