1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (c) 2013
4 * Minchan Kim <minchan@kernel.org>
5 */
6 #include <linux/types.h>
7 #include <linux/mutex.h>
8 #include <linux/slab.h>
9 #include <linux/bio.h>
10 #include <linux/sched.h>
11 #include <linux/wait.h>
12 #include <linux/cpumask.h>
13
14 #include "squashfs_fs.h"
15 #include "squashfs_fs_sb.h"
16 #include "decompressor.h"
17 #include "squashfs.h"
18
19 /*
20 * This file implements multi-threaded decompression in the
21 * decompressor framework
22 */
23
24
25 /*
26 * The reason that multiply two is that a CPU can request new I/O
27 * while it is waiting previous request.
28 */
29 #define MAX_DECOMPRESSOR (num_online_cpus() * 2)
30
31
32 static int squashfs_max_decompressors(void)
33 {
34 return MAX_DECOMPRESSOR;
35 }
36
37 struct squashfs_stream {
38 void *comp_opts;
39 struct list_head strm_list;
40 struct mutex mutex;
41 int avail_decomp;
42 wait_queue_head_t wait;
43 };
44
45
46 struct decomp_stream {
47 void *stream;
48 struct list_head list;
49 };
50
51
52 static void put_decomp_stream(struct decomp_stream *decomp_strm,
53 struct squashfs_stream *stream)
54 {
55 mutex_lock(&stream->mutex);
56 list_add(&decomp_strm->list, &stream->strm_list);
57 mutex_unlock(&stream->mutex);
58 wake_up(&stream->wait);
59 }
60
61 static void *squashfs_decompressor_create(struct squashfs_sb_info *msblk,
62 void *comp_opts)
63 {
64 struct squashfs_stream *stream;
65 struct decomp_stream *decomp_strm = NULL;
66 int err = -ENOMEM;
67
68 stream = kzalloc(sizeof(*stream), GFP_KERNEL);
69 if (!stream)
70 goto out;
71
72 stream->comp_opts = comp_opts;
73 mutex_init(&stream->mutex);
74 INIT_LIST_HEAD(&stream->strm_list);
75 init_waitqueue_head(&stream->wait);
76
77 /*
78 * We should have a decompressor at least as default
79 * so if we fail to allocate new decompressor dynamically,
80 * we could always fall back to default decompressor and
81 * file system works.
82 */
83 decomp_strm = kmalloc(sizeof(*decomp_strm), GFP_KERNEL);
84 if (!decomp_strm)
85 goto out;
86
87 decomp_strm->stream = msblk->decompressor->init(msblk,
88 stream->comp_opts);
89 if (IS_ERR(decomp_strm->stream)) {
90 err = PTR_ERR(decomp_strm->stream);
91 goto out;
92 }
93
94 list_add(&decomp_strm->list, &stream->strm_list);
95 stream->avail_decomp = 1;
96 return stream;
97
98 out:
99 kfree(decomp_strm);
100 kfree(stream);
101 return ERR_PTR(err);
102 }
103
104
105 static void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk)
106 {
107 struct squashfs_stream *stream = msblk->stream;
108 if (stream) {
109 struct decomp_stream *decomp_strm;
110
111 while (!list_empty(&stream->strm_list)) {
112 decomp_strm = list_entry(stream->strm_list.prev,
113 struct decomp_stream, list);
114 list_del(&decomp_strm->list);
115 msblk->decompressor->free(decomp_strm->stream);
116 kfree(decomp_strm);
117 stream->avail_decomp--;
118 }
119 WARN_ON(stream->avail_decomp);
120 kfree(stream->comp_opts);
121 kfree(stream);
122 }
123 }
124
125
126 static struct decomp_stream *get_decomp_stream(struct squashfs_sb_info *msblk,
127 struct squashfs_stream *stream)
128 {
129 struct decomp_stream *decomp_strm;
130
131 while (1) {
132 mutex_lock(&stream->mutex);
133
134 /* There is available decomp_stream */
135 if (!list_empty(&stream->strm_list)) {
136 decomp_strm = list_entry(stream->strm_list.prev,
137 struct decomp_stream, list);
138 list_del(&decomp_strm->list);
139 mutex_unlock(&stream->mutex);
140 break;
141 }
142
143 /*
144 * If there is no available decomp and already full,
145 * let's wait for releasing decomp from other users.
146 */
147 if (stream->avail_decomp >= msblk->max_thread_num)
148 goto wait;
149
150 /* Let's allocate new decomp */
151 decomp_strm = kmalloc(sizeof(*decomp_strm), GFP_KERNEL);
152 if (!decomp_strm)
153 goto wait;
154
155 decomp_strm->stream = msblk->decompressor->init(msblk,
156 stream->comp_opts);
157 if (IS_ERR(decomp_strm->stream)) {
158 kfree(decomp_strm);
159 goto wait;
160 }
161
162 stream->avail_decomp++;
163 WARN_ON(stream->avail_decomp > msblk->max_thread_num);
164
165 mutex_unlock(&stream->mutex);
166 break;
167 wait:
168 /*
169 * If system memory is tough, let's for other's
170 * releasing instead of hurting VM because it could
171 * make page cache thrashing.
172 */
173 mutex_unlock(&stream->mutex);
174 wait_event(stream->wait,
175 !list_empty(&stream->strm_list));
176 }
177
178 return decomp_strm;
179 }
180
181
182 static int squashfs_decompress(struct squashfs_sb_info *msblk, struct bio *bio,
183 int offset, int length,
184 struct squashfs_page_actor *output)
185 {
186 int res;
187 struct squashfs_stream *stream = msblk->stream;
188 struct decomp_stream *decomp_stream = get_decomp_stream(msblk, stream);
189 res = msblk->decompressor->decompress(msblk, decomp_stream->stream,
190 bio, offset, length, output);
191 put_decomp_stream(decomp_stream, stream);
192 if (res < 0)
193 ERROR("%s decompression failed, data probably corrupt\n",
194 msblk->decompressor->name);
195 return res;
196 }
197
198 const struct squashfs_decompressor_thread_ops squashfs_decompressor_multi = {
199 .create = squashfs_decompressor_create,
200 .destroy = squashfs_decompressor_destroy,
201 .decompress = squashfs_decompress,
202 .max_decompressors = squashfs_max_decompressors,
203 };
204
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