code: func roundUpSizeInt(volumeSizeBytes int64, allocationUnitBytes int64) (int, error) {
  	roundedUp := roundUpSize(volumeSizeBytes, allocationUnitBytes)
  	roundedUpInt := int(roundedUp)
  	if int64(roundedUpInt) != roundedUp {
  		return 0, fmt.Errorf("capacity %v is too great, casting results in integer overflow", roundedUp)
  	}
  	return roundedUpInt, nil
  }
docs: // roundUpSizeInt calculates how many allocation units are needed to accommodate
  // a volume of given size. It returns an int instead of an int64 and an error if
  // there's overflow