code: func getISCSIVolumeInfo(spec *volume.Spec) (bool, string, error) {
  	// for volume source, readonly is in volume spec
  	// for PV, readonly is in PV spec. PV gets the ReadOnly flag indirectly through the PVC source
  	if spec.Volume != nil && spec.Volume.ISCSI != nil {
  		return spec.Volume.ISCSI.ReadOnly, spec.Volume.ISCSI.FSType, nil
  	} else if spec.PersistentVolume != nil &&
  		spec.PersistentVolume.Spec.ISCSI != nil {
  		return spec.ReadOnly, spec.PersistentVolume.Spec.ISCSI.FSType, nil
  	}
  
  	return false, "", fmt.Errorf("Spec does not reference an ISCSI volume type")
  }
docs: // get iSCSI volume info: readOnly and fstype