code: func (daemon *Daemon) Mount(container *container.Container) error {
  	if container.RWLayer == nil {
  		return errors.New("RWLayer of container " + container.ID + " is unexpectedly nil")
  	}
  	dir, err := container.RWLayer.Mount(container.GetMountLabel())
  	if err != nil {
  		return err
  	}
  	logrus.Debugf("container mounted via layerStore: %v", dir)
  
  	if container.BaseFS != nil && container.BaseFS.Path() != dir.Path() {
  		// The mount path reported by the graph driver should always be trusted on Windows, since the
  		// volume path for a given mounted layer may change over time.  This should only be an error
  		// on non-Windows operating systems.
  		if runtime.GOOS != "windows" {
  			daemon.Unmount(container)
  			return fmt.Errorf("Error: driver %s is returning inconsistent paths for container %s ('%s' then '%s')",
  				daemon.imageService.GraphDriverForOS(container.OS), container.ID, container.BaseFS, dir)
  		}
  	}
  	container.BaseFS = dir // TODO: combine these fields
  	return nil
  }
docs: // Mount sets container.BaseFS
  // (is it not set coming in? why is it unset?)