[PATCH v3 8/9] zram: use crypto API for compression

From: Joonsoo Kim
Date: Fri Sep 18 2015 - 01:20:59 EST

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. 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.

There is one problem that crypto API requires tfm object to (de)compress
something and zram abstract it on zstrm which is very limited resource.
If number of zstrm is set to low and is contended, zram's performace could
be down-graded due to this change. But, following patch support to use
crypto decompress_noctx API and would restore the performance as is.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
---
drivers/block/zram/Kconfig | 8 +++----
drivers/block/zram/Makefile | 4 +---
drivers/block/zram/zcomp.c | 54 +++++++++++++++++++++++-------------------
drivers/block/zram/zcomp.h | 30 ++++++-----------------
drivers/block/zram/zcomp_lz4.c | 47 ------------------------------------
drivers/block/zram/zcomp_lz4.h | 17 -------------
drivers/block/zram/zcomp_lzo.c | 47 ------------------------------------
drivers/block/zram/zcomp_lzo.h | 17 -------------
drivers/block/zram/zram_drv.c | 6 ++---
9 files changed, 44 insertions(+), 186 deletions(-)
delete mode 100644 drivers/block/zram/zcomp_lz4.c
delete mode 100644 drivers/block/zram/zcomp_lz4.h
delete mode 100644 drivers/block/zram/zcomp_lzo.c
delete mode 100644 drivers/block/zram/zcomp_lzo.h

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 3456d5a..c2ed7c8 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(compress, 0, 0))
break;
i++;
}
@@ -64,8 +61,8 @@ 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);
+ if (zstrm->tfm)
+ crypto_free_comp(zstrm->tfm);
free_pages((unsigned long)zstrm->buffer, 1);
kfree(zstrm);
}
@@ -80,13 +77,18 @@ static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp)
if (!zstrm)
return NULL;

- zstrm->private = comp->backend->create();
+ zstrm->tfm = crypto_alloc_comp(comp->backend, 0, 0);
+ if (IS_ERR(zstrm->tfm)) {
+ kfree(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
*/
zstrm->buffer = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
- if (!zstrm->private || !zstrm->buffer) {
+ if (!zstrm->buffer) {
zcomp_strm_free(comp, zstrm);
zstrm = NULL;
}
@@ -274,12 +276,12 @@ 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");
@@ -317,10 +319,10 @@ void zcomp_compress_end(struct zcomp *comp, struct zcomp_strm *zstrm)
zcomp_strm_release(comp, zstrm);
}

-/* May return NULL, may sleep */
+/* Never return NULL, may sleep */
struct zcomp_strm *zcomp_decompress_begin(struct zcomp *comp)
{
- return NULL;
+ return zcomp_strm_find(comp);
}

void zcomp_decompress_end(struct zcomp *comp, struct zcomp_strm *zstrm)
@@ -330,17 +332,21 @@ 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_comp_compress(zstrm->tfm, src, PAGE_SIZE,
+ zstrm->buffer, dst_len);
}

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;
+
+ return crypto_comp_decompress(zstrm->tfm, src, src_len, dst, &size);
}

void zcomp_destroy(struct zcomp *comp)
@@ -359,7 +365,7 @@ 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;

backend = find_backend(compress);
if (!backend)
diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h
index 4c09c01..4f9df8e 100644
--- a/drivers/block/zram/zcomp.h
+++ b/drivers/block/zram/zcomp.h
@@ -11,38 +11,22 @@
#define _ZCOMP_H_

#include <linux/mutex.h>
+#include <linux/crypto.h>

struct zcomp_strm {
+ struct crypto_comp *tfm;
+
/* compression/decompression buffer */
void *buffer;
- /*
- * The private data of the compression stream, only compression
- * stream backend can touch this (e.g. compression algorithm
- * working memory)
- */
- void *private;
+
/* used in multi stream backend, protected by backend strm_lock */
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;
+ const char *backend;

