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                printk(KERN_WARNING "Failed to allocate lzo deflate workspace\n");
  37                free_workspace();
  38                return -ENOMEM;
  39        }
  40
  41        return 0;
  42}
  43
  44static int jffs2_lzo_compress(unsigned char *data_in, unsigned char *cpage_out,
  45                              uint32_t *sourcelen, uint32_t *dstlen)
  46{
  47        size_t compress_size;
  48        int ret;
  49
  50        mutex_lock(&deflate_mutex);
  51        ret = lzo1x_1_compress(data_in, *sourcelen, lzo_compress_buf, &compress_size, lzo_mem);
  52        if (ret != LZO_E_OK)
  53                goto fail;
  54
  55        if (compress_size > *dstlen)
  56                goto fail;
  57
  58        memcpy(cpage_out, lzo_compress_buf, compress_size);
  59        mutex_unlock(&deflate_mutex);
  60
  61        *dstlen = compress_size;
  62        return 0;
  63
  64 fail:
  65        mutex_unlock(&deflate_mutex);
  66        return -1;
  67}
  68
  69static int jffs2_lzo_decompress(unsigned char *data_in, unsigned char *cpage_out,
  70                                 uint32_t srclen, uint32_t destlen)
  71{
  72        size_t dl = destlen;
  73        int ret;
  74
  75        ret = lzo1x_decompress_safe(data_in, srclen, cpage_out, &dl);
  76
  77        if (ret != LZO_E_OK || dl != destlen)
  78                return -1;
  79
  80        return 0;
  81}
  82
  83static struct jffs2_compressor jffs2_lzo_comp = {
  84        .priority = JFFS2_LZO_PRIORITY,
  85        .name = "lzo",
  86        .compr = JFFS2_COMPR_LZO,
  87        .compress = &jffs2_lzo_compress,
  88        .decompress = &jffs2_lzo_decompress,
  89        .disabled = 0,
  90};
  91
  92int __init jffs2_lzo_init(void)
  93{
  94        int ret;
  95
  96        ret = alloc_workspace();
  97        if (ret < 0)
  98                return ret;
  99
 100        ret = jffs2_register_compressor(&jffs2_lzo_comp);
 101        if (ret)
 102                free_workspace();
 103
 104        return ret;
 105}
 106
 107void jffs2_lzo_exit(void)
 108{
 109        jffs2_unregister_compressor(&jffs2_lzo_comp);
 110        free_workspace();
 111}
 112