zram: add zlib compression backend support

Add s/w zlib (inflate/deflate) compression.

Link: https://lkml.kernel.org/r/20240902105656.1383858-11-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nick Terrell <terrelln@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

drivers/block/zram/Kconfig

@@ -38,6 +38,12 @@ config ZRAM_BACKEND_ZSTD
 	select ZSTD_COMPRESS
 	select ZSTD_DECOMPRESS
 
+config ZRAM_BACKEND_DEFLATE
+	bool "deflate compression support"
+	depends on ZRAM
+	select ZLIB_DEFLATE
+	select ZLIB_INFLATE
+
 choice
 	prompt "Default zram compressor"
 	default ZRAM_DEF_COMP_LZORLE
@@ -63,6 +69,10 @@ config ZRAM_DEF_COMP_ZSTD
 	bool "zstd"
 	depends on ZRAM_BACKEND_ZSTD
 
+config ZRAM_DEF_COMP_DEFLATE
+	bool "deflate"
+	depends on ZRAM_BACKEND_DEFLATE
+
 endchoice
 
 config ZRAM_DEF_COMP
@@ -72,6 +82,7 @@ config ZRAM_DEF_COMP
 	default "lz4" if ZRAM_DEF_COMP_LZ4
 	default "lz4hc" if ZRAM_DEF_COMP_LZ4HC
 	default "zstd" if ZRAM_DEF_COMP_ZSTD
+	default "deflate" if ZRAM_DEF_COMP_DEFLATE
 	default "unset-value"
 
 config ZRAM_WRITEBACK

drivers/block/zram/Makefile

@@ -6,5 +6,6 @@ zram-$(CONFIG_ZRAM_BACKEND_LZO)		+= backend_lzorle.o backend_lzo.o
 zram-$(CONFIG_ZRAM_BACKEND_LZ4)		+= backend_lz4.o
 zram-$(CONFIG_ZRAM_BACKEND_LZ4HC)	+= backend_lz4hc.o
 zram-$(CONFIG_ZRAM_BACKEND_ZSTD)	+= backend_zstd.o
+zram-$(CONFIG_ZRAM_BACKEND_DEFLATE)	+= backend_deflate.o
 
 obj-$(CONFIG_ZRAM)	+=	zram.o

drivers/block/zram/backend_deflate.c

@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/zlib.h>
+
+#include "backend_deflate.h"
+
+/* Use the same value as crypto API */
+#define DEFLATE_DEF_WINBITS		11
+#define DEFLATE_DEF_MEMLEVEL		MAX_MEM_LEVEL
+
+struct deflate_ctx {
+	struct z_stream_s cctx;
+	struct z_stream_s dctx;
+	s32 level;
+};
+
+static void deflate_destroy(void *ctx)
+{
+	struct deflate_ctx *zctx = ctx;
+
+	if (zctx->cctx.workspace) {
+		zlib_deflateEnd(&zctx->cctx);
+		vfree(zctx->cctx.workspace);
+	}
+	if (zctx->dctx.workspace) {
+		zlib_inflateEnd(&zctx->dctx);
+		vfree(zctx->dctx.workspace);
+	}
+	kfree(zctx);
+}
+
+static void *deflate_create(void)
+{
+	struct deflate_ctx *ctx;
+	size_t sz;
+	int ret;
+
+	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return NULL;
+
+	/* @FIXME: using a hardcoded Z_DEFAULT_COMPRESSION for now */
+	ctx->level = Z_DEFAULT_COMPRESSION;
+	sz = zlib_deflate_workspacesize(-DEFLATE_DEF_WINBITS, MAX_MEM_LEVEL);
+	ctx->cctx.workspace = vzalloc(sz);
+	if (!ctx->cctx.workspace)
+		goto error;
+
+	ret = zlib_deflateInit2(&ctx->cctx, ctx->level, Z_DEFLATED,
+				-DEFLATE_DEF_WINBITS, DEFLATE_DEF_MEMLEVEL,
+				Z_DEFAULT_STRATEGY);
+	if (ret != Z_OK)
+		goto error;
+
+	sz = zlib_inflate_workspacesize();
+	ctx->dctx.workspace = vzalloc(sz);
+	if (!ctx->dctx.workspace)
+		goto error;
+
+	ret = zlib_inflateInit2(&ctx->dctx, -DEFLATE_DEF_WINBITS);
+	if (ret != Z_OK)
+		goto error;
+
+	return ctx;
+
+error:
+	deflate_destroy(ctx);
+	return NULL;
+}
+
+static int deflate_compress(void *ctx, const unsigned char *src,
+			    size_t src_len, unsigned char *dst,
+			    size_t *dst_len)
+{
+	struct deflate_ctx *zctx = ctx;
+	struct z_stream_s *deflate;
+	int ret;
+
+	deflate = &zctx->cctx;
+	ret = zlib_deflateReset(deflate);
+	if (ret != Z_OK)
+		return -EINVAL;
+
+	deflate->next_in = (u8 *)src;
+	deflate->avail_in = src_len;
+	deflate->next_out = (u8 *)dst;
+	deflate->avail_out = *dst_len;
+
+	ret = zlib_deflate(deflate, Z_FINISH);
+	if (ret != Z_STREAM_END)
+		return -EINVAL;
+
+	*dst_len = deflate->total_out;
+	return 0;
+}
+
+static int deflate_decompress(void *ctx, const unsigned char *src,
+			      size_t src_len, unsigned char *dst,
+			      size_t dst_len)
+{
+	struct deflate_ctx *zctx = ctx;
+	struct z_stream_s *inflate;
+	int ret;
+
+	inflate = &zctx->dctx;
+
+	ret = zlib_inflateReset(inflate);
+	if (ret != Z_OK)
+		return -EINVAL;
+
+	inflate->next_in = (u8 *)src;
+	inflate->avail_in = src_len;
+	inflate->next_out = (u8 *)dst;
+	inflate->avail_out = dst_len;
+
+	ret = zlib_inflate(inflate, Z_SYNC_FLUSH);
+	if (ret != Z_STREAM_END)
+		return -EINVAL;
+
+	return 0;
+}
+
+const struct zcomp_ops backend_deflate = {
+	.compress	= deflate_compress,
+	.decompress	= deflate_decompress,
+	.create_ctx	= deflate_create,
+	.destroy_ctx	= deflate_destroy,
+	.name		= "deflate",
+};

drivers/block/zram/backend_deflate.h

@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#ifndef __BACKEND_DEFLATE_H__
+#define __BACKEND_DEFLATE_H__
+
+#include "zcomp.h"
+
+extern const struct zcomp_ops backend_deflate;
+
+#endif /* __BACKEND_DEFLATE_H__ */

drivers/block/zram/zcomp.c

@@ -17,6 +17,7 @@
 #include "backend_lz4.h"
 #include "backend_lz4hc.h"
 #include "backend_zstd.h"
+#include "backend_deflate.h"
 
 static const struct zcomp_ops *backends[] = {
 #if IS_ENABLED(CONFIG_ZRAM_BACKEND_LZO)
@@ -31,6 +32,9 @@ static const struct zcomp_ops *backends[] = {
 #endif
 #if IS_ENABLED(CONFIG_ZRAM_BACKEND_ZSTD)
 	&backend_zstd,
+#endif
+#if IS_ENABLED(CONFIG_ZRAM_BACKEND_DEFLATE)
+	&backend_deflate,
 #endif
 	NULL
 };