drivers/md/dm-rq.c

   1 /*
   2  * Copyright (C) 2016 Red Hat, Inc. All rights reserved.
   3  *
   4  * This file is released under the GPL.
   5  */
   6
   7 #include "dm-core.h"
   8 #include "dm-rq.h"
   9
  10 #include <linux/blk-mq.h>
  11
  12 #define DM_MSG_PREFIX "core-rq"
  13
  14 /*
  15  * One of these is allocated per request.
  16  */
  17 struct dm_rq_target_io {
  18         struct mapped_device *md;
  19         struct dm_target *ti;
  20         struct request *orig, *clone;
  21         struct kthread_work work;
  22         blk_status_t error;
  23         union map_info info;
  24         struct dm_stats_aux stats_aux;
  25         unsigned long duration_jiffies;
  26         unsigned n_sectors;
  27         unsigned completed;
  28 };
  29
  30 #define DM_MQ_NR_HW_QUEUES 1
  31 #define DM_MQ_QUEUE_DEPTH 2048
  32 static unsigned dm_mq_nr_hw_queues = DM_MQ_NR_HW_QUEUES;
  33 static unsigned dm_mq_queue_depth = DM_MQ_QUEUE_DEPTH;
  34
  35 /*
  36  * Request-based DM's mempools' reserved IOs set by the user.
  37  */
  38 #define RESERVED_REQUEST_BASED_IOS      256
  39 static unsigned reserved_rq_based_ios = RESERVED_REQUEST_BASED_IOS;
  40
  41 unsigned dm_get_reserved_rq_based_ios(void)
  42 {
  43         return __dm_get_module_param(&reserved_rq_based_ios,
  44                                      RESERVED_REQUEST_BASED_IOS, DM_RESERVED_MAX_IOS);
  45 }
  46 EXPORT_SYMBOL_GPL(dm_get_reserved_rq_based_ios);
  47
  48 static unsigned dm_get_blk_mq_nr_hw_queues(void)
  49 {
  50         return __dm_get_module_param(&dm_mq_nr_hw_queues, 1, 32);
  51 }
  52
  53 static unsigned dm_get_blk_mq_queue_depth(void)
  54 {
  55         return __dm_get_module_param(&dm_mq_queue_depth,
  56                                      DM_MQ_QUEUE_DEPTH, BLK_MQ_MAX_DEPTH);
  57 }
  58
  59 int dm_request_based(struct mapped_device *md)
  60 {
  61         return queue_is_mq(md->queue);
  62 }
  63
  64 void dm_start_queue(struct request_queue *q)
  65 {
  66         blk_mq_unquiesce_queue(q);
  67         blk_mq_kick_requeue_list(q);
  68 }
  69
  70 void dm_stop_queue(struct request_queue *q)
  71 {
  72         blk_mq_quiesce_queue(q);
  73 }
  74
  75 /*
  76  * Partial completion handling for request-based dm
  77  */
  78 static void end_clone_bio(struct bio *clone)
  79 {
  80         struct dm_rq_clone_bio_info *info =
  81                 container_of(clone, struct dm_rq_clone_bio_info, clone);
  82         struct dm_rq_target_io *tio = info->tio;
  83         unsigned int nr_bytes = info->orig->bi_iter.bi_size;
  84         blk_status_t error = clone->bi_status;
  85         bool is_last = !clone->bi_next;
  86
  87         bio_put(clone);
  88
  89         if (tio->error)
  90                 /*
  91                  * An error has already been detected on the request.
  92                  * Once error occurred, just let clone->end_io() handle
  93                  * the remainder.
  94                  */
  95                 return;
  96         else if (error) {
  97                 /*
  98                  * Don't notice the error to the upper layer yet.
  99                  * The error handling decision is made by the target driver,
 100                  * when the request is completed.
 101                  */
 102                 tio->error = error;
 103                 goto exit;
 104         }
 105
 106         /*
 107          * I/O for the bio successfully completed.
 108          * Notice the data completion to the upper layer.
 109          */
 110         tio->completed += nr_bytes;
 111
 112         /*
 113          * Update the original request.
 114          * Do not use blk_mq_end_request() here, because it may complete
 115          * the original request before the clone, and break the ordering.
