code: func (iscsi *iscsiDisk) GetGlobalMapPath(spec *volume.Spec) (string, error) {
  	return iscsi.iscsiGlobalMapPath(spec)
  }
docs: // GetGlobalMapPath returns global map path and error
  // path: plugins/kubernetes.io/{PluginName}/volumeDevices/{ifaceName}/{portal-some_iqn-lun-lun_id}