compr_lzo.c

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/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright © 2007 Nokia Corporation. All rights reserved.
 * Copyright © 2004-2010 David Woodhouse <[email protected]>
 *
 * Created by Richard Purdie <[email protected]>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/lzo.h>
#include "compr.h"

static void *lzo_mem;
static void *lzo_compress_buf;
static DEFINE_MUTEX(deflate_mutex); /* for lzo_mem and lzo_compress_buf */

static void free_workspace(void)
{
    vfree(lzo_mem);
    vfree(lzo_compress_buf);
}

static int __init alloc_workspace(void)
{
    lzo_mem = vmalloc(LZO1X_MEM_COMPRESS);
    lzo_compress_buf = vmalloc(lzo1x_worst_compress(PAGE_SIZE));

    if (!lzo_mem || !lzo_compress_buf) {
        free_workspace();
        return -ENOMEM;
    }

    return 0;
}

static int jffs2_lzo_compress(unsigned char *data_in, unsigned char *cpage_out,
                  uint32_t *sourcelen, uint32_t *dstlen)
{
    size_t compress_size;
    int ret;

    mutex_lock(&deflate_mutex);
    ret = lzo1x_1_compress(data_in, *sourcelen, lzo_compress_buf, &compress_size, lzo_mem);
    if (ret != LZO_E_OK)
        goto fail;

    if (compress_size > *dstlen)
        goto fail;

    memcpy(cpage_out, lzo_compress_buf, compress_size);
    mutex_unlock(&deflate_mutex);

    *dstlen = compress_size;
    return 0;

 fail:
    mutex_unlock(&deflate_mutex);
    return -1;
}

static int jffs2_lzo_decompress(unsigned char *data_in, unsigned char *cpage_out,
                 uint32_t srclen, uint32_t destlen)
{
    size_t dl = destlen;
    int ret;

    ret = lzo1x_decompress_safe(data_in, srclen, cpage_out, &dl);

    if (ret != LZO_E_OK || dl != destlen)
        return -1;

    return 0;
}

static struct jffs2_compressor jffs2_lzo_comp = {
    .priority = JFFS2_LZO_PRIORITY,
    .name = "lzo",
    .compr = JFFS2_COMPR_LZO,
    .compress = &jffs2_lzo_compress,
    .decompress = &jffs2_lzo_decompress,
    .disabled = 0,
};

int __init jffs2_lzo_init(void)
{
    int ret;

    ret = alloc_workspace();
    if (ret < 0)
        return ret;

    ret = jffs2_register_compressor(&jffs2_lzo_comp);
    if (ret)
        free_workspace();

    return ret;
}

void jffs2_lzo_exit(void)
{
    jffs2_unregister_compressor(&jffs2_lzo_comp);
    free_workspace();
}