 116          */
 117         if (is_last)
 118  exit:
 119                 blk_update_request(tio->orig, BLK_STS_OK, tio->completed);
 120 }
 121
 122 static struct dm_rq_target_io *tio_from_request(struct request *rq)
 123 {
 124         return blk_mq_rq_to_pdu(rq);
 125 }
 126
 127 static void rq_end_stats(struct mapped_device *md, struct request *orig)
 128 {
 129         if (unlikely(dm_stats_used(&md->stats))) {
 130                 struct dm_rq_target_io *tio = tio_from_request(orig);
 131                 tio->duration_jiffies = jiffies - tio->duration_jiffies;
 132                 dm_stats_account_io(&md->stats, rq_data_dir(orig),
 133                                     blk_rq_pos(orig), tio->n_sectors, true,
 134                                     tio->duration_jiffies, &tio->stats_aux);
 135         }
 136 }
 137
 138 /*
 139  * Don't touch any member of the md after calling this function because
 140  * the md may be freed in dm_put() at the end of this function.
 141  * Or do dm_get() before calling this function and dm_put() later.
 142  */
 143 static void rq_completed(struct mapped_device *md)
 144 {
 145         /*
 146          * dm_put() must be at the end of this function. See the comment above
 147          */
 148         dm_put(md);
 149 }
 150
 151 /*
 152  * Complete the clone and the original request.
 153  * Must be called without clone's queue lock held,
 154  * see end_clone_request() for more details.
 155  */
 156 static void dm_end_request(struct request *clone, blk_status_t error)
 157 {
 158         struct dm_rq_target_io *tio = clone->end_io_data;
 159         struct mapped_device *md = tio->md;
 160         struct request *rq = tio->orig;
 161
 162         blk_rq_unprep_clone(clone);
 163         tio->ti->type->release_clone_rq(clone, NULL);
 164
 165         rq_end_stats(md, rq);
 166         blk_mq_end_request(rq, error);
 167         rq_completed(md);
 168 }
 169
 170 static void __dm_mq_kick_requeue_list(struct request_queue *q, unsigned long msecs)
 171 {
 172         blk_mq_delay_kick_requeue_list(q, msecs);
 173 }
 174
 175 void dm_mq_kick_requeue_list(struct mapped_device *md)
 176 {
 177         __dm_mq_kick_requeue_list(md->queue, 0);
 178 }
 179 EXPORT_SYMBOL(dm_mq_kick_requeue_list);
 180
 181 static void dm_mq_delay_requeue_request(struct request *rq, unsigned long msecs)
 182 {
 183         blk_mq_requeue_request(rq, false);
 184         __dm_mq_kick_requeue_list(rq->q, msecs);
 185 }
 186
 187 static void dm_requeue_original_request(struct dm_rq_target_io *tio, bool delay_requeue)
 188 {
 189         struct mapped_device *md = tio->md;
 190         struct request *rq = tio->orig;
 191         unsigned long delay_ms = delay_requeue ? 100 : 0;
 192
 193         rq_end_stats(md, rq);
 194         if (tio->clone) {
 195                 blk_rq_unprep_clone(tio->clone);
 196                 tio->ti->type->release_clone_rq(tio->clone, NULL);
 197         }
 198
 199         dm_mq_delay_requeue_request(rq, delay_ms);
 200         rq_completed(md);
 201 }
 202
 203 static void dm_done(struct request *clone, blk_status_t error, bool mapped)
 204 {
 205         int r = DM_ENDIO_DONE;
 206         struct dm_rq_target_io *tio = clone->end_io_data;
 207         dm_request_endio_fn rq_end_io = NULL;
 208
 209         if (tio->ti) {
 210                 rq_end_io = tio->ti->type->rq_end_io;
 211
 212                 if (mapped && rq_end_io)
 213                         r = rq_end_io(tio->ti, clone, error, &tio->info);
 214         }
 215
 216         if (unlikely(error == BLK_STS_TARGET)) {
 217                 if (req_op(clone) == REQ_OP_DISCARD &&
 218                     !clone->q->limits.max_discard_sectors)
 219                         disable_discard(tio->md);
 220                 else if (req_op(clone) == REQ_OP_WRITE_SAME &&
 221                          !clone->q->limits.max_write_same_sectors)
 222                         disable_write_same(tio->md);
 223                 else if (req_op(clone) == REQ_OP_WRITE_ZEROES &&
 224                          !clone->q->limits.max_write_zeroes_sectors)
 225                         disable_write_zeroes(tio->md);
 226         }
 227
 228         switch (r) {
 229         case DM_ENDIO_DONE:
 230                 /* The target wants to complete the I/O */
 231                 dm_end_request(clone, error);
 232                 break;
 233         case DM_ENDIO_INCOMPLETE:
 234                 /* The target will handle the I/O */
 235                 return;
 236         case DM_ENDIO_REQUEUE:
 237                 /* The target wants to requeue the I/O */
 238                 dm_requeue_original_request(tio, false);
 239                 break;
 240         case DM_ENDIO_DELAY_REQUEUE:
 241                 /* The target wants to requeue the I/O after a delay */
 242                 dm_requeue_original_request(tio, true);
 243                 break;
 244         default:
 245                 DMWARN("unimplemented target endio return value: %d", r);
 246                 BUG();
 247         }
 248 }
 249
 250 /*
 251  * Request completion handler for request-based dm
 252  */
 253 static void dm_softirq_done(struct request *rq)
 254 {
 255         bool mapped = true;
 256         struct dm_rq_target_io *tio = tio_from_request(rq);
 257         struct request *clone = tio->clone;
 258
 259         if (!clone) {
 260                 struct mapped_device *md = tio->md;
 261
 262                 rq_end_stats(md, rq);
 263                 blk_mq_end_request(rq, tio->error);
 264                 rq_completed(md);
 265                 return;
 266         }
 267
 268         if (rq->rq_flags & RQF_FAILED)
 269                 mapped = false;
 270
 271         dm_done(clone, tio->error, mapped);
 272 }
 273
 274 /*
 275  * Complete the clone and the original request with the error status
 276  * through softirq context.
