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 c0ae808..9849114 100644 (file)
--- 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);