1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2005-2007 Red Hat GmbH 4 * 5 * A target that delays reads and/or writes and can send 6 * them to different devices. 7 * 8 * This file is released under the GPL. 9 */ 10 11 #include <linux/module.h> 12 #include <linux/init.h> 13 #include <linux/blkdev.h> 14 #include <linux/bio.h> 15 #include <linux/slab.h> 16 17 #include <linux/device-mapper.h> 18 19 #define DM_MSG_PREFIX "delay" 20 21 struct delay_class { 22 struct dm_dev *dev; 23 sector_t start; 24 unsigned int delay; 25 unsigned int ops; 26 }; 27 28 struct delay_c { 29 struct timer_list delay_timer; 30 struct mutex timer_lock; 31 struct workqueue_struct *kdelayd_wq; 32 struct work_struct flush_expired_bios; 33 struct list_head delayed_bios; 34 atomic_t may_delay; 35 36 struct delay_class read; 37 struct delay_class write; 38 struct delay_class flush; 39 40 int argc; 41 }; 42 43 struct dm_delay_info { 44 struct delay_c *context; 45 struct delay_class *class; 46 struct list_head list; 47 unsigned long expires; 48 }; 49 50 static DEFINE_MUTEX(delayed_bios_lock); 51 52 static void handle_delayed_timer(struct timer_list *t) 53 { 54 struct delay_c *dc = from_timer(dc, t, delay_timer); 55 56 queue_work(dc->kdelayd_wq, &dc->flush_expired_bios); 57 } 58 59 static void queue_timeout(struct delay_c *dc, unsigned long expires) 60 { 61 mutex_lock(&dc->timer_lock); 62 63 if (!timer_pending(&dc->delay_timer) || expires < dc->delay_timer.expires) 64 mod_timer(&dc->delay_timer, expires); 65 66 mutex_unlock(&dc->timer_lock); 67 } 68 69 static void flush_bios(struct bio *bio) 70 { 71 struct bio *n; 72 73 while (bio) { 74 n = bio->bi_next; 75 bio->bi_next = NULL; 76 dm_submit_bio_remap(bio, NULL); 77 bio = n; 78 } 79 } 80 81 static struct bio *flush_delayed_bios(struct delay_c *dc, int flush_all) 82 { 83 struct dm_delay_info *delayed, *next; 84 unsigned long next_expires = 0; 85 unsigned long start_timer = 0; 86 struct bio_list flush_bios = { }; 87 88 mutex_lock(&delayed_bios_lock); 89 list_for_each_entry_safe(delayed, next, &dc->delayed_bios, list) { 90 if (flush_all || time_after_eq(jiffies, delayed->expires)) { 91 struct bio *bio = dm_bio_from_per_bio_data(delayed, 92 sizeof(struct dm_delay_info)); 93 list_del(&delayed->list); 94 bio_list_add(&flush_bios, bio); 95 delayed->class->ops--; 96 continue; 97 } 98 99 if (!start_timer) { 100 start_timer = 1; 101 next_expires = delayed->expires; 102 } else 103 next_expires = min(next_expires, delayed->expires); 104 } 105 mutex_unlock(&delayed_bios_lock); 106 107 if (start_timer) 108 queue_timeout(dc, next_expires); 109 110 return bio_list_get(&flush_bios); 111 } 112 113 static void flush_expired_bios(struct work_struct *work) 114 { 115 struct delay_c *dc; 116 117 dc = container_of(work, struct delay_c, flush_expired_bios); 118 flush_bios(flush_delayed_bios(dc, 0)); 119 } 120 121 static void delay_dtr(struct dm_target *ti) 122 { 123 struct delay_c *dc = ti->private; 124 125 if (dc->kdelayd_wq) 126 destroy_workqueue(dc->kdelayd_wq); 127 128 if (dc->read.dev) 129 dm_put_device(ti, dc->read.dev); 130 if (dc->write.dev) 131 dm_put_device(ti, dc->write.dev); 132 if (dc->flush.dev) 133 dm_put_device(ti, dc->flush.dev); 134 135 