xapi_vm_snapshot: do not leak CD VBDs

Because all the snapshot's CD VBDs are cloned in all cases, the reverted
VM's CD VBDs must be destroyed in all cases, add them unconditionally to
the VBDs being destroyed.

Signed-off-by: Pau Ruiz Safont <pau.safont@vates.tech>

Author: psafont

ocaml/xapi/xapi_vm_snapshot.ml

@@ -253,9 +253,9 @@ let revert_vbds ~__context ~rpc ~session_id ~snapshot ~vm =
   let snap_disks_snapshot_of = VDISet.map get_snapshot_of snap_disks_all in
 
   let vm_VBDs_all = Db.VM.get_VBDs ~__context ~self:vm |> VBDSet.of_list in
-  let vm_VBDs_disk =
+  let vm_VBDs_disk, vm_VBDs_CD =
     (* Filter VBDs to ensure that we don't read empty CDROMs *)
-    VBDSet.filter
+    VBDSet.partition
       (fun vbd -> Db.VBD.get_type ~__context ~self:vbd = `Disk)
       vm_VBDs_all
   in
@@ -309,7 +309,8 @@ let revert_vbds ~__context ~rpc ~session_id ~snapshot ~vm =
   in
 
   let vm_vbds_to_be_destroyed =
-    filter_vbds_from_vdis vm_VBDs_all vm_disks_to_be_destroyed
+    let ( +++ ) = VBDSet.union in
+    filter_vbds_from_vdis vm_VBDs_all vm_disks_to_be_destroyed +++ vm_VBDs_CD
   in
 
   let snap_VBDs_reverted =