[PATCHv2] staging: zcache: crypto API support

From: Seth Jennings
Date: Tue Jan 03 2012 - 17:32:13 EST

This patch allow zcache to use the crypto API for page compression.
It replaces the direct LZO compress/decompress calls with calls
into the crypto compression API. The compressor to be used is
specified in the kernel boot line with the zcache parameter like:
zcache=lzo or zcache=deflate. If the specified compressor can't
be loaded, zcache uses lzo as the default compressor.

Signed-off-by: Seth Jennings <sjenning@xxxxxxxxxxxxxxxxxx>
---
drivers/staging/zcache/Kconfig | 7 +-
drivers/staging/zcache/zcache-main.c | 150 ++++++++++++++++++++++++++++------
2 files changed, 126 insertions(+), 31 deletions(-)

diff --git a/drivers/staging/zcache/Kconfig b/drivers/staging/zcache/Kconfig
index 7fabcb2..1b7bba7 100644
--- a/drivers/staging/zcache/Kconfig
+++ b/drivers/staging/zcache/Kconfig
@@ -1,13 +1,12 @@
config ZCACHE
tristate "Dynamic compression of swap pages and clean pagecache pages"
- depends on CLEANCACHE || FRONTSWAP
+ depends on (CLEANCACHE || FRONTSWAP) && CRYPTO
select XVMALLOC
- select LZO_COMPRESS
- select LZO_DECOMPRESS
+ select CRYPTO_LZO
default n
help
Zcache doubles RAM efficiency while providing a significant
- performance boosts on many workloads. Zcache uses lzo1x
+ performance boosts on many workloads. Zcache uses
compression and an in-kernel implementation of transcendent
memory to store clean page cache pages and swap in RAM,
providing a noticeable reduction in disk I/O.
diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
index 56c1f9c..a4384eb 100644
--- a/drivers/staging/zcache/zcache-main.c
+++ b/drivers/staging/zcache/zcache-main.c
@@ -6,7 +6,8 @@
*
* Zcache provides an in-kernel "host implementation" for transcendent memory
* and, thus indirectly, for cleancache and frontswap. Zcache includes two
- * page-accessible memory [1] interfaces, both utilizing lzo1x compression:
+ * page-accessible memory [1] interfaces, both utilizing the crypto compression
+ * API:
* 1) "compression buddies" ("zbud") is used for ephemeral pages
* 2) xvmalloc is used for persistent pages.
* Xvmalloc (based on the TLSF allocator) has very low fragmentation
@@ -23,12 +24,13 @@
#include <linux/cpu.h>
#include <linux/highmem.h>
#include <linux/list.h>
-#include <linux/lzo.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/atomic.h>
#include <linux/math64.h>
+#include <linux/crypto.h>
+#include <linux/string.h>
#include "tmem.h"

#include "../zram/xvmalloc.h" /* if built in drivers/staging */
@@ -81,6 +83,38 @@ static inline bool is_local_client(struct zcache_client *cli)
return cli == &zcache_host;
}

+/* crypto API for zcache */
+#define ZCACHE_COMP_NAME_SZ CRYPTO_MAX_ALG_NAME
+static char zcache_comp_name[ZCACHE_COMP_NAME_SZ];
+static struct crypto_comp * __percpu *zcache_comp_pcpu_tfms;
+
+enum comp_op {
+ ZCACHE_COMPOP_COMPRESS,
+ ZCACHE_COMPOP_DECOMPRESS
+};
+
+static inline int zcache_comp_op(enum comp_op op,
+ const u8 *src, unsigned int slen,
+ u8 *dst, unsigned int *dlen)
+{
+ struct crypto_comp *tfm;
+ int ret;
+
+ BUG_ON(!zcache_comp_pcpu_tfms);
+ tfm = *per_cpu_ptr(zcache_comp_pcpu_tfms, get_cpu());
+ BUG_ON(!tfm);
+ switch (op) {
+ case ZCACHE_COMPOP_COMPRESS:
+ ret = crypto_comp_compress(tfm, src, slen, dst, dlen);
+ break;
+ case ZCACHE_COMPOP_DECOMPRESS:
+ ret = crypto_comp_decompress(tfm, src, slen, dst, dlen);
+ break;
+ }
+ put_cpu();
+ return ret;
+}
+
/**********
* Compression buddies ("zbud") provides for packing two (or, possibly
* in the future, more) compressed ephemeral pages into a single "raw"
@@ -408,7 +442,7 @@ static int zbud_decompress(struct page *page, struct zbud_hdr *zh)
{
struct zbud_page *zbpg;
unsigned budnum = zbud_budnum(zh);
- size_t out_len = PAGE_SIZE;
+ unsigned int out_len = PAGE_SIZE;
char *to_va, *from_va;
unsigned size;
int ret = 0;
@@ -425,8 +459,9 @@ static int zbud_decompress(struct page *page, struct zbud_hdr *zh)
to_va = kmap_atomic(page, KM_USER0);
size = zh->size;
from_va = zbud_data(zh, size);
- ret = lzo1x_decompress_safe(from_va, size, to_va, &out_len);
- BUG_ON(ret != LZO_E_OK);
+ ret = zcache_comp_op(ZCACHE_COMPOP_DECOMPRESS, from_va, size,
+ to_va, &out_len);
+ BUG_ON(ret);
BUG_ON(out_len != PAGE_SIZE);
kunmap_atomic(to_va, KM_USER0);
out:
@@ -624,7 +659,7 @@ static int zbud_show_cumul_chunk_counts(char *buf)

