code: func makePDNameInternal(host volume.VolumeHost, wwns []string, lun string, wwids []string) string {
  	if len(wwns) != 0 {
  		w := strings.Join(wwns, "-")
  		return filepath.Join(host.GetPluginDir(fcPluginName), w+"-lun-"+lun)
  	}
  	return filepath.Join(host.GetPluginDir(fcPluginName), strings.Join(wwids, "-"))
  }
docs: // make a directory like /var/lib/kubelet/plugins/kubernetes.io/fc/target1-target2-lun-0