code: func diskTearDown(manager diskManager, c rbdUnmounter, volPath string, mounter mount.Interface) error {
  	notMnt, err := mounter.IsLikelyNotMountPoint(volPath)
  	if err != nil && !os.IsNotExist(err) {
  		klog.Errorf("cannot validate mountpoint: %s", volPath)
  		return err
  	}
  	if notMnt {
  		klog.V(3).Infof("volume path %s is not a mountpoint, deleting", volPath)
  		return os.Remove(volPath)
  	}
  
  	// Unmount the bind-mount inside this pod.
  	if err := mounter.Unmount(volPath); err != nil {
  		klog.Errorf("failed to umount %s", volPath)
  		return err
  	}
  
  	notMnt, mntErr := mounter.IsLikelyNotMountPoint(volPath)
  	if mntErr != nil && !os.IsNotExist(mntErr) {
  		klog.Errorf("IsLikelyNotMountPoint check failed: %v", mntErr)
  		return mntErr
  	}
  	if notMnt {
  		if err := os.Remove(volPath); err != nil {
  			klog.V(2).Info("Error removing mountpoint ", volPath, ": ", err)
  			return err
  		}
  	}
  	return nil
  }
docs: // utility to tear down a disk based filesystem