func readDirFn(dirPath string, fn func(name string, typ os.FileMode) error) error {
	fd, err := openFileWithFD(dirPath, readMode, 0o666)
	if err != nil {
		if osErrToFileErr(err) == errFileNotFound {
			return nil
		}
		if !osIsPermission(err) {
			return osErrToFileErr(err)
		}
		// There may be permission error when dirPath
		// is at the root of the disk mount that may
		// not have the permissions to avoid 'noatime'

	d, err := Open(dirPath)
	if err != nil {
		if osErrToFileErr(err) == errFileNotFound {
			return nil
		}
		return osErrToFileErr(err)
	}
	defer d.Close()

	maxEntries := 1000
	for {
		// Read up to max number of entries.
		fis, err := d.Readdir(maxEntries)
		if err != nil {
			if err == io.EOF {
				break
			}
			err = osErrToFileErr(err)
			if err == errFileNotFound {
				return nil
			}

	for ; ; err = syscall.FindNextFile(handle, data) {
		if err != nil {
			if err == syscall.ERROR_NO_MORE_FILES {
				break
			} else {
				if isSysErrPathNotFound(err) {
					return nil
				}
				err = osErrToFileErr(&os.PathError{
					Op:   "FindNextFile",
					Path: dirPath,
					Err:  err,
				})
				if err == errFileNotFound {
					return nil
				}
				return err
			}
		}

// Is a one place function which converts all os.PathError
// into a more FS object layer friendly form, converts
// known errors into their typed form for top level
// interpretation.
func osErrToFileErr(err error) error {
	if err == nil {
		return nil
	}
	if osIsNotExist(err) {
		return errFileNotFound
	}
	if osIsPermission(err) {
		return errFileAccessDenied
	}

			// This is a special case should be handled only for
			// windows, because windows API does not return "not a
			// directory" error message. Handle this specifically here.
			return errFileAccessDenied
		}
		return osErrToFileErr(err)
	}

	return nil
}

// Reliably retries os.MkdirAll if for some reason os.MkdirAll returns
// syscall.ENOENT (parent does not exist).