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
32static int squashfs_max_decompressors(void)
33{
34	return MAX_DECOMPRESSOR;
35}
36
37struct 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
46struct decomp_stream {
47	void *stream;
48	struct list_head list;
49};
50
51
52static 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
61static 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
98out:
99	kfree(decomp_strm);
100	kfree(stream);
101	return ERR_PTR(err);
102}
103
104
105static 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
126static 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;
167wait:
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
182static 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
198const 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