File systems are used to organize data on storage devices. The file systems may crash due to external failures, such as an unexpected power outage. Therefore, the robustness of the file system is essential. Although some existing works evaluated the robustness of file systems, they are not comprehensive enough and cost many resources. In this work, we design a file system model and verify properties related to the correctness of the file using the SPIN model checker. The robustness of the file system has been comprehensively evaluated in both single-thread and multi-thread modes. There is a critical error in the file system. By analyzing counterexamples given by model checking, we propose a mechanism to prevent it. Based on the mechanism, the robustness of the file system is effectively improved.