[PATCH v2 08/14] dm: record old_sector in dm_target_io before calling map function

[Mike Snitzer <snitzer@redhat.com>]

Prep for being able to defer trace_block_bio_remap() until when the
bio is remapped and submitted by the DM target.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
---
 drivers/md/dm-core.h | 1 +
 drivers/md/dm.c      | 7 ++++---
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h
index 72d18c3fbf1f..f40be01cca81 100644
--- a/drivers/md/dm-core.h
+++ b/drivers/md/dm-core.h
@@ -214,6 +214,7 @@ struct dm_target_io {
 	unsigned int target_bio_nr;
 	unsigned int *len_ptr;
 	bool inside_dm_io;
+	sector_t old_sector;
 	struct bio clone;
 };
 
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 164cccf59297..2f2002348b26 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -567,6 +567,7 @@ static struct bio *alloc_tio(struct clone_info *ci, struct dm_target *ti,
 	tio->ti = ti;
 	tio->target_bio_nr = target_bio_nr;
 	tio->len_ptr = len;
+	tio->old_sector = 0;
 
 	return &tio->clone;
 }
@@ -1120,7 +1121,6 @@ static void __map_bio(struct bio *clone)
 {
 	struct dm_target_io *tio = clone_to_tio(clone);
 	int r;
-	sector_t sector;
 	struct dm_io *io = tio->io;
 	struct dm_target *ti = tio->ti;
 
@@ -1132,7 +1132,7 @@ static void __map_bio(struct bio *clone)
 	 * this io.
 	 */
 	dm_io_inc_pending(io);
-	sector = clone->bi_iter.bi_sector;
+	tio->old_sector = clone->bi_iter.bi_sector;
 
 	if (unlikely(swap_bios_limit(ti, clone))) {
 		struct mapped_device *md = io->md;
@@ -1157,7 +1157,8 @@ static void __map_bio(struct bio *clone)
 		break;
 	case DM_MAPIO_REMAPPED:
 		/* the bio has been remapped so dispatch it */
-		trace_block_bio_remap(clone, bio_dev(io->orig_bio), sector);
+		trace_block_bio_remap(clone, bio_dev(io->orig_bio),
+				      tio->old_sector);
 		submit_bio_noacct(clone);
 		break;
 	case DM_MAPIO_KILL:
-- 
2.15.0