Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * Copyright (C) 2001 Sistina Software (UK) Limited | |
3 | * | |
4 | * This file is released under the GPL. | |
5 | */ | |
6 | ||
7 | #include "dm.h" | |
8 | ||
9 | #include <linux/module.h> | |
10 | #include <linux/init.h> | |
11 | #include <linux/kmod.h> | |
12 | #include <linux/bio.h> | |
13 | #include <linux/slab.h> | |
14 | ||
72d94861 AK |
15 | #define DM_MSG_PREFIX "target" |
16 | ||
1da177e4 LT |
17 | static LIST_HEAD(_targets); |
18 | static DECLARE_RWSEM(_lock); | |
19 | ||
20 | #define DM_MOD_NAME_SIZE 32 | |
21 | ||
45194e4f | 22 | static inline struct target_type *__find_target_type(const char *name) |
1da177e4 | 23 | { |
45194e4f | 24 | struct target_type *tt; |
1da177e4 | 25 | |
45194e4f CR |
26 | list_for_each_entry(tt, &_targets, list) |
27 | if (!strcmp(name, tt->name)) | |
28 | return tt; | |
1da177e4 LT |
29 | |
30 | return NULL; | |
31 | } | |
32 | ||
45194e4f | 33 | static struct target_type *get_target_type(const char *name) |
1da177e4 | 34 | { |
45194e4f | 35 | struct target_type *tt; |
1da177e4 LT |
36 | |
37 | down_read(&_lock); | |
38 | ||
45194e4f CR |
39 | tt = __find_target_type(name); |
40 | if (tt && !try_module_get(tt->module)) | |
41 | tt = NULL; | |
1da177e4 LT |
42 | |
43 | up_read(&_lock); | |
45194e4f | 44 | return tt; |
1da177e4 LT |
45 | } |
46 | ||
47 | static void load_module(const char *name) | |
48 | { | |
49 | request_module("dm-%s", name); | |
50 | } | |
51 | ||
52 | struct target_type *dm_get_target_type(const char *name) | |
53 | { | |
45194e4f | 54 | struct target_type *tt = get_target_type(name); |
1da177e4 | 55 | |
45194e4f | 56 | if (!tt) { |
1da177e4 | 57 | load_module(name); |
45194e4f | 58 | tt = get_target_type(name); |
1da177e4 LT |
59 | } |
60 | ||
45194e4f | 61 | return tt; |
1da177e4 LT |
62 | } |
63 | ||
45194e4f | 64 | void dm_put_target_type(struct target_type *tt) |
1da177e4 | 65 | { |
1da177e4 | 66 | down_read(&_lock); |
45194e4f | 67 | module_put(tt->module); |
1da177e4 | 68 | up_read(&_lock); |
1da177e4 LT |
69 | } |
70 | ||
1da177e4 LT |
71 | int dm_target_iterate(void (*iter_func)(struct target_type *tt, |
72 | void *param), void *param) | |
73 | { | |
45194e4f | 74 | struct target_type *tt; |
1da177e4 LT |
75 | |
76 | down_read(&_lock); | |
45194e4f CR |
77 | list_for_each_entry(tt, &_targets, list) |
78 | iter_func(tt, param); | |
1da177e4 LT |
79 | up_read(&_lock); |
80 | ||
81 | return 0; | |
82 | } | |
83 | ||
45194e4f | 84 | int dm_register_target(struct target_type *tt) |
1da177e4 LT |
85 | { |
86 | int rv = 0; | |
1da177e4 LT |
87 | |
88 | down_write(&_lock); | |
45194e4f | 89 | if (__find_target_type(tt->name)) |
1da177e4 LT |
90 | rv = -EEXIST; |
91 | else | |
45194e4f | 92 | list_add(&tt->list, &_targets); |
1da177e4 LT |
93 | |
94 | up_write(&_lock); | |
1da177e4 LT |
95 | return rv; |
96 | } | |
97 | ||
45194e4f | 98 | void dm_unregister_target(struct target_type *tt) |
1da177e4 | 99 | { |
1da177e4 | 100 | down_write(&_lock); |
45194e4f CR |
101 | if (!__find_target_type(tt->name)) { |
102 | DMCRIT("Unregistering unrecognised target: %s", tt->name); | |
10d3bd09 | 103 | BUG(); |
1da177e4 LT |
104 | } |
105 | ||
45194e4f | 106 | list_del(&tt->list); |
1da177e4 LT |
107 | |
108 | up_write(&_lock); | |
1da177e4 LT |
109 | } |
110 | ||
111 | /* | |
112 | * io-err: always fails an io, useful for bringing | |
113 | * up LVs that have holes in them. | |
114 | */ | |
45194e4f | 115 | static int io_err_ctr(struct dm_target *tt, unsigned int argc, char **args) |
1da177e4 LT |
116 | { |
117 | return 0; | |
118 | } | |
119 | ||
45194e4f | 120 | static void io_err_dtr(struct dm_target *tt) |
1da177e4 LT |
121 | { |
122 | /* empty */ | |
123 | } | |
124 | ||
45194e4f | 125 | static int io_err_map(struct dm_target *tt, struct bio *bio, |
1da177e4 LT |
126 | union map_info *map_context) |
127 | { | |
128 | return -EIO; | |
129 | } | |
130 | ||
131 | static struct target_type error_target = { | |
132 | .name = "error", | |
133 | .version = {1, 0, 1}, | |
134 | .ctr = io_err_ctr, | |
135 | .dtr = io_err_dtr, | |
136 | .map = io_err_map, | |
137 | }; | |
138 | ||
139 | int __init dm_target_init(void) | |
140 | { | |
141 | return dm_register_target(&error_target); | |
142 | } | |
143 | ||
144 | void dm_target_exit(void) | |
145 | { | |
10d3bd09 | 146 | dm_unregister_target(&error_target); |
1da177e4 LT |
147 | } |
148 | ||
149 | EXPORT_SYMBOL(dm_register_target); | |
150 | EXPORT_SYMBOL(dm_unregister_target); |