erofs-freebsd-out-tree/tests/TC159-special-setattr-combinations.md

Test Case: Special Vnode Combined Setattr Rejection

Test ID: TC159-special-setattr-combinations Category: Read-Only Vnode Operations Priority: Critical Regression: A special-vnode size field caused early success and hid other requested mutations

Objective

Verify that size-only setattr remains an ignored no-op for special vnodes, while a single VOP_SETATTR containing size plus mode, ownership, timestamps, or all three classes returns EROFS.

Fixture and Probe

Use special-setattr.erofs and its FIFO /special.fifo. Build the kernel-side probe against the same FreeBSD 15 source tree:

mkdir setattr-probe
cp tests/final_review_setattr_probe.c setattr-probe/
cp tests/final_review_setattr_probe.mk setattr-probe/Makefile
make -C setattr-probe SYSDIR=/path/to/freebsd/sys

The probe performs one locked vnode lookup and one VOP_SETATTR per sysctl trigger, avoiding userspace syscalls that split attributes across operations.

Procedure

1. Mount the fixture read-only and record mode, uid, gid, atime, and mtime.
2. Load erofs_setattr_probe.ko and set debug.erofs_setattr_probe.path to the FIFO.
3. Trigger operation 1 (size only); require result 0.
4. Trigger operations 2 through 5 (size+mode, size+owner, size+times, all); require result 30 (EROFS) after each trigger.
5. Require the metadata snapshot to remain unchanged, then unload the probe, unmount, detach, and unload EROFS.

Expected Results

• Size-only special-vnode setattr returns 0.
• Every combined mutation returns EROFS, never false success.
• No mode, ownership, or timestamp changes are observable.