maintenance/maintenance.go
func (s *FileStore) On() (changed bool, err error) {
	if _, err = os.Stat(s.filename); err == nil {
		return
	}
	err = os.MkdirAll(filepath.Dir(s.filename), 0777)
	if err != nil {
		return
	}
	f, err := os.Create(s.filename)
	if err != nil {
		return
	}
	f.Close()
	changed = true
	return
}
func (s *FileStore) On() (changed bool, err error) {
	if _, err = os.Stat(s.filename); err == nil {
		return
	}
	err = os.MkdirAll(filepath.Dir(s.filename), 0777)
	if err != nil {
		return
	}
	f, err := os.Create(s.filename)
	if err != nil {
		return
	}
	f.Close()
	changed = true
	return
}
// On enables maintenance.