Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | |
Alasdair G Kergon | 72d9486 | 2006-06-26 00:27:35 -0700 | [diff] [blame] | 15 | #define DM_MSG_PREFIX "target" |
| 16 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 17 | struct tt_internal { |
| 18 | struct target_type tt; |
| 19 | |
| 20 | struct list_head list; |
| 21 | long use; |
| 22 | }; |
| 23 | |
| 24 | static LIST_HEAD(_targets); |
| 25 | static DECLARE_RWSEM(_lock); |
| 26 | |
| 27 | #define DM_MOD_NAME_SIZE 32 |
| 28 | |
| 29 | static inline struct tt_internal *__find_target_type(const char *name) |
| 30 | { |
| 31 | struct tt_internal *ti; |
| 32 | |
| 33 | list_for_each_entry (ti, &_targets, list) |
| 34 | if (!strcmp(name, ti->tt.name)) |
| 35 | return ti; |
| 36 | |
| 37 | return NULL; |
| 38 | } |
| 39 | |
| 40 | static struct tt_internal *get_target_type(const char *name) |
| 41 | { |
| 42 | struct tt_internal *ti; |
| 43 | |
| 44 | down_read(&_lock); |
| 45 | |
| 46 | ti = __find_target_type(name); |
| 47 | if (ti) { |
| 48 | if ((ti->use == 0) && !try_module_get(ti->tt.module)) |
| 49 | ti = NULL; |
| 50 | else |
| 51 | ti->use++; |
| 52 | } |
| 53 | |
| 54 | up_read(&_lock); |
| 55 | return ti; |
| 56 | } |
| 57 | |
| 58 | static void load_module(const char *name) |
| 59 | { |
| 60 | request_module("dm-%s", name); |
| 61 | } |
| 62 | |
| 63 | struct target_type *dm_get_target_type(const char *name) |
| 64 | { |
| 65 | struct tt_internal *ti = get_target_type(name); |
| 66 | |
| 67 | if (!ti) { |
| 68 | load_module(name); |
| 69 | ti = get_target_type(name); |
| 70 | } |
| 71 | |
| 72 | return ti ? &ti->tt : NULL; |
| 73 | } |
| 74 | |
| 75 | void dm_put_target_type(struct target_type *t) |
| 76 | { |
| 77 | struct tt_internal *ti = (struct tt_internal *) t; |
| 78 | |
| 79 | down_read(&_lock); |
| 80 | if (--ti->use == 0) |
| 81 | module_put(ti->tt.module); |
| 82 | |
Eric Sesterhenn | 543cb2a | 2006-04-01 01:08:12 +0200 | [diff] [blame] | 83 | BUG_ON(ti->use < 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 84 | up_read(&_lock); |
| 85 | |
| 86 | return; |
| 87 | } |
| 88 | |
| 89 | static struct tt_internal *alloc_target(struct target_type *t) |
| 90 | { |
Dmitry Monakhov | 094262d | 2007-10-19 22:38:51 +0100 | [diff] [blame] | 91 | struct tt_internal *ti = kzalloc(sizeof(*ti), GFP_KERNEL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 92 | |
Dmitry Monakhov | 094262d | 2007-10-19 22:38:51 +0100 | [diff] [blame] | 93 | if (ti) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 94 | ti->tt = *t; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 95 | |
| 96 | return ti; |
| 97 | } |
| 98 | |
| 99 | |
| 100 | int dm_target_iterate(void (*iter_func)(struct target_type *tt, |
| 101 | void *param), void *param) |
| 102 | { |
| 103 | struct tt_internal *ti; |
| 104 | |
| 105 | down_read(&_lock); |
| 106 | list_for_each_entry (ti, &_targets, list) |
| 107 | iter_func(&ti->tt, param); |
| 108 | up_read(&_lock); |
| 109 | |
| 110 | return 0; |
| 111 | } |
| 112 | |
| 113 | int dm_register_target(struct target_type *t) |
| 114 | { |
| 115 | int rv = 0; |
| 116 | struct tt_internal *ti = alloc_target(t); |
| 117 | |
| 118 | if (!ti) |
| 119 | return -ENOMEM; |
| 120 | |
| 121 | down_write(&_lock); |
| 122 | if (__find_target_type(t->name)) |
| 123 | rv = -EEXIST; |
| 124 | else |
| 125 | list_add(&ti->list, &_targets); |
| 126 | |
| 127 | up_write(&_lock); |
| 128 | if (rv) |
| 129 | kfree(ti); |
| 130 | return rv; |
| 131 | } |
| 132 | |
Mikulas Patocka | 10d3bd0 | 2009-01-06 03:04:58 +0000 | [diff] [blame] | 133 | void dm_unregister_target(struct target_type *t) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 134 | { |
| 135 | struct tt_internal *ti; |
| 136 | |
| 137 | down_write(&_lock); |
| 138 | if (!(ti = __find_target_type(t->name))) { |
Mikulas Patocka | 10d3bd0 | 2009-01-06 03:04:58 +0000 | [diff] [blame] | 139 | DMCRIT("Unregistering unrecognised target: %s", t->name); |
| 140 | BUG(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 141 | } |
| 142 | |
| 143 | if (ti->use) { |
Mikulas Patocka | 10d3bd0 | 2009-01-06 03:04:58 +0000 | [diff] [blame] | 144 | DMCRIT("Attempt to unregister target still in use: %s", |
| 145 | t->name); |
| 146 | BUG(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 147 | } |
| 148 | |
| 149 | list_del(&ti->list); |
| 150 | kfree(ti); |
| 151 | |
| 152 | up_write(&_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 153 | } |
| 154 | |
| 155 | /* |
| 156 | * io-err: always fails an io, useful for bringing |
| 157 | * up LVs that have holes in them. |
| 158 | */ |
| 159 | static int io_err_ctr(struct dm_target *ti, unsigned int argc, char **args) |
| 160 | { |
| 161 | return 0; |
| 162 | } |
| 163 | |
| 164 | static void io_err_dtr(struct dm_target *ti) |
| 165 | { |
| 166 | /* empty */ |
| 167 | } |
| 168 | |
| 169 | static int io_err_map(struct dm_target *ti, struct bio *bio, |
| 170 | union map_info *map_context) |
| 171 | { |
| 172 | return -EIO; |
| 173 | } |
| 174 | |
| 175 | static struct target_type error_target = { |
| 176 | .name = "error", |
| 177 | .version = {1, 0, 1}, |
| 178 | .ctr = io_err_ctr, |
| 179 | .dtr = io_err_dtr, |
| 180 | .map = io_err_map, |
| 181 | }; |
| 182 | |
| 183 | int __init dm_target_init(void) |
| 184 | { |
| 185 | return dm_register_target(&error_target); |
| 186 | } |
| 187 | |
| 188 | void dm_target_exit(void) |
| 189 | { |
Mikulas Patocka | 10d3bd0 | 2009-01-06 03:04:58 +0000 | [diff] [blame] | 190 | dm_unregister_target(&error_target); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 191 | } |
| 192 | |
| 193 | EXPORT_SYMBOL(dm_register_target); |
| 194 | EXPORT_SYMBOL(dm_unregister_target); |