> Network file systems can cause UID/GID mismatches and add network overhead. With VirtIO-FS, I use the Linux kernel's Virtual File System to translate the hypervisor's UID to the guest's unprivileged UID. This avoids exposing the host file structure. I utilize the `X-mount.idmap` fstab option for this. Documentation on this specific implementation is not easy to find. It builds upon the idmapped mounts feature introduced by Christian Brauner in Linux 5.12 [1] and its later integration with util-linux v2.39 into the standard `mount` utility [2].
[1]: https://github.com/brauner/mount-idmapped + https://docs.kernel.org/filesystems/idmappings.html
[2]: https://github.com/systemd/systemd/releases/tag/v254 [1]: https://github.com/gristlabs/grist-core
[2]: https://github.com/scality/cloudserver
[3]: https://www.min.io/
[4]: https://garagehq.deuxfleurs.fr/
[5]: https://git.deuxfleurs.fr/Deuxfleurs/garage/issues/166
[6]: https://github.com/scality/Zenko/discussions/1779#discussioncomment-15869532
[1]: https://du.nkel.dev/blog/2026-05-16_rootless_docker_virtiofs...