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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 | ||
4cc96131 | 7 | #include "dm-core.h" |
1da177e4 LT |
8 | |
9 | #include <linux/module.h> | |
10 | #include <linux/init.h> | |
11 | #include <linux/kmod.h> | |
12 | #include <linux/bio.h> | |
1da177e4 | 13 | |
72d94861 AK |
14 | #define DM_MSG_PREFIX "target" |
15 | ||
1da177e4 LT |
16 | static LIST_HEAD(_targets); |
17 | static DECLARE_RWSEM(_lock); | |
18 | ||
45194e4f | 19 | static inline struct target_type *__find_target_type(const char *name) |
1da177e4 | 20 | { |
45194e4f | 21 | struct target_type *tt; |
1da177e4 | 22 | |
45194e4f CR |
23 | list_for_each_entry(tt, &_targets, list) |
24 | if (!strcmp(name, tt->name)) | |
25 | return tt; | |
1da177e4 LT |
26 | |
27 | return NULL; | |
28 | } | |
29 | ||
45194e4f | 30 | static struct target_type *get_target_type(const char *name) |
1da177e4 | 31 | { |
45194e4f | 32 | struct target_type *tt; |
1da177e4 LT |
33 | |
34 | down_read(&_lock); | |
35 | ||
45194e4f CR |
36 | tt = __find_target_type(name); |
37 | if (tt && !try_module_get(tt->module)) | |
38 | tt = NULL; | |
1da177e4 LT |
39 | |
40 | up_read(&_lock); | |
45194e4f | 41 | return tt; |
1da177e4 LT |
42 | } |
43 | ||
44 | static void load_module(const char *name) | |
45 | { | |
46 | request_module("dm-%s", name); | |
47 | } | |
48 | ||
49 | struct target_type *dm_get_target_type(const char *name) | |
50 | { | |
45194e4f | 51 | struct target_type *tt = get_target_type(name); |
1da177e4 | 52 | |
45194e4f | 53 | if (!tt) { |
1da177e4 | 54 | load_module(name); |
45194e4f | 55 | tt = get_target_type(name); |
1da177e4 LT |
56 | } |
57 | ||
45194e4f | 58 | return tt; |
1da177e4 LT |
59 | } |
60 | ||
45194e4f | 61 | void dm_put_target_type(struct target_type *tt) |
1da177e4 | 62 | { |
1da177e4 | 63 | down_read(&_lock); |
45194e4f | 64 | module_put(tt->module); |
1da177e4 | 65 | up_read(&_lock); |
1da177e4 LT |
66 | } |
67 | ||
1da177e4 LT |
68 | int dm_target_iterate(void (*iter_func)(struct target_type *tt, |
69 | void *param), void *param) | |
70 | { | |
45194e4f | 71 | struct target_type *tt; |
1da177e4 LT |
72 | |
73 | down_read(&_lock); | |
45194e4f CR |
74 | list_for_each_entry(tt, &_targets, list) |
75 | iter_func(tt, param); | |
1da177e4 LT |
76 | up_read(&_lock); |
77 | ||
78 | return 0; | |
79 | } | |
80 | ||
45194e4f | 81 | int dm_register_target(struct target_type *tt) |
1da177e4 LT |
82 | { |
83 | int rv = 0; | |
1da177e4 LT |
84 | |
85 | down_write(&_lock); | |
45194e4f | 86 | if (__find_target_type(tt->name)) |
1da177e4 LT |
87 | rv = -EEXIST; |
88 | else | |
45194e4f | 89 | list_add(&tt->list, &_targets); |
1da177e4 LT |
90 | |
91 | up_write(&_lock); | |
1da177e4 LT |
92 | return rv; |
93 | } | |
94 | ||
45194e4f | 95 | void dm_unregister_target(struct target_type *tt) |
1da177e4 | 96 | { |
1da177e4 | 97 | down_write(&_lock); |
45194e4f CR |
98 | if (!__find_target_type(tt->name)) { |
99 | DMCRIT("Unregistering unrecognised target: %s", tt->name); | |
10d3bd09 | 100 | BUG(); |
1da177e4 LT |
101 | } |
102 | ||
45194e4f | 103 | list_del(&tt->list); |
1da177e4 LT |
104 | |
105 | up_write(&_lock); | |
1da177e4 LT |
106 | } |
107 | ||
108 | /* | |
109 | * io-err: always fails an io, useful for bringing | |
110 | * up LVs that have holes in them. | |
111 | */ | |
45194e4f | 112 | static int io_err_ctr(struct dm_target *tt, unsigned int argc, char **args) |
1da177e4 | 113 | { |
38e1b257 MS |
114 | /* |
115 | * Return error for discards instead of -EOPNOTSUPP | |
116 | */ | |
55a62eef | 117 | tt->num_discard_bios = 1; |
38e1b257 | 118 | |
1da177e4 LT |
119 | return 0; |
120 | } | |
121 | ||
45194e4f | 122 | static void io_err_dtr(struct dm_target *tt) |
1da177e4 LT |
123 | { |
124 | /* empty */ | |
125 | } | |
126 | ||
7de3ee57 | 127 | static int io_err_map(struct dm_target *tt, struct bio *bio) |
1da177e4 | 128 | { |
846785e6 | 129 | return DM_MAPIO_KILL; |
1da177e4 LT |
130 | } |
131 | ||
e5863d9a MS |
132 | static int io_err_clone_and_map_rq(struct dm_target *ti, struct request *rq, |
133 | union map_info *map_context, | |
134 | struct request **clone) | |
135 | { | |
412445ac | 136 | return DM_MAPIO_KILL; |
e5863d9a MS |
137 | } |
138 | ||
5de719e3 YY |
139 | static void io_err_release_clone_rq(struct request *clone, |
140 | union map_info *map_context) | |
e5863d9a MS |
141 | { |
142 | } | |
143 | ||
817bf402 DW |
144 | static long io_err_dax_direct_access(struct dm_target *ti, pgoff_t pgoff, |
145 | long nr_pages, void **kaddr, pfn_t *pfn) | |
f8df1fdf MS |
146 | { |
147 | return -EIO; | |
148 | } | |
149 | ||
1da177e4 LT |
150 | static struct target_type error_target = { |
151 | .name = "error", | |
f8df1fdf | 152 | .version = {1, 5, 0}, |
f083b09b | 153 | .features = DM_TARGET_WILDCARD, |
1da177e4 LT |
154 | .ctr = io_err_ctr, |
155 | .dtr = io_err_dtr, | |
156 | .map = io_err_map, | |
e5863d9a MS |
157 | .clone_and_map_rq = io_err_clone_and_map_rq, |
158 | .release_clone_rq = io_err_release_clone_rq, | |
817bf402 | 159 | .direct_access = io_err_dax_direct_access, |
1da177e4 LT |
160 | }; |
161 | ||
162 | int __init dm_target_init(void) | |
163 | { | |
164 | return dm_register_target(&error_target); | |
165 | } | |
166 | ||
167 | void dm_target_exit(void) | |
168 | { | |
10d3bd09 | 169 | dm_unregister_target(&error_target); |
1da177e4 LT |
170 | } |
171 | ||
172 | EXPORT_SYMBOL(dm_register_target); | |
173 | EXPORT_SYMBOL(dm_unregister_target); |