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/buffer_head.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
squashfs_max_decompressors(void)32 int squashfs_max_decompressors(void)
33 {
34 return MAX_DECOMPRESSOR;
35 }
36
37
38 struct squashfs_stream {
39 void *comp_opts;
40 struct list_head strm_list;
41 struct mutex mutex;
42 int avail_decomp;
43 wait_queue_head_t wait;
44 };
45
46
47 struct decomp_stream {
48 void *stream;
49 struct list_head list;
50 };
51
52
put_decomp_stream(struct decomp_stream * decomp_strm,struct squashfs_stream * stream)53 static void put_decomp_stream(struct decomp_stream *decomp_strm,
54 struct squashfs_stream *stream)
55 {
56 mutex_lock(&stream->mutex);
57 list_add(&decomp_strm->list, &stream->strm_list);
58 mutex_unlock(&stream->mutex);
59 wake_up(&stream->wait);
60 }
61
squashfs_decompressor_create(struct squashfs_sb_info * msblk,void * comp_opts)62 void *squashfs_decompressor_create(struct squashfs_sb_info *msblk,
63 void *comp_opts)
64 {
65 struct squashfs_stream *stream;
66 struct decomp_stream *decomp_strm = NULL;
67 int err = -ENOMEM;
68
69 stream = kzalloc(sizeof(*stream), GFP_KERNEL);
70 if (!stream)
71 goto out;
72
73 stream->comp_opts = comp_opts;
74 mutex_init(&stream->mutex);
75 INIT_LIST_HEAD(&stream->strm_list);
76 init_waitqueue_head(&stream->wait);
77
78 /*
79 * We should have a decompressor at least as default
80 * so if we fail to allocate new decompressor dynamically,
81 * we could always fall back to default decompressor and
82 * file system works.
83 */
84 decomp_strm = kmalloc(sizeof(*decomp_strm), GFP_KERNEL);
85 if (!decomp_strm)
86 goto out;
87
88 decomp_strm->stream = msblk->decompressor->init(msblk,
89 stream->comp_opts);
90 if (IS_ERR(decomp_strm->stream)) {
91 err = PTR_ERR(decomp_strm->stream);
92 goto out;
93 }
94
95 list_add(&decomp_strm->list, &stream->strm_list);
96 stream->avail_decomp = 1;
97 return stream;
98
99 out:
100 kfree(decomp_strm);
101 kfree(stream);
102 return ERR_PTR(err);
103 }
104
105
squashfs_decompressor_destroy(struct squashfs_sb_info * msblk)106 void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk)
107 {
108 struct squashfs_stream *stream = msblk->stream;
109 if (stream) {
110 struct decomp_stream *decomp_strm;
111
112 while (!list_empty(&stream->strm_list)) {
113 decomp_strm = list_entry(stream->strm_list.prev,
114 struct decomp_stream, list);
115 list_del(&decomp_strm->list);
116 msblk->decompressor->free(decomp_strm->stream);
117 kfree(decomp_strm);
118 stream->avail_decomp--;
119 }
120 WARN_ON(stream->avail_decomp);
121 kfree(stream->comp_opts);
122 kfree(stream);
123 }
124 }
125
126
get_decomp_stream(struct squashfs_sb_info * msblk,struct squashfs_stream * stream)127 static struct decomp_stream *get_decomp_stream(struct squashfs_sb_info *msblk,
128 struct squashfs_stream *stream)
129 {
130 struct decomp_stream *decomp_strm;
131
132 while (1) {
133 mutex_lock(&stream->mutex);
134
135 /* There is available decomp_stream */
136 if (!list_empty(&stream->strm_list)) {
137 decomp_strm = list_entry(stream->strm_list.prev,
138 struct decomp_stream, list);
139 list_del(&decomp_strm->list);
140 mutex_unlock(&stream->mutex);
141 break;
142 }
143
144 /*
145 * If there is no available decomp and already full,
146 * let's wait for releasing decomp from other users.
147 */
148 if (stream->avail_decomp >= MAX_DECOMPRESSOR)
149 goto wait;
150
151 /* Let's allocate new decomp */
152 decomp_strm = kmalloc(sizeof(*decomp_strm), GFP_KERNEL);
153 if (!decomp_strm)
154 goto wait;
155
156 decomp_strm->stream = msblk->decompressor->init(msblk,
157 stream->comp_opts);
158 if (IS_ERR(decomp_strm->stream)) {
159 kfree(decomp_strm);
160 goto wait;
161 }
162
163 stream->avail_decomp++;
164 WARN_ON(stream->avail_decomp > MAX_DECOMPRESSOR);
165
166 mutex_unlock(&stream->mutex);
167 break;
168 wait:
169 /*
170 * If system memory is tough, let's for other's
171 * releasing instead of hurting VM because it could
172 * make page cache thrashing.
173 */
174 mutex_unlock(&stream->mutex);
175 wait_event(stream->wait,
176 !list_empty(&stream->strm_list));
177 }
178
179 return decomp_strm;
180 }
181
182
squashfs_decompress(struct squashfs_sb_info * msblk,struct buffer_head ** bh,int b,int offset,int length,struct squashfs_page_actor * output)183 int squashfs_decompress(struct squashfs_sb_info *msblk, struct buffer_head **bh,
184 int b, int offset, int length, 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 bh, b, 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