code: func (f *mounterDefaults) SetUpAt(dir string, fsGroup *int64) error {
  	klog.Warning(logPrefix(f.plugin), "using default SetUpAt to ", dir)
  
  	src, err := f.plugin.getDeviceMountPath(f.spec)
  	if err != nil {
  		return err
  	}
  
  	if err := doMount(f.mounter, src, dir, "auto", []string{"bind"}); err != nil {
  		return err
  	}
  
  	return nil
  }
docs: // SetUpAt is part of the volume.Mounter interface.
  // This implementation relies on the attacher's device mount path and does a bind mount to dir.