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 | |
24 | EXPORT_TRACEPOINT_SYMBOL(fscache_access_cache); |
25 | EXPORT_TRACEPOINT_SYMBOL(fscache_access_volume); |
26 | EXPORT_TRACEPOINT_SYMBOL(fscache_access); |
27 | |
28 | struct workqueue_struct *fscache_wq; |
29 | EXPORT_SYMBOL(fscache_wq); |
30 | |
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(val: y ^ __hash_32(val: 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 | |
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(fmt: "fscache" , flags: WQ_UNBOUND | WQ_FREEZABLE, max_active: 0); |
79 | if (!fscache_wq) |
80 | goto error_wq; |
81 | |
82 | ret = fscache_proc_init(); |
83 | if (ret < 0) |
84 | goto error_proc; |
85 | |
86 | fscache_cookie_jar = kmem_cache_create(name: "fscache_cookie_jar" , |
87 | size: sizeof(struct fscache_cookie), |
88 | align: 0, flags: 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 | |
95 | pr_notice("Loaded\n" ); |
96 | return 0; |
97 | |
98 | error_cookie_jar: |
99 | fscache_proc_cleanup(); |
100 | error_proc: |
101 | destroy_workqueue(wq: 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 | |
115 | kmem_cache_destroy(s: fscache_cookie_jar); |
116 | fscache_proc_cleanup(); |
117 | destroy_workqueue(wq: fscache_wq); |
118 | pr_notice("Unloaded\n" ); |
119 | } |
120 | |
121 | module_exit(fscache_exit); |
122 | |