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d7e09d03 PT |
1 | /* |
2 | * GPL HEADER START | |
3 | * | |
4 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 only, | |
8 | * as published by the Free Software Foundation. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, but | |
11 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | * General Public License version 2 for more details (a copy is included | |
14 | * in the LICENSE file that accompanied this code). | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * version 2 along with this program; If not, see | |
18 | * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf | |
19 | * | |
20 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
21 | * CA 95054 USA or visit www.sun.com if you need additional information or | |
22 | * have any questions. | |
23 | * | |
24 | * GPL HEADER END | |
25 | */ | |
26 | /* | |
27 | * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved. | |
28 | * Use is subject to license terms. | |
29 | */ | |
30 | /* | |
31 | * This file is part of Lustre, http://www.lustre.org/ | |
32 | * Lustre is a trademark of Sun Microsystems, Inc. | |
33 | */ | |
34 | ||
35 | #define DEBUG_SUBSYSTEM S_FILTER | |
36 | ||
37 | #include <linux/fs.h> | |
d7e09d03 PT |
38 | #include <linux/module.h> |
39 | #include <linux/kmod.h> | |
40 | #include <linux/slab.h> | |
9fdaf8c0 | 41 | #include "../../include/linux/libcfs/libcfs.h" |
d7e09d03 PT |
42 | #include <lustre_fsfilt.h> |
43 | ||
44 | LIST_HEAD(fsfilt_types); | |
45 | ||
46 | static struct fsfilt_operations *fsfilt_search_type(const char *type) | |
47 | { | |
48 | struct fsfilt_operations *found; | |
49 | struct list_head *p; | |
50 | ||
51 | list_for_each(p, &fsfilt_types) { | |
52 | found = list_entry(p, struct fsfilt_operations, fs_list); | |
497aaa5c | 53 | if (!strcmp(found->fs_type, type)) |
d7e09d03 | 54 | return found; |
d7e09d03 PT |
55 | } |
56 | return NULL; | |
57 | } | |
58 | ||
59 | int fsfilt_register_ops(struct fsfilt_operations *fs_ops) | |
60 | { | |
61 | struct fsfilt_operations *found; | |
62 | ||
63 | /* lock fsfilt_types list */ | |
3e67cdf5 JB |
64 | found = fsfilt_search_type(fs_ops->fs_type); |
65 | if (found) { | |
d7e09d03 PT |
66 | if (found != fs_ops) { |
67 | CERROR("different operations for type %s\n", | |
68 | fs_ops->fs_type); | |
69 | /* unlock fsfilt_types list */ | |
0a3bdb00 | 70 | return -EEXIST; |
d7e09d03 PT |
71 | } |
72 | } else { | |
73 | try_module_get(THIS_MODULE); | |
74 | list_add(&fs_ops->fs_list, &fsfilt_types); | |
75 | } | |
76 | ||
77 | /* unlock fsfilt_types list */ | |
78 | return 0; | |
79 | } | |
80 | EXPORT_SYMBOL(fsfilt_register_ops); | |
81 | ||
82 | void fsfilt_unregister_ops(struct fsfilt_operations *fs_ops) | |
83 | { | |
84 | struct list_head *p; | |
85 | ||
86 | /* lock fsfilt_types list */ | |
87 | list_for_each(p, &fsfilt_types) { | |
88 | struct fsfilt_operations *found; | |
89 | ||
90 | found = list_entry(p, typeof(*found), fs_list); | |
91 | if (found == fs_ops) { | |
92 | list_del(p); | |
93 | module_put(THIS_MODULE); | |
94 | break; | |
95 | } | |
96 | } | |
97 | /* unlock fsfilt_types list */ | |
98 | } | |
99 | EXPORT_SYMBOL(fsfilt_unregister_ops); | |
100 | ||
101 | struct fsfilt_operations *fsfilt_get_ops(const char *type) | |
102 | { | |
103 | struct fsfilt_operations *fs_ops; | |
104 | ||
105 | /* lock fsfilt_types list */ | |
3e67cdf5 JB |
106 | fs_ops = fsfilt_search_type(type); |
107 | if (!fs_ops) { | |
d7e09d03 PT |
108 | char name[32]; |
109 | int rc; | |
110 | ||
111 | snprintf(name, sizeof(name) - 1, "fsfilt_%s", type); | |
112 | name[sizeof(name) - 1] = '\0'; | |
113 | ||
3e67cdf5 JB |
114 | rc = request_module("%s", name); |
115 | if (!rc) { | |
d7e09d03 PT |
116 | fs_ops = fsfilt_search_type(type); |
117 | CDEBUG(D_INFO, "Loaded module '%s'\n", name); | |
118 | if (!fs_ops) | |
119 | rc = -ENOENT; | |
120 | } | |
121 | ||
122 | if (rc) { | |
123 | CERROR("Can't find %s interface\n", name); | |
0a3bdb00 | 124 | return ERR_PTR(rc < 0 ? rc : -rc); |
d7e09d03 PT |
125 | /* unlock fsfilt_types list */ |
126 | } | |
127 | } | |
128 | try_module_get(fs_ops->fs_owner); | |
129 | /* unlock fsfilt_types list */ | |
130 | ||
131 | return fs_ops; | |
132 | } | |
133 | EXPORT_SYMBOL(fsfilt_get_ops); | |
134 | ||
135 | void fsfilt_put_ops(struct fsfilt_operations *fs_ops) | |
136 | { | |
137 | module_put(fs_ops->fs_owner); | |
138 | } | |
139 | EXPORT_SYMBOL(fsfilt_put_ops); |