This patchset is for updating the LZ4 compression module to a version based on LZ4 v1.7.3 allowing to use the fast compression algorithm aka LZ4 fast which provides an "acceleration" parameter as a tradeoff between high compression ratio and high compression speed. We want to use LZ4 fast in order to support compression in lustre and (mostly, based on that) investigate data reduction techniques in behalf of storage systems. Also, it will be useful for other users of LZ4 compression, as with LZ4 fast it is possible to enable applications to use fast and/or high compression depending on the usecase. For instance, ZRAM is offering a LZ4 backend and could benefit from an updated LZ4 in the kernel. LZ4 homepage: http://www.lz4.org/ LZ4 source repository: https://github.com/lz4/lz4 Source version: 1.7.3 Benchmark (taken from [1], Core i5-4300U @1.9GHz): ----------------|--------------|----------------|---------- Compressor | Compression | Decompression | Ratio ----------------|--------------|----------------|---------- memcpy | 4200 MB/s | 4200 MB/s | 1.000 LZ4 fast 50 | 1080 MB/s | 2650 MB/s | 1.375 LZ4 fast 17 | 680 MB/s | 2220 MB/s | 1.607 LZ4 fast 5 | 475 MB/s | 1920 MB/s | 1.886 LZ4 default | 385 MB/s | 1850 MB/s | 2.101 [1] http://fastcompression.blogspot.de/2015/04/sampling-or-faster-lz4.html [PATCH 1/5] lib: Update LZ4 compressor module [PATCH 2/5] lib/decompress_unlz4: Change module to work with new LZ4 module version [PATCH 3/5] crypto: Change LZ4 modules to work with new LZ4 module version [PATCH 4/5] fs/pstore: fs/squashfs: Change usage of LZ4 to work with new LZ4 version [PATCH 5/5] lib/lz4: Remove back-compat wrappers Changes: v8: - Rewrote the architecture-dependent definitions in lz4defs.h, such as LZ4_read*, LZ4_write* and LZ4_NbCommonBytes as proposed by Eric Biggers - Added -O3 compiler flag to Makefile, also suggested by Eric - Defined FORCE_INLINE, as used in upstream LZ4, as __always_inline and force-inlined most of the small functions in lz4defs.h - lz4_decompress: Wrapped the EXPORT_SYMBOL and MODULE_* macros in a #ifdef STATIC the way suggested by Andrew Morton, fixing the breakage of CONFIG_KERNEL_LZ4 in x86 as reported by Arnd Bergman v7: - Fixed errors reported by the Smatch tool - Changed function documentation comments in lz4.h to match kernel-doc style - Fixed a misbehaviour of LZ4HC caused by the wrong level of indentation concerning two for loops introduced after I refactored the code style using checkpatch.pl (upstream LZ4 put dozens of stuff in just one line, gnah) - Updated the crypto tests for LZ4 since they did fail for the new code and hence zram did fail to allocate memory for LZ4 v6: - Fixed LZ4_NBCOMMONBYTES() for 64-bit little endian - Reset LZ4_MEMORY_USAGE to 14 (which is the value used in upstream LZ4 as well as the previous kernel module) - Fixed that weird double-indentation in lz4defs.h and lz4.h - Adjusted general styling issues in lz4defs.h (e.g. lines consisting of more than one instruction) - Removed the architecture-dependent typedef to reg_t since upstream LZ4 is just using size_t and that works fine - Changed error messages in pstore/platform.c: * LZ4_compress_default always returns 0 in case of an error (no need to print the return value) * LZ4_decompress_safe returns a negative error message (return value _does_ matter) v5: - Added a fifth patch to remove the back-compat wrappers introduced to ensure bisectibility between the patches (the functions are no longer needed since there's no callers left) v4: - Fixed kbuild errors - Re-added lz4_compressbound as alias for LZ4_compressBound to ensure backwards compatibility - Wrapped LZ4_hash5 with check for LZ4_ARCH64 since it is only used there and triggers an unused function warning when false v3: - Adjusted the code to satisfy kernel coding style (checkpatch.pl) - Made sure the changes to LZ4 in Kernel (overflow checks etc.) are included in the new module (they are) - Removed the second LZ4_compressBound function with related name but different return type - Corrected version number (was LZ4 1.7.3) - Added missing LZ4 streaming functions v2: - Changed order of the patches since in the initial patchset the lz4.h was in the last patch but was referenced by the other ones - Split lib/decompress_unlz4.c in an own patch - Fixed errors reported by the buildbot - Further refactorings - Added more appropriate copyright note to include/linux/lz4.h
