erofs-freebsd-out-tree/tests/TC152-extent-hole-bounded-read.md

Test Case: Bounded Read of 5 GiB Extent Hole

Test ID: TC152-extent-hole-bounded-read Category: Compression Extent Mapping Priority: Critical

Objective

Verify a 5 GiB plus one page unmapped compression extent clears only the requested byte/page, with bounded allocation.

Procedure

Record final/fixture-evidence.txt and the extent-hole-5g.erofs hash. On a fresh mount, record stat and the erofs vmstat -m row, then run twice:

/usr/bin/time -l ./sparse_hole_probe \
  /tmp/repo22-g3/mnt/hole.dat 3221225472

Record the post-run allocation row, dmesg, and cleanup.

Expected Results

The mounted size is 5368713216. Both one-byte pread calls and real one-page mmap faults at 3 GiB return zero promptly; allocation does not scale with the 5 GiB logical hole. No OOM, hang, trap, or panic occurs.