Support pre-trained dictionary param. lz4 doesn't mandate specific format of the dictionary and even zstd --train can be used to train a dictionary for lz4, according to [1]. TEST ==== - default lz4 /sys/block/zram0/mm_stat 1750323200 664258735 676990976 0 676990976 2 0 34288 34288 - lz4 dict=/etc/dictionary /sys/block/zram0/mm_stat 1750310912 620608254 632852480 0 632852480 1 0 34288 34288 [1] https://github.com/lz4/lz4/issues/557 Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx> --- drivers/block/zram/backend_lz4.c | 54 ++++++++++++++++++++++++++++---- 1 file changed, 48 insertions(+), 6 deletions(-) diff --git a/drivers/block/zram/backend_lz4.c b/drivers/block/zram/backend_lz4.c index cf39bfc30f5b..47d0e719d5d7 100644 --- a/drivers/block/zram/backend_lz4.c +++ b/drivers/block/zram/backend_lz4.c @@ -8,6 +8,12 @@ struct lz4_ctx { void *mem; s32 level; + LZ4_streamDecode_t *dstrm; + LZ4_stream_t *cstrm; + + /* Shared between C/D streams */ + void *dict; + size_t dict_sz; }; static int lz4_init_config(struct zcomp_config *config) @@ -26,6 +32,8 @@ static void lz4_destroy(void *ctx) { struct lz4_ctx *zctx = ctx; + kfree(zctx->dstrm); + kfree(zctx->cstrm); vfree(zctx->mem); kfree(zctx); } @@ -39,9 +47,22 @@ static void *lz4_create(struct zcomp_config *config) return NULL; ctx->level = config->level; - ctx->mem = vmalloc(LZ4_MEM_COMPRESS); - if (!ctx->mem) - goto error; + if (!config->dict) { + ctx->mem = vmalloc(LZ4_MEM_COMPRESS); + if (!ctx->mem) + goto error; + } else { + ctx->dstrm = kzalloc(sizeof(*ctx->dstrm), GFP_KERNEL); + if (!ctx->dstrm) + goto error; + + ctx->cstrm = kzalloc(sizeof(*ctx->cstrm), GFP_KERNEL); + if (!ctx->cstrm) + goto error; + + ctx->dict = config->dict; + ctx->dict_sz = config->dict_sz; + } return ctx; error: @@ -55,8 +76,18 @@ static int lz4_compress(void *ctx, const unsigned char *src, struct lz4_ctx *zctx = ctx; int ret; - ret = LZ4_compress_fast(src, dst, PAGE_SIZE, *dst_len, - zctx->level, zctx->mem); + if (!zctx->cstrm) { + ret = LZ4_compress_fast(src, dst, PAGE_SIZE, *dst_len, + zctx->level, zctx->mem); + } else { + /* Cstrm needs to be reset */ + ret = LZ4_loadDict(zctx->cstrm, zctx->dict, zctx->dict_sz); + if (ret != zctx->dict_sz) + return -EINVAL; + ret = LZ4_compress_fast_continue(zctx->cstrm, src, dst, + PAGE_SIZE, *dst_len, + zctx->level); + } if (!ret) return -EINVAL; *dst_len = ret; @@ -66,10 +97,21 @@ static int lz4_compress(void *ctx, const unsigned char *src, static int lz4_decompress(void *ctx, const unsigned char *src, size_t src_len, unsigned char *dst) { + struct lz4_ctx *zctx = ctx; int dst_len = PAGE_SIZE; int ret; - ret = LZ4_decompress_safe(src, dst, src_len, dst_len); + if (!zctx->dstrm) { + ret = LZ4_decompress_safe(src, dst, src_len, dst_len); + } else { + /* Dstrm needs to be reset */ + ret = LZ4_setStreamDecode(zctx->dstrm, zctx->dict, + zctx->dict_sz); + if (!ret) + return -EINVAL; + ret = LZ4_decompress_safe_continue(zctx->dstrm, src, dst, + src_len, dst_len); + } if (ret < 0) return -EINVAL; return 0; -- 2.45.0.rc1.225.g2a3ae87e7f-goog
