code: func (daemon *Daemon) isOnlineFSOperationPermitted(container *container.Container) error {
  	if !container.IsRunning() {
  		return nil
  	}
  
  	// Determine isolation. If not specified in the hostconfig, use daemon default.
  	actualIsolation := container.HostConfig.Isolation
  	if containertypes.Isolation.IsDefault(containertypes.Isolation(actualIsolation)) {
  		actualIsolation = daemon.defaultIsolation
  	}
  	if containertypes.Isolation.IsHyperV(actualIsolation) {
  		return errors.New("filesystem operations against a running Hyper-V container are not supported")
  	}
  	return nil
  }
docs: // isOnlineFSOperationPermitted returns an error if an online filesystem operation
  // is not permitted (such as stat or for copying). Running Hyper-V containers
  // cannot have their file-system interrogated from the host as the filter is
  // loaded inside the utility VM, not the host.
  // IMPORTANT: The container lock must NOT be held when calling this function.