Prevents libvirt from treating RBD backing stores as files. Without this patch,

creating a domain with a qcow2 overlay on an RBD would fail.

This patch essentially extends 9c7c4a4fc533598e59e9a0038ec783e61a38e664,

which allows nbd backing stores, to allow rbd backing stores.

diff --git a/src/util/storage_file.c b/src/util/storage_file.c

index f38aa8e..101518a 100644

--- a/src/util/storage_file.c

+++ b/src/util/storage_file.c

@@ -589,8 +589,8 @@ virStorageFileMatchesVersion(int format,

 static bool

 virBackingStoreIsFile(const char *backing)

 {

-    /* Backing store is a network block device */

-    if (STRPREFIX(backing, "nbd:"))

+    /* Backing store is a network block device or Rados block device */

+    if (STRPREFIX(backing, "nbd:") || STRPREFIX(backing, "rbd:"))

         return false;

     return true;

 }