dm exception store: fix failed set_chunk_size error path

Properly close the device if failing because of an invalid chunk size.

Cc: stable@kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

drivers/md/dm-exception-store.c

@@ -251,7 +251,7 @@ int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
 
 	r = set_chunk_size(tmp_store, argv[2], &ti->error);
 	if (r)
-		goto bad_cow;
+		goto bad_ctr;
 
 	r = type->ctr(tmp_store, 0, NULL);
 	if (r) {