fs/squashfs/lz4_wrapper.c

   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
  23 struct lz4_comp_opts {
  24         __le32 version;
  25         __le32 flags;
  26 };
  27
  28 struct squashfs_lz4 {
  29         void *input;
  30         void *output;
  31 };
  32
  33
  34 static 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
  54 static 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
  71 failed3:
  72         vfree(stream->input);
  73 failed2:
  74         kfree(stream);
  75 failed:
  76         ERROR("Failed to initialise LZ4 decompressor\n");
  77         return ERR_PTR(-ENOMEM);
  78 }
  79
  80
  81 static 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
  93 static 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
 134 const 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 };