[PATCHv3 2/4] zram: use zram_comp compressing backends

From: Sergey Senozhatsky
Date: Tue Feb 11 2014 - 17:25:05 EST


Do not perform direct LZO compress/decompress calls,
initialise and use zram_comp LZO backend instead.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
---
drivers/block/zram/Makefile | 2 +-
drivers/block/zram/zram_drv.c | 62 +++++++++++++++++++------------------------
drivers/block/zram/zram_drv.h | 8 +++---
3 files changed, 33 insertions(+), 39 deletions(-)

diff --git a/drivers/block/zram/Makefile b/drivers/block/zram/Makefile
index cb0f9ce..4c2e829 100644
--- a/drivers/block/zram/Makefile
+++ b/drivers/block/zram/Makefile
@@ -1,3 +1,3 @@
-zram-y := zram_drv.o
+zram-y := zcomp_lzo.o zram_comp.o zram_drv.o

obj-$(CONFIG_ZRAM) += zram.o
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 9baac5b..4875a16 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -29,15 +29,14 @@
#include <linux/genhd.h>
#include <linux/highmem.h>
#include <linux/slab.h>
-#include <linux/lzo.h>
#include <linux/string.h>
-#include <linux/vmalloc.h>

#include "zram_drv.h"

/* Globals */
static int zram_major;
static struct zram *zram_devices;
+static const char *default_compressor = "lzo";

/* Module params (documentation at end) */
static unsigned int num_devices = 1;
@@ -160,8 +159,6 @@ 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);
}
@@ -173,22 +170,11 @@ 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;
- }
-
num_pages = disksize >> PAGE_SHIFT;
meta->table = vzalloc(num_pages * sizeof(*meta->table));
if (!meta->table) {
pr_err("Error allocating zram address table\n");
- goto free_buffer;
+ goto free_meta;
}

meta->mem_pool = zs_create_pool(GFP_NOIO | __GFP_HIGHMEM);
@@ -198,15 +184,10 @@ static struct zram_meta *zram_meta_alloc(u64 disksize)
}

rwlock_init(&meta->tb_lock);
- mutex_init(&meta->buffer_lock);
return meta;

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;
@@ -280,7 +261,7 @@ 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;
@@ -301,12 +282,12 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
if (size == PAGE_SIZE)
copy_page(mem, cmem);
else
- ret = lzo1x_decompress_safe(cmem, size, mem, &clen);
+ ret = zcomp_decompress(zram->comp, cmem, size, mem, &clen);
zs_unmap_object(meta->mem_pool, handle);
read_unlock(&meta->tb_lock);

/* Should NEVER happen. Return bio error if it does. */
- if (unlikely(ret != LZO_E_OK)) {
+ if (unlikely(ret)) {
pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
atomic64_inc(&zram->stats.failed_reads);
return ret;
@@ -349,7 +330,7 @@ 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))
goto out_cleanup;

if (is_partial_io(bvec))
@@ -374,11 +355,10 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
struct page *page;
unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
struct zram_meta *meta = zram->meta;
+ struct zcomp_workmem *wm;
bool locked = false;

page = bvec->bv_page;
- src = meta->compress_buffer;
-
if (is_partial_io(bvec)) {
/*
* This is a partial IO. We need to read the full page
@@ -394,7 +374,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
goto out;
}

- mutex_lock(&meta->buffer_lock);
+ wm = zcomp_workmem_get(zram->comp);
locked = true;
user_mem = kmap_atomic(page);

@@ -420,19 +400,18 @@ 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 = zcomp_compress(zram->comp, wm, uncmem, bvec->bv_len, &clen);
if (!is_partial_io(bvec)) {
kunmap_atomic(user_mem);
user_mem = NULL;
uncmem = NULL;
}

- if (unlikely(ret != LZO_E_OK)) {
+ if (unlikely(ret)) {
pr_err("Compression failed! err=%d\n", ret);
goto out;
}
-
+ src = wm->buffer;
if (unlikely(clen > max_zpage_size)) {
clen = PAGE_SIZE;
src = NULL;
@@ -457,6 +436,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
memcpy(cmem, src, clen);
}

+ zcomp_workmem_put(zram->comp, wm);
+ locked = false;
zs_unmap_object(meta->mem_pool, handle);

/*
@@ -475,10 +456,9 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
atomic64_inc(&zram->stats.pages_stored);
out:
if (locked)
- mutex_unlock(&meta->buffer_lock);
+ zcomp_workmem_put(zram->comp, wm);
if (is_partial_io(bvec))
kfree(uncmem);
-
if (ret)
atomic64_inc(&zram->stats.failed_writes);
return ret;
@@ -522,6 +502,10 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
zs_free(meta->mem_pool, handle);
}

+ if (zram->comp)
+ zcomp_destroy(zram->comp);
+ zram->comp = NULL;
+
zram_meta_free(zram->meta);
zram->meta = NULL;
/* Reset stats */
@@ -550,9 +534,18 @@ static ssize_t disksize_store(struct device *dev,
return -EBUSY;
}

+ zram->comp = zcomp_create(default_compressor);
+ if (!zram->comp) {
+ up_write(&zram->init_lock);
+ pr_info("Cannot initialise compressing backend\n");
+ return -EINVAL;
+ }
+
disksize = PAGE_ALIGN(disksize);
zram->meta = zram_meta_alloc(disksize);
if (!zram->meta) {
+ zcomp_destroy(zram->comp);
+ zram->comp = NULL;
up_write(&zram->init_lock);
return -ENOMEM;
}
@@ -790,6 +783,7 @@ static int create_device(struct zram *zram, int device_id)
}

zram->meta = NULL;
+ zram->comp = NULL;
return 0;

out_free_disk:
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 1d5b1f5..a2e17d7 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -16,9 +16,10 @@
#define _ZRAM_DRV_H_

#include <linux/spinlock.h>
-#include <linux/mutex.h>
#include <linux/zsmalloc.h>

+#include "zram_comp.h"
+
/*
* Some arbitrary value. This is just to catch
* invalid value for num_devices module parameter.
@@ -81,17 +82,16 @@ struct zram_stats {

struct zram_meta {
rwlock_t tb_lock; /* protect table */
- void *compress_workmem;
- void *compress_buffer;
struct table *table;
struct zs_pool *mem_pool;
- struct mutex buffer_lock; /* protect compress buffers */
};

struct zram {
struct zram_meta *meta;
struct request_queue *queue;
struct gendisk *disk;
+ struct zram_comp *comp;
+
/* Prevent concurrent execution of device init, reset and R/W request */
struct rw_semaphore init_lock;
/*
--
1.9.0.rc3.244.g3497008

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