Actually what we chose is a primary child. Let's stress it in the code.
We are going to drop indirect pointer logic here in future. Actually
this commit simplifies the future work: we drop use of indirection in
the assertion now.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@yandex-team.ru>
Reviewed-by: Hanna Reitz <hre...@redhat.com>
---
block/snapshot.c | 30 ++++++++++--------------------
1 file changed, 10 insertions(+), 20 deletions(-)
diff --git a/block/snapshot.c b/block/snapshot.c
index d6f53c3065..75e8d3a937 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -161,21 +161,14 @@ bool bdrv_snapshot_find_by_id_and_name(BlockDriverState
*bs,
static BdrvChild **bdrv_snapshot_fallback_ptr(BlockDriverState *bs)
{
BdrvChild **fallback;
- BdrvChild *child;
+ BdrvChild *child = bdrv_primary_child(bs);
- /*
- * The only BdrvChild pointers that are safe to modify (and which
- * we can thus return a reference to) are bs->file and
- * bs->backing.
- */
- fallback = &bs->file;
- if (!*fallback && bs->drv && bs->drv->is_filter) {
- fallback = &bs->backing;
- }
-
- if (!*fallback) {
+ /* We allow fallback only to primary child */
+ if (!child) {
return NULL;
}
+ fallback = (child == bs->file ? &bs->file : &bs->backing);
+ assert(*fallback == child);
/*
* Check that there are no other children that would need to be
@@ -309,15 +302,12 @@ int bdrv_snapshot_goto(BlockDriverState *bs,
}
/*
- * fallback_ptr is &bs->file or &bs->backing. *fallback_ptr
- * was closed above and set to NULL, but the .bdrv_open() call
- * has opened it again, because we set the respective option
- * (with the qdict_put_str() call above).
- * Assert that .bdrv_open() has attached some child on
- * *fallback_ptr, and that it has attached the one we wanted
- * it to (i.e., fallback_bs).
+ * fallback was a primary child. It was closed above and set to NULL,
+ * but the .bdrv_open() call has opened it again, because we set the
+ * respective option (with the qdict_put_str() call above).
+ * Assert that .bdrv_open() has attached the right BDS as primary
child.
*/
- assert(*fallback_ptr && fallback_bs == (*fallback_ptr)->bs);
+ assert(bdrv_primary_bs(bs) == fallback_bs);
bdrv_unref(fallback_bs);
return ret;
}
--
2.25.1