/**********
* This "zv" PAM implementation combines the TLSF-based xvMalloc
- * with lzo1x compression to maximize the amount of data that can
+ * with the crypto compression API to maximize the amount of data that can
* be packed into a physical page.
*
* Zv represents a PAM page with the index and object (plus a "size" value
@@ -711,7 +746,7 @@ static void zv_free(struct xv_pool *xvpool, struct zv_hdr *zv)

static void zv_decompress(struct page *page, struct zv_hdr *zv)
{
- size_t clen = PAGE_SIZE;
+ unsigned int clen = PAGE_SIZE;
char *to_va;
unsigned size;
int ret;
@@ -720,10 +755,10 @@ static void zv_decompress(struct page *page, struct zv_hdr *zv)
size = xv_get_object_size(zv) - sizeof(*zv);
BUG_ON(size == 0);
to_va = kmap_atomic(page, KM_USER0);
- ret = lzo1x_decompress_safe((char *)zv + sizeof(*zv),
- size, to_va, &clen);
+ ret = zcache_comp_op(ZCACHE_COMPOP_DECOMPRESS, (char *)zv + sizeof(*zv),
+ size, to_va, &clen);
kunmap_atomic(to_va, KM_USER0);
- BUG_ON(ret != LZO_E_OK);
+ BUG_ON(ret);
BUG_ON(clen != PAGE_SIZE);
}

@@ -1286,25 +1321,24 @@ static struct tmem_pamops zcache_pamops = {
* zcache compression/decompression and related per-cpu stuff
*/

-#define LZO_WORKMEM_BYTES LZO1X_1_MEM_COMPRESS
-#define LZO_DSTMEM_PAGE_ORDER 1
-static DEFINE_PER_CPU(unsigned char *, zcache_workmem);
static DEFINE_PER_CPU(unsigned char *, zcache_dstmem);
+#define ZCACHE_DSTMEM_ORDER 1

static int zcache_compress(struct page *from, void **out_va, size_t *out_len)
{
int ret = 0;
unsigned char *dmem = __get_cpu_var(zcache_dstmem);
- unsigned char *wmem = __get_cpu_var(zcache_workmem);
char *from_va;

BUG_ON(!irqs_disabled());
- if (unlikely(dmem == NULL || wmem == NULL))
- goto out; /* no buffer, so can't compress */
+ if (unlikely(dmem == NULL))
+ goto out; /* no buffer or no compressor so can't compress */
+ *out_len = PAGE_SIZE << ZCACHE_DSTMEM_ORDER;
from_va = kmap_atomic(from, KM_USER0);
mb();
- ret = lzo1x_1_compress(from_va, PAGE_SIZE, dmem, out_len, wmem);
- BUG_ON(ret != LZO_E_OK);
+ ret = zcache_comp_op(ZCACHE_COMPOP_COMPRESS, from_va, PAGE_SIZE, dmem,
+ (unsigned int *)out_len);
+ BUG_ON(ret);
*out_va = dmem;
kunmap_atomic(from_va, KM_USER0);
ret = 1;
@@ -1312,29 +1346,48 @@ out:
return ret;
}

