dm: fix redundant IO accounting for bios that need splitting

[uclinux-h8/linux.git] / drivers / md / dm.c

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index fcb97b0..fbadda6 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1584,6 +1584,9 @@ 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.
  */
@@ -1638,6 +1641,19 @@ static blk_qc_t __split_and_process_bio(struct mapped_device *md,
                                struct bio *b = bio_split(bio, bio_sectors(bio) - ci.sector_count,
                                                          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);
                                ret = generic_make_request(bio);
                                break;