source: src/linux/universal/linux-4.9/fs/squashfs/decompressor_multi.c @ 31630

Last change on this file since 31630 was 31630, checked in by brainslayer, 3 months ago

new fs is compatible with standard squashfs, just smaller

File size: 4.6 KB
Line 
1/*
2 *  Copyright (c) 2013
3 *  Minchan Kim <minchan@kernel.org>
4 *
5 *  This work is licensed under the terms of the GNU GPL, version 2. See
6 *  the COPYING file in the top-level directory.
7 */
8#include <linux/types.h>
9#include <linux/mutex.h>
10#include <linux/slab.h>
11#include <linux/buffer_head.h>
12#include <linux/sched.h>
13#include <linux/wait.h>
14#include <linux/cpumask.h>
15
16#include "squashfs_fs.h"
17#include "squashfs_fs_sb.h"
18#include "decompressor.h"
19#include "squashfs.h"
20
21/*
22 * This file implements multi-threaded decompression in the
23 * decompressor framework
24 */
25
26
27/*
28 * The reason that multiply two is that a CPU can request new I/O
29 * while it is waiting previous request.
30 */
31#define MAX_DECOMPRESSOR        (num_online_cpus() * 2)
32
33
34int squashfs_max_decompressors(void)
35{
36        return MAX_DECOMPRESSOR;
37}
38
39
40struct squashfs_stream {
41        void                    *comp_opts;
42        struct list_head        strm_list;
43        struct mutex            mutex;
44        int                     avail_decomp;
45        wait_queue_head_t       wait;
46};
47
48
49struct decomp_stream {
50        void *stream;
51        struct list_head list;
52};
53
54
55static void put_decomp_stream(struct decomp_stream *decomp_strm,
56                                struct squashfs_stream *stream)
57{
58        mutex_lock(&stream->mutex);
59        list_add(&decomp_strm->list, &stream->strm_list);
60        mutex_unlock(&stream->mutex);
61        wake_up(&stream->wait);
62}
63
64void *squashfs_decompressor_create(struct squashfs_sb_info *msblk,
65                                void *comp_opts)
66{
67        struct squashfs_stream *stream;
68        struct decomp_stream *decomp_strm = NULL;
69        int err = -ENOMEM;
70
71        stream = kzalloc(sizeof(*stream), GFP_KERNEL);
72        if (!stream)
73                goto out;
74
75        stream->comp_opts = comp_opts;
76        mutex_init(&stream->mutex);
77        INIT_LIST_HEAD(&stream->strm_list);
78        init_waitqueue_head(&stream->wait);
79
80        /*
81         * We should have a decompressor at least as default
82         * so if we fail to allocate new decompressor dynamically,
83         * we could always fall back to default decompressor and
84         * file system works.
85         */
86        decomp_strm = kmalloc(sizeof(*decomp_strm), GFP_KERNEL);
87        if (!decomp_strm)
88                goto out;
89
90        decomp_strm->stream = msblk->decompressor->init(msblk,
91                                                stream->comp_opts);
92        if (IS_ERR(decomp_strm->stream)) {
93                err = PTR_ERR(decomp_strm->stream);
94                goto out;
95        }
96
97        list_add(&decomp_strm->list, &stream->strm_list);
98        stream->avail_decomp = 1;
99        return stream;
100
101out:
102        kfree(decomp_strm);
103        kfree(stream);
104        return ERR_PTR(err);
105}
106
107
108void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk)
109{
110        struct squashfs_stream *stream = msblk->stream;
111        if (stream) {
112                struct decomp_stream *decomp_strm;
113
114                while (!list_empty(&stream->strm_list)) {
115                        decomp_strm = list_entry(stream->strm_list.prev,
116                                                struct decomp_stream, list);
117                        list_del(&decomp_strm->list);
118                        msblk->decompressor->free(decomp_strm->stream);
119                        kfree(decomp_strm);
120                        stream->avail_decomp--;
121                }
122                WARN_ON(stream->avail_decomp);
123                kfree(stream->comp_opts);
124                kfree(stream);
125        }
126}
127
128
129static struct decomp_stream *get_decomp_stream(struct squashfs_sb_info *msblk,
130                                        struct squashfs_stream *stream)
131{
132        struct decomp_stream *decomp_strm;
133
134        while (1) {
135                mutex_lock(&stream->mutex);
136
137                /* There is available decomp_stream */
138                if (!list_empty(&stream->strm_list)) {
139                        decomp_strm = list_entry(stream->strm_list.prev,
140                                struct decomp_stream, list);
141                        list_del(&decomp_strm->list);
142                        mutex_unlock(&stream->mutex);
143                        break;
144                }
145
146                /*
147                 * If there is no available decomp and already full,
148                 * let's wait for releasing decomp from other users.
149                 */
150                if (stream->avail_decomp >= MAX_DECOMPRESSOR)
151                        goto wait;
152
153                /* Let's allocate new decomp */
154                decomp_strm = kmalloc(sizeof(*decomp_strm), GFP_KERNEL);
155                if (!decomp_strm)
156                        goto wait;
157
158                decomp_strm->stream = msblk->decompressor->init(msblk,
159                                                stream->comp_opts);
160                if (IS_ERR(decomp_strm->stream)) {
161                        kfree(decomp_strm);
162                        goto wait;
163                }
164
165                stream->avail_decomp++;
166                WARN_ON(stream->avail_decomp > MAX_DECOMPRESSOR);
167
168                mutex_unlock(&stream->mutex);
169                break;
170wait:
171                /*
172                 * If system memory is tough, let's for other's
173                 * releasing instead of hurting VM because it could
174                 * make page cache thrashing.
175                 */
176                mutex_unlock(&stream->mutex);
177                wait_event(stream->wait,
178                        !list_empty(&stream->strm_list));
179        }
180
181        return decomp_strm;
182}
183
184
185int squashfs_decompress(struct squashfs_sb_info *msblk, struct buffer_head **bh,
186        int b, int offset, int length, struct squashfs_page_actor *output)
187{
188        int res;
189        struct squashfs_stream *stream = msblk->stream;
190        struct decomp_stream *decomp_stream = get_decomp_stream(msblk, stream);
191        res = msblk->decompressor->decompress(msblk, decomp_stream->stream,
192                bh, b, offset, length, output);
193        put_decomp_stream(decomp_stream, stream);
194        if (res < 0)
195                ERROR("%s decompression failed, data probably corrupt\n",
196                        msblk->decompressor->name);
197        return res;
198}
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