Message-Id: <1444808304-29320-8-git-send-email-iamjoonsoo.kim@lge.com>
Date:	Wed, 14 Oct 2015 16:38:23 +0900
From:	Joonsoo Kim <js1304@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Minchan Kim <minchan@...nel.org>, Nitin Gupta <ngupta@...are.org>,
	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	"David S. Miller" <davem@...emloft.net>,
	Stephan Mueller <smueller@...onox.de>,
	linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
	Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: [PATCH v4 7/8] zram: use crypto contextless compression API to (de)compress

Until now, zram uses compression algorithm through direct call
to core algorithm function, but, it has drawback that we need to add
compression algorithm manually to zram if needed. Without this work,
we cannot utilize various compression algorithms in the system.
Moreover, to add new compression algorithm, we need to know how to use it
and this is somewhat time-consuming.

When I tested new algorithms such as zlib, these problems make me hard
to test them. To prevent these problem in the future, I think that
using crypto API for compression is better approach and this patch
implements it.

The reason we need to support vairous compression algorithms is that
zram's performance is highly depend on workload and compression algorithm
and architecture. Every compression algorithm has it's own strong point.
For example, zlib is the best for compression ratio, but, it's
(de)compression speed is rather slow. Against my expectation, in my kernel
build test with zram swap, in low-memory condition on x86, zlib shows best
performance than others. In this case, I guess that compression ratio is
the most important factor.

Kernel build elapsed time in QEMU 8 CPUs 448 MB with zram swap
lzo : deflate
188.3 s : 181.9 s
(3% improvement)

Unlike this situation, on ARM, maybe fast (de)compression speed is
the most important because it's computation speed is slower than x86.

We can't expect what algorithm is the best fit for one's system, because
it needs too complex calculation. We need to test it in case by case and
easy to use new compression algorithm by this patch will help
that situation.

Note that this patch just convert zram to use crypto contextless
compression API but doesn't change compression algorithm selection
interface in zram. So it doesn't support zlib yet. Following patch
will change this interface and enable various compression algorithm.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>
---
 drivers/block/zram/Kconfig    |  8 +++---
 drivers/block/zram/Makefile   |  4 +--
 drivers/block/zram/zcomp.c    | 63 ++++++++++++++++++++++++++++---------------
 drivers/block/zram/zcomp.h    | 21 +++------------
 drivers/block/zram/zram_drv.c |  6 ++---
 5 files changed, 52 insertions(+), 50 deletions(-)

diff --git a/drivers/block/zram/Kconfig b/drivers/block/zram/Kconfig
index 386ba3d..7619bed 100644
--- a/drivers/block/zram/Kconfig
+++ b/drivers/block/zram/Kconfig
@@ -1,8 +1,7 @@
 config ZRAM
 	tristate "Compressed RAM block device support"
 	depends on BLOCK && SYSFS && ZSMALLOC
-	select LZO_COMPRESS
-	select LZO_DECOMPRESS
+	select CRYPTO_LZO
 	default n
 	help
 	  Creates virtual block devices called /dev/zramX (X = 0, 1, ...).
@@ -18,9 +17,8 @@ config ZRAM
 config ZRAM_LZ4_COMPRESS
 	bool "Enable LZ4 algorithm support"
 	depends on ZRAM
-	select LZ4_COMPRESS
-	select LZ4_DECOMPRESS
+	select CRYPTO_LZ4
 	default n
 	help
 	  This option enables LZ4 compression algorithm support. Compression
-	  algorithm can be changed using `comp_algorithm' device attribute.
\ No newline at end of file
+	  algorithm can be changed using `comp_algorithm' device attribute.
diff --git a/drivers/block/zram/Makefile b/drivers/block/zram/Makefile
index be0763f..9e2b79e 100644
--- a/drivers/block/zram/Makefile
+++ b/drivers/block/zram/Makefile
@@ -1,5 +1,3 @@
-zram-y	:=	zcomp_lzo.o zcomp.o zram_drv.o
-
-zram-$(CONFIG_ZRAM_LZ4_COMPRESS) += zcomp_lz4.o
+zram-y	:=	zcomp.o zram_drv.o
 
 obj-$(CONFIG_ZRAM)	+=	zram.o
diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
index e3016da..9be83db 100644
--- a/drivers/block/zram/zcomp.c
+++ b/drivers/block/zram/zcomp.c
@@ -15,10 +15,6 @@
 #include <linux/sched.h>
 
