GetDirUsage from fs.go doing recursive directory walks

fs.go

func GetDirUsage(dir string) (UsageInfo, error) {
	var usage UsageInfo

	if dir == "" {
		return usage, fmt.Errorf("invalid directory")
	}

	rootInfo, err := os.Stat(dir)
	if err != nil {
		return usage, fmt.Errorf("could not stat %q to get inode usage: %v", dir, err)
	}

	rootStat, ok := rootInfo.Sys().(*syscall.Stat_t)
	if !ok {
		return usage, fmt.Errorf("unsuported fileinfo for getting inode usage of %q", dir)
	}

	rootDevID := rootStat.Dev

	// dedupedInode stores inodes that could be duplicates (nlink > 1)
	dedupedInodes := make(map[uint64]struct{})

	err = filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {