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Subject[PATCH 1/2] staging: zram: add Crypto API support
Date
Current version of zram does not allow any substitution of a default
compression algorithm. Therefore, I decided to change the existing
implementation of page compression by adding Crypto API compability.

All direct calls to lzo1x compression/decompression methods are now
replaced by calls consistent with Crypto. Also, I removed "workmem"
field from struct zram_meta, as it was there for lzo1x purposes only
and is no longer needed. Finally, I added a set of functions required
by Crypto API to work properly.

In order to substitute the default algorithm (lzo), change the value
of zram.compressor module parameter to a proper name (e.g. lz4).

Signed-off-by: Piotr Sarna <p.sarna@partner.samsung.com>
Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
---
drivers/staging/zram/Kconfig | 5 +-
drivers/staging/zram/zram_drv.c | 106 ++++++++++++++++++++++++++++++++-------
drivers/staging/zram/zram_drv.h | 1 -
3 files changed, 89 insertions(+), 23 deletions(-)

diff --git a/drivers/staging/zram/Kconfig b/drivers/staging/zram/Kconfig
index 983314c..b51cac5 100644
--- a/drivers/staging/zram/Kconfig
+++ b/drivers/staging/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
+ depends on BLOCK && SYSFS && ZSMALLOC && CRYPTO=y
+ select CRYPTO_LZO
default n
help
Creates virtual block devices called /dev/zramX (X = 0, 1, ...).
diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index 7ebf91d..d6f1f67 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -29,12 +29,14 @@
#include <linux/genhd.h>
#include <linux/highmem.h>
#include <linux/slab.h>
-#include <linux/lzo.h>
+#include <linux/crypto.h>
#include <linux/string.h>
#include <linux/vmalloc.h>

#include "zram_drv.h"

+#define ZRAM_COMPRESSOR_DEFAULT "lzo"
+
/* Globals */
static int zram_major;
static struct zram *zram_devices;
@@ -42,6 +44,64 @@ static struct zram *zram_devices;
/* Module params (documentation at end) */
static unsigned int num_devices = 1;

+/* Cryptographic API features */
+static char *zram_compressor = ZRAM_COMPRESSOR_DEFAULT;
+static struct crypto_comp *zram_comp_tfm;
+
+enum comp_op {
+ ZRAM_COMPOP_COMPRESS,
+ ZRAM_COMPOP_DECOMPRESS
+};
+
+static int zram_comp_op(enum comp_op op, const u8 *src, unsigned int slen,
+ u8 *dst, unsigned int *dlen)
+{
+ struct crypto_comp *tfm;
+ int ret;
+
+ tfm = zram_comp_tfm;
+ switch (op) {
+ case ZRAM_COMPOP_COMPRESS:
+ ret = crypto_comp_compress(tfm, src, slen, dst, dlen);
+ break;
+ case ZRAM_COMPOP_DECOMPRESS:
+ ret = crypto_comp_decompress(tfm, src, slen, dst, dlen);
+ break;
+ default:
+ ret = -EINVAL;
+ }
+
+ return ret;
+}
+
+static int __init zram_comp_init(void)
+{
+ int ret;
+ ret = crypto_has_comp(zram_compressor, 0, 0);
+ if (!ret) {
+ pr_info("%s is not available\n", zram_compressor);
+ zram_compressor = ZRAM_COMPRESSOR_DEFAULT;
+ ret = crypto_has_comp(zram_compressor, 0, 0);
+ if (!ret)
+ return -ENODEV;
+ }
+ pr_info("using %s compressor\n", zram_compressor);
+
+ /* alloc transform */
+ zram_comp_tfm = crypto_alloc_comp(zram_compressor, 0, 0);
+ if (!zram_comp_tfm)
+ return -ENOMEM;
+
+ return 0;
+}
+
+static inline void zram_comp_exit(void)
+{
+ if (zram_comp_tfm)
+ crypto_free_comp(zram_comp_tfm);
+}
+/* end of Cryptographic API features */
+
static inline struct zram *dev_to_zram(struct device *dev)
{
return (struct zram *)dev_to_disk(dev)->private_data;
@@ -190,7 +250,6 @@ static inline int valid_io_request(struct zram *zram, struct bio *bio)
static void zram_meta_free(struct zram_meta *meta)
{
zs_destroy_pool(meta->mem_pool);
- kfree(meta->compress_workmem);
free_pages((unsigned long)meta->compress_buffer, 1);
vfree(meta->table);
kfree(meta);
@@ -203,15 +262,11 @@ static struct zram_meta *zram_meta_alloc(u64 disksize)
if (!meta)
goto out;

- meta->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
- if (!meta->compress_workmem)
- goto free_meta;
-
meta->compress_buffer =
(void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
if (!meta->compress_buffer) {
pr_err("Error allocating compressor buffer space\n");
- goto free_workmem;
+ goto free_meta;
}

num_pages = disksize >> PAGE_SHIFT;
@@ -233,8 +288,6 @@ free_table:
vfree(meta->table);
free_buffer:
free_pages((unsigned long)meta->compress_buffer, 1);
-free_workmem:
- kfree(meta->compress_workmem);
free_meta:
kfree(meta);
meta = NULL;
@@ -314,7 +367,7 @@ static void zram_free_page(struct zram *zram, size_t index)

static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
{
- int ret = LZO_E_OK;
+ int ret = 0;
size_t clen = PAGE_SIZE;
unsigned char *cmem;
struct zram_meta *meta = zram->meta;
@@ -329,12 +382,13 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
if (meta->table[index].size == PAGE_SIZE)
copy_page(mem, cmem);
else
- ret = lzo1x_decompress_safe(cmem, meta->table[index].size,
- mem, &clen);
+ ret = zram_comp_op(ZRAM_COMPOP_DECOMPRESS, cmem,
+ meta->table[index].size, mem, &clen);
+
zs_unmap_object(meta->mem_pool, handle);

/* Should NEVER happen. Return bio error if it does. */
- if (unlikely(ret != LZO_E_OK)) {
+ if (unlikely(ret != 0)) {
pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
atomic64_inc(&zram->stats.failed_reads);
return ret;
@@ -374,7 +428,7 @@ static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,

ret = zram_decompress_page(zram, uncmem, index);
/* Should NEVER happen. Return bio error if it does. */
- if (unlikely(ret != LZO_E_OK))
+ if (unlikely(ret != 0))
goto out_cleanup;

if (is_partial_io(bvec))
@@ -440,8 +494,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
goto out;
}

- ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen,
- meta->compress_workmem);
+ ret = zram_comp_op(ZRAM_COMPOP_COMPRESS, uncmem,
+ PAGE_SIZE, src, &clen);

if (!is_partial_io(bvec)) {
kunmap_atomic(user_mem);
@@ -449,7 +503,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
uncmem = NULL;
}

- if (unlikely(ret != LZO_E_OK)) {
+ if (unlikely(ret != 0)) {
pr_err("Compression failed! err=%d\n", ret);
goto out;
}
@@ -854,18 +908,26 @@ static int __init zram_init(void)
{
int ret, dev_id;

+ /* Initialize Cryptographic API */
+ pr_info("Loading Crypto API features\n");
+ if (zram_comp_init()) {
+ pr_err("Compressor initialization failed\n");
+ ret = -ENOMEM;
+ goto out;
+ }
+
if (num_devices > max_num_devices) {
pr_warn("Invalid value for num_devices: %u\n",
num_devices);
ret = -EINVAL;
- goto out;
+ goto free_comp;
}

zram_major = register_blkdev(0, "zram");
if (zram_major <= 0) {
pr_warn("Unable to get major number\n");
ret = -EBUSY;
- goto out;
+ goto free_comp;
}

/* Allocate the device array and initialize each one */
@@ -891,6 +953,8 @@ free_devices:
kfree(zram_devices);
unregister:
unregister_blkdev(zram_major, "zram");
+free_comp:
+ zram_comp_exit();
out:
return ret;
}
@@ -912,6 +976,7 @@ static void __exit zram_exit(void)
unregister_blkdev(zram_major, "zram");

kfree(zram_devices);
+ zram_comp_exit();
pr_debug("Cleanup done!\n");
}

@@ -921,6 +986,9 @@ module_exit(zram_exit);
module_param(num_devices, uint, 0);
MODULE_PARM_DESC(num_devices, "Number of zram devices");

+module_param_named(compressor, zram_compressor, charp, 0);
+MODULE_PARM_DESC(compressor, "Compressor type");
+
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
MODULE_DESCRIPTION("Compressed RAM Block Device");
diff --git a/drivers/staging/zram/zram_drv.h b/drivers/staging/zram/zram_drv.h
index 9e57bfb..93f4d14 100644
--- a/drivers/staging/zram/zram_drv.h
+++ b/drivers/staging/zram/zram_drv.h
@@ -88,7 +88,6 @@ struct zram_stats {
};

struct zram_meta {
- void *compress_workmem;
void *compress_buffer;
struct table *table;
struct zs_pool *mem_pool;
--
1.7.9.5


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