Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2005-2007 Red Hat GmbH |
| 3 | * |
| 4 | * A target that delays reads and/or writes and can send |
| 5 | * them to different devices. |
| 6 | * |
| 7 | * This file is released under the GPL. |
| 8 | */ |
| 9 | |
| 10 | #include <linux/module.h> |
| 11 | #include <linux/init.h> |
| 12 | #include <linux/blkdev.h> |
| 13 | #include <linux/bio.h> |
| 14 | #include <linux/slab.h> |
| 15 | |
Mikulas Patocka | 586e80e | 2008-10-21 17:44:59 +0100 | [diff] [blame] | 16 | #include <linux/device-mapper.h> |
| 17 | |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 18 | #define DM_MSG_PREFIX "delay" |
| 19 | |
| 20 | struct delay_c { |
| 21 | struct timer_list delay_timer; |
Alasdair G Kergon | ac81864 | 2007-07-12 17:26:47 +0100 | [diff] [blame] | 22 | struct mutex timer_lock; |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 23 | struct work_struct flush_expired_bios; |
| 24 | struct list_head delayed_bios; |
| 25 | atomic_t may_delay; |
| 26 | mempool_t *delayed_pool; |
| 27 | |
| 28 | struct dm_dev *dev_read; |
| 29 | sector_t start_read; |
| 30 | unsigned read_delay; |
| 31 | unsigned reads; |
| 32 | |
| 33 | struct dm_dev *dev_write; |
| 34 | sector_t start_write; |
| 35 | unsigned write_delay; |
| 36 | unsigned writes; |
| 37 | }; |
| 38 | |
Alasdair G Kergon | 028867a | 2007-07-12 17:26:32 +0100 | [diff] [blame] | 39 | struct dm_delay_info { |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 40 | struct delay_c *context; |
| 41 | struct list_head list; |
| 42 | struct bio *bio; |
| 43 | unsigned long expires; |
| 44 | }; |
| 45 | |
| 46 | static DEFINE_MUTEX(delayed_bios_lock); |
| 47 | |
| 48 | static struct workqueue_struct *kdelayd_wq; |
| 49 | static struct kmem_cache *delayed_cache; |
| 50 | |
| 51 | static void handle_delayed_timer(unsigned long data) |
| 52 | { |
| 53 | struct delay_c *dc = (struct delay_c *)data; |
| 54 | |
| 55 | queue_work(kdelayd_wq, &dc->flush_expired_bios); |
| 56 | } |
| 57 | |
| 58 | static void queue_timeout(struct delay_c *dc, unsigned long expires) |
| 59 | { |
Alasdair G Kergon | ac81864 | 2007-07-12 17:26:47 +0100 | [diff] [blame] | 60 | mutex_lock(&dc->timer_lock); |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 61 | |
| 62 | if (!timer_pending(&dc->delay_timer) || expires < dc->delay_timer.expires) |
| 63 | mod_timer(&dc->delay_timer, expires); |
| 64 | |
Alasdair G Kergon | ac81864 | 2007-07-12 17:26:47 +0100 | [diff] [blame] | 65 | mutex_unlock(&dc->timer_lock); |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 66 | } |
| 67 | |
| 68 | static void flush_bios(struct bio *bio) |
| 69 | { |
| 70 | struct bio *n; |
| 71 | |
| 72 | while (bio) { |
| 73 | n = bio->bi_next; |
| 74 | bio->bi_next = NULL; |
| 75 | generic_make_request(bio); |
| 76 | bio = n; |
| 77 | } |
| 78 | } |
| 79 | |
| 80 | static struct bio *flush_delayed_bios(struct delay_c *dc, int flush_all) |
| 81 | { |
Alasdair G Kergon | 028867a | 2007-07-12 17:26:32 +0100 | [diff] [blame] | 82 | struct dm_delay_info *delayed, *next; |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 83 | unsigned long next_expires = 0; |
