fs/squashfs/zstd_wrapper.c

   1 /*
   2  * Squashfs - a compressed read only filesystem for Linux
   3  *
   4  * Copyright (c) 2016-present, Facebook, Inc.
   5  * All rights reserved.
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * as published by the Free Software Foundation; either version 2,
  10  * or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * zstd_wrapper.c
  18  */
  19
  20 #include <linux/mutex.h>
  21 #include <linux/buffer_head.h>
  22 #include <linux/slab.h>
  23 #include <linux/zstd.h>
  24 #include <linux/vmalloc.h>
  25
  26 #include "squashfs_fs.h"
  27 #include "squashfs_fs_sb.h"
  28 #include "squashfs.h"
  29 #include "decompressor.h"
  30 #include "page_actor.h"
  31
  32 struct workspace {
  33         void *mem;
  34         size_t mem_size;
  35         size_t window_size;
  36 };
  37
  38 static void *zstd_init(struct squashfs_sb_info *msblk, void *buff)
  39 {
  40         struct workspace *wksp = kmalloc(sizeof(*wksp), GFP_KERNEL);
  41
  42         if (wksp == NULL)
  43                 goto failed;
  44         wksp->window_size = max_t(size_t,
  45                         msblk->block_size, SQUASHFS_METADATA_SIZE);
  46         wksp->mem_size = ZSTD_DStreamWorkspaceBound(wksp->window_size);
  47         wksp->mem = vmalloc(wksp->mem_size);
  48         if (wksp->mem == NULL)
  49                 goto failed;
  50
  51         return wksp;
  52
  53 failed:
  54         ERROR("Failed to allocate zstd workspace\n");
  55         kfree(wksp);
  56         return ERR_PTR(-ENOMEM);
  57 }
  58
  59
  60 static void zstd_free(void *strm)
  61 {
  62         struct workspace *wksp = strm;
  63
  64         if (wksp)
  65                 vfree(wksp->mem);
  66         kfree(wksp);
  67 }
  68
  69
  70 static int zstd_uncompress(struct squashfs_sb_info *msblk, void *strm,
  71         struct buffer_head **bh, int b, int offset, int length,
  72         struct squashfs_page_actor *output)
  73 {
  74         struct workspace *wksp = strm;
  75         ZSTD_DStream *stream;
  76         size_t total_out = 0;
  77         size_t zstd_err;
  78         int k = 0;
  79         ZSTD_inBuffer in_buf = { NULL, 0, 0 };
  80         ZSTD_outBuffer out_buf = { NULL, 0, 0 };
  81
  82         stream = ZSTD_initDStream(wksp->window_size, wksp->mem, wksp->mem_size);
  83
  84         if (!stream) {
  85                 ERROR("Failed to initialize zstd decompressor\n");
  86                 goto out;
  87         }
  88
  89         out_buf.size = PAGE_SIZE;
  90         out_buf.dst = squashfs_first_page(output);
  91
  92         do {
  93                 if (in_buf.pos == in_buf.size && k < b) {
  94                         int avail = min(length, msblk->devblksize - offset);
  95
  96                         length -= avail;
  97                         in_buf.src = bh[k]->b_data + offset;
  98                         in_buf.size = avail;
  99                         in_buf.pos = 0;
 100                         offset = 0;
 101                 }
 102
 103                 if (out_buf.pos == out_buf.size) {
 104                         out_buf.dst = squashfs_next_page(output);
 105                         if (out_buf.dst == NULL) {
 106                                 /* Shouldn't run out of pages
 107                                  * before stream is done.
 108                                  */
 109                                 squashfs_finish_page(output);
 110                                 goto out;
 111                         }
 112                         out_buf.pos = 0;
 113                         out_buf.size = PAGE_SIZE;
 114                 }
 115
 116                 total_out -= out_buf.pos;
 117                 zstd_err = ZSTD_decompressStream(stream, &out_buf, &in_buf);
 118                 total_out += out_buf.pos; /* add the additional data produced */
 119
 120                 if (in_buf.pos == in_buf.size && k < b)
 121                         put_bh(bh[k++]);
 122         } while (zstd_err != 0 && !ZSTD_isError(zstd_err));
 123
 124         squashfs_finish_page(output);
 125
 126         if (ZSTD_isError(zstd_err)) {
 127                 ERROR("zstd decompression error: %d\n",
 128                                 (int)ZSTD_getErrorCode(zstd_err));
 129                 goto out;
 130         }
 131
 132         if (k < b)
 133                 goto out;
 134
 135         return (int)total_out;
 136
 137 out:
 138         for (; k < b; k++)
 139                 put_bh(bh[k]);
 140
 141         return -EIO;
 142 }
 143
 144 const struct squashfs_decompressor squashfs_zstd_comp_ops = {
 145         .init = zstd_init,
 146         .free = zstd_free,
 147         .decompress = zstd_uncompress,
 148         .id = ZSTD_COMPRESSION,
 149         .name = "zstd",
 150         .supported = 1
 151 };