RefFS: a small, fast file system for Metis as a reference with efficient ioctl API

Introducation

RefFS, or formerly known as VeriFS2, is a FUSE-based in-memory file system used as a reference file system for the Metis model checking framework. RefFS is based on Peter Watkins's fuse-cpp-ramfs, but we made major changes to the entire file system structure and provided four novel APIs: checkpoint/restore and pickle/load to support more efficient model checking than other file systems. Please refer to our FAST '24 paper "Metis: File System Model Checking via Versatile Input and State Exploration" for details.

Requirements

We used and tested RefFS on Ubuntu 20.04 and Ubuntu 22.04 with Linux kernel version 5.4 or greater. RefFS builds with CMake version 3.0 or greater and requires the libfuse2-2.9 (or later) filesystem-in-userspace library and header files for successful compilation. libfuse is available at: https://github.com/libfuse/libfuse (for Linux) and https://osxfuse.github.io (for Mac)

Quick run

To build and mount RefFS, you can run the script setup_verifs2.sh.

sudo ./setup_verifs2.sh

If you run the mount command, you should be able to see the following output to indicate that RefFS is mounted successfully:

verifs2 on /mnt/test-verifs2 type fuse.verifs2 (rw,nosuid,nodev,relatime,user_id=0,group_id=0,default_permissions,allow_other)

Alternatively, you can build and mount RefFS manually by the following commands:

mkdir build
cd build
cmake ../src
make
sudo make install
sudo mkdir -p /mnt/test-verifs2
sudo mount -t fuse.fuse-cpp-ramfs verifs2 /mnt/test-verifs2

Citation

@INPROCEEDINGS{fast24metis,
  TITLE =        "{Metis}: File System Model Checking via Versatile Input and State Exploration",
  AUTHOR =       "Yifei Liu and Manish Adkar and Gerard Holzmann and Geoff Kuenning and Pei Liu and Scott Smolka and Wei Su and Erez Zadok",
  NOTE =         "To appear",
  BOOKTITLE =    "Proceedings of the 22nd USENIX Conference on File and Storage Technologies (FAST '24)",
  ADDRESS =      "Santa Clara, CA",
  MONTH =        "February",
  YEAR =         "2024",
  PUBLISHER =    "USENIX Association"
}

@INPROCEEDINGS{hotstorage21mcfs,
  TITLE =        "Model-Checking Support for File System Development",
  AUTHOR =       "Wei Su and Yifei Liu and Gomathi Ganesan and Gerard Holzmann and Scott Smolka and Erez Zadok and Geoff Kuenning",
  DOI =          "https://doi.org/10.1145/3465332.3470878",
  PAGES =        "103--110",
  BOOKTITLE =    "Proceedings of the 13th ACM Workshop on Hot Topics in Storage (HotStorage '21)",
  MONTH =        "July",
  YEAR =         "2021",
  PUBLISHER =    "ACM",
  ADDRESS =      "Virtual"
}

Contact

For any question, please feel free to contact Yifei Liu (yifeliu@cs.stonybrook.edu) and Erez Zadok (ezk@cs.stonybrook.edu).