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SubjectRE: [PATCHv2] staging: zcache: crypto API support
> From: Seth Jennings [mailto:sjenning@linux.vnet.ibm.com]
> Sent: Tuesday, January 03, 2012 3:32 PM
> To: Greg Kroah-Hartman
> Cc: Seth Jennings; Dan Magenheimer; Nitin Gupta; Dave Hansen; devel@driverdev.osuosl.org; linux-
> kernel@vger.kernel.org; Thadeu Lima de Souza Cascardo; Brian King; Robert Jennings
> Subject: [PATCHv2] staging: zcache: crypto API support
>
> 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@linux.vnet.ibm.com>

Acked-by: Dan Magenheimer <dan.magenheimer@oracle.com>

> ---
> 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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