Re: [PATCH RFC 5/9] lib/lz4: switch the compressor to the vendored sources

[sashiko-bot@kernel.org]

> Replace the forked compressor with thin entry points over the vendored
> lz4.c.
> 
> LZ4_compress_default(), LZ4_compress_fast() and LZ4_compress_destSize()
> keep the trailing wrkmem argument and forward to upstream's *_extState()
> entry points. The rest are plain forwarders.
> 
> Compressed output is not quite bit-for-bit identical: it differs on a
> small fraction of inputs by a byte or two, with no measurable change in
> ratio. Both implementations decode each other's output, so nothing
> already on disk changes meaning.
> 
> <linux/lz4.h> spelled out LZ4_stream_t's layout for the fork's benefit:
> lz4defs.h included the public header and the fork read internal_donotuse
> back out. The vendored compressor brings upstream's own definition, so
> make the public type incomplete, repeating upstream's forward
> declaration. Both headers then name the same type, which
> lib/decompress_unlz4.c needs since it ends up including both.
> 
> LZ4_MEMORY_USAGE, LZ4_HASHLOG, LZ4_HASHTABLESIZE, LZ4_HASH_SIZE_U32,
> LZ4_STREAMSIZE_U64 and LZ4_STREAMSIZE only existed to lay that structure
> out, and go with it. LZ4_MEM_COMPRESS keeps its value, 16416, as a
> plain number.
> 
> Callers now allocate LZ4_MEM_COMPRESS bytes instead of
> sizeof(LZ4_stream_t). Every caller but zram already did; zram is
> adjusted here.
> 
> Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260925-lz4-vendor-upstream-v1-0-1c7ffbe21c4b@samsung.com?part=5