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

[Aurelien DESBRIERES <aurelien@hackers.camp>]

On Mon, Apr 13, 2026 at 04:06:07PM +0100, Matthew Wilcox wrote:
> Might be nice to link to a non-paywalled copy of that paper, eg:
> https://www.cfuchs.net/chris/publication-list/ARCS2015/FTRFS.pdf

Done in v2 and v3 cover letters.

> Can I ask why? Is the original code not available or too ugly?

The original FTRFS from the ARCS 2015 paper was a research prototype
targeting a custom RTOS (not Linux). There is no upstream Linux
implementation. This series is an independent open-source realization
of the published design for the mainline Linux kernel.

> This is very old-school. That may be appropriate for the intended
> use-case, but it ignores about five decades of filesystem research.

Intentional. The design constraints are auditability (DO-178C,
ECSS-E-ST-40C, IEC 61508) and minimal code size (target < 5000 lines).
Five decades of filesystem research produced ext4 (~100k lines) and
btrfs (~200k lines), neither of which is certifiable under these
frameworks. The old-school approach is a feature, not a limitation.

The iomap IO path was adopted in v3 as you requested, replacing the
buffer_head based read/write. buffer_head is retained for metadata
IO (inode table, directory blocks) pending further review.

Aurelien DESBRIERES <aurelien@hackers.camp>