code: func findDisk(wwn, lun string, io ioHandler, deviceUtil volumeutil.DeviceUtil) (string, string) {
  	fcPath := "-fc-0x" + wwn + "-lun-" + lun
  	devPath := byPath
  	if dirs, err := io.ReadDir(devPath); err == nil {
  		for _, f := range dirs {
  			name := f.Name()
  			if strings.Contains(name, fcPath) {
  				if disk, err1 := io.EvalSymlinks(devPath + name); err1 == nil {
  					dm := deviceUtil.FindMultipathDeviceForDevice(disk)
  					klog.Infof("fc: find disk: %v, dm: %v", disk, dm)
  					return disk, dm
  				}
  			}
  		}
  	}
  	return "", ""
  }
docs: // given a wwn and lun, find the device and associated devicemapper parent