This adds support for pre-trained zstd dictionaries [1] Dictionary is loaded once (per-config) and then loaded to Cctx and Dctx by reference, so we don't allocate extra memory. Regarding GFP_ATOMIC in Cctx customAlloc(), we probably would want to do something about it. Either make sure that we always (somehow) fully setup all Cctx contexts from non-atomic context before we attempt to use them, come up with some sort of custom allocator or stop calling zcomp_compress() from atomic context. TEST ==== - default zstd /sys/block/zram0/mm_stat 1750315008 504602831 514256896 0 514256896 1 0 34204 34204 - zstd level=7 dict=/etc/dictionary /sys/block/zram0/mm_stat 1750310912 432540606 441712640 0 441712640 1 0 34187 34187 [1] https://github.com/facebook/zstd/blob/dev/programs/zstd.1.md#dictionary-builder Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx> --- drivers/block/zram/backend_zstd.c | 126 ++++++++++++++++++++++++------ 1 file changed, 101 insertions(+), 25 deletions(-) diff --git a/drivers/block/zram/backend_zstd.c b/drivers/block/zram/backend_zstd.c index d392d364ad2c..4be149370e0b 100644 --- a/drivers/block/zram/backend_zstd.c +++ b/drivers/block/zram/backend_zstd.c @@ -12,23 +12,52 @@ struct zstd_ctx { zstd_dctx *dctx; void *cctx_mem; void *dctx_mem; + zstd_custom_mem ctx_mem; + zstd_cdict *cdict; + zstd_ddict *ddict; s32 level; }; +/* + * Cctx allocator.customAlloc() can be called from zcomp_compress() under + * local-lock (per-CPU compression stream), in which case we must use + * GFP_ATOMIC. + */ +static void *zstd_ctx_alloc(void *opaque, size_t size) +{ + if (!preemptible()) + return kvzalloc(size, GFP_ATOMIC); + + return kvzalloc(size, GFP_KERNEL); +} + +static void zstd_ctx_free(void *opaque, void *address) +{ + kvfree(address); +} + static void zstd_destroy(void *ctx) { struct zstd_ctx *zctx = ctx; - vfree(zctx->cctx_mem); - vfree(zctx->dctx_mem); + if (zctx->cctx_mem) + vfree(zctx->cctx_mem); + else + zstd_free_cctx(zctx->cctx); + + if (zctx->dctx_mem) + vfree(zctx->dctx_mem); + else + zstd_free_dctx(zctx->dctx); + + zstd_free_cdict(zctx->cdict); + zstd_free_ddict(zctx->ddict); kfree(zctx); } static void *zstd_create(struct zcomp_config *config) { - zstd_parameters params; struct zstd_ctx *ctx; - size_t sz; ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); if (!ctx) @@ -39,24 +68,62 @@ static void *zstd_create(struct zcomp_config *config) else ctx->level = zstd_default_clevel(); - params = zstd_get_params(ctx->level, PAGE_SIZE); - sz = zstd_cctx_workspace_bound(¶ms.cParams); - ctx->cctx_mem = vzalloc(sz); - if (!ctx->cctx_mem) - goto error; - - ctx->cctx = zstd_init_cctx(ctx->cctx_mem, sz); - if (!ctx->cctx) - goto error; - - sz = zstd_dctx_workspace_bound(); - ctx->dctx_mem = vzalloc(sz); - if (!ctx->dctx_mem) - goto error; - - ctx->dctx = zstd_init_dctx(ctx->dctx_mem, sz); - if (!ctx->dctx) - goto error; + ctx->ctx_mem.customAlloc = zstd_ctx_alloc; + ctx->ctx_mem.customFree = zstd_ctx_free; + + if (config->dict_sz == 0) { + zstd_parameters params; + size_t sz; + + params = zstd_get_params(ctx->level, PAGE_SIZE); + sz = zstd_cctx_workspace_bound(¶ms.cParams); + ctx->cctx_mem = vzalloc(sz); + if (!ctx->cctx_mem) + goto error; + + ctx->cctx = zstd_init_cctx(ctx->cctx_mem, sz); + if (!ctx->cctx) + goto error; + + sz = zstd_dctx_workspace_bound(); + ctx->dctx_mem = vzalloc(sz); + if (!ctx->dctx_mem) + goto error; + + ctx->dctx = zstd_init_dctx(ctx->dctx_mem, sz); + if (!ctx->dctx) + goto error; + } else { + zstd_compression_parameters params; + + ctx->cctx = zstd_create_cctx_advanced(ctx->ctx_mem); + if (!ctx->cctx) + goto error; + + ctx->dctx = zstd_create_dctx_advanced(ctx->ctx_mem); + if (!ctx->dctx) + goto error; + + params = zstd_get_cparams(ctx->level, PAGE_SIZE, + config->dict_sz); + + ctx->cdict = zstd_create_cdict_advanced(config->dict, + config->dict_sz, + ZSTD_dlm_byRef, + ZSTD_dct_auto, + params, + ctx->ctx_mem); + if (!ctx->cdict) + goto error; + + ctx->ddict = zstd_create_ddict_advanced(config->dict, + config->dict_sz, + ZSTD_dlm_byRef, + ZSTD_dct_auto, + ctx->ctx_mem); + if (!ctx->ddict) + goto error; + } return ctx; @@ -72,8 +139,12 @@ static int zstd_compress(void *ctx, const unsigned char *src, const zstd_parameters params = zstd_get_params(zctx->level, PAGE_SIZE); size_t ret; - ret = zstd_compress_cctx(zctx->cctx, dst, *dst_len, - src, PAGE_SIZE, ¶ms); + if (!zctx->cdict) + ret = zstd_compress_cctx(zctx->cctx, dst, *dst_len, + src, PAGE_SIZE, ¶ms); + else + ret = zstd_compress_using_cdict(zctx->cctx, dst, *dst_len, + src, PAGE_SIZE, zctx->cdict); if (zstd_is_error(ret)) return -EINVAL; *dst_len = ret; @@ -86,7 +157,12 @@ static int zstd_decompress(void *ctx, const unsigned char *src, size_t src_len, struct zstd_ctx *zctx = ctx; size_t ret; - ret = zstd_decompress_dctx(zctx->dctx, dst, PAGE_SIZE, src, src_len); + if (!zctx->ddict) + ret = zstd_decompress_dctx(zctx->dctx, dst, PAGE_SIZE, + src, src_len); + else + ret = zstd_decompress_using_ddict(zctx->dctx, dst, PAGE_SIZE, + src, src_len, zctx->ddict); if (zstd_is_error(ret)) return -EINVAL; return 0; -- 2.45.0.rc1.225.g2a3ae87e7f-goog
