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