code: func (daemon *Daemon) populateVolumes(c *container.Container) error {
  	for _, mnt := range c.MountPoints {
  		if mnt.Volume == nil {
  			continue
  		}
  
  		if mnt.Type != mounttypes.TypeVolume || !mnt.CopyData {
  			continue
  		}
  
  		logrus.Debugf("copying image data from %s:%s, to %s", c.ID, mnt.Destination, mnt.Name)
  		if err := c.CopyImagePathContent(mnt.Volume, mnt.Destination); err != nil {
  			return err
  		}
  	}
  	return nil
  }
docs: // populateVolumes copies data from the container's rootfs into the volume for non-binds.
  // this is only called when the container is created.