[PATCHv4 03/21] zram: add lz4 compression backend support

[Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>]

Add s/w lz4 compression support.

Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
---
 drivers/block/zram/Kconfig       | 11 +++++
 drivers/block/zram/Makefile      |  1 +
 drivers/block/zram/backend_lz4.c | 73 ++++++++++++++++++++++++++++++++
 drivers/block/zram/backend_lz4.h | 10 +++++
 drivers/block/zram/zcomp.c       |  4 ++
 5 files changed, 99 insertions(+)
 create mode 100644 drivers/block/zram/backend_lz4.c
 create mode 100644 drivers/block/zram/backend_lz4.h

diff --git a/drivers/block/zram/Kconfig b/drivers/block/zram/Kconfig
index 5d329a887b12..f1e76fc8431a 100644
--- a/drivers/block/zram/Kconfig
+++ b/drivers/block/zram/Kconfig
@@ -20,6 +20,12 @@ config ZRAM_BACKEND_LZO
 	select LZO_COMPRESS
 	select LZO_DECOMPRESS
 
+config ZRAM_BACKEND_LZ4
+	bool "lz4 compression support"
+	depends on ZRAM
+	select LZ4_COMPRESS
+	select LZ4_DECOMPRESS
+
 choice
 	prompt "Default zram compressor"
 	default ZRAM_DEF_COMP_LZORLE
@@ -33,12 +39,17 @@ config ZRAM_DEF_COMP_LZO
 	bool "lzo"
 	depends on ZRAM_BACKEND_LZO
 
+config ZRAM_DEF_COMP_LZ4
+	bool "lz4"
+	depends on ZRAM_BACKEND_LZ4
+
 endchoice
 
 config ZRAM_DEF_COMP
 	string
 	default "lzo-rle" if ZRAM_DEF_COMP_LZORLE
 	default "lzo" if ZRAM_DEF_COMP_LZO
+	default "lz4" if ZRAM_DEF_COMP_LZ4
 	default "unset-value"
 
 config ZRAM_WRITEBACK
diff --git a/drivers/block/zram/Makefile b/drivers/block/zram/Makefile
index 2a3db3368af9..567f4434aee8 100644
--- a/drivers/block/zram/Makefile
+++ b/drivers/block/zram/Makefile
@@ -3,5 +3,6 @@
 zram-y	:=	zcomp.o zram_drv.o
 
 zram-$(CONFIG_ZRAM_BACKEND_LZO)	+= backend_lzorle.o backend_lzo.o
+zram-$(CONFIG_ZRAM_BACKEND_LZ4)	+= backend_lz4.o
 
 obj-$(CONFIG_ZRAM)	+=	zram.o
diff --git a/drivers/block/zram/backend_lz4.c b/drivers/block/zram/backend_lz4.c
new file mode 100644
index 000000000000..6ea67511d782
--- /dev/null
+++ b/drivers/block/zram/backend_lz4.c
@@ -0,0 +1,73 @@
+#include <linux/kernel.h>
+#include <linux/lz4.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+
+#include "backend_lz4.h"
+
+struct lz4_ctx {
+	void *mem;
+	s32 level;
+};
+
+static void lz4_destroy(void *ctx)
+{
+	struct lz4_ctx *zctx = ctx;
+
+	vfree(zctx->mem);
+	kfree(zctx);
+}
+
+static void *lz4_create(void)
+{
+	struct lz4_ctx *ctx;
+
+	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return NULL;
+
+	/* @FIXME: using a hardcoded LZ4_ACCELERATION_DEFAULT for now */
+	ctx->level = LZ4_ACCELERATION_DEFAULT;
+	ctx->mem = vmalloc(LZ4_MEM_COMPRESS);
+	if (!ctx->mem)
+		goto error;
+
+	return ctx;
+error:
+	lz4_destroy(ctx);
+	return NULL;
+}
+
+static int lz4_compress(void *ctx, const unsigned char *src,
+			unsigned char *dst, size_t *dst_len)
+{
+	struct lz4_ctx *zctx = ctx;
+	int ret;
+
+	ret = LZ4_compress_fast(src, dst, PAGE_SIZE, *dst_len,
+				zctx->level, zctx->mem);
+	if (!ret)
+		return -EINVAL;
+	*dst_len = ret;
+	return 0;
+}
+
+static int lz4_decompress(void *ctx, const unsigned char *src,
+			  size_t src_len, unsigned char *dst)
+{
+	int dst_len = PAGE_SIZE;
+	int ret;
+
+	ret = LZ4_decompress_safe(src, dst, src_len, dst_len);
+	if (ret < 0)
+		return -EINVAL;
+	return 0;
+}
+
+struct zcomp_backend backend_lz4 = {
+	.compress	= lz4_compress,
+	.decompress	= lz4_decompress,
+	.create_ctx	= lz4_create,
+	.destroy_ctx	= lz4_destroy,
+	.name		= "lz4",
+};
diff --git a/drivers/block/zram/backend_lz4.h b/drivers/block/zram/backend_lz4.h
new file mode 100644
index 000000000000..a5fb5564835c
--- /dev/null
+++ b/drivers/block/zram/backend_lz4.h
@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#ifndef __BACKEND_LZ4_H__
+#define __BACKEND_LZ4_H__
+
+#include "zcomp.h"
+
+extern struct zcomp_backend backend_lz4;
+
+#endif /* __BACKEND_LZ4_H__ */
diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
index 58fb3ac91f4b..902bdaf7e299 100644
--- a/drivers/block/zram/zcomp.c
+++ b/drivers/block/zram/zcomp.c
@@ -17,11 +17,15 @@
 
 #include "backend_lzo.h"
 #include "backend_lzorle.h"
+#include "backend_lz4.h"
 
 static struct zcomp_backend *backends[] = {
 #if IS_ENABLED(CONFIG_ZRAM_BACKEND_LZO)
 	&backend_lzorle,
 	&backend_lzo,
+#endif
+#if IS_ENABLED(CONFIG_ZRAM_BACKEND_LZ4)
+	&backend_lz4,
 #endif
 	NULL
 };
-- 
2.45.0.rc1.225.g2a3ae87e7f-goog