LXR linux/fs/jffs2/compr

   1/*
   2 * JFFS2 -- Journalling Flash File System, Version 2.
   3 *
   4 * Copyright © 2007 Nokia Corporation. All rights reserved.
   5 * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
   6 *
   7 * Created by Richard Purdie <rpurdie@openedhand.com>
   8 *
   9 * For licensing information, see the file 'LICENCE' in this directory.
  10 *
  11 */
  12
  13#include <linux/kernel.h>
  14#include <linux/sched.h>
  15#include <linux/vmalloc.h>
  16#include <linux/init.h>
  17#include <linux/lzo.h>
  18#include "compr.h"
  19
  20static void *lzo_mem;
  21static void *lzo_compress_buf;
  22static DEFINE_MUTEX(deflate_mutex);     /* for lzo_mem and lzo_compress_buf */
  23
  24static void free_workspace(void)
  25{
  26        vfree(lzo_mem);
  27        vfree(lzo_compress_buf);
  28}
  29
  30static int __init alloc_workspace(void)
  31{
  32        lzo_mem = vmalloc(LZO1X_MEM_COMPRESS);
  33        lzo_compress_buf = vmalloc(lzo1x_worst_compress(PAGE_SIZE));
  34
  35        if (!lzo_mem || !lzo_compress_buf) {
  36                free_workspace();
  37                return -ENOMEM;
  38        }
  39
  40        return 0;
  41}
  42
  43static int jffs2_lzo_compress(unsigned char *data_in, unsigned char *cpage_out,
  44                              uint32_t *sourcelen, uint32_t *dstlen)
  45{
  46        size_t compress_size;
  47        int ret;
  48
  49        mutex_lock(&deflate_mutex);
  50        ret = lzo1x_1_compress(data_in, *sourcelen, lzo_compress_buf, &compress_size, lzo_mem);
  51        if (ret != LZO_E_OK)
  52                goto fail;
  53
  54        if (compress_size > *dstlen)
  55                goto fail;
  56
  57        memcpy(cpage_out, lzo_compress_buf, compress_size);
  58        mutex_unlock(&deflate_mutex);
  59
  60        *dstlen = compress_size;
  61        return 0;
  62
  63 fail:
  64        mutex_unlock(&deflate_mutex);
  65        return -1;
  66}
  67
  68static int jffs2_lzo_decompress(unsigned char *data_in, unsigned char *cpage_out,
  69                                 uint32_t srclen, uint32_t destlen)
  70{
  71        size_t dl = destlen;
  72        int ret;
  73
  74        ret = lzo1x_decompress_safe(data_in, srclen, cpage_out, &dl);
  75
  76        if (ret != LZO_E_OK || dl != destlen)
  77                return -1;
  78
  79        return 0;
  80}
  81
  82static struct jffs2_compressor jffs2_lzo_comp = {
  83        .priority = JFFS2_LZO_PRIORITY,
  84        .name = "lzo",
  85        .compr = JFFS2_COMPR_LZO,
  86        .compress = &jffs2_lzo_compress,
  87        .decompress = &jffs2_lzo_decompress,
  88        .disabled = 0,
  89};
  90
  91int __init jffs2_lzo_init(void)
  92{
  93        int ret;
  94
  95        ret = alloc_workspace();
  96        if (ret < 0)
  97                return ret;
  98
  99        ret = jffs2_register_compressor(&jffs2_lzo_comp);
 100        if (ret)
 101                free_workspace();
 102
 103        return ret;
 104}
 105
 106void jffs2_lzo_exit(void)
 107{
 108        jffs2_unregister_compressor(&jffs2_lzo_comp);
 109        free_workspace();
 110}
 111