code: func (s *CpusetGroup) ensureParent(current, root string) error {
  	parent := filepath.Dir(current)
  	if filepath.Clean(parent) == root {
  		return nil
  	}
  	if err := s.ensureParent(parent, root); err != nil {
  		return err
  	}
  	if err := os.MkdirAll(current, 0755); err != nil && !os.IsExist(err) {
  		return err
  	}
  	return s.copyIfNeeded(current, parent)
  }
docs: // ensureParent makes sure that the parent directory of current is created
  // and populated with the proper cpus and mems files copied from
  // it's parent.