[PATCH v3 4/6] block/vvfat: inherit child_vvfat_qcow from child_of_bds

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

Recently we've fixed a crash by adding .get_parent_aio_context handler
to child_vvfat_qcow. Now we want it to support .get_parent_desc as
well. child_vvfat_qcow wants to implement own .inherit_options, it's
not bad. But omitting all other handlers is a bad idea. Let's inherit
the class from child_of_bds instead, similar to chain_child_class and
detach_by_driver_cb_class in test-bdrv-drain.c.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/vvfat.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/block/vvfat.c b/block/vvfat.c
index 86d99c899c..ae9d387da7 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -3127,11 +3127,7 @@ static void vvfat_qcow_options(BdrvChildRole role, bool parent_is_format,
     qdict_set_default_str(child_options, BDRV_OPT_CACHE_NO_FLUSH, "on");
 }
 
-static const BdrvChildClass child_vvfat_qcow = {
-    .parent_is_bds      = true,
-    .inherit_options    = vvfat_qcow_options,
-    .get_parent_aio_context = child_of_bds_get_parent_aio_context,
-};
+static BdrvChildClass child_vvfat_qcow;
 
 static int enable_write_target(BlockDriverState *bs, Error **errp)
 {
@@ -3268,6 +3264,8 @@ static BlockDriver bdrv_vvfat = {
 
 static void bdrv_vvfat_init(void)
 {
+    child_vvfat_qcow = child_of_bds;
+    child_vvfat_qcow.inherit_options = vvfat_qcow_options;
     bdrv_register(&bdrv_vvfat);
 }
 
-- 
2.29.2