drivers/md/dm-delay.c

   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 module_dm(delay);
 371
 372 MODULE_DESCRIPTION(DM_NAME " delay target");
 373 MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>");
 374 MODULE_LICENSE("GPL");