fs/squashfs/lz4_wrapper.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2013, 2014
   4  * Phillip Lougher <phillip@squashfs.org.uk>
   5  */
   6
   7 #include <linux/bio.h>
   8 #include <linux/mutex.h>
   9 #include <linux/slab.h>
  10 #include <linux/vmalloc.h>
  11 #include <linux/lz4.h>
  12
  13 #include "squashfs_fs.h"
  14 #include "squashfs_fs_sb.h"
  15 #include "squashfs.h"
  16 #include "decompressor.h"
  17 #include "page_actor.h"
  18
  19 #define LZ4_LEGACY      1
  20
  21 struct lz4_comp_opts {
  22         __le32 version;
  23         __le32 flags;
  24 };
  25
  26 struct squashfs_lz4 {
  27         void *input;
  28         void *output;
  29 };
  30
  31
  32 static void *lz4_comp_opts(struct squashfs_sb_info *msblk,
  33         void *buff, int len)
  34 {
  35         struct lz4_comp_opts *comp_opts = buff;
  36
  37         /* LZ4 compressed filesystems always have compression options */
  38         if (comp_opts == NULL || len < sizeof(*comp_opts))
  39                 return ERR_PTR(-EIO);
  40
  41         if (le32_to_cpu(comp_opts->version) != LZ4_LEGACY) {
  42                 /* LZ4 format currently used by the kernel is the 'legacy'
  43                  * format */
  44                 ERROR("Unknown LZ4 version\n");
  45                 return ERR_PTR(-EINVAL);
  46         }
  47
  48         return NULL;
  49 }
  50
  51
  52 static void *lz4_init(struct squashfs_sb_info *msblk, void *buff)
  53 {
  54         int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);
  55         struct squashfs_lz4 *stream;
  56
  57         stream = kzalloc(sizeof(*stream), GFP_KERNEL);
  58         if (stream == NULL)
  59                 goto failed;
  60         stream->input = vmalloc(block_size);
  61         if (stream->input == NULL)
  62                 goto failed2;
  63         stream->output = vmalloc(block_size);
  64         if (stream->output == NULL)
  65                 goto failed3;
  66
  67         return stream;
  68
  69 failed3:
  70         vfree(stream->input);
  71 failed2:
  72         kfree(stream);
  73 failed:
  74         ERROR("Failed to initialise LZ4 decompressor\n");
  75         return ERR_PTR(-ENOMEM);
  76 }
  77
  78
  79 static void lz4_free(void *strm)
  80 {
  81         struct squashfs_lz4 *stream = strm;
  82
  83         if (stream) {
  84                 vfree(stream->input);
  85                 vfree(stream->output);
  86         }
  87         kfree(stream);
  88 }
  89
  90
  91 static int lz4_uncompress(struct squashfs_sb_info *msblk, void *strm,
  92         struct bio *bio, int offset, int length,
  93         struct squashfs_page_actor *output)
  94 {
  95         struct bvec_iter_all iter_all = {};
  96         struct bio_vec *bvec = bvec_init_iter_all(&iter_all);
  97         struct squashfs_lz4 *stream = strm;
  98         void *buff = stream->input, *data;
  99         int bytes = length, res;
 100
 101         while (bio_next_segment(bio, &iter_all)) {
 102                 int avail = min(bytes, ((int)bvec->bv_len) - offset);
 103
 104                 data = page_address(bvec->bv_page) + bvec->bv_offset;
 105                 memcpy(buff, data + offset, avail);
 106                 buff += avail;
 107                 bytes -= avail;
 108                 offset = 0;
 109         }
 110
 111         res = LZ4_decompress_safe(stream->input, stream->output,
 112                 length, output->length);
 113
 114         if (res < 0)
 115                 return -EIO;
 116
 117         bytes = res;
 118         data = squashfs_first_page(output);
 119         buff = stream->output;
 120         while (data) {
 121                 if (bytes <= PAGE_SIZE) {
 122                         memcpy(data, buff, bytes);
 123                         break;
 124                 }
 125                 memcpy(data, buff, PAGE_SIZE);
 126                 buff += PAGE_SIZE;
 127                 bytes -= PAGE_SIZE;
 128                 data = squashfs_next_page(output);
 129         }
 130         squashfs_finish_page(output);
 131
 132         return res;
 133 }
 134
 135 const struct squashfs_decompressor squashfs_lz4_comp_ops = {
 136         .init = lz4_init,
 137         .comp_opts = lz4_comp_opts,
 138         .free = lz4_free,
 139         .decompress = lz4_uncompress,
 140         .id = LZ4_COMPRESSION,
 141         .name = "lz4",
 142         .supported = 1
 143 };