struct zcomp_strm *(*strm_find)(struct zcomp *comp);
void (*strm_release)(struct zcomp *comp, struct zcomp_strm *zstrm);
@@ -61,14 +45,14 @@ 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/zcomp_lz4.c b/drivers/block/zram/zcomp_lz4.c
deleted file mode 100644
index f2afb7e..0000000
--- a/drivers/block/zram/zcomp_lz4.c
+++ /dev/null
@@ -1,47 +0,0 @@
-/*
- * Copyright (C) 2014 Sergey Senozhatsky.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version
- * 2 of the License, or (at your option) any later version.
- */
-
-#include <linux/kernel.h>
-#include <linux/slab.h>
-#include <linux/lz4.h>
-
-#include "zcomp_lz4.h"
-
-static void *zcomp_lz4_create(void)
-{
- return kzalloc(LZ4_MEM_COMPRESS, GFP_KERNEL);
-}
-
-static void zcomp_lz4_destroy(void *private)
-{
- kfree(private);
-}
-
-static int zcomp_lz4_compress(const unsigned char *src, unsigned char *dst,
- size_t *dst_len, void *private)
-{
- /* return : Success if return 0 */
- return lz4_compress(src, PAGE_SIZE, dst, dst_len, private);
-}
-
-static int zcomp_lz4_decompress(const unsigned char *src, size_t src_len,
- unsigned char *dst)
-{
- size_t dst_len = PAGE_SIZE;
- /* return : Success if return 0 */
- return lz4_decompress_unknownoutputsize(src, src_len, dst, &dst_len);
-}
-
-struct zcomp_backend zcomp_lz4 = {
- .compress = zcomp_lz4_compress,
- .decompress = zcomp_lz4_decompress,
- .create = zcomp_lz4_create,
- .destroy = zcomp_lz4_destroy,
- .name = "lz4",
-};
diff --git a/drivers/block/zram/zcomp_lz4.h b/drivers/block/zram/zcomp_lz4.h
deleted file mode 100644
index 60613fb..0000000
--- a/drivers/block/zram/zcomp_lz4.h
+++ /dev/null
@@ -1,17 +0,0 @@
-/*
- * Copyright (C) 2014 Sergey Senozhatsky.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version
- * 2 of the License, or (at your option) any later version.
- */
-
-#ifndef _ZCOMP_LZ4_H_
-#define _ZCOMP_LZ4_H_
-
-#include "zcomp.h"
-
-extern struct zcomp_backend zcomp_lz4;
-
-#endif /* _ZCOMP_LZ4_H_ */
diff --git a/drivers/block/zram/zcomp_lzo.c b/drivers/block/zram/zcomp_lzo.c
deleted file mode 100644
index da1bc47..0000000
--- a/drivers/block/zram/zcomp_lzo.c
+++ /dev/null
@@ -1,47 +0,0 @@
-/*
- * Copyright (C) 2014 Sergey Senozhatsky.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version
- * 2 of the License, or (at your option) any later version.
- */
-
-#include <linux/kernel.h>
-#include <linux/slab.h>
-#include <linux/lzo.h>
-
-#include "zcomp_lzo.h"
-
-static void *lzo_create(void)
-{
- return kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
-}
-
-static void lzo_destroy(void *private)
-{
- kfree(private);
-}
-
-static int lzo_compress(const unsigned char *src, unsigned char *dst,
- size_t *dst_len, void *private)
-{
- int ret = lzo1x_1_compress(src, PAGE_SIZE, dst, dst_len, private);
- return ret == LZO_E_OK ? 0 : ret;
-}
-
-static int lzo_decompress(const unsigned char *src, size_t src_len,
- unsigned char *dst)
-{
- size_t dst_len = PAGE_SIZE;
- int ret = lzo1x_decompress_safe(src, src_len, dst, &dst_len);
- return ret == LZO_E_OK ? 0 : ret;
-}
-
-struct zcomp_backend zcomp_lzo = {
- .compress = lzo_compress,
- .decompress = lzo_decompress,
- .create = lzo_create,
- .destroy = lzo_destroy,
- .name = "lzo",
-};
diff --git a/drivers/block/zram/zcomp_lzo.h b/drivers/block/zram/zcomp_lzo.h
deleted file mode 100644
index 128c580..0000000
--- a/drivers/block/zram/zcomp_lzo.h
+++ /dev/null
@@ -1,17 +0,0 @@
-/*
- * Copyright (C) 2014 Sergey Senozhatsky.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version
- * 2 of the License, or (at your option) any later version.
- */
-
-#ifndef _ZCOMP_LZO_H_
-#define _ZCOMP_LZO_H_
-
-#include "zcomp.h"
-
-extern struct zcomp_backend zcomp_lzo;
-
-#endif /* _ZCOMP_LZO_H_ */
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 55e09db1..834f452 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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