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1e1236b8 DH |
1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* General filesystem local caching manager | |
3 | * | |
4 | * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. | |
5 | * Written by David Howells (dhowells@redhat.com) | |
6 | */ | |
7 | ||
8 | #define FSCACHE_DEBUG_LEVEL CACHE | |
9 | #include <linux/module.h> | |
10 | #include <linux/init.h> | |
11 | #define CREATE_TRACE_POINTS | |
12 | #include "internal.h" | |
13 | ||
14 | MODULE_DESCRIPTION("FS Cache Manager"); | |
15 | MODULE_AUTHOR("Red Hat, Inc."); | |
16 | MODULE_LICENSE("GPL"); | |
17 | ||
18 | unsigned fscache_debug; | |
19 | module_param_named(debug, fscache_debug, uint, | |
20 | S_IWUSR | S_IRUGO); | |
21 | MODULE_PARM_DESC(fscache_debug, | |
22 | "FS-Cache debugging mask"); | |
23 | ||
23e12e28 | 24 | EXPORT_TRACEPOINT_SYMBOL(fscache_access_cache); |
e6acd329 | 25 | EXPORT_TRACEPOINT_SYMBOL(fscache_access_volume); |
a7733fb6 | 26 | EXPORT_TRACEPOINT_SYMBOL(fscache_access); |
23e12e28 | 27 | |
1e1236b8 DH |
28 | struct workqueue_struct *fscache_wq; |
29 | EXPORT_SYMBOL(fscache_wq); | |
30 | ||
e8a07c9d DH |
31 | /* |
32 | * Mixing scores (in bits) for (7,20): | |
33 | * Input delta: 1-bit 2-bit | |
34 | * 1 round: 330.3 9201.6 | |
35 | * 2 rounds: 1246.4 25475.4 | |
36 | * 3 rounds: 1907.1 31295.1 | |
37 | * 4 rounds: 2042.3 31718.6 | |
38 | * Perfect: 2048 31744 | |
39 | * (32*64) (32*31/2 * 64) | |
40 | */ | |
41 | #define HASH_MIX(x, y, a) \ | |
42 | ( x ^= (a), \ | |
43 | y ^= x, x = rol32(x, 7),\ | |
44 | x += y, y = rol32(y,20),\ | |
45 | y *= 9 ) | |
46 | ||
47 | static inline unsigned int fold_hash(unsigned long x, unsigned long y) | |
48 | { | |
49 | /* Use arch-optimized multiply if one exists */ | |
50 | return __hash_32(y ^ __hash_32(x)); | |
51 | } | |
52 | ||
53 | /* | |
54 | * Generate a hash. This is derived from full_name_hash(), but we want to be | |
55 | * sure it is arch independent and that it doesn't change as bits of the | |
56 | * computed hash value might appear on disk. The caller must guarantee that | |
57 | * the source data is a multiple of four bytes in size. | |
58 | */ | |
59 | unsigned int fscache_hash(unsigned int salt, const void *data, size_t len) | |
60 | { | |
61 | const __le32 *p = data; | |
62 | unsigned int a, x = 0, y = salt, n = len / sizeof(__le32); | |
63 | ||
64 | for (; n; n--) { | |
65 | a = le32_to_cpu(*p++); | |
66 | HASH_MIX(x, y, a); | |
67 | } | |
68 | return fold_hash(x, y); | |
69 | } | |
70 | ||
1e1236b8 DH |
71 | /* |
72 | * initialise the fs caching module | |
73 | */ | |
74 | static int __init fscache_init(void) | |
75 | { | |
76 | int ret = -ENOMEM; | |
77 | ||
78 | fscache_wq = alloc_workqueue("fscache", WQ_UNBOUND | WQ_FREEZABLE, 0); | |
79 | if (!fscache_wq) | |
80 | goto error_wq; | |
81 | ||
82 | ret = fscache_proc_init(); | |
83 | if (ret < 0) | |
84 | goto error_proc; | |
85 | ||
7f3283ab DH |
86 | fscache_cookie_jar = kmem_cache_create("fscache_cookie_jar", |
87 | sizeof(struct fscache_cookie), | |
88 | 0, 0, NULL); | |
89 | if (!fscache_cookie_jar) { | |
90 | pr_notice("Failed to allocate a cookie jar\n"); | |
91 | ret = -ENOMEM; | |
92 | goto error_cookie_jar; | |
93 | } | |
94 | ||
1e1236b8 DH |
95 | pr_notice("Loaded\n"); |
96 | return 0; | |
97 | ||
7f3283ab DH |
98 | error_cookie_jar: |
99 | fscache_proc_cleanup(); | |
1e1236b8 DH |
100 | error_proc: |
101 | destroy_workqueue(fscache_wq); | |
102 | error_wq: | |
103 | return ret; | |
104 | } | |
105 | ||
106 | fs_initcall(fscache_init); | |
107 | ||
108 | /* | |
109 | * clean up on module removal | |
110 | */ | |
111 | static void __exit fscache_exit(void) | |
112 | { | |
113 | _enter(""); | |
114 | ||
7f3283ab | 115 | kmem_cache_destroy(fscache_cookie_jar); |
1e1236b8 DH |
116 | fscache_proc_cleanup(); |
117 | destroy_workqueue(fscache_wq); | |
118 | pr_notice("Unloaded\n"); | |
119 | } | |
120 | ||
121 | module_exit(fscache_exit); |