spring data mongodb 操作保存文件出现couldn't save chunks

spring data mongodb 操作保存时为什么一直出现com.mongodb.MongoException: couldn't save chunks异常
代码如下 ：
public GridFSFile upload(InputStream inputStream,String fileName,String fileType){
    Assert.notNull(inputStream,"输入流不能为空!");
    Assert.notNull(fileName,"文件不能为空!");
    Assert.notNull(inputStream,"输入流不能为空!");
        ApplicationContext ctx = new AnnotationConfigApplicationContext(SpringMongoConfig.class);
        gridOperations = (GridFsOperations) ctx.getBean("gridFsTemplate");
        GridFSFile gridfs = gridOperations.store(inputStream, fileName,fileType);
        return gridfs;
}

参考：https://groups.google.com/d/topic/mongodb-user/tcxEmdBNz5g