Test Case: LZ4 Compression Configuration Handling

Test ID: TC088-lz4-config-handling

G5 fixture contract: Use G5-MANUAL-SETUP.md. Its generated paths, source comparisons, structured corruption offsets, and cleanup rules supersede placeholder examples in this file. Category: Compression
Priority: Medium
Regression: None

Objective

Verify correct handling of different LZ4 compression configurations.

Preconditions

Multiple EROFS images with different LZ4 configs:
- lz4-pcluster-4k.erofs (4KB pcluster)
- lz4-pcluster-64k.erofs (64KB pcluster)
- lz4-pcluster-256k.erofs (256KB pcluster)
Test file in each: /files/test.dat (identical content)
Mount points: /mnt/test1, /mnt/test2, /mnt/test3

Generate the images explicitly with mkfs.erofs 1.8.6:

mkfs.erofs -zlz4 -C4096 lz4-pcluster-4k.erofs source
mkfs.erofs -zlz4 -C65536 lz4-pcluster-64k.erofs source
mkfs.erofs -zlz4 -C262144 lz4-pcluster-256k.erofs source

Confirm the requested feature/configuration with dump.erofs -s before treating an image as a valid fixture.

Test Steps

Mount all three images:

mount -t erofs /dev/md0 /mnt/test1
mount -t erofs /dev/md1 /mnt/test2
mount -t erofs /dev/md2 /mnt/test3

Read from each and verify identical output:

sha256 /mnt/test1/files/test.dat
sha256 /mnt/test2/files/test.dat
sha256 /mnt/test3/files/test.dat

Record image sizes without assuming a monotonic compression ratio:

stat -f %z /root/lz4-pcluster-4k.erofs
stat -f %z /root/lz4-pcluster-64k.erofs
stat -f %z /root/lz4-pcluster-256k.erofs

Verify the same offset read with each pcluster size. Timing is diagnostic only and is not a functional pass criterion:

time dd if=/mnt/test1/files/test.dat of=/dev/null bs=4K skip=100 count=10
time dd if=/mnt/test2/files/test.dat of=/dev/null bs=4K skip=100 count=10
time dd if=/mnt/test3/files/test.dat of=/dev/null bs=4K skip=100 count=10

Expected Results

Step 1: All mounts succeed
Step 2: All three checksums identical (data integrity)
Step 3: Image sizes are recorded for the exact corpus and mkfs version
Step 4: All reads succeed and return identical data at the tested offset

Verification Method

Verify all pcluster configurations work correctly
Record pcluster size effects without assuming they are monotonic for every corpus or under a QEMU TCG guest
Test driver handles different configs transparently

Cleanup

umount /mnt/test1 /mnt/test2 /mnt/test3
mdconfig -d -u "${unit1#md}"
mdconfig -d -u "${unit2#md}"
mdconfig -d -u "${unit3#md}"

Notes

Pcluster size is compression unit (physical cluster)
Larger pcluster -> better compression, worse random access
Typical sizes: 4KB, 16KB, 64KB, 256KB
Related tests: TC089 (pcluster mapping)

2.8 KiB Raw Blame History