code: func (m *execMounter) doExecMount(source, target, fstype string, options []string) error {
  	klog.V(5).Infof("Exec Mounting %s %s %s %v", source, target, fstype, options)
  	mountArgs := mount.MakeMountArgs(source, target, fstype, options)
  	output, err := m.exec.Run("mount", mountArgs...)
  	klog.V(5).Infof("Exec mounted %v: %v: %s", mountArgs, err, string(output))
  	if err != nil {
  		return fmt.Errorf("mount failed: %v\nMounting command: %s\nMounting arguments: %s %s %s %v\nOutput: %s",
  			err, "mount", source, target, fstype, options, string(output))
  	}
  
  	return err
  }
docs: // doExecMount calls exec(mount <what> <where>) using given exec interface.