code: func mountFsRO(m fs.Mounter, mountPoint string, flags uintptr) error {
  	flags = flags |
  		syscall.MS_BIND |
  		syscall.MS_REMOUNT |
  		syscall.MS_RDONLY
  
  	if err := m.Mount(mountPoint, mountPoint, "", flags, ""); err != nil {
  		return errwrap.Wrap(fmt.Errorf("error remounting read-only %q", mountPoint), err)
  	}
  
  	return nil
  }
docs: // mountFsRO remounts the given mountPoint using the given flags read-only.