If we are merging invalidated snapshot, redirect all accesses to the origin device. Userspace code will remove the invalidated snapshot anyway after a few seconds, but during this period, the origin device must be active (it may for example contain root filesystem and having unbootable computer is not desirable). Signed-off-by: Mikulas Patocka --- drivers/md/dm-snap.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) Index: linux-2.6.28-devel/drivers/md/dm-snap.c =================================================================== --- linux-2.6.28-devel.orig/drivers/md/dm-snap.c 2009-02-20 17:13:03.000000000 +0100 +++ linux-2.6.28-devel/drivers/md/dm-snap.c 2009-02-20 17:13:07.000000000 +0100 @@ -1342,11 +1342,9 @@ static int snapshot_merge_map(struct dm_ down_write(&s->lock); - /* Full snapshots are not usable */ - if (!s->valid) { - r = -EIO; - goto out_unlock; - } + /* Full merging snapshots are redirected to the origin */ + if (!s->valid) + goto redirect_to_origin; /* If the block is already remapped - use that */ e = lookup_exception(&s->complete, chunk); @@ -1369,6 +1367,7 @@ static int snapshot_merge_map(struct dm_ goto out_unlock; } +redirect_to_origin: bio->bi_bdev = s->origin->bdev; if (bio_rw(bio) == WRITE) {