| 84 | int start_timer = 0; |
Alasdair G Kergon | 051814c | 2007-10-19 22:38:55 +0100 | [diff] [blame] | 85 | struct bio_list flush_bios = { }; |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 86 | |
| 87 | mutex_lock(&delayed_bios_lock); |
| 88 | list_for_each_entry_safe(delayed, next, &dc->delayed_bios, list) { |
| 89 | if (flush_all || time_after_eq(jiffies, delayed->expires)) { |
| 90 | list_del(&delayed->list); |
| 91 | bio_list_add(&flush_bios, delayed->bio); |
| 92 | if ((bio_data_dir(delayed->bio) == WRITE)) |
| 93 | delayed->context->writes--; |
| 94 | else |
| 95 | delayed->context->reads--; |
| 96 | mempool_free(delayed, dc->delayed_pool); |
| 97 | continue; |
| 98 | } |
| 99 | |
| 100 | if (!start_timer) { |
| 101 | start_timer = 1; |
| 102 | next_expires = delayed->expires; |
| 103 | } else |
| 104 | next_expires = min(next_expires, delayed->expires); |
| 105 | } |
| 106 | |
| 107 | mutex_unlock(&delayed_bios_lock); |
| 108 | |
| 109 | if (start_timer) |
| 110 | queue_timeout(dc, next_expires); |
| 111 | |
| 112 | return bio_list_get(&flush_bios); |
| 113 | } |
| 114 | |
| 115 | static void flush_expired_bios(struct work_struct *work) |
| 116 | { |
| 117 | struct delay_c *dc; |
| 118 | |
| 119 | dc = container_of(work, struct delay_c, flush_expired_bios); |
| 120 | flush_bios(flush_delayed_bios(dc, 0)); |
| 121 | } |
| 122 | |
| 123 | /* |
| 124 | * Mapping parameters: |
| 125 | * <device> <offset> <delay> [<write_device> <write_offset> <write_delay>] |
| 126 | * |
| 127 | * With separate write parameters, the first set is only used for reads. |
| 128 | * Delays are specified in milliseconds. |
| 129 | */ |
| 130 | static int delay_ctr(struct dm_target *ti, unsigned int argc, char **argv) |
| 131 | { |
| 132 | struct delay_c *dc; |
| 133 | unsigned long long tmpll; |
| 134 | |
| 135 | if (argc != 3 && argc != 6) { |
| 136 | ti->error = "requires exactly 3 or 6 arguments"; |
| 137 | return -EINVAL; |
| 138 | } |
| 139 | |
| 140 | dc = kmalloc(sizeof(*dc), GFP_KERNEL); |
| 141 | if (!dc) { |
| 142 | ti->error = "Cannot allocate context"; |
| 143 | return -ENOMEM; |
| 144 | } |
| 145 | |
| 146 | dc->reads = dc->writes = 0; |
| 147 | |
| 148 | if (sscanf(argv[1], "%llu", &tmpll) != 1) { |
| 149 | ti->error = "Invalid device sector"; |
| 150 | goto bad; |
| 151 | } |
| 152 | dc->start_read = tmpll; |
| 153 | |
| 154 | if (sscanf(argv[2], "%u", &dc->read_delay) != 1) { |
| 155 | ti->error = "Invalid delay"; |
| 156 | goto bad; |
| 157 | } |
| 158 | |
Nikanth Karthikesan | 8215d6e | 2010-03-06 02:32:27 +0000 | [diff] [blame] | 159 | if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), |
| 160 | &dc->dev_read)) { |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 161 | ti->error = "Device lookup failed"; |
| 162 | goto bad; |
| 163 | } |
| 164 | |
Dmitry Monakhov | 2e64a0f | 2007-10-19 22:38:41 +0100 | [diff] [blame] | 165 | dc->dev_write = NULL; |
| 166 | if (argc == 3) |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 167 | goto out; |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 168 | |
