最简单的方法来模拟没有可用磁盘空间的情况？

I need to test my web app in a scenario where there’s no disk space remaining, i.e. I cannot write any more files. But I don’t want to fill my hard drive with junk just to make sure there’s really no space left. What I want is to simulate this situation withing a particular process (actually, a PHP app).I need to test my web app in a scenario where t