The patch below does not apply to the 5.4-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@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From f524d9c95fab54783d0038f7a3e8c014d5b56857 Mon Sep 17 00:00:00 2001 From: Mike Snitzer snitzer@redhat.com Date: Fri, 28 Jan 2022 10:58:40 -0500 Subject: [PATCH] dm: revert partial fix for redundant bio-based IO accounting
Reverts a1e1cb72d9649 ("dm: fix redundant IO accounting for bios that need splitting") because it was too narrow in scope (only addressed redundant 'sectors[]' accounting and not ios, nsecs[], etc).
Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer snitzer@redhat.com Link: https://lore.kernel.org/r/20220128155841.39644-3-snitzer@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk
diff --git a/drivers/md/dm.c b/drivers/md/dm.c index c0ae8087c602..9849114b3c08 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1442,9 +1442,6 @@ static void init_clone_info(struct clone_info *ci, struct mapped_device *md, ci->sector = bio->bi_iter.bi_sector; }
-#define __dm_part_stat_sub(part, field, subnd) \ - (part_stat_get(part, field) -= (subnd)) - /* * Entry point to split a bio into clones and submit them to the targets. */ @@ -1480,18 +1477,6 @@ static void __split_and_process_bio(struct mapped_device *md, GFP_NOIO, &md->queue->bio_split); ci.io->orig_bio = b;
- /* - * Adjust IO stats for each split, otherwise upon queue - * reentry there will be redundant IO accounting. - * NOTE: this is a stop-gap fix, a proper fix involves - * significant refactoring of DM core's bio splitting - * (by eliminating DM's splitting and just using bio_split) - */ - part_stat_lock(); - __dm_part_stat_sub(dm_disk(md)->part0, - sectors[op_stat_group(bio_op(bio))], ci.sector_count); - part_stat_unlock(); - bio_chain(b, bio); trace_block_split(b, bio->bi_iter.bi_sector); submit_bio_noacct(bio);