| 169 | if (sscanf(argv[4], "%llu", &tmpll) != 1) { |
| 170 | ti->error = "Invalid write device sector"; |
Dmitry Monakhov | 2e64a0f | 2007-10-19 22:38:41 +0100 | [diff] [blame] | 171 | goto bad_dev_read; |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 172 | } |
| 173 | dc->start_write = tmpll; |
| 174 | |
| 175 | if (sscanf(argv[5], "%u", &dc->write_delay) != 1) { |
| 176 | ti->error = "Invalid write delay"; |
Dmitry Monakhov | 2e64a0f | 2007-10-19 22:38:41 +0100 | [diff] [blame] | 177 | goto bad_dev_read; |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 178 | } |
| 179 | |
Nikanth Karthikesan | 8215d6e | 2010-03-06 02:32:27 +0000 | [diff] [blame] | 180 | if (dm_get_device(ti, argv[3], dm_table_get_mode(ti->table), |
| 181 | &dc->dev_write)) { |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 182 | ti->error = "Write device lookup failed"; |
Dmitry Monakhov | 2e64a0f | 2007-10-19 22:38:41 +0100 | [diff] [blame] | 183 | goto bad_dev_read; |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 184 | } |
| 185 | |
| 186 | out: |
| 187 | dc->delayed_pool = mempool_create_slab_pool(128, delayed_cache); |
| 188 | if (!dc->delayed_pool) { |
| 189 | DMERR("Couldn't create delayed bio pool."); |
Dmitry Monakhov | 2e64a0f | 2007-10-19 22:38:41 +0100 | [diff] [blame] | 190 | goto bad_dev_write; |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 191 | } |
| 192 | |
Alasdair G Kergon | ac81864 | 2007-07-12 17:26:47 +0100 | [diff] [blame] | 193 | setup_timer(&dc->delay_timer, handle_delayed_timer, (unsigned long)dc); |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 194 | |
| 195 | INIT_WORK(&dc->flush_expired_bios, flush_expired_bios); |
| 196 | INIT_LIST_HEAD(&dc->delayed_bios); |
Alasdair G Kergon | ac81864 | 2007-07-12 17:26:47 +0100 | [diff] [blame] | 197 | mutex_init(&dc->timer_lock); |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 198 | atomic_set(&dc->may_delay, 1); |
| 199 | |
Mikulas Patocka | c927259 | 2009-06-22 10:12:23 +0100 | [diff] [blame] | 200 | ti->num_flush_requests = 1; |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 201 | ti->private = dc; |
| 202 | return 0; |
| 203 | |
Dmitry Monakhov | 2e64a0f | 2007-10-19 22:38:41 +0100 | [diff] [blame] | 204 | bad_dev_write: |
| 205 | if (dc->dev_write) |
| 206 | dm_put_device(ti, dc->dev_write); |
| 207 | bad_dev_read: |
| 208 | dm_put_device(ti, dc->dev_read); |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 209 | bad: |
| 210 | kfree(dc); |
| 211 | return -EINVAL; |
| 212 | } |
| 213 | |
| 214 | static void delay_dtr(struct dm_target *ti) |
| 215 | { |
| 216 | struct delay_c *dc = ti->private; |
| 217 | |
| 218 | flush_workqueue(kdelayd_wq); |
| 219 | |
| 220 | dm_put_device(ti, dc->dev_read); |
| 221 | |
| 222 | if (dc->dev_write) |
| 223 | dm_put_device(ti, dc->dev_write); |
| 224 | |
| 225 | mempool_destroy(dc->delayed_pool); |
| 226 | kfree(dc); |
| 227 | } |
| 228 | |
| 229 | static int delay_bio(struct delay_c *dc, int delay, struct bio *bio) |
| 230 | { |
Alasdair G Kergon | 028867a | 2007-07-12 17:26:32 +0100 | [diff] [blame] | 231 | struct dm_delay_info *delayed; |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 232 | unsigned long expires = 0; |
