关于多进程同时读写文件操作的问题(语言-c#)

请问各位！我做了一个定时器每隔一秒自动执行文件的剪贴操作。
但有时候文件过大，程序一秒钟肯定处理不完，这时候定时器又触发了下一次操作，文件就会被拒绝访问而报错

请问这种应该怎么解决呢

    private void diaoYong(object sender, System.Timers.ElapsedEventArgs e)
    {
        string jcPath = this.zhongZhuanX.Text;
        string jsPath = this.jsonBX.Text;
        string jsZPath = this.jsonX.Text;
        string baojiaPath = this.baoJiaX.Text;
        string bujianPath = this.buJianX.Text;
        string qianziPath = this.qianZiX.Text;
        string tuzhiPath = this.tuZhiX.Text;
        string mprPath = this.mprX.Text;
        tool.geShi(jcPath,jsPath,jsZPath,baojiaPath,bujianPath,qianziPath,tuzhiPath,mprPath);
    }

    public void geShi(string jcpath, string jsPath, string jsZPath, string baojiaPath, string bujianPath, string qianziPath, string tuzhiPath,string mprPath)
    {
        if (DirisNull(jcpath))
        {
            //取得所有文件名
            string[] fi = Directory.GetFiles(jcpath);
            //日期
            string date1 = "";
            for (int j = 0; j < fi.Length; j++)
            {
                string fName = fi[j].Substring(fi[j].LastIndexOf(@"\") + 1, fi[j].Length - fi[j].LastIndexOf(@"\") - 1);
                string ges = fName.Substring(fName.LastIndexOf("."));
                date1 = fName.Substring(2, 4);
                //JSON备份和炸单 jsPath  jsZPath
                    if (!Directory.Exists(jsPath))
                    {
                        Directory.CreateDirectory(jsPath);
                    }
                    #endregion
                    //备份路径
                    File.Copy(fi[j], jsPath + @"\" + fName, true);
                    //炸单路径
                    File.Copy(fi[j], jsZPath + @"\" + fName, true);
                    File.Delete(fi[j]);
                }
        }
    }

    private void SorP_Click(object sender, EventArgs e)
    {
        string zt = this.SorP.Text;
        System.Timers.Timer tm = new System.Timers.Timer(2000);
        tm.Elapsed += new System.Timers.ElapsedEventHandler(diaoYong);
        tm.AutoReset = true;
        if (zt.Equals("开始"))
        {
            tm.Enabled = true;
            this.state.Text = "转存执行中。。。。。。";
            this.SorP.Text = "暂停";
            this.Form2_Load(this, null);
        }
        else
        {
            tm.Enabled = false;
            this.state.Text = "转存已暂停。。。。。。";
            this.SorP.Text = "开始";
            this.Form2_Load(this, null);
        }

设置一个全局变量，记住当前是否正在处理，如果发现重入，什么也不做直接返回。