[PATCH 05/14] tests-bdrv-drain: bdrv_replace_test driver: declare supports_backing

[Vladimir Sementsov-Ogievskiy]

We do add COW child to the node.  In future we are going to forbid
adding COW child to the node that doesn't support backing. So, fix it
here now.

Don't worry about setting bs->backing itself: it further commit we'll
update the block-layer to automatically set/unset this field in generic
code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 tests/unit/test-bdrv-drain.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/unit/test-bdrv-drain.c b/tests/unit/test-bdrv-drain.c
index 2d3c17e566..45edbd867f 100644
--- a/tests/unit/test-bdrv-drain.c
+++ b/tests/unit/test-bdrv-drain.c
@@ -1944,6 +1944,7 @@ static void coroutine_fn 
bdrv_replace_test_co_drain_end(BlockDriverState *bs)
 static BlockDriver bdrv_replace_test = {
     .format_name            = "replace_test",
     .instance_size          = sizeof(BDRVReplaceTestState),
+    .supports_backing       = true,
 
     .bdrv_close             = bdrv_replace_test_close,
     .bdrv_co_preadv         = bdrv_replace_test_co_preadv,
-- 
2.31.1