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 16 #include <linux/device-mapper.h> 17 18 #define DM_MSG_PREFIX "delay" 19 20 struct delay_class { 21 struct dm_dev *dev; 22 sector_t start; 23 unsigned delay; 24 unsigned ops; 25 }; 26 27 struct delay_c { 28 struct timer_list delay_timer; 29 struct mutex timer_lock; 30 struct workqueue_struct *kdelayd_wq; 31 struct work_struct flush_expired_bios; 32 struct list_head delayed_bios; 33 atomic_t may_delay; 34 35 struct delay_class read; 36 struct delay_class write; 37 struct delay_class flush; 38 39 int argc; 40 }; 41 42 struct dm_delay_info { 43 struct delay_c *context; 44 struct delay_class *class; 45 struct list_head list; 46 unsigned long expires; 47 }; 48 49 static DEFINE_MUTEX(delayed_bios_lock); 50 51 static void handle_delayed_timer(struct timer_list *t) 52 { 53 struct delay_c *dc = from_timer(dc, t, delay_timer); 54 55 queue_work(dc->kdelayd_wq, &dc->flush_expired_bios); 56 } 57 58 static void queue_timeout(struct delay_c *dc, unsigned long expires) 59 { 60 mutex_lock(&dc->timer_lock); 61 62 if (!timer_pending(&dc->delay_timer) || expires < dc->delay_timer.expires) 63 mod_timer(&dc->delay_timer, expires); 64 65 mutex_unlock(&dc->timer_lock); 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 { 82 struct dm_delay_info *delayed, *next; 83 unsigned long next_expires = 0; 84 unsigned long start_timer = 0; 85 struct bio_list flush_bios = { }; 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 struct bio *bio = dm_bio_from_per_bio_data(delayed, 91 sizeof(struct dm_delay_info)); 92 list_del(&delayed->list); 93 bio_list_add(&flush_bios, bio); 94 delayed->class->ops--; 95 continue; 96 } 97 98 if (!start_timer) { 99 start_timer = 1; 100 next_expires = delayed->expires; 101 } else 102 next_expires = min(next_expires, delayed->expires); 103 } 104 mutex_unlock(&delayed_bios_lock); 105 106 if (start_timer) 107 queue_timeout(dc, next_expires); 108 109 return bio_list_get(&flush_bios); 110 } 111 112 static void flush_expired_bios(struct work_struct *work) 113 { 114 struct delay_c *dc; 115 116 dc = container_of(work, struct delay_c, flush_expired_bios); 117 flush_bios(flush_delayed_bios(dc, 0)); 118 } 119 120 static void delay_dtr(struct dm_target *ti) 121 { 122 struct delay_c *dc = ti->private; 123 124 destroy_workqueue(dc->kdelayd_wq); 125 126 if (dc->read.dev) 127 dm_put_device(ti, dc->read.dev); 128 if (dc->write.dev) 129 dm_put_device(ti, dc->write.dev); 130 if (dc->flush.dev) 131 dm_put_device(ti, dc->flush.dev); 132 133 mutex_destroy(&dc->timer_lock); 134 135 kfree(dc); 136 } 137 138 static int delay_class_ctr(struct dm_target *ti, struct delay_class *c, char **argv) 139 { 140 int ret; 141 unsigned long long tmpll; 142 char dummy; 143 144 if (sscanf(argv[1], "%llu%c", &tmpll, &dummy) != 1) { 145 ti->error = "Invalid device sector"; 146 return -EINVAL; 147 } 148 c->start = tmpll; 149 150 if (sscanf(argv[2], "%u%c", &c->delay, &dummy) != 1) { 151 ti->error = "Invalid delay"; 152 return -EINVAL; 153 } 154 155 ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &c->dev); 156 if (ret) { 157 ti->error = "Device lookup failed"; 158 return ret; 159 } 160 161 return 0; 162 } 163 164 /* 165 * Mapping parameters: 166 * <device> <offset> <delay> [<write_device> <write_offset> <write_delay>] 167 * 168 * With separate write parameters, the first set is only used for reads. 169 * Offsets are specified in sectors. 170 * Delays are specified in milliseconds. 171 */ 172 static int delay_ctr(struct dm_target *ti, unsigned int argc, char **argv) 173 { 174 struct delay_c *dc; 175 int ret; 176 177 if (argc != 3 && argc != 6 && argc != 9) { 178 ti->error = "Requires exactly 3, 6 or 9 arguments"; 179 return -EINVAL; 180 } 181 182 dc = kzalloc(sizeof(*dc), GFP_KERNEL); 183 if (!dc) { 184 ti->error = "Cannot allocate context"; 185 return -ENOMEM; 186 } 187 188 ti->private = dc; 189 timer_setup(&dc->delay_timer, handle_delayed_timer, 0); 190 INIT_WORK(&dc->flush_expired_bios, flush_expired_bios); 191 INIT_LIST_HEAD(&dc->delayed_bios); 192 mutex_init(&dc->timer_lock); 193 atomic_set(&dc->may_delay, 1); 194 dc->argc = argc; 195 196 ret = delay_class_ctr(ti, &dc->read, argv); 197 if (ret) 198 goto bad; 199 200 if (argc == 3) { 201 ret = delay_class_ctr(ti, &dc->write, argv); 202 if (ret) 203 goto bad; 204 ret = delay_class_ctr(ti, &dc->flush, argv); 205 if (ret) 206 goto bad; 207 goto out; 208 } 209 210 ret = delay_class_ctr(ti, &dc->write, argv + 3); 211 if (ret) 212 goto bad; 213 if (argc == 6) { 214 ret = delay_class_ctr(ti, &dc->flush, argv + 3); 215 if (ret) 216 goto bad; 217 goto out; 218 } 219 220 ret = delay_class_ctr(ti, &dc->flush, argv + 6); 221 if (ret) 222 goto bad; 223 224 out: 225 dc->kdelayd_wq = alloc_workqueue("kdelayd", WQ_MEM_RECLAIM, 0); 226 if (!dc->kdelayd_wq) { 227 ret = -EINVAL; 228 DMERR("Couldn't start kdelayd"); 229 goto bad; 230 } 231 232 ti->num_flush_bios = 1; 233 ti->num_discard_bios = 1; 234 ti->per_io_data_size = sizeof(struct dm_delay_info); 235 return 0; 236 237 bad: 238 delay_dtr(ti); 239 return ret; 240 } 241 242 static int delay_bio(struct delay_c *dc, struct delay_class *c, struct bio *bio) 243 { 244 struct dm_delay_info *delayed; 245 unsigned long expires = 0; 246 247 if (!c->delay || !atomic_read(&dc->may_delay)) 248 return DM_MAPIO_REMAPPED; 249 250 delayed = dm_per_bio_data(bio, sizeof(struct dm_delay_info)); 251 252 delayed->context = dc; 253 delayed->expires = expires = jiffies + msecs_to_jiffies(c->delay); 254 255 mutex_lock(&delayed_bios_lock); 256 c->ops++; 257 list_add_tail(&delayed->list, &dc->delayed_bios); 258 mutex_unlock(&delayed_bios_lock); 259 260 queue_timeout(dc, expires); 261 262 return DM_MAPIO_SUBMITTED; 263 } 264 265 static void delay_presuspend(struct dm_target *ti) 266 { 267 struct delay_c *dc = ti->private; 268 269 atomic_set(&dc->may_delay, 0); 270 del_timer_sync(&dc->delay_timer); 271 flush_bios(flush_delayed_bios(dc, 1)); 272 } 273 274 static void delay_resume(struct dm_target *ti) 275 { 276 struct delay_c *dc = ti->private; 277 278 atomic_set(&dc->may_delay, 1); 279 } 280 281 static int delay_map(struct dm_target *ti, struct bio *bio) 282 { 283 struct delay_c *dc = ti->private; 284 struct delay_class *c; 285 struct dm_delay_info *delayed = dm_per_bio_data(bio, sizeof(struct dm_delay_info)); 286 287 if (bio_data_dir(bio) == WRITE) { 288 if (unlikely(bio->bi_opf & REQ_PREFLUSH)) 289 c = &dc->flush; 290 else 291 c = &dc->write; 292 } else { 293 c = &dc->read; 294 } 295 delayed->class = c; 296 bio_set_dev(bio, c->dev->bdev); 297 if (bio_sectors(bio)) 298 bio->bi_iter.bi_sector = c->start + dm_target_offset(ti, bio->bi_iter.bi_sector); 299 300 return delay_bio(dc, c, bio); 301 } 302 303 #define DMEMIT_DELAY_CLASS(c) \ 304 DMEMIT("%s %llu %u", (c)->dev->name, (unsigned long long)(c)->start, (c)->delay) 305 306 static void delay_status(struct dm_target *ti, status_type_t type, 307 unsigned status_flags, char *result, unsigned maxlen) 308 { 309 struct delay_c *dc = ti->private; 310 int sz = 0; 311 312 switch (type) { 313 case STATUSTYPE_INFO: 314 DMEMIT("%u %u %u", dc->read.ops, dc->write.ops, dc->flush.ops); 315 break; 316 317 case STATUSTYPE_TABLE: 318 DMEMIT_DELAY_CLASS(&dc->read); 319 if (dc->argc >= 6) { 320 DMEMIT(" "); 321 DMEMIT_DELAY_CLASS(&dc->write); 322 } 323 if (dc->argc >= 9) { 324 DMEMIT(" "); 325 DMEMIT_DELAY_CLASS(&dc->flush); 326 } 327 break; 328 } 329 } 330 331 static int delay_iterate_devices(struct dm_target *ti, 332 iterate_devices_callout_fn fn, void *data) 333 { 334 struct delay_c *dc = ti->private; 335 int ret = 0; 336 337 ret = fn(ti, dc->read.dev, dc->read.start, ti->len, data); 338 if (ret) 339 goto out; 340 ret = fn(ti, dc->write.dev, dc->write.start, ti->len, data); 341 if (ret) 342 goto out; 343 ret = fn(ti, dc->flush.dev, dc->flush.start, ti->len, data); 344 if (ret) 345 goto out; 346 347 out: 348 return ret; 349 } 350 351 static struct target_type delay_target = { 352 .name = "delay", 353 .version = {1, 2, 1}, 354 .features = DM_TARGET_PASSES_INTEGRITY, 355 .module = THIS_MODULE, 356 .ctr = delay_ctr, 357 .dtr = delay_dtr, 358 .map = delay_map, 359 .presuspend = delay_presuspend, 360 .resume = delay_resume, 361 .status = delay_status, 362 .iterate_devices = delay_iterate_devices, 363 }; 364 365 static int __init dm_delay_init(void) 366 { 367 int r; 368 369 r = dm_register_target(&delay_target); 370 if (r < 0) { 371 DMERR("register failed %d", r); 372 goto bad_register; 373 } 374 375 return 0; 376 377 bad_register: 378 return r; 379 } 380 381 static void __exit dm_delay_exit(void) 382 { 383 dm_unregister_target(&delay_target); 384 } 385 386 /* Module hooks */ 387 module_init(dm_delay_init); 388 module_exit(dm_delay_exit); 389 390 MODULE_DESCRIPTION(DM_NAME " delay target"); 391 MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>"); 392 MODULE_LICENSE("GPL"); 393