// Negative value for bytes means that a non-enforcing quota
	// should be applied (perhaps by setting a quota too large to
	// be hit)
	SetQuotaOnDir(path string, id QuotaID, bytes int64) error

	// QuotaIDIsInUse determines whether the quota ID is in use.
	// Implementations should not check /etc/project or /etc/projid,
	// only whether their underlying mechanism already has the ID in
	// use.

func (v linuxVolumeQuotaApplier) GetInodes(_ string, id QuotaID) (int64, error) {
	return getQuantity(v.mountpoint, id, "-i", 1, v.allowEmptyOutput)
}

// QuotaIDIsInUse checks whether the specified quota ID is in use on the specified
// filesystem
func (v linuxVolumeQuotaApplier) QuotaIDIsInUse(id QuotaID) (bool, error) {
	bytes, err := v.GetConsumption(v.mountpoint, id)
	if err != nil {
		return false, err
	}
	if bytes > 0 {

// it returns error if QuotaIDIsInUse returns error when getting quota id in use;
// it searches at most maxUnusedQuotasToSearch(128) time
func findAvailableQuota(path string, idMap map[common.QuotaID]bool) (common.QuotaID, error) {
	unusedQuotasSearched := 0
	for id := common.FirstQuota; true; id++ {
		if _, ok := idMap[id]; !ok {
			isInUse, err := getApplier(path).QuotaIDIsInUse(id)
			if err != nil {

	id, ok := testQuotaIDMap[path]
	if ok {
		return id, nil
	}
	return common.BadQuotaID, fmt.Errorf("no quota available for %s", path)
}

func (v testVolumeQuota) QuotaIDIsInUse(id common.QuotaID) (bool, error) {
	if _, ok := testIDQuotaMap[id]; ok {
		return true, nil
	}
	// So that we reject some
	if id%3 == 0 {
		return false, nil
	}
	return false, nil
}