rbd: free snapshot resources after allocation

Not all snapshot objects are free'd correctly after they were allocated.
It is possible that some connections to the Ceph cluster were never
closed. This does not need to be a noticeable problem, as connections
are re-used where possible, but it isn't clean either.

Signed-off-by: Niels de Vos <ndevos@ibm.com>

internal/rbd/controllerserver.go

@@ -340,6 +340,12 @@ func (cs *ControllerServer) CreateVolume(
 	if err != nil {
 		return nil, err
 	}
+	if parentVol != nil {
+		defer parentVol.Destroy()
+	}
+	if rbdSnap != nil {
+		defer rbdSnap.Destroy()
+	}
 
 	found, err := rbdVol.Exists(ctx, parentVol)
 	if err != nil {
@@ -642,6 +648,7 @@ func (cs *ControllerServer) createVolumeFromSnapshot(
 
 		return status.Error(codes.Internal, err.Error())
 	}
+	defer rbdSnap.Destroy()
 
 	// update parent name(rbd image name in snapshot)
 	rbdSnap.RbdImageName = rbdSnap.RbdSnapName
@@ -1445,6 +1452,7 @@ func (cs *ControllerServer) DeleteSnapshot(
 
 		return nil, status.Error(codes.Internal, err.Error())
 	}
+	defer rbdSnap.Destroy()
 
 	// safeguard against parallel create or delete requests against the same
 	// name