| 233 | |
| 234 | if (!delay || !atomic_read(&dc->may_delay)) |
| 235 | return 1; |
| 236 | |
| 237 | delayed = mempool_alloc(dc->delayed_pool, GFP_NOIO); |
| 238 | |
| 239 | delayed->context = dc; |
| 240 | delayed->bio = bio; |
| 241 | delayed->expires = expires = jiffies + (delay * HZ / 1000); |
| 242 | |
| 243 | mutex_lock(&delayed_bios_lock); |
| 244 | |
| 245 | if (bio_data_dir(bio) == WRITE) |
| 246 | dc->writes++; |
| 247 | else |
| 248 | dc->reads++; |
| 249 | |
| 250 | list_add_tail(&delayed->list, &dc->delayed_bios); |
| 251 | |
| 252 | mutex_unlock(&delayed_bios_lock); |
| 253 | |
| 254 | queue_timeout(dc, expires); |
| 255 | |
| 256 | return 0; |
| 257 | } |
| 258 | |
| 259 | static void delay_presuspend(struct dm_target *ti) |
| 260 | { |
| 261 | struct delay_c *dc = ti->private; |
| 262 | |
| 263 | atomic_set(&dc->may_delay, 0); |
| 264 | del_timer_sync(&dc->delay_timer); |
| 265 | flush_bios(flush_delayed_bios(dc, 1)); |
| 266 | } |
| 267 | |
| 268 | static void delay_resume(struct dm_target *ti) |
| 269 | { |
| 270 | struct delay_c *dc = ti->private; |
| 271 | |
| 272 | atomic_set(&dc->may_delay, 1); |
| 273 | } |
| 274 | |
| 275 | static int delay_map(struct dm_target *ti, struct bio *bio, |
| 276 | union map_info *map_context) |
| 277 | { |
| 278 | struct delay_c *dc = ti->private; |
| 279 | |
| 280 | if ((bio_data_dir(bio) == WRITE) && (dc->dev_write)) { |
| 281 | bio->bi_bdev = dc->dev_write->bdev; |
Mikulas Patocka | c927259 | 2009-06-22 10:12:23 +0100 | [diff] [blame] | 282 | if (bio_sectors(bio)) |
| 283 | bio->bi_sector = dc->start_write + |
Alasdair G Kergon | b441a262 | 2010-08-12 04:14:11 +0100 | [diff] [blame^] | 284 | dm_target_offset(ti, bio->bi_sector); |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 285 | |
| 286 | return delay_bio(dc, dc->write_delay, bio); |
| 287 | } |
| 288 | |
| 289 | bio->bi_bdev = dc->dev_read->bdev; |
Alasdair G Kergon | b441a262 | 2010-08-12 04:14:11 +0100 | [diff] [blame^] | 290 | bio->bi_sector = dc->start_read + dm_target_offset(ti, bio->bi_sector); |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 291 | |
| 292 | return delay_bio(dc, dc->read_delay, bio); |
| 293 | } |
| 294 | |
| 295 | static int delay_status(struct dm_target *ti, status_type_t type, |
| 296 | char *result, unsigned maxlen) |
| 297 | { |
| 298 | struct delay_c *dc = ti->private; |
| 299 | int sz = 0; |
| 300 | |
| 301 | switch (type) { |
| 302 | case STATUSTYPE_INFO: |
| 303 | DMEMIT("%u %u", dc->reads, dc->writes); |
| 304 | break; |
| 305 | |
| 306 | case STATUSTYPE_TABLE: |
| 307 | DMEMIT("%s %llu %u", dc->dev_read->name, |
| 308 | (unsigned long long) dc->start_read, |
| 309 | dc->read_delay); |
| 310 | if (dc->dev_write) |
Milan Broz | 79662d1 | 2007-10-19 22:38:42 +0100 | [diff] [blame] | 311 | DMEMIT(" %s %llu %u", dc->dev_write->name, |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 312 | (unsigned long long) dc->start_write, |
| 313 | dc->write_delay); |
| 314 | break; |
| 315 | } |
| 316 | |
| 317 | return 0; |
| 318 | } |
| 319 | |