+static int zcache_comp_cpu_up(int cpu)
+{
+ struct crypto_comp *tfm;
+
+ tfm = crypto_alloc_comp(zcache_comp_name, 0, 0);
+ if (IS_ERR(tfm))
+ return NOTIFY_BAD;
+ *per_cpu_ptr(zcache_comp_pcpu_tfms, cpu) = tfm;
+ return NOTIFY_OK;
+}
+
+static void zcache_comp_cpu_down(int cpu)
+{
+ struct crypto_comp *tfm;
+
+ tfm = *per_cpu_ptr(zcache_comp_pcpu_tfms, cpu);
+ crypto_free_comp(tfm);
+ *per_cpu_ptr(zcache_comp_pcpu_tfms, cpu) = NULL;
+}

static int zcache_cpu_notifier(struct notifier_block *nb,
unsigned long action, void *pcpu)
{
- int cpu = (long)pcpu;
+ int ret, cpu = (long)pcpu;
struct zcache_preload *kp;

switch (action) {
case CPU_UP_PREPARE:
+ ret = zcache_comp_cpu_up(cpu);
+ if (ret != NOTIFY_OK) {
+ pr_err("zcache: can't allocate compressor transform\n");
+ return ret;
+ }
per_cpu(zcache_dstmem, cpu) = (void *)__get_free_pages(
- GFP_KERNEL | __GFP_REPEAT,
- LZO_DSTMEM_PAGE_ORDER),
- per_cpu(zcache_workmem, cpu) =
- kzalloc(LZO1X_MEM_COMPRESS,
- GFP_KERNEL | __GFP_REPEAT);
+ GFP_KERNEL | __GFP_REPEAT, ZCACHE_DSTMEM_ORDER);
break;
case CPU_DEAD:
case CPU_UP_CANCELED:
+ zcache_comp_cpu_down(cpu);
free_pages((unsigned long)per_cpu(zcache_dstmem, cpu),
- LZO_DSTMEM_PAGE_ORDER);
+ ZCACHE_DSTMEM_ORDER);
per_cpu(zcache_dstmem, cpu) = NULL;
- kfree(per_cpu(zcache_workmem, cpu));
- per_cpu(zcache_workmem, cpu) = NULL;
kp = &per_cpu(zcache_preloads, cpu);
while (kp->nr) {
kmem_cache_free(zcache_objnode_cache,
@@ -1919,6 +1972,44 @@ static int __init no_frontswap(char *s)

__setup("nofrontswap", no_frontswap);

+static int __init enable_zcache_compressor(char *s)
+{
+ strncpy(zcache_comp_name, s, ZCACHE_COMP_NAME_SZ);
+ zcache_enabled = 1;
+ return 1;
+}
+__setup("zcache=", enable_zcache_compressor);
+
+
+static int zcache_comp_init(void)
+{
+ int ret = 0;
+
+ /* check crypto algorithm */
+ if (*zcache_comp_name != '\0') {
+ ret = crypto_has_comp(zcache_comp_name, 0, 0);
+ if (!ret)
+ pr_info("zcache: %s not supported\n",
+ zcache_comp_name);
+ }
+ if (!ret)
+ strcpy(zcache_comp_name, "lzo");
+ ret = crypto_has_comp(zcache_comp_name, 0, 0);
+ if (!ret) {
+ ret = 1;
+ goto out;
+ }
+ pr_info("zcache: using %s compressor\n", zcache_comp_name);
+
+ /* alloc percpu transforms */
+ ret = 0;
+ zcache_comp_pcpu_tfms = alloc_percpu(struct crypto_comp *);
+ if (!zcache_comp_pcpu_tfms)
+ ret = 1;
+out:
+ return ret;
+}
+
static int __init zcache_init(void)
{
int ret = 0;
@@ -1941,6 +2032,11 @@ static int __init zcache_init(void)
pr_err("zcache: can't register cpu notifier\n");
goto out;
}
+ ret = zcache_comp_init();
+ if (ret) {
+ pr_err("zcache: compressor initialization failed\n");
+ goto out;
+ }
for_each_online_cpu(cpu) {
void *pcpu = (void *)(long)cpu;
zcache_cpu_notifier(&zcache_cpu_notifier_block,
--
1.7.5.4

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