code: func (cd *cinderVolume) GetGlobalMapPath(spec *volume.Spec) (string, error) {
  	pdName, _, _, err := getVolumeInfo(spec)
  	if err != nil {
  		return "", err
  	}
  	return filepath.Join(cd.plugin.host.GetVolumeDevicePluginDir(cinderVolumePluginName), pdName), nil
  }
docs: // GetGlobalMapPath returns global map path and error
  // path: plugins/kubernetes.io/{PluginName}/volumeDevices/volumeID
  //       plugins/kubernetes.io/cinder/volumeDevices/vol-XXXXXX