erofs-freebsd-out-tree/tests/results/manual/2026-08-08T1444Z/manual-test-report.md

repo22 legacy full-index fix manual report

• Date: 2026-08-08 UTC
• Source baseline: 377d467a652beb2124d4adc0d1f8e735fca22344
• FreeBSD guest: 15.0-RELEASE-p8 amd64, QEMU TCG
• Module SHA256: f3b9fa70bfb8e98e2cef436583fd13cb91787514a5be76f9f108698d7586ca3c
• Scope: legacy full-index and partial-reference minimum regression only

Root cause and fix

The proven legacy Layout 1 fixture maps its second extent as HEAD1 with clusterofs=28, pblk=2, m_la=639004, m_llen=409572, and m_plen=4096. The LZ4 stream completes after consuming 2627 bytes; the remaining 1469 bytes of the pcluster are zero padding. The repo22 decoder incorrectly required all 4096 input bytes to be consumed and returned EIO.

The decoder now accepts complete output only when the remaining pcluster bytes are all zero, while continuing to reject nonzero trailing data. The mapping recorder also no longer clears compressedblks and partialref on every lcluster load, matching the Linux state machine and preserving lookback state.

Results

Test	Mount	Full SHA256	Boundary read	Result
Legacy full index /shape.dat	PASS	370eb0a8df86868c4842ca535ed64670f0277ea2ed47a703f089bbb13ee4ac52 matches	offset 638972, 128 bytes: 941b6e3cb9a7384428d93ca248eb9630782538e04caba30dbfbe31baacca8f60 matches	PASS
Partial reference /b.dat	PASS	read returns EIO	offset 641020 read returns no data	KERNEL-FAIL

./build.sh, kldload, and exact-name kldunload passed. The isolated dmesg delta was empty, with no panic, trap, or integrity diagnostic.

Remaining partial-reference hypothesis

The minimal reproducer is the existing lz4-partial-ref.erofs fixture: mount it and read /b.dat; the companion compact /a.dat remains the known-good source extent. The full-index mapping blocker is removed, but zdata.c still invokes z_erofs_decompress() with partial=false for every mapped extent even when EROFS_MAP_PARTIAL_REF is set. Linux propagates this state to partial LZ4 decoding. Per the convergence instruction, this batch records that hypothesis without further debugging or additional source changes.