Mike Snitzer | af4874e | 2009-06-22 10:12:33 +0100 | [diff] [blame] | 320 | static int delay_iterate_devices(struct dm_target *ti, |
| 321 | iterate_devices_callout_fn fn, void *data) |
| 322 | { |
| 323 | struct delay_c *dc = ti->private; |
| 324 | int ret = 0; |
| 325 | |
Mike Snitzer | 5dea271 | 2009-07-23 20:30:42 +0100 | [diff] [blame] | 326 | ret = fn(ti, dc->dev_read, dc->start_read, ti->len, data); |
Mike Snitzer | af4874e | 2009-06-22 10:12:33 +0100 | [diff] [blame] | 327 | if (ret) |
| 328 | goto out; |
| 329 | |
| 330 | if (dc->dev_write) |
Mike Snitzer | 5dea271 | 2009-07-23 20:30:42 +0100 | [diff] [blame] | 331 | ret = fn(ti, dc->dev_write, dc->start_write, ti->len, data); |
Mike Snitzer | af4874e | 2009-06-22 10:12:33 +0100 | [diff] [blame] | 332 | |
| 333 | out: |
| 334 | return ret; |
| 335 | } |
| 336 | |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 337 | static struct target_type delay_target = { |
| 338 | .name = "delay", |
Mike Snitzer | af4874e | 2009-06-22 10:12:33 +0100 | [diff] [blame] | 339 | .version = {1, 1, 0}, |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 340 | .module = THIS_MODULE, |
| 341 | .ctr = delay_ctr, |
| 342 | .dtr = delay_dtr, |
| 343 | .map = delay_map, |
| 344 | .presuspend = delay_presuspend, |
| 345 | .resume = delay_resume, |
| 346 | .status = delay_status, |
Mike Snitzer | af4874e | 2009-06-22 10:12:33 +0100 | [diff] [blame] | 347 | .iterate_devices = delay_iterate_devices, |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 348 | }; |
| 349 | |
| 350 | static int __init dm_delay_init(void) |
| 351 | { |
| 352 | int r = -ENOMEM; |
| 353 | |
| 354 | kdelayd_wq = create_workqueue("kdelayd"); |
| 355 | if (!kdelayd_wq) { |
| 356 | DMERR("Couldn't start kdelayd"); |
| 357 | goto bad_queue; |
| 358 | } |
| 359 | |
Alasdair G Kergon | 028867a | 2007-07-12 17:26:32 +0100 | [diff] [blame] | 360 | delayed_cache = KMEM_CACHE(dm_delay_info, 0); |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 361 | if (!delayed_cache) { |
| 362 | DMERR("Couldn't create delayed bio cache."); |
| 363 | goto bad_memcache; |
| 364 | } |
| 365 | |
| 366 | r = dm_register_target(&delay_target); |
| 367 | if (r < 0) { |
| 368 | DMERR("register failed %d", r); |
| 369 | goto bad_register; |
| 370 | } |
| 371 | |
| 372 | return 0; |
| 373 | |
| 374 | bad_register: |
| 375 | kmem_cache_destroy(delayed_cache); |
| 376 | bad_memcache: |
| 377 | destroy_workqueue(kdelayd_wq); |
| 378 | bad_queue: |
| 379 | return r; |
| 380 | } |
| 381 | |
| 382 | static void __exit dm_delay_exit(void) |
| 383 | { |
Mikulas Patocka | 10d3bd0 | 2009-01-06 03:04:58 +0000 | [diff] [blame] | 384 | dm_unregister_target(&delay_target); |
Heinz Mauelshagen | 26b9f22 | 2007-05-09 02:33:06 -0700 | [diff] [blame] | 385 | kmem_cache_destroy(delayed_cache); |
| 386 | destroy_workqueue(kdelayd_wq); |
| 387 | } |
| 388 | |
| 389 | /* Module hooks */ |
| 390 | module_init(dm_delay_init); |
| 391 | module_exit(dm_delay_exit); |
| 392 | |
| 393 | MODULE_DESCRIPTION(DM_NAME " delay target"); |
| 394 | MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>"); |
| 395 | MODULE_LICENSE("GPL"); |