code: func percentUsed(path string) (float64, error) {
  	var stat syscall.Statfs_t
  	err := syscall.Statfs(path, &stat)
  	if err != nil {
  		return 0, trace.Wrap(err)
  	}
  	ratio := float64(stat.Blocks-stat.Bfree) / float64(stat.Blocks)
  	return math.Round(ratio * 100), nil
  }
docs: // percentUsed returns percentage of disk space used. The percentage of disk
  // space used is calculated from (total blocks - free blocks)/total blocks.
  // The value is rounded to the nearest whole integer.