[RFC PATCH 0/10] ftrfs: Fault-Tolerant Radiation-Robust Filesystem

Aurelien DESBRIERES
2026-04-13T12:24:15Z

From: Aurélien DESBRIERES <aurelien@hackers.camp>

This RFC introduces FTRFS, a new Linux filesystem designed for dependable
storage in radiation-intensive environments, targeting embedded Linux systems
operating in space or other harsh conditions.

FTRFS was originally described in:

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

This implementation is an independent open-source realization of the
concepts described in that paper, developed for the Linux kernel.

== Design ==

FTRFS provides three layers of data integrity:

- CRC32 per block and per inode (hardware-accelerated via crc32_le)
- Reed-Solomon FEC (encoder implemented, decoder planned)
- EDAC-compatible error tracking

On-disk layout:

Block 0 : superblock (magic 0x46545246, CRC32-protected)
Block 1..N : inode table (128 bytes/inode, CRC32 per inode)
Block N+1..end : data blocks (CRC32 + RS FEC per block)

Inodes use direct addressing (12 direct block pointers) plus single
and double indirection. Directory entries are fixed-size (268 bytes)
stored in direct blocks.

== Current Status ==

- Superblock: mount/umount, CRC32 validation [done]
- Inodes: read with CRC32 verification [done]
- Directories: readdir, lookup [done]
- Files: read via generic page cache helpers [done]
- Allocator: in-memory bitmap for blocks and inodes [done]
- Write path: create, mkdir, unlink, rmdir, link [done]
- Reed-Solomon: encoder done, decoder planned [partial]
- xattrs / SELinux [planned]
- fsck.ftrfs [planned]
- Indirect block support for large files [planned]

== Validation ==

FTRFS has been validated on arm64 (cortex-a57) running Linux 7.0-rc7,
built with Yocto Styhead (5.1), deployed as a data partition in a
3-node Slurm HPC cluster on KVM/QEMU:

insmod ftrfs.ko -> module loaded
mount -t ftrfs /dev/vdb /mnt -> success
ls /mnt -> returns empty directory correctly

Compile-tested on x86_64 with Linux 7.0 (this series).
checkpatch.pl: 0 errors on all patches.

== Feedback Requested ==

This is an RFC. Feedback is welcome on:

1. On-disk format: is the superblock/inode layout reasonable?
2. Directory entry design: fixed 268-byte entries vs. variable length
3. Reed-Solomon: use lib/reed_solomon or keep custom GF(2^8) tables?
4. Allocator: in-memory bitmap vs. dedicated on-disk bitmap block
5. Any VFS API misuse or missing locking

The code is also available at:
https://github.com/roastercode/FTRFS

Aurélien DESBRIERES (10):
ftrfs: add on-disk format and in-memory data structures
ftrfs: add superblock operations
ftrfs: add inode operations
ftrfs: add directory operations
ftrfs: add file operations
ftrfs: add block and inode allocator
ftrfs: add filename and directory entry operations
ftrfs: add CRC32 checksumming and Reed-Solomon FEC skeleton
ftrfs: add Kconfig, Makefile and fs/ tree integration
MAINTAINERS: add entry for FTRFS filesystem

MAINTAINERS | 6 +
fs/Kconfig | 1 +
fs/Makefile | 1 +
fs/ftrfs/Kconfig | 49 +++
fs/ftrfs/Makefile | 16 +
fs/ftrfs/alloc.c | 251 +++++++++++++++
fs/ftrfs/dir.c | 132 ++++++++
fs/ftrfs/edac.c | 84 +++++
fs/ftrfs/file.c | 25 ++
fs/ftrfs/ftrfs.h | 168 ++++++++++
fs/ftrfs/inode.c | 103 +++++++
fs/ftrfs/namei.c | 428 +++++++++++++++++++++++++++
fs/ftrfs/super.c | 274 ++++++++++++++++
13 files changed, 1538 insertions(+)

Signed-off-by: Aurélien DESBRIERES <aurelien@hackers.camp>