 277  */
 278 static void dm_complete_request(struct request *rq, blk_status_t error)
 279 {
 280         struct dm_rq_target_io *tio = tio_from_request(rq);
 281
 282         tio->error = error;
 283         if (likely(!blk_should_fake_timeout(rq->q)))
 284                 blk_mq_complete_request(rq);
 285 }
 286
 287 /*
 288  * Complete the not-mapped clone and the original request with the error status
 289  * through softirq context.
 290  * Target's rq_end_io() function isn't called.
 291  * This may be used when the target's clone_and_map_rq() function fails.
 292  */
 293 static void dm_kill_unmapped_request(struct request *rq, blk_status_t error)
 294 {
 295         rq->rq_flags |= RQF_FAILED;
 296         dm_complete_request(rq, error);
 297 }
 298
 299 static void end_clone_request(struct request *clone, blk_status_t error)
 300 {
 301         struct dm_rq_target_io *tio = clone->end_io_data;
 302
 303         dm_complete_request(tio->orig, error);
 304 }
 305
 306 static blk_status_t dm_dispatch_clone_request(struct request *clone, struct request *rq)
 307 {
 308         blk_status_t r;
 309
 310         if (blk_queue_io_stat(clone->q))
 311                 clone->rq_flags |= RQF_IO_STAT;
 312
 313         clone->start_time_ns = ktime_get_ns();
 314         r = blk_insert_cloned_request(clone->q, clone);
 315         if (r != BLK_STS_OK && r != BLK_STS_RESOURCE && r != BLK_STS_DEV_RESOURCE)
 316                 /* must complete clone in terms of original request */
 317                 dm_complete_request(rq, r);
 318         return r;
 319 }
 320
 321 static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
 322                                  void *data)
 323 {
 324         struct dm_rq_target_io *tio = data;
 325         struct dm_rq_clone_bio_info *info =
 326                 container_of(bio, struct dm_rq_clone_bio_info, clone);
 327
 328         info->orig = bio_orig;
 329         info->tio = tio;
 330         bio->bi_end_io = end_clone_bio;
 331
 332         return 0;
 333 }
 334
 335 static int setup_clone(struct request *clone, struct request *rq,
 336                        struct dm_rq_target_io *tio, gfp_t gfp_mask)
 337 {
 338         int r;
 339
 340         r = blk_rq_prep_clone(clone, rq, &tio->md->bs, gfp_mask,
 341                               dm_rq_bio_constructor, tio);
 342         if (r)
 343                 return r;
 344
 345         clone->end_io = end_clone_request;
 346         clone->end_io_data = tio;
 347
 348         tio->clone = clone;
 349
 350         return 0;
 351 }
 352
 353 static void init_tio(struct dm_rq_target_io *tio, struct request *rq,
 354                      struct mapped_device *md)
 355 {
 356         tio->md = md;
 357         tio->ti = NULL;
 358         tio->clone = NULL;
 359         tio->orig = rq;
 360         tio->error = 0;
 361         tio->completed = 0;
 362         /*
 363          * Avoid initializing info for blk-mq; it passes
 364          * target-specific data through info.ptr
 365          * (see: dm_mq_init_request)
 366          */
 367         if (!md->init_tio_pdu)
 368                 memset(&tio->info, 0, sizeof(tio->info));
 369 }
 370
 371 /*
 372  * Returns:
 373  * DM_MAPIO_*       : the request has been processed as indicated
 374  * DM_MAPIO_REQUEUE : the original request needs to be immediately requeued
 375  * < 0              : the request was completed due to failure
 376  */
 377 static int map_request(struct dm_rq_target_io *tio)
 378 {
 379         int r;
 380         struct dm_target *ti = tio->ti;
 381         struct mapped_device *md = tio->md;
 382         struct request *rq = tio->orig;
 383         struct request *clone = NULL;
 384         blk_status_t ret;
 385
 386         r = ti->type->clone_and_map_rq(ti, rq, &tio->info, &clone);
 387         switch (r) {
 388         case DM_MAPIO_SUBMITTED:
 389                 /* The target has taken the I/O to submit by itself later */
 390                 break;
 391         case DM_MAPIO_REMAPPED:
 392                 if (setup_clone(clone, rq, tio, GFP_ATOMIC)) {
 393                         /* -ENOMEM */
 394                         ti->type->release_clone_rq(clone, &tio->info);
 395                         return DM_MAPIO_REQUEUE;
