LXR linux/fs/squashfs/lz4

   1/*
   2 * Copyright (c) 2013, 2014
   3 * Phillip Lougher <phillip@squashfs.org.uk>
   4 *
   5 * This work is licensed under the terms of the GNU GPL, version 2. See
   6 * the COPYING file in the top-level directory.
   7 */
   8
   9#include <linux/buffer_head.h>
  10#include <linux/mutex.h>
  11#include <linux/slab.h>
  12#include <linux/vmalloc.h>
  13#include <linux/lz4.h>
  14
  15#include "squashfs_fs.h"
  16#include "squashfs_fs_sb.h"
  17#include "squashfs.h"
  18#include "decompressor.h"
  19#include "page_actor.h"
  20
  21#define LZ4_LEGACY      1
  22
  23struct lz4_comp_opts {
  24        __le32 version;
  25        __le32 flags;
  26};
  27
  28struct squashfs_lz4 {
  29        void *input;
  30        void *output;
  31};
  32
  33
  34static void *lz4_comp_opts(struct squashfs_sb_info *msblk,
  35        void *buff, int len)
  36{
  37        struct lz4_comp_opts *comp_opts = buff;
  38
  39        /* LZ4 compressed filesystems always have compression options */
  40        if (comp_opts == NULL || len < sizeof(*comp_opts))
  41                return ERR_PTR(-EIO);
  42
  43        if (le32_to_cpu(comp_opts->version) != LZ4_LEGACY) {
  44                /* LZ4 format currently used by the kernel is the 'legacy'
  45                 * format */
  46                ERROR("Unknown LZ4 version\n");
  47                return ERR_PTR(-EINVAL);
  48        }
  49
  50        return NULL;
  51}
  52
  53
  54static void *lz4_init(struct squashfs_sb_info *msblk, void *buff)
  55{
  56        int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);
  57        struct squashfs_lz4 *stream;
  58
  59        stream = kzalloc(sizeof(*stream), GFP_KERNEL);
  60        if (stream == NULL)
  61                goto failed;
  62        stream->input = vmalloc(block_size);
  63        if (stream->input == NULL)
  64                goto failed2;
  65        stream->output = vmalloc(block_size);
  66        if (stream->output == NULL)
  67                goto failed3;
  68
  69        return stream;
  70
  71failed3:
  72        vfree(stream->input);
  73failed2:
  74        kfree(stream);
  75failed:
  76        ERROR("Failed to initialise LZ4 decompressor\n");
  77        return ERR_PTR(-ENOMEM);
  78}
  79
  80
  81static void lz4_free(void *strm)
  82{
  83        struct squashfs_lz4 *stream = strm;
  84
  85        if (stream) {
  86                vfree(stream->input);
  87                vfree(stream->output);
  88        }
  89        kfree(stream);
  90}
  91
  92
  93static int lz4_uncompress(struct squashfs_sb_info *msblk, void *strm,
  94        struct buffer_head **bh, int b, int offset, int length,
  95        struct squashfs_page_actor *output)
  96{
  97        struct squashfs_lz4 *stream = strm;
  98        void *buff = stream->input, *data;
  99        int avail, i, bytes = length, res;
 100        size_t dest_len = output->length;
 101
 102        for (i = 0; i < b; i++) {
 103                avail = min(bytes, msblk->devblksize - offset);
 104                memcpy(buff, bh[i]->b_data + offset, avail);
 105                buff += avail;
 106                bytes -= avail;
 107                offset = 0;
 108                put_bh(bh[i]);
 109        }
 110
 111        res = lz4_decompress_unknownoutputsize(stream->input, length,
 112                                        stream->output, &dest_len);
 113        if (res)
 114                return -EIO;
 115
 116        bytes = dest_len;
 117        data = squashfs_first_page(output);
 118        buff = stream->output;
 119        while (data) {
 120                if (bytes <= PAGE_CACHE_SIZE) {
 121                        memcpy(data, buff, bytes);
 122                        break;
 123                }
 124                memcpy(data, buff, PAGE_CACHE_SIZE);
 125                buff += PAGE_CACHE_SIZE;
 126                bytes -= PAGE_CACHE_SIZE;
 127                data = squashfs_next_page(output);
 128        }
 129        squashfs_finish_page(output);
 130
 131        return dest_len;
 132}
 133
 134const struct squashfs_decompressor squashfs_lz4_comp_ops = {
 135        .init = lz4_init,
 136        .comp_opts = lz4_comp_opts,
 137        .free = lz4_free,
 138        .decompress = lz4_uncompress,
 139        .id = LZ4_COMPRESSION,
 140        .name = "lz4",
 141        .supported = 1
 142};
 143