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> | |
e511c4a3 | 13 | #include <linux/dax.h> |
1da177e4 | 14 | |
72d94861 AK |
15 | #define DM_MSG_PREFIX "target" |
16 | ||
1da177e4 LT |
17 | static LIST_HEAD(_targets); |
18 | static DECLARE_RWSEM(_lock); | |
19 | ||
45194e4f | 20 | static inline struct target_type *__find_target_type(const char *name) |
1da177e4 | 21 | { |
45194e4f | 22 | struct target_type *tt; |
1da177e4 | 23 | |
45194e4f CR |
24 | list_for_each_entry(tt, &_targets, list) |
25 | if (!strcmp(name, tt->name)) | |
26 | return tt; | |
1da177e4 LT |
27 | |
28 | return NULL; | |
29 | } | |
30 | ||
45194e4f | 31 | static struct target_type *get_target_type(const char *name) |
1da177e4 | 32 | { |
45194e4f | 33 | struct target_type *tt; |
1da177e4 LT |
34 | |
35 | down_read(&_lock); | |
36 | ||
45194e4f CR |
37 | tt = __find_target_type(name); |
38 | if (tt && !try_module_get(tt->module)) | |
39 | tt = NULL; | |
1da177e4 LT |
40 | |
41 | up_read(&_lock); | |
45194e4f | 42 | return tt; |
1da177e4 LT |
43 | } |
44 | ||
45 | static void load_module(const char *name) | |
46 | { | |
47 | request_module("dm-%s", name); | |
48 | } | |
49 | ||
50 | struct target_type *dm_get_target_type(const char *name) | |
51 | { | |
45194e4f | 52 | struct target_type *tt = get_target_type(name); |
1da177e4 | 53 | |
45194e4f | 54 | if (!tt) { |
1da177e4 | 55 | load_module(name); |
45194e4f | 56 | tt = get_target_type(name); |
1da177e4 LT |
57 | } |
58 | ||
45194e4f | 59 | return tt; |
1da177e4 LT |
60 | } |
61 | ||
45194e4f | 62 | void dm_put_target_type(struct target_type *tt) |
1da177e4 | 63 | { |
1da177e4 | 64 | down_read(&_lock); |
45194e4f | 65 | module_put(tt->module); |
1da177e4 | 66 | up_read(&_lock); |
1da177e4 LT |
67 | } |
68 | ||
1da177e4 LT |
69 | int dm_target_iterate(void (*iter_func)(struct target_type *tt, |
70 | void *param), void *param) | |
71 | { | |
45194e4f | 72 | struct target_type *tt; |
1da177e4 LT |
73 | |
74 | down_read(&_lock); | |
45194e4f CR |
75 | list_for_each_entry(tt, &_targets, list) |
76 | iter_func(tt, param); | |
1da177e4 LT |
77 | up_read(&_lock); |
78 | ||
79 | return 0; | |
80 | } | |
81 | ||
45194e4f | 82 | int dm_register_target(struct target_type *tt) |
1da177e4 LT |
83 | { |
84 | int rv = 0; | |
1da177e4 LT |
85 | |
86 | down_write(&_lock); | |
45194e4f | 87 | if (__find_target_type(tt->name)) |
1da177e4 LT |
88 | rv = -EEXIST; |
89 | else | |
45194e4f | 90 | list_add(&tt->list, &_targets); |
1da177e4 LT |
91 | |
92 | up_write(&_lock); | |
1da177e4 LT |
93 | return rv; |
94 | } | |
95 | ||
45194e4f | 96 | void dm_unregister_target(struct target_type *tt) |
1da177e4 | 97 | { |
1da177e4 | 98 | down_write(&_lock); |
45194e4f CR |
99 | if (!__find_target_type(tt->name)) { |
100 | DMCRIT("Unregistering unrecognised target: %s", tt->name); | |
10d3bd09 | 101 | BUG(); |
1da177e4 LT |
102 | } |
103 | ||
45194e4f | 104 | list_del(&tt->list); |
1da177e4 LT |
105 | |
106 | up_write(&_lock); | |
1da177e4 LT |
107 | } |
108 | ||
109 | /* | |
110 | * io-err: always fails an io, useful for bringing | |
111 | * up LVs that have holes in them. | |
112 | */ | |
45194e4f | 113 | static int io_err_ctr(struct dm_target *tt, unsigned int argc, char **args) |
1da177e4 | 114 | { |
38e1b257 MS |
115 | /* |
116 | * Return error for discards instead of -EOPNOTSUPP | |
117 | */ | |
55a62eef | 118 | tt->num_discard_bios = 1; |
38e1b257 | 119 | |
1da177e4 LT |
120 | return 0; |
121 | } | |
122 | ||
45194e4f | 123 | static void io_err_dtr(struct dm_target *tt) |
1da177e4 LT |
124 | { |
125 | /* empty */ | |
126 | } | |
127 | ||
7de3ee57 | 128 | static int io_err_map(struct dm_target *tt, struct bio *bio) |
1da177e4 | 129 | { |
846785e6 | 130 | return DM_MAPIO_KILL; |
1da177e4 LT |
131 | } |
132 | ||
e5863d9a MS |
133 | static int io_err_clone_and_map_rq(struct dm_target *ti, struct request *rq, |
134 | union map_info *map_context, | |
135 | struct request **clone) | |
136 | { | |
412445ac | 137 | return DM_MAPIO_KILL; |
e5863d9a MS |
138 | } |
139 | ||
5de719e3 YY |
140 | static void io_err_release_clone_rq(struct request *clone, |
141 | union map_info *map_context) | |
e5863d9a MS |
142 | { |
143 | } | |
144 | ||
817bf402 | 145 | static long io_err_dax_direct_access(struct dm_target *ti, pgoff_t pgoff, |
e511c4a3 JC |
146 | long nr_pages, enum dax_access_mode mode, void **kaddr, |
147 | pfn_t *pfn) | |
f8df1fdf MS |
148 | { |
149 | return -EIO; | |
150 | } | |
151 | ||
1da177e4 LT |
152 | static struct target_type error_target = { |
153 | .name = "error", | |
f8df1fdf | 154 | .version = {1, 5, 0}, |
f083b09b | 155 | .features = DM_TARGET_WILDCARD, |
1da177e4 LT |
156 | .ctr = io_err_ctr, |
157 | .dtr = io_err_dtr, | |
158 | .map = io_err_map, | |
e5863d9a MS |
159 | .clone_and_map_rq = io_err_clone_and_map_rq, |
160 | .release_clone_rq = io_err_release_clone_rq, | |
817bf402 | 161 | .direct_access = io_err_dax_direct_access, |
1da177e4 LT |
162 | }; |
163 | ||
164 | int __init dm_target_init(void) | |
165 | { | |
166 | return dm_register_target(&error_target); | |
167 | } | |
168 | ||
169 | void dm_target_exit(void) | |
170 | { | |
10d3bd09 | 171 | dm_unregister_target(&error_target); |
1da177e4 LT |
172 | } |
173 | ||
174 | EXPORT_SYMBOL(dm_register_target); | |
175 | EXPORT_SYMBOL(dm_unregister_target); |