[PATCH 05/14] dm: set flush bio device on demand

[Dennis Zhou]

The next patch changes the macro bio_set_dev() to associate a bio with a
blkg based on the device set. However, dm creates a static bio to be
used as the basis for cloning empty flush bios on creation. This
association is with a not-opened bdev so bd_disk is %NULL. To easily get
around this, we will set the device on the static bio every time and use
that to copy to the other bios.

Signed-off-by: Dennis Zhou <dennis@xxxxxxxxxx>
---
 drivers/md/dm.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index a733e4c920af..b5e996c5c709 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1417,10 +1417,14 @@ static int __send_empty_flush(struct clone_info *ci)
 	unsigned target_nr = 0;
 	struct dm_target *ti;
 
+	bio_set_dev(ci->bio, ci->io->md->bdev);
+
 	BUG_ON(bio_has_data(ci->bio));
 	while ((ti = dm_table_get_target(ci->map, target_nr++)))
 		__send_duplicate_bios(ci, ti, ti->num_flush_bios, NULL);
 
+	bio_disassociate_blkg(ci->bio);
+
 	return 0;
 }
 
@@ -1939,7 +1943,6 @@ static struct mapped_device *alloc_dev(int minor)
 		goto bad;
 
 	bio_init(&md->flush_bio, NULL, 0);
-	bio_set_dev(&md->flush_bio, md->bdev);
 	md->flush_bio.bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC;
 
 	dm_stats_init(&md->stats);
-- 
2.17.1