mutex_destroy(&dc->timer_lock); 136 137 kfree(dc); 138 } 139 140 static int delay_class_ctr(struct dm_target *ti, struct delay_class *c, char **argv) 141 { 142 int ret; 143 unsigned long long tmpll; 144 char dummy; 145 146 if (sscanf(argv[1], "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) { 147 ti->error = "Invalid device sector"; 148 return -EINVAL; 149 } 150 c->start = tmpll; 151 152 if (sscanf(argv[2], "%u%c", &c->delay, &dummy) != 1) { 153 ti->error = "Invalid delay"; 154 return -EINVAL; 155 } 156 157 ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &c->dev); 158 if (ret) { 159 ti->error = "Device lookup failed"; 160 return ret; 161 } 162 163 return 0; 164 } 165 166 /* 167 * Mapping parameters: 168 * <device> <offset> <delay> [<write_device> <write_offset> <write_delay>] 169 * 170 * With separate write parameters, the first set is only used for reads. 171 * Offsets are specified in sectors. 172 * Delays are specified in milliseconds. 173 */ 174 static int delay_ctr(struct dm_target *ti, unsigned int argc, char **argv) 175 { 176 struct delay_c *dc; 177 int ret; 178 179 if (argc != 3 && argc != 6 && argc != 9) { 180 ti->error = "Requires exactly 3, 6 or 9 arguments"; 181 return -EINVAL; 182 } 183 184 dc = kzalloc(sizeof(*dc), GFP_KERNEL); 185 if (!dc) { 186 ti->error = "Cannot allocate context"; 187 return -ENOMEM; 188 } 189 190 ti->private = dc; 191 timer_setup(&dc->delay_timer, handle_delayed_timer, 0); 192 INIT_WORK(&dc->flush_expired_bios, flush_expired_bios); 193 INIT_LIST_HEAD(&dc->delayed_bios); 194 mutex_init(&dc->timer_lock); 195 atomic_set(&dc->may_delay, 1); 196 dc->argc = argc; 197 198 ret = delay_class_ctr(ti, &dc->read, argv); 199 if (ret) 200 goto bad; 201 202 if (argc == 3) { 203 ret = delay_class_ctr(ti, &dc->write, argv); 204 if (ret) 205 goto bad; 206 ret = delay_class_ctr(ti, &dc->flush, argv); 207 if (ret) 208 goto bad; 209 goto out; 210 } 211 212 ret = delay_class_ctr(ti, &dc->write, argv + 3); 213 if (ret) 214 goto bad; 215 if (argc == 6) { 216 ret = delay_class_ctr(ti, &dc->flush, argv + 3); 217 if (ret) 218 goto bad; 219 goto out; 220 } 221 222 ret = delay_class_ctr(ti, &dc->flush, argv + 6); 223 if (ret) 224 goto bad; 225 226 out: 227 dc->kdelayd_wq = alloc_workqueue("kdelayd", WQ_MEM_RECLAIM, 0); 228 if (!dc->kdelayd_wq) { 229 ret = -EINVAL; 230 DMERR("Couldn't start kdelayd"); 231 goto bad; 232 } 233 234 ti->num_flush_bios = 1; 235 ti->num_discard_bios = 1; 236 ti->accounts_remapped_io = true; 237 ti->per_io_data_size = sizeof(struct dm_delay_info); 238 return 0; 239 240 bad: 241 delay_dtr(ti); 242 return ret; 243 } 244 245 static int delay_bio(struct delay_c *dc, struct delay_class *c, struct bio *bio) 246 { 247 struct dm_delay_info *delayed; 248 unsigned long expires = 0; 249 250 if (!c->delay || !atomic_read(&dc->may_delay)) 251 return DM_MAPIO_REMAPPED; 252 253 delayed = dm_per_bio_data(bio, sizeof(struct dm_delay_info)); 254 255 delayed->context = dc; 256 delayed->expires = expires = jiffies + msecs_to_jiffies(c->delay); 257 258 mutex_lock(&delayed_bios_lock); 259 c->ops++; 260 list_add_tail(&delayed->list, &dc->delayed_bios); 261 mutex_unlock(&delayed_bios_lock); 262 263 queue_timeout(dc, expires); 264 265 return