code: func (q *Control) SetQuota(targetPath string, quota Quota) error {
  
  	projectID, ok := q.quotas[targetPath]
  	if !ok {
  		projectID = q.nextProjectID
  
  		//
  		// assign project id to new container directory
  		//
  		err := setProjectID(targetPath, projectID)
  		if err != nil {
  			return err
  		}
  
  		q.quotas[targetPath] = projectID
  		q.nextProjectID++
  	}
  
  	//
  	// set the quota limit for the container's project id
  	//
  	logrus.Debugf("SetQuota(%s, %d): projectID=%d", targetPath, quota.Size, projectID)
  	return setProjectQuota(q.backingFsBlockDev, projectID, quota)
  }
docs: // SetQuota - assign a unique project id to directory and set the quota limits
  // for that project id