 396                 }
 397
 398                 /* The target has remapped the I/O so dispatch it */
 399                 trace_block_rq_remap(clone, disk_devt(dm_disk(md)),
 400                                      blk_rq_pos(rq));
 401                 ret = dm_dispatch_clone_request(clone, rq);
 402                 if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) {
 403                         blk_rq_unprep_clone(clone);
 404                         blk_mq_cleanup_rq(clone);
 405                         tio->ti->type->release_clone_rq(clone, &tio->info);
 406                         tio->clone = NULL;
 407                         return DM_MAPIO_REQUEUE;
 408                 }
 409                 break;
 410         case DM_MAPIO_REQUEUE:
 411                 /* The target wants to requeue the I/O */
 412                 break;
 413         case DM_MAPIO_DELAY_REQUEUE:
 414                 /* The target wants to requeue the I/O after a delay */
 415                 dm_requeue_original_request(tio, true);
 416                 break;
 417         case DM_MAPIO_KILL:
 418                 /* The target wants to complete the I/O */
 419                 dm_kill_unmapped_request(rq, BLK_STS_IOERR);
 420                 break;
 421         default:
 422                 DMWARN("unimplemented target map return value: %d", r);
 423                 BUG();
 424         }
 425
 426         return r;
 427 }
 428
 429 /* DEPRECATED: previously used for request-based merge heuristic in dm_request_fn() */
 430 ssize_t dm_attr_rq_based_seq_io_merge_deadline_show(struct mapped_device *md, char *buf)
 431 {
 432         return sprintf(buf, "%u\n", 0);
 433 }
 434
 435 ssize_t dm_attr_rq_based_seq_io_merge_deadline_store(struct mapped_device *md,
 436                                                      const char *buf, size_t count)
 437 {
 438         return count;
 439 }
 440
 441 static void dm_start_request(struct mapped_device *md, struct request *orig)
 442 {
 443         blk_mq_start_request(orig);
 444
 445         if (unlikely(dm_stats_used(&md->stats))) {
 446                 struct dm_rq_target_io *tio = tio_from_request(orig);
 447                 tio->duration_jiffies = jiffies;
 448                 tio->n_sectors = blk_rq_sectors(orig);
 449                 dm_stats_account_io(&md->stats, rq_data_dir(orig),
 450                                     blk_rq_pos(orig), tio->n_sectors, false, 0,
 451                                     &tio->stats_aux);
 452         }
 453
 454         /*
 455          * Hold the md reference here for the in-flight I/O.
 456          * We can't rely on the reference count by device opener,
 457          * because the device may be closed during the request completion
 458          * when all bios are completed.
 459          * See the comment in rq_completed() too.
 460          */
 461         dm_get(md);
 462 }
 463
 464 static int dm_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
 465                               unsigned int hctx_idx, unsigned int numa_node)
 466 {
 467         struct mapped_device *md = set->driver_data;
 468         struct dm_rq_target_io *tio = blk_mq_rq_to_pdu(rq);
 469
 470         /*
 471          * Must initialize md member of tio, otherwise it won't
 472          * be available in dm_mq_queue_rq.
 473          */
 474         tio->md = md;
 475
 476         if (md->init_tio_pdu) {
 477                 /* target-specific per-io data is immediately after the tio */
 478                 tio->info.ptr = tio + 1;
 479         }
 480
 481         return 0;
 482 }
 483
 484 static blk_status_t dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
 485                           const struct blk_mq_queue_data *bd)
 486 {
 487         struct request *rq = bd->rq;
 488         struct dm_rq_target_io *tio = blk_mq_rq_to_pdu(rq);
 489         struct mapped_device *md = tio->md;
 490         struct dm_target *ti = md->immutable_target;
 491
 492         /*
 493          * blk-mq's unquiesce may come from outside events, such as
 494          * elevator switch, updating nr_requests or others, and request may
 495          * come during suspend, so simply ask for blk-mq to requeue it.
