86 lines
2.8 KiB
Markdown
86 lines
2.8 KiB
Markdown
# Test Case: LZ4 Compression Configuration Handling
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**Test ID**: TC088-lz4-config-handling
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**G5 fixture contract**: Use [G5-MANUAL-SETUP.md](G5-MANUAL-SETUP.md).
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Its generated paths, source comparisons, structured corruption offsets, and
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cleanup rules supersede placeholder examples in this file.
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**Category**: Compression
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**Priority**: Medium
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**Regression**: None
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## Objective
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Verify correct handling of different LZ4 compression configurations.
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## Preconditions
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- Multiple EROFS images with different LZ4 configs:
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- `lz4-pcluster-4k.erofs` (4KB pcluster)
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- `lz4-pcluster-64k.erofs` (64KB pcluster)
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- `lz4-pcluster-256k.erofs` (256KB pcluster)
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- Test file in each: `/files/test.dat` (identical content)
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- Mount points: `/mnt/test1`, `/mnt/test2`, `/mnt/test3`
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- Generate the images explicitly with `mkfs.erofs 1.8.6`:
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```
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mkfs.erofs -zlz4 -C4096 lz4-pcluster-4k.erofs source
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mkfs.erofs -zlz4 -C65536 lz4-pcluster-64k.erofs source
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mkfs.erofs -zlz4 -C262144 lz4-pcluster-256k.erofs source
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```
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- Confirm the requested feature/configuration with `dump.erofs -s` before
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treating an image as a valid fixture.
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## Test Steps
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1. Mount all three images:
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```
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mount -t erofs /dev/md0 /mnt/test1
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mount -t erofs /dev/md1 /mnt/test2
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mount -t erofs /dev/md2 /mnt/test3
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```
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2. Read from each and verify identical output:
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```
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sha256 /mnt/test1/files/test.dat
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sha256 /mnt/test2/files/test.dat
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sha256 /mnt/test3/files/test.dat
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```
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3. Record image sizes without assuming a monotonic compression ratio:
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```
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stat -f %z /root/lz4-pcluster-4k.erofs
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stat -f %z /root/lz4-pcluster-64k.erofs
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stat -f %z /root/lz4-pcluster-256k.erofs
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```
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4. Verify the same offset read with each pcluster size. Timing is diagnostic
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only and is not a functional pass criterion:
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```
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time dd if=/mnt/test1/files/test.dat of=/dev/null bs=4K skip=100 count=10
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time dd if=/mnt/test2/files/test.dat of=/dev/null bs=4K skip=100 count=10
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time dd if=/mnt/test3/files/test.dat of=/dev/null bs=4K skip=100 count=10
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```
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## Expected Results
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- Step 1: All mounts succeed
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- Step 2: All three checksums identical (data integrity)
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- Step 3: Image sizes are recorded for the exact corpus and mkfs version
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- Step 4: All reads succeed and return identical data at the tested offset
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## Verification Method
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- Verify all pcluster configurations work correctly
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- Record pcluster size effects without assuming they are monotonic for every
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corpus or under a QEMU TCG guest
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- Test driver handles different configs transparently
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## Cleanup
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```
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umount /mnt/test1 /mnt/test2 /mnt/test3
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mdconfig -d -u "${unit1#md}"
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mdconfig -d -u "${unit2#md}"
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mdconfig -d -u "${unit3#md}"
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```
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## Notes
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- Pcluster size is compression unit (physical cluster)
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- Larger pcluster -> better compression, worse random access
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- Typical sizes: 4KB, 16KB, 64KB, 256KB
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- Related tests: TC089 (pcluster mapping)
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