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    Subject[PATCHv5 2/4] zram: use zcomp compressing backends
    Date
    Do not perform direct LZO compress/decompress calls,
    initialise and use zcomp LZO backend instead.

    Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
    ---
    drivers/block/zram/Makefile | 2 +-
    drivers/block/zram/zram_drv.c | 62 +++++++++++++++++++------------------------
    drivers/block/zram/zram_drv.h | 8 +++---
    3 files changed, 32 insertions(+), 40 deletions(-)

    diff --git a/drivers/block/zram/Makefile b/drivers/block/zram/Makefile
    index cb0f9ce..757c6a5 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 zcomp.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..200c12a 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;
    @@ -280,8 +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;
    - size_t clen = PAGE_SIZE;
    + int ret = 0;
    unsigned char *cmem;
    struct zram_meta *meta = zram->meta;
    unsigned long handle;
    @@ -301,12 +281,12 @@ 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);
    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 +329,7 @@ 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 +354,10 @@ 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_strm *zstrm;
    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 +373,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
    goto out;
    }

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

    @@ -420,19 +399,18 @@ 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, zstrm, uncmem, &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 = zstrm->buffer;
    if (unlikely(clen > max_zpage_size)) {
    clen = PAGE_SIZE;
    src = NULL;
    @@ -457,6 +435,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
    memcpy(cmem, src, clen);
    }

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

    /*
    @@ -475,10 +455,9 @@ 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_strm_put(zram->comp, zstrm);
    if (is_partial_io(bvec))
    kfree(uncmem);
    -
    if (ret)
    atomic64_inc(&zram->stats.failed_writes);
    return ret;
    @@ -522,6 +501,9 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
    zs_free(meta->mem_pool, handle);
    }

    + zcomp_destroy(zram->comp);
    + zram->comp = NULL;
    +
    zram_meta_free(zram->meta);
    zram->meta = NULL;
    /* Reset stats */
    @@ -550,9 +532,18 @@ 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 +781,7 @@ 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..45e04f7 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 "zcomp.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 zcomp *comp;
    +
    /* Prevent concurrent execution of device init, reset and R/W request */
    struct rw_semaphore init_lock;
    /*
    --
    1.9.0.rc3.260.g4cf525c


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