code: func ignoreUnsupportedXAttrs() fs.CopyDirOpt {
  	xeh := func(dst, src, xattrKey string, err error) error {
  		if errors.Cause(err) != syscall.ENOTSUP {
  			return err
  		}
  		return nil
  	}
  	return fs.WithXAttrErrorHandler(xeh)
  }
docs: // ignoreUnsupportedXAttrs ignores errors when extended attributes
  // are not supported