1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (c) 2013
4  * Phillip Lougher <phillip@squashfs.org.uk>
5  */
6 
7 #include <linux/types.h>
8 #include <linux/slab.h>
9 #include <linux/percpu.h>
10 #include <linux/buffer_head.h>
11 #include <linux/local_lock.h>
12 
13 #include "squashfs_fs.h"
14 #include "squashfs_fs_sb.h"
15 #include "decompressor.h"
16 #include "squashfs.h"
17 
18 /*
19  * This file implements multi-threaded decompression using percpu
20  * variables, one thread per cpu core.
21  */
22 
23 struct squashfs_stream {
24 	void			*stream;
25 	local_lock_t	lock;
26 };
27 
28 static void *squashfs_decompressor_create(struct squashfs_sb_info *msblk,
29 						void *comp_opts)
30 {
31 	struct squashfs_stream *stream;
32 	struct squashfs_stream __percpu *percpu;
33 	int err, cpu;
34 
35 	percpu = alloc_percpu(struct squashfs_stream);
36 	if (percpu == NULL)
37 		return ERR_PTR(-ENOMEM);
38 
39 	for_each_possible_cpu(cpu) {
40 		stream = per_cpu_ptr(percpu, cpu);
41 		stream->stream = msblk->decompressor->init(msblk, comp_opts);
42 		if (IS_ERR(stream->stream)) {
43 			err = PTR_ERR(stream->stream);
44 			goto out;
45 		}
46 		local_lock_init(&stream->lock);
47 	}
48 
49 	kfree(comp_opts);
50 	return (__force void *) percpu;
51 
52 out:
53 	for_each_possible_cpu(cpu) {
54 		stream = per_cpu_ptr(percpu, cpu);
55 		if (!IS_ERR_OR_NULL(stream->stream))
56 			msblk->decompressor->free(stream->stream);
57 	}
58 	free_percpu(percpu);
59 	return ERR_PTR(err);
60 }
61 
62 static void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk)
63 {
64 	struct squashfs_stream __percpu *percpu =
65 			(struct squashfs_stream __percpu *) msblk->stream;
66 	struct squashfs_stream *stream;
67 	int cpu;
68 
69 	if (msblk->stream) {
70 		for_each_possible_cpu(cpu) {
71 			stream = per_cpu_ptr(percpu, cpu);
72 			msblk->decompressor->free(stream->stream);
73 		}
74 		free_percpu(percpu);
75 	}
76 }
77 
78 static int squashfs_decompress(struct squashfs_sb_info *msblk, struct bio *bio,
79 	int offset, int length, struct squashfs_page_actor *output)
80 {
81 	struct squashfs_stream *stream;
82 	struct squashfs_stream __percpu *percpu =
83 			(struct squashfs_stream __percpu *) msblk->stream;
84 	int res;
85 
86 	local_lock(&percpu->lock);
87 	stream = this_cpu_ptr(percpu);
88 
89 	res = msblk->decompressor->decompress(msblk, stream->stream, bio,
90 					      offset, length, output);
91 
92 	local_unlock(&percpu->lock);
93 
94 	if (res < 0)
95 		ERROR("%s decompression failed, data probably corrupt\n",
96 			msblk->decompressor->name);
97 
98 	return res;
99 }
100 
101 static int squashfs_max_decompressors(void)
102 {
103 	return num_possible_cpus();
104 }
105 
106 const struct squashfs_decompressor_thread_ops squashfs_decompressor_percpu = {
107 	.create = squashfs_decompressor_create,
108 	.destroy = squashfs_decompressor_destroy,
109 	.decompress = squashfs_decompress,
110 	.max_decompressors = squashfs_max_decompressors,
111 };
112