GEFS, a new crash-safe, snapshotting, copy-on-write filesystem written for 9front, is being ported to OpenBSD. The port is a rough, buggy preview not ready for production, with data loss expected on error. The filesystem is under 9,000 lines of kernel code.

The port aims to keep the data structure and fiddly code fairly in sync between Plan 9 and OpenBSD, but code is copied and pasted rather than ported via an abstraction layer. Major remaining problems include the consistency protocol, error handling largely commented out, and missing userspace tools.

Other issues: POSIX constraints, lack of regression tests for OpenBSD, hardlinks, kqueue, NFS hooks, and missing pieces like bootloader support and quotas. The author is not looking to fix KNF yet.

Get it as one patch or via git from shithub, but use GitHub for initial clone to avoid overloading the server.