fs/squashfs/zstd_wrapper.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Squashfs - a compressed read only filesystem for Linux
   4  *
   5  * Copyright (c) 2016-present, Facebook, Inc.
   6  * All rights reserved.
   7  *
   8  * zstd_wrapper.c
   9  */
  10
  11 #include <linux/mutex.h>
  12 #include <linux/buffer_head.h>
  13 #include <linux/slab.h>
  14 #include <linux/zstd.h>
  15 #include <linux/vmalloc.h>
  16
  17 #include "squashfs_fs.h"
  18 #include "squashfs_fs_sb.h"
  19 #include "squashfs.h"
  20 #include "decompressor.h"
  21 #include "page_actor.h"
  22
  23 struct workspace {
  24         void *mem;
  25         size_t mem_size;
  26         size_t window_size;
  27 };
  28
  29 static void *zstd_init(struct squashfs_sb_info *msblk, void *buff)
  30 {
  31         struct workspace *wksp = kmalloc(sizeof(*wksp), GFP_KERNEL);
  32
  33         if (wksp == NULL)
  34                 goto failed;
  35         wksp->window_size = max_t(size_t,
  36                         msblk->block_size, SQUASHFS_METADATA_SIZE);
  37         wksp->mem_size = ZSTD_DStreamWorkspaceBound(wksp->window_size);
  38         wksp->mem = vmalloc(wksp->mem_size);
  39         if (wksp->mem == NULL)
  40                 goto failed;
  41
  42         return wksp;
  43
  44 failed:
  45         ERROR("Failed to allocate zstd workspace\n");
  46         kfree(wksp);
  47         return ERR_PTR(-ENOMEM);
  48 }
  49
  50
  51 static void zstd_free(void *strm)
  52 {
  53         struct workspace *wksp = strm;
  54
  55         if (wksp)
  56                 vfree(wksp->mem);
  57         kfree(wksp);
  58 }
  59
  60
  61 static int zstd_uncompress(struct squashfs_sb_info *msblk, void *strm,
  62         struct buffer_head **bh, int b, int offset, int length,
  63         struct squashfs_page_actor *output)
  64 {
  65         struct workspace *wksp = strm;
  66         ZSTD_DStream *stream;
  67         size_t total_out = 0;
  68         size_t zstd_err;
  69         int k = 0;
  70         ZSTD_inBuffer in_buf = { NULL, 0, 0 };
  71         ZSTD_outBuffer out_buf = { NULL, 0, 0 };
  72
  73         stream = ZSTD_initDStream(wksp->window_size, wksp->mem, wksp->mem_size);
  74
  75         if (!stream) {
  76                 ERROR("Failed to initialize zstd decompressor\n");
  77                 goto out;
  78         }
  79
  80         out_buf.size = PAGE_SIZE;
  81         out_buf.dst = squashfs_first_page(output);
  82
  83         do {
  84                 if (in_buf.pos == in_buf.size && k < b) {
  85                         int avail = min(length, msblk->devblksize - offset);
  86
  87                         length -= avail;
  88                         in_buf.src = bh[k]->b_data + offset;
  89                         in_buf.size = avail;
  90                         in_buf.pos = 0;
  91                         offset = 0;
  92                 }
  93
  94                 if (out_buf.pos == out_buf.size) {
  95                         out_buf.dst = squashfs_next_page(output);
  96                         if (out_buf.dst == NULL) {
  97                                 /* Shouldn't run out of pages
  98                                  * before stream is done.
  99                                  */
 100                                 squashfs_finish_page(output);
 101                                 goto out;
 102                         }
 103                         out_buf.pos = 0;
 104                         out_buf.size = PAGE_SIZE;
 105                 }
 106
 107                 total_out -= out_buf.pos;
 108                 zstd_err = ZSTD_decompressStream(stream, &out_buf, &in_buf);
 109                 total_out += out_buf.pos; /* add the additional data produced */
 110
 111                 if (in_buf.pos == in_buf.size && k < b)
 112                         put_bh(bh[k++]);
 113         } while (zstd_err != 0 && !ZSTD_isError(zstd_err));
 114
 115         squashfs_finish_page(output);
 116
 117         if (ZSTD_isError(zstd_err)) {
 118                 ERROR("zstd decompression error: %d\n",
 119                                 (int)ZSTD_getErrorCode(zstd_err));
 120                 goto out;
 121         }
 122
 123         if (k < b)
 124                 goto out;
 125
 126         return (int)total_out;
 127
 128 out:
 129         for (; k < b; k++)
 130                 put_bh(bh[k]);
 131
 132         return -EIO;
 133 }
 134
 135 const struct squashfs_decompressor squashfs_zstd_comp_ops = {
 136         .init = zstd_init,
 137         .free = zstd_free,
 138         .decompress = zstd_uncompress,
 139         .id = ZSTD_COMPRESSION,
 140         .name = "zstd",
 141         .supported = 1
 142 };