| 1 | /* |
| 2 | * Copyright (C) 2001 Sistina Software (UK) Limited |
| 3 | * |
| 4 | * This file is released under the GPL. |
| 5 | */ |
| 6 | |
| 7 | #include "dm-core.h" |
| 8 | |
| 9 | #include <linux/module.h> |
| 10 | #include <linux/init.h> |
| 11 | #include <linux/kmod.h> |
| 12 | #include <linux/bio.h> |
| 13 | |
| 14 | #define DM_MSG_PREFIX "target" |
| 15 | |
| 16 | static LIST_HEAD(_targets); |
| 17 | static DECLARE_RWSEM(_lock); |
| 18 | |
| 19 | #define DM_MOD_NAME_SIZE 32 |
| 20 | |
| 21 | static inline struct target_type *__find_target_type(const char *name) |
| 22 | { |
| 23 | struct target_type *tt; |
| 24 | |
| 25 | list_for_each_entry(tt, &_targets, list) |
| 26 | if (!strcmp(name, tt->name)) |
| 27 | return tt; |
| 28 | |
| 29 | return NULL; |
| 30 | } |
| 31 | |
| 32 | static struct target_type *get_target_type(const char *name) |
| 33 | { |
| 34 | struct target_type *tt; |
| 35 | |
| 36 | down_read(&_lock); |
| 37 | |
| 38 | tt = __find_target_type(name); |
| 39 | if (tt && !try_module_get(tt->module)) |
| 40 | tt = NULL; |
| 41 | |
| 42 | up_read(&_lock); |
| 43 | return tt; |
| 44 | } |
| 45 | |
| 46 | static void load_module(const char *name) |
| 47 | { |
| 48 | request_module("dm-%s", name); |
| 49 | } |
| 50 | |
| 51 | struct target_type *dm_get_target_type(const char *name) |
| 52 | { |
| 53 | struct target_type *tt = get_target_type(name); |
| 54 | |
| 55 | if (!tt) { |
| 56 | load_module(name); |
| 57 | tt = get_target_type(name); |
| 58 | } |
| 59 | |
| 60 | return tt; |
| 61 | } |
| 62 | |
| 63 | void dm_put_target_type(struct target_type *tt) |
| 64 | { |
| 65 | down_read(&_lock); |
| 66 | module_put(tt->module); |
| 67 | up_read(&_lock); |
| 68 | } |
| 69 | |
| 70 | int dm_target_iterate(void (*iter_func)(struct target_type *tt, |
| 71 | void *param), void *param) |
| 72 | { |
| 73 | struct target_type *tt; |
| 74 | |
| 75 | down_read(&_lock); |
| 76 | list_for_each_entry(tt, &_targets, list) |
| 77 | iter_func(tt, param); |
| 78 | up_read(&_lock); |
| 79 | |
| 80 | return 0; |
| 81 | } |
| 82 | |
| 83 | int dm_register_target(struct target_type *tt) |
| 84 | { |
| 85 | int rv = 0; |
| 86 | |
| 87 | down_write(&_lock); |
| 88 | if (__find_target_type(tt->name)) |
| 89 | rv = -EEXIST; |
| 90 | else |
| 91 | list_add(&tt->list, &_targets); |
| 92 | |
| 93 | up_write(&_lock); |
| 94 | return rv; |
| 95 | } |
| 96 | |
| 97 | void dm_unregister_target(struct target_type *tt) |
| 98 | { |
| 99 | down_write(&_lock); |
| 100 | if (!__find_target_type(tt->name)) { |
| 101 | DMCRIT("Unregistering unrecognised target: %s", tt->name); |
| 102 | BUG(); |
| 103 | } |
| 104 | |
| 105 | list_del(&tt->list); |
| 106 | |
| 107 | up_write(&_lock); |
| 108 | } |
| 109 | |
| 110 | /* |
| 111 | * io-err: always fails an io, useful for bringing |
| 112 | * up LVs that have holes in them. |
| 113 | */ |
| 114 | static int io_err_ctr(struct dm_target *tt, unsigned int argc, char **args) |
| 115 | { |
| 116 | /* |
| 117 | * Return error for discards instead of -EOPNOTSUPP |
| 118 | */ |
| 119 | tt->num_discard_bios = 1; |
| 120 | |
| 121 | return 0; |
| 122 | } |
| 123 | |
| 124 | static void io_err_dtr(struct dm_target *tt) |
| 125 | { |
| 126 | /* empty */ |
| 127 | } |
| 128 | |
| 129 | static int io_err_map(struct dm_target *tt, struct bio *bio) |
| 130 | { |
| 131 | return -EIO; |
| 132 | } |
| 133 | |
| 134 | static int io_err_map_rq(struct dm_target *ti, struct request *clone, |
| 135 | union map_info *map_context) |
| 136 | { |
| 137 | return -EIO; |
| 138 | } |
| 139 | |
| 140 | static int io_err_clone_and_map_rq(struct dm_target *ti, struct request *rq, |
| 141 | union map_info *map_context, |
| 142 | struct request **clone) |
| 143 | { |
| 144 | return -EIO; |
| 145 | } |
| 146 | |
| 147 | static void io_err_release_clone_rq(struct request *clone) |
| 148 | { |
| 149 | } |
| 150 | |
| 151 | static long io_err_direct_access(struct dm_target *ti, sector_t sector, |
| 152 | void **kaddr, pfn_t *pfn, long size) |
| 153 | { |
| 154 | return -EIO; |
| 155 | } |
| 156 | |
| 157 | static struct target_type error_target = { |
| 158 | .name = "error", |
| 159 | .version = {1, 5, 0}, |
| 160 | .features = DM_TARGET_WILDCARD, |
| 161 | .ctr = io_err_ctr, |
| 162 | .dtr = io_err_dtr, |
| 163 | .map = io_err_map, |
| 164 | .map_rq = io_err_map_rq, |
| 165 | .clone_and_map_rq = io_err_clone_and_map_rq, |
| 166 | .release_clone_rq = io_err_release_clone_rq, |
| 167 | .direct_access = io_err_direct_access, |
| 168 | }; |
| 169 | |
| 170 | int __init dm_target_init(void) |
| 171 | { |
| 172 | return dm_register_target(&error_target); |
| 173 | } |
| 174 | |
| 175 | void dm_target_exit(void) |
| 176 | { |
| 177 | dm_unregister_target(&error_target); |
| 178 | } |
| 179 | |
| 180 | EXPORT_SYMBOL(dm_register_target); |
| 181 | EXPORT_SYMBOL(dm_unregister_target); |