1 /*
2  * Copyright (c) 2013
3  * Phillip Lougher <phillip@squashfs.org.uk>
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 
9 #include <linux/types.h>
10 #include <linux/slab.h>
11 #include <linux/percpu.h>
12 #include <linux/buffer_head.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 using percpu
21  * variables, one thread per cpu core.
22  */
23 
24 struct squashfs_stream {
25 	void		*stream;
26 };
27 
28 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 	}
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 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 int squashfs_decompress(struct squashfs_sb_info *msblk, struct buffer_head **bh,
78 	int b, int offset, int length, struct squashfs_page_actor *output)
79 {
80 	struct squashfs_stream __percpu *percpu =
81 			(struct squashfs_stream __percpu *) msblk->stream;
82 	struct squashfs_stream *stream = get_cpu_ptr(percpu);
83 	int res = msblk->decompressor->decompress(msblk, stream->stream, bh, b,
84 		offset, length, output);
85 	put_cpu_ptr(stream);
86 
87 	if (res < 0)
88 		ERROR("%s decompression failed, data probably corrupt\n",
89 			msblk->decompressor->name);
90 
91 	return res;
92 }
93 
94 int squashfs_max_decompressors(void)
95 {
96 	return num_possible_cpus();
97 }
98