in pkg/nfs/controllerserver.go [529:539]
func (cs *ControllerServer) internalUnmount(ctx context.Context, vol *nfsVolume) error {
targetPath := getInternalMountPath(cs.Driver.workingMountDir, vol)
// Unmount nfs server at base-dir
klog.V(4).Infof("internally unmounting %v", targetPath)
_, err := cs.Driver.ns.NodeUnpublishVolume(ctx, &csi.NodeUnpublishVolumeRequest{
VolumeId: vol.id,
TargetPath: targetPath,
})
return err
}