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