block: Catch backing files assigned to non-COW drivers

[mirror_qemu.git] / block / cow.c

diff --git a/block/cow.c b/block/cow.c
index a05a92cadaa1df0fb720ae9540e9af449bb7185b..8f81ee6d56bce1f09d84e1221cd49ebe6929f2d3 100644 (file)
--- a/block/cow.c
+++ b/block/cow.c
@@ -414,6 +414,7 @@ static BlockDriver bdrv_cow = {
     .bdrv_close     = cow_close,
     .bdrv_create    = cow_create,
     .bdrv_has_zero_init     = bdrv_has_zero_init_1,
+    .supports_backing       = true,
 
     .bdrv_read              = cow_co_read,
     .bdrv_write             = cow_co_write,