beamfs - resilient filesystem

Status: PRE-DEMO. Not for publication, not for push, not for Zenodo, not for kernel.org. This tree exists to validate the recovery calculus of the companion paper before any public release.

beamfs is the implementation successor to FTRFS. Where FTRFS reaches its empirical ceiling (per the FTRFS v1 Technical Report, doi:10.5281/zenodo.19824442), beamfs targets the formal recovery calculus described in the beamfs v1 Technical Report (under papers/2026-04-beamfs-v1/).

Lineage

The FTRFS name and original concept originates in:

Fuchs, C.M., Langer, M., Trinitis, C. (2015). FTRFS: A Fault-Tolerant Radiation-Robust Filesystem for Space Use. ARCS 2015, Lecture Notes in Computer Science, vol 9017. Springer. DOI: https://doi.org/10.1007/978-3-319-16086-3_8

That work was developed at TU Munich (Institute for Astronautics) in the context of the MOVE-II CubeSat mission. FTRFS v1 (Desbrieres, 2026) is an independent open-source realization of the Fuchs et al. design with contemporary Linux kernel infrastructure. beamfs v1 (this repository) extends FTRFS v1 with a formal recovery operator and a soundness theorem (see papers/2026-04-beamfs-v1/paper.tex, Theorem IV.1).

Repository layout (current)

• *.c, *.h kernel module sources (rebadged from FTRFS v1)
• mkfs.beamfs.c userspace mkfs tool
• Kconfig, Makefile kernel module build glue
• Documentation/ design notes, threat model, roadmap, testing
• tools/ helper scripts (decode_raf_journal.py, etc.)
• papers/2026-04-beamfs-v1/ LaTeX source of the beamfs v1 paper. Build via cd papers/2026-04-beamfs-v1 && make.

Build (kernel module)

The reference target is the Yocto Scarthgap research image at ~/yocto/poky/build-qemu-arm64/, which packages recipes-kernel/beamfs/ from ~/git/yocto-hardened/. The ~/git/beamfs/ tree is the canonical source; it is mirrored byte-exact under yocto-hardened/recipes-kernel/beamfs/files/beamfs-0.1.0/ (lockstep).

For a host smoke-test against a Yocto-built kernel tree:

make KDIR=<path-to-yocto-kernel-build>

Compiling against the host kernel (for example Gentoo 6.18.x) is not supported and is expected to fail on missing kernel APIs (such as inode_state_read_once, added in mainline 7.0).

Status flag

• beamfs recovery calculus (Theorem IV.1) implemented in kernel
• Bench M6 (corrupt-then-mount) implemented and passing
• Bench M1/M2/M4/M5 reproducing FTRFS baseline within 5%
• Yocto research image builds, mounts, runs benchmarks
• Published on Zenodo
• Published on GitHub (roastercode/beamfs)
• Submitted to kernel.org / linux-fsdevel

When all checkboxes are ticked, this section is removed and the README gets a proper public-facing introduction.

License

GPL-2.0-only (kernel module + userspace tools), CC-BY-4.0 (paper). See COPYING and papers/2026-04-beamfs-v1/paper.tex header.