// The last entry can be used as a marker to resume the listing.
func (r *metacacheReader) filter(o listPathOptions) (entries metaCacheEntriesSorted, err error) {
	// Forward to prefix, if any
	err = r.forwardTo(o.Prefix)
	if err != nil {
		return entries, err
	}
	if o.Marker != "" {
		err = r.forwardTo(o.Marker)
		if err != nil {
			return entries, err
		}
	}