lib: zstd: export API needed for dictionary support

Patch series "zram: introduce custom comp backends API", v7.

This series introduces support for run-time compression algorithms tuning,
so users, for instance, can adjust compression/acceleration levels and
provide pre-trained compression/decompression dictionaries which certain
algorithms support.

At this point we stop supporting (old/deprecated) comp API.  We may add
new acomp API support in the future, but before that zram needs to undergo
some major rework (we are not ready for async compression).

Some benchmarks for reference (look at column #2)

*** init zstd
/sys/block/zram0/mm_stat
1750659072 504622188 514355200        0 514355200        1        0    34204    34204

*** init zstd dict=/home/ss/zstd-dict-amd64
/sys/block/zram0/mm_stat
1750650880 465908890 475398144        0 475398144        1        0    34185    34185

*** init zstd level=8 dict=/home/ss/zstd-dict-amd64
/sys/block/zram0/mm_stat
1750654976 430803319 439873536        0 439873536        1        0    34185    34185

*** init lz4
/sys/block/zram0/mm_stat
1750646784 664266564 677060608        0 677060608        1        0    34288    34288

*** init lz4 dict=/home/ss/lz4-dict-amd64
/sys/block/zram0/mm_stat
1750650880 619990300 632102912        0 632102912        1        0    34278    34278

*** init lz4hc
/sys/block/zram0/mm_stat
1750630400 609023822 621232128        0 621232128        1        0    34288    34288

*** init lz4hc dict=/home/ss/lz4-dict-amd64
/sys/block/zram0/mm_stat
1750659072 505133172 515231744        0 515231744        1        0    34278    34278


Recompress
init zram zstd (prio=0), zstd level=5 (prio 1), zstd with dict (prio 2)

*** zstd
/sys/block/zram0/mm_stat
1750982656 504630584 514269184        0 514269184        1        0    34204    34204

*** idle recompress priority=1 (zstd level=5)
/sys/block/zram0/mm_stat
1750982656 488645601 525438976        0 514269184        1        0    34204    34204

*** idle recompress priority=2 (zstd dict)
/sys/block/zram0/mm_stat
1750982656 460869640 517914624        0 514269184        1        0    34185    34204


This patch (of 24):

We need to export a number of API functions that enable advanced zstd
usage - C/D dictionaries, dictionaries sharing between contexts, etc.

Link: https://lkml.kernel.org/r/20240902105656.1383858-1-senozhatsky@chromium.org
Link: https://lkml.kernel.org/r/20240902105656.1383858-2-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Nick Terrell <terrelln@fb.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 36 insertions, 0 deletions

diff --git a/lib/zstd/zstd_decompress_module.c b/lib/zstd/zstd_decompress_module.c
index f4ed952ed485..469fc3059be0 100644
--- a/lib/zstd/zstd_decompress_module.c
+++ b/lib/zstd/zstd_decompress_module.c
@@ -44,6 +44,33 @@ size_t zstd_dctx_workspace_bound(void)
 }
 EXPORT_SYMBOL(zstd_dctx_workspace_bound);
 
+zstd_dctx *zstd_create_dctx_advanced(zstd_custom_mem custom_mem)
+{
+	return ZSTD_createDCtx_advanced(custom_mem);
+}
+EXPORT_SYMBOL(zstd_create_dctx_advanced);
+
+size_t zstd_free_dctx(zstd_dctx *dctx)
+{
+	return ZSTD_freeDCtx(dctx);
+}
+EXPORT_SYMBOL(zstd_free_dctx);
+
+zstd_ddict *zstd_create_ddict_byreference(const void *dict, size_t dict_size,
+					  zstd_custom_mem custom_mem)
+{
+	return ZSTD_createDDict_advanced(dict, dict_size, ZSTD_dlm_byRef,
+					 ZSTD_dct_auto, custom_mem);
+
+}
+EXPORT_SYMBOL(zstd_create_ddict_byreference);
+
+size_t zstd_free_ddict(zstd_ddict *ddict)
+{
+	return ZSTD_freeDDict(ddict);
+}
+EXPORT_SYMBOL(zstd_free_ddict);
+
 zstd_dctx *zstd_init_dctx(void *workspace, size_t workspace_size)
 {
 	if (workspace == NULL)
@@ -59,6 +86,15 @@ size_t zstd_decompress_dctx(zstd_dctx *dctx, void *dst, size_t dst_capacity,
 }
 EXPORT_SYMBOL(zstd_decompress_dctx);
 
+size_t zstd_decompress_using_ddict(zstd_dctx *dctx,
+	void *dst, size_t dst_capacity, const void* src, size_t src_size,
+	const zstd_ddict* ddict)
+{
+	return ZSTD_decompress_usingDDict(dctx, dst, dst_capacity, src,
+					  src_size, ddict);
+}
+EXPORT_SYMBOL(zstd_decompress_using_ddict);
+
 size_t zstd_dstream_workspace_bound(size_t max_window_size)
 {
 	return ZSTD_estimateDStreamSize(max_window_size);