 496          */
 497         if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)))
 498                 return BLK_STS_RESOURCE;
 499
 500         if (unlikely(!ti)) {
 501                 int srcu_idx;
 502                 struct dm_table *map = dm_get_live_table(md, &srcu_idx);
 503
 504                 ti = dm_table_find_target(map, 0);
 505                 dm_put_live_table(md, srcu_idx);
 506         }
 507
 508         if (ti->type->busy && ti->type->busy(ti))
 509                 return BLK_STS_RESOURCE;
 510
 511         dm_start_request(md, rq);
 512
 513         /* Init tio using md established in .init_request */
 514         init_tio(tio, rq, md);
 515
 516         /*
 517          * Establish tio->ti before calling map_request().
 518          */
 519         tio->ti = ti;
 520
 521         /* Direct call is fine since .queue_rq allows allocations */
 522         if (map_request(tio) == DM_MAPIO_REQUEUE) {
 523                 /* Undo dm_start_request() before requeuing */
 524                 rq_end_stats(md, rq);
 525                 rq_completed(md);
 526                 return BLK_STS_RESOURCE;
 527         }
 528
 529         return BLK_STS_OK;
 530 }
 531
 532 static const struct blk_mq_ops dm_mq_ops = {
 533         .queue_rq = dm_mq_queue_rq,
 534         .complete = dm_softirq_done,
 535         .init_request = dm_mq_init_request,
 536 };
 537
 538 int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t)
 539 {
 540         struct dm_target *immutable_tgt;
 541         int err;
 542
 543         md->tag_set = kzalloc_node(sizeof(struct blk_mq_tag_set), GFP_KERNEL, md->numa_node_id);
 544         if (!md->tag_set)
 545                 return -ENOMEM;
 546
 547         md->tag_set->ops = &dm_mq_ops;
 548         md->tag_set->queue_depth = dm_get_blk_mq_queue_depth();
 549         md->tag_set->numa_node = md->numa_node_id;
 550         md->tag_set->flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING;
 551         md->tag_set->nr_hw_queues = dm_get_blk_mq_nr_hw_queues();
 552         md->tag_set->driver_data = md;
 553
 554         md->tag_set->cmd_size = sizeof(struct dm_rq_target_io);
 555         immutable_tgt = dm_table_get_immutable_target(t);
 556         if (immutable_tgt && immutable_tgt->per_io_data_size) {
 557                 /* any target-specific per-io data is immediately after the tio */
 558                 md->tag_set->cmd_size += immutable_tgt->per_io_data_size;
 559                 md->init_tio_pdu = true;
 560         }
 561
 562         err = blk_mq_alloc_tag_set(md->tag_set);
 563         if (err)
 564                 goto out_kfree_tag_set;
 565
 566         err = blk_mq_init_allocated_queue(md->tag_set, md->queue);
 567         if (err)
 568                 goto out_tag_set;
 569         return 0;
 570
 571 out_tag_set:
 572         blk_mq_free_tag_set(md->tag_set);
 573 out_kfree_tag_set:
 574         kfree(md->tag_set);
 575         md->tag_set = NULL;
 576
 577         return err;
 578 }
 579
 580 void dm_mq_cleanup_mapped_device(struct mapped_device *md)
 581 {
 582         if (md->tag_set) {
 583                 blk_mq_free_tag_set(md->tag_set);
 584                 kfree(md->tag_set);
 585                 md->tag_set = NULL;
 586         }
 587 }
 588
 589 module_param(reserved_rq_based_ios, uint, S_IRUGO | S_IWUSR);
 590 MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools");
 591
 592 /* Unused, but preserved for userspace compatibility */
 593 static bool use_blk_mq = true;
 594 module_param(use_blk_mq, bool, S_IRUGO | S_IWUSR);
 595 MODULE_PARM_DESC(use_blk_mq, "Use block multiqueue for request-based DM devices");
 596
 597 module_param(dm_mq_nr_hw_queues, uint, S_IRUGO | S_IWUSR);
 598 MODULE_PARM_DESC(dm_mq_nr_hw_queues, "Number of hardware queues for request-based dm-mq devices");
 599
 600 module_param(dm_mq_queue_depth, uint, S_IRUGO | S_IWUSR);
 601 MODULE_PARM_DESC(dm_mq_queue_depth, "Queue depth for request-based dm-mq devices");