 #include "zcomp.h"
-#include "zcomp_lzo.h"
-#ifdef CONFIG_ZRAM_LZ4_COMPRESS
-#include "zcomp_lz4.h"
-#endif
 
 /*
  * single zcomp_strm backend
@@ -43,19 +39,20 @@ struct zcomp_strm_multi {
 	wait_queue_head_t strm_wait;
 };
 
-static struct zcomp_backend *backends[] = {
-	&zcomp_lzo,
+static const char * const backends[] = {
+	"lzo",
 #ifdef CONFIG_ZRAM_LZ4_COMPRESS
-	&zcomp_lz4,
+	"lz4",
 #endif
 	NULL
 };
 
-static struct zcomp_backend *find_backend(const char *compress)
+static const char *find_backend(const char *compress)
 {
 	int i = 0;
 	while (backends[i]) {
-		if (sysfs_streq(compress, backends[i]->name))
+		if (sysfs_streq(compress, backends[i]) &&
+			crypto_has_comp(backends[i], 0, 0))
 			break;
 		i++;
 	}
@@ -65,7 +62,7 @@ static struct zcomp_backend *find_backend(const char *compress)
 static void zcomp_strm_free(struct zcomp *comp, struct zcomp_strm *zstrm)
 {
 	if (zstrm->private)
-		comp->backend->destroy(zstrm->private);
+		crypto_ccomp_free_context(comp->tfm, zstrm->private);
 	free_pages((unsigned long)zstrm->buffer, 1);
 	kfree(zstrm);
 }
@@ -80,7 +77,13 @@ static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp)
 	if (!zstrm)
 		return NULL;
 
-	zstrm->private = comp->backend->create();
+	zstrm->private = crypto_ccomp_alloc_context(comp->tfm);
+	if (IS_ERR(zstrm->private)) {
+		zstrm->private = NULL;
+		zcomp_strm_free(comp, zstrm);
+		return NULL;
+	}
+
 	/*
 	 * allocate 2 pages. 1 for compressed data, plus 1 extra for the
 	 * case when compressed size is larger than the original one
@@ -274,12 +277,12 @@ ssize_t zcomp_available_show(const char *comp, char *buf)
 	int i = 0;
 
 	while (backends[i]) {
-		if (!strcmp(comp, backends[i]->name))
+		if (!strcmp(comp, backends[i]))
 			sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
-					"[%s] ", backends[i]->name);
+					"[%s] ", backends[i]);
 		else
 			sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
-					"%s ", backends[i]->name);
+					"%s ", backends[i]);
 		i++;
 	}
 	sz += scnprintf(buf + sz, PAGE_SIZE - sz, "\n");
@@ -320,7 +323,10 @@ void zcomp_compress_end(struct zcomp *comp, struct zcomp_strm *zstrm)
 /* May return NULL, may sleep */
 struct zcomp_strm *zcomp_decompress_begin(struct zcomp *comp)
 {
-	return NULL;
+	if (crypto_ccomp_decomp_noctx(comp->tfm))
+		return NULL;
+
+	return zcomp_strm_find(comp);
 }
 
 void zcomp_decompress_end(struct zcomp *comp, struct zcomp_strm *zstrm)
@@ -330,22 +336,29 @@ void zcomp_decompress_end(struct zcomp *comp, struct zcomp_strm *zstrm)
 }
 
 int zcomp_compress(struct zcomp *comp, struct zcomp_strm *zstrm,
-		const unsigned char *src, size_t *dst_len)
+		const unsigned char *src, unsigned int *dst_len)
 {
-	return comp->backend->compress(src, zstrm->buffer, dst_len,
-			zstrm->private);
+	*dst_len = PAGE_SIZE << 1;
+
+	return crypto_ccomp_compress(comp->tfm, src, PAGE_SIZE,
+			zstrm->buffer, dst_len, zstrm->private);
 }
 
 int zcomp_decompress(struct zcomp *comp, struct zcomp_strm *zstrm,
 		const unsigned char *src,
-		size_t src_len, unsigned char *dst)
+		unsigned int src_len, unsigned char *dst)
 {
-	return comp->backend->decompress(src, src_len, dst);
+	unsigned int size = PAGE_SIZE;
+	void *private = zstrm ? zstrm->private : NULL;
+
+	return crypto_ccomp_decompress(comp->tfm, src, src_len,
+					dst, &size, private);
 }
 
 void zcomp_destroy(struct zcomp *comp)
 {
 	comp->destroy(comp);
+	crypto_free_ccomp(comp->tfm);
 	kfree(comp);
 }
 
