The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From b879f915bc48a18d4f4462729192435bb0f17052 Mon Sep 17 00:00:00 2001
From: Mike Snitzer <snitzer@xxxxxxxxxx>
Date: Fri, 28 Jan 2022 10:58:41 -0500
Subject: [PATCH] dm: properly fix redundant bio-based IO accounting
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@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Depends-on: e45c47d1f94e ("block: add bio_start_io_acct_time() to control start_time")
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220128155841.39644-4-snitzer@xxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 9849114b3c08..dcbd6d201619 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -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));
