code: func (p *criStatsProvider) ImageFsDevice() (string, error) {
  	resp, err := p.imageService.ImageFsInfo()
  	if err != nil {
  		return "", err
  	}
  	for _, fs := range resp {
  		fsInfo := p.getFsInfo(fs.GetFsId())
  		if fsInfo != nil {
  			return fsInfo.Device, nil
  		}
  	}
  	return "", errors.New("imagefs device is not found")
  }
docs: // ImageFsDevice returns name of the device where the image filesystem locates,
  // e.g. /dev/sda1.