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
zstd_init(struct squashfs_sb_info * msblk,void * buff)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
zstd_free(void * strm)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
zstd_uncompress(struct squashfs_sb_info * msblk,void * strm,struct buffer_head ** bh,int b,int offset,int length,struct squashfs_page_actor * output)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 };
143