@@ -360,7 +373,7 @@ void zcomp_destroy(struct zcomp *comp)
 struct zcomp *zcomp_create(const char *compress, int max_strm)
 {
 	struct zcomp *comp;
-	struct zcomp_backend *backend;
+	const char *backend;
 	int error;
 
 	backend = find_backend(compress);
@@ -371,12 +384,18 @@ struct zcomp *zcomp_create(const char *compress, int max_strm)
 	if (!comp)
 		return ERR_PTR(-ENOMEM);
 
-	comp->backend = backend;
+	comp->tfm = crypto_alloc_ccomp(backend, 0, 0);
+	if (IS_ERR(comp->tfm)) {
+		kfree(comp);
+		return ERR_CAST(comp->tfm);
+	}
+
 	if (max_strm > 1)
 		error = zcomp_strm_multi_create(comp, max_strm);
 	else
 		error = zcomp_strm_single_create(comp);
 	if (error) {
+		crypto_free_ccomp(comp->tfm);
 		kfree(comp);
 		return ERR_PTR(error);
 	}
diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h
index 4c09c01..df9268d 100644
--- a/drivers/block/zram/zcomp.h
+++ b/drivers/block/zram/zcomp.h
@@ -11,6 +11,7 @@
 #define _ZCOMP_H_
 
 #include <linux/mutex.h>
+#include <crypto/compress.h>
 
 struct zcomp_strm {
 	/* compression/decompression buffer */
@@ -25,24 +26,10 @@ struct zcomp_strm {
 	struct list_head list;
 };
 
-/* static compression backend */
-struct zcomp_backend {
-	int (*compress)(const unsigned char *src, unsigned char *dst,
-			size_t *dst_len, void *private);
-
-	int (*decompress)(const unsigned char *src, size_t src_len,
-			unsigned char *dst);
-
-	void *(*create)(void);
-	void (*destroy)(void *private);
-
-	const char *name;
-};
-
 /* dynamic per-device compression frontend */
 struct zcomp {
 	void *stream;
-	struct zcomp_backend *backend;
+	struct crypto_ccomp *tfm;
 
 	struct zcomp_strm *(*strm_find)(struct zcomp *comp);
 	void (*strm_release)(struct zcomp *comp, struct zcomp_strm *zstrm);
@@ -61,14 +48,14 @@ struct zcomp_strm *zcomp_compress_begin(struct zcomp *comp);
 void zcomp_compress_end(struct zcomp *comp, struct zcomp_strm *zstrm);
 
 int zcomp_compress(struct zcomp *comp, struct zcomp_strm *zstrm,
-		const unsigned char *src, size_t *dst_len);
+		const unsigned char *src, unsigned int *dst_len);
 
 struct zcomp_strm *zcomp_decompress_begin(struct zcomp *comp);
 void zcomp_decompress_end(struct zcomp *comp, struct zcomp_strm *zstrm);
 
 int zcomp_decompress(struct zcomp *comp, struct zcomp_strm *zstrm,
 		const unsigned char *src,
-		size_t src_len, unsigned char *dst);
+		unsigned int src_len, unsigned char *dst);
 
 bool zcomp_set_max_streams(struct zcomp *comp, int num_strm);
 #endif /* _ZCOMP_H_ */
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 85d5301..6f04fb2 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -567,7 +567,7 @@ static int zram_decompress_page(struct zram *zram, struct zcomp_strm *zstrm,
 	unsigned char *cmem;
 	struct zram_meta *meta = zram->meta;
 	unsigned long handle;
-	size_t size;
+	unsigned int size;
 
 	bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
 	handle = meta->table[index].handle;
@@ -656,7 +656,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 			   int offset)
 {
 	int ret = 0;
-	size_t clen;
+	unsigned int clen;
 	unsigned long handle;
 	struct page *page;
 	unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
@@ -731,7 +731,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 
 	handle = zs_malloc(meta->mem_pool, clen);
 	if (!handle) {
-		pr_err("Error allocating memory for compressed page: %u, size=%zu\n",
+		pr_err("Error allocating memory for compressed page: %u, size=%u\n",
 			index, clen);
 		ret = -ENOMEM;
 		goto out;
-- 
1.9.1

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