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orlop

POSIX compatibility

Orlop implements filesystem semantics explicitly; it does not silently accept operations that cannot be persisted. Linux FUSE is the production POSIX surface. macOS uses the in-process nfsserve NFSv3 adapter and has a smaller operation surface.

Operation Linux FUSE macOS NFSv3 Notes
create, read, write, truncate yes yes writes use manifest CAS
atomic rename yes yes metadata transaction
symlink / readlink yes no the current NFS adapter returns NFS3ERR_NOTSUPP
hard link yes no the current nfsserve VFS trait has no LINK hook
chmod yes yes stored metadata; optional kernel permission enforcement
chown, atime yes no Linux FUSE only
FIFO / socket / device node metadata yes no Linux FUSE only
Section titled “Hard-link guarantees”

Every regular file has a stable server-side inode_id. All directory entries for that inode share content, mode, ownership, timestamps, and manifest version.

  • link(2) adds a directory entry without incrementing chunk ownership.
  • A write through any name updates all names in one SQLite transaction.
  • Removing a non-final name preserves the chunks; removing the final name decrements their references.
  • rename(a, b) is a no-op when a and b already name the same inode.
  • Session revert restores a deleted hard-link name onto a surviving inode, rather than creating a duplicate inode.

Linux CI runs a regular-file hard-link smoke plus pjdfstest’s link error semantics against a real FUSE mount and the complete mTLS data plane. The full suite (which also checks special-node hard links that Orlop does not claim) can be run locally:

Terminal window
PJDFS_STRICT=1 scripts/pjdfstest-docker.sh

The compatibility table is the contract. New POSIX claims require an end-to-end conformance test, not only an in-memory unit test.