[dm-devel] [PATCH v2 15/17] dm snapshot: make exceptions if merge is dispatching to origin

[Mike Snitzer]

From: Mikulas Patocka <mpatocka at redhat.com>

If write request to merging snapshot device is to be dispatched
directly to the origin (because the chunk is not remapped or was
already merged), we must make exceptions in other snapshots.

Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>
Reviewed-by: Mike Snitzer <snitzer at redhat.com>
---
 drivers/md/dm-snap.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 7f0d261..f67bfff 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1529,6 +1529,11 @@ static int snapshot_merge_map(struct dm_target *ti, struct bio *bio,
 
 	bio->bi_bdev = s->origin->bdev;
 
+	if (bio_rw(bio) == WRITE) {
+		up_write(&s->lock);
+		return do_origin(s->origin, bio);
+	}
+
  out_unlock:
 	up_write(&s->lock);
 
-- 
1.6.5.rc2