DM_MAPIO_SUBMITTED; 266 } 267 268 static void delay_presuspend(struct dm_target *ti) 269 { 270 struct delay_c *dc = ti->private; 271 272 atomic_set(&dc->may_delay, 0); 273 del_timer_sync(&dc->delay_timer); 274 flush_bios(flush_delayed_bios(dc, 1)); 275 } 276 277 static void delay_resume(struct dm_target *ti) 278 { 279 struct delay_c *dc = ti->private; 280 281 atomic_set(&dc->may_delay, 1); 282 } 283 284 static int delay_map(struct dm_target *ti, struct bio *bio) 285 { 286 struct delay_c *dc = ti->private; 287 struct delay_class *c; 288 struct dm_delay_info *delayed = dm_per_bio_data(bio, sizeof(struct dm_delay_info)); 289 290 if (bio_data_dir(bio) == WRITE) { 291 if (unlikely(bio->bi_opf & REQ_PREFLUSH)) 292 c = &dc->flush; 293 else 294 c = &dc->write; 295 } else { 296 c = &dc->read; 297 } 298 delayed->class = c; 299 bio_set_dev(bio, c->dev->bdev); 300 bio->bi_iter.bi_sector = c->start + dm_target_offset(ti, bio->bi_iter.bi_sector); 301 302 return delay_bio(dc, c, bio); 303 } 304 305 #define DMEMIT_DELAY_CLASS(c) \ 306 DMEMIT("%s %llu %u", (c)->dev->name, (unsigned long long)(c)->start, (c)->delay) 307 308 static void delay_status(struct dm_target *ti, status_type_t type, 309 unsigned int status_flags, char *result, unsigned int maxlen) 310 { 311 struct delay_c *dc = ti->private; 312 int sz = 0; 313 314 switch (type) { 315 case STATUSTYPE_INFO: 316 DMEMIT("%u %u %u", dc->read.ops, dc->write.ops, dc->flush.ops); 317 break; 318 319 case STATUSTYPE_TABLE: 320 DMEMIT_DELAY_CLASS(&dc->read); 321 if (dc->argc >= 6) { 322 DMEMIT(" "); 323 DMEMIT_DELAY_CLASS(&dc->write); 324 } 325 if (dc->argc >= 9) { 326 DMEMIT(" "); 327 DMEMIT_DELAY_CLASS(&dc->flush); 328 } 329 break; 330 331 case STATUSTYPE_IMA: 332 *result = '\0'; 333 break; 334 } 335 } 336 337 static int delay_iterate_devices(struct dm_target *ti, 338 iterate_devices_callout_fn fn, void *data) 339 { 340 struct delay_c *dc = ti->private; 341 int ret = 0; 342 343 ret = fn(ti, dc->read.dev, dc->read.start, ti->len, data); 344 if (ret) 345 goto out; 346 ret = fn(ti, dc->write.dev, dc->write.start, ti->len, data); 347 if (ret) 348 goto out; 349 ret = fn(ti, dc->flush.dev, dc->flush.start, ti->len, data); 350 if (ret) 351 goto out; 352 353 out: 354 return ret; 355 } 356 357 static struct target_type delay_target = { 358 .name = "delay", 359 .version = {1, 3, 0}, 360 .features = DM_TARGET_PASSES_INTEGRITY, 361 .module = THIS_MODULE, 362 .ctr = delay_ctr, 363 .dtr = delay_dtr, 364 .map = delay_map, 365 .presuspend = delay_presuspend, 366 .resume = delay_resume, 367 .status = delay_status, 368 .iterate_devices = delay_iterate_devices, 369 }; 370 371 static int __init dm_delay_init(void) 372 { 373 int r; 374 375 r = dm_register_target(&delay_target); 376 if (r < 0) { 377 DMERR("register failed %d", r); 378 goto bad_register; 379 } 380 381 return 0; 382 383 bad_register: 384 return r; 385 } 386 387 static void __exit dm_delay_exit(void) 388 { 389 dm_unregister_target(&delay_target); 390 } 391 392 /* Module hooks */ 393 module_init(dm_delay_init); 394 module_exit(dm_delay_exit); 395 396 MODULE_DESCRIPTION(DM_NAME " delay target"); 397 MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>"); 398 MODULE_LICENSE("GPL"); 399