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/elevator.h> /* for rq_end_sector() */
  11 #include <linux/blk-mq.h>
  12
  13 #define DM_MSG_PREFIX "core-rq"
  14
  15 #define DM_MQ_NR_HW_QUEUES 1
  16 #define DM_MQ_QUEUE_DEPTH 2048
  17 static unsigned dm_mq_nr_hw_queues = DM_MQ_NR_HW_QUEUES;
  18 static unsigned dm_mq_queue_depth = DM_MQ_QUEUE_DEPTH;
  19
  20 /*
  21  * Request-based DM's mempools' reserved IOs set by the user.
  22  */
  23 #define RESERVED_REQUEST_BASED_IOS      256
  24 static unsigned reserved_rq_based_ios = RESERVED_REQUEST_BASED_IOS;
  25
  26 static bool use_blk_mq = IS_ENABLED(CONFIG_DM_MQ_DEFAULT);
  27
  28 bool dm_use_blk_mq_default(void)
  29 {
  30         return use_blk_mq;
  31 }
  32
  33 bool dm_use_blk_mq(struct mapped_device *md)
  34 {
  35         return md->use_blk_mq;
  36 }
  37 EXPORT_SYMBOL_GPL(dm_use_blk_mq);
  38
  39 unsigned dm_get_reserved_rq_based_ios(void)
  40 {
  41         return __dm_get_module_param(&reserved_rq_based_ios,
  42                                      RESERVED_REQUEST_BASED_IOS, DM_RESERVED_MAX_IOS);
  43 }
  44 EXPORT_SYMBOL_GPL(dm_get_reserved_rq_based_ios);
  45
  46 static unsigned dm_get_blk_mq_nr_hw_queues(void)
  47 {
  48         return __dm_get_module_param(&dm_mq_nr_hw_queues, 1, 32);
  49 }
  50
  51 static unsigned dm_get_blk_mq_queue_depth(void)
  52 {
  53         return __dm_get_module_param(&dm_mq_queue_depth,
  54                                      DM_MQ_QUEUE_DEPTH, BLK_MQ_MAX_DEPTH);
  55 }
  56
  57 int dm_request_based(struct mapped_device *md)
  58 {
  59         return blk_queue_stackable(md->queue);
  60 }
  61
  62 static void dm_old_start_queue(struct request_queue *q)
  63 {
  64         unsigned long flags;
  65
  66         spin_lock_irqsave(q->queue_lock, flags);
  67         if (blk_queue_stopped(q))
  68                 blk_start_queue(q);
  69         spin_unlock_irqrestore(q->queue_lock, flags);
  70 }
  71
  72 static void dm_mq_start_queue(struct request_queue *q)
  73 {
  74         blk_mq_start_stopped_hw_queues(q, true);
  75         blk_mq_kick_requeue_list(q);
  76 }
  77
  78 void dm_start_queue(struct request_queue *q)
  79 {
  80         if (!q->mq_ops)
  81                 dm_old_start_queue(q);
  82         else
  83                 dm_mq_start_queue(q);
  84 }
  85
  86 static void dm_old_stop_queue(struct request_queue *q)
  87 {
  88         unsigned long flags;
  89
  90         spin_lock_irqsave(q->queue_lock, flags);
  91         if (!blk_queue_stopped(q))
  92                 blk_stop_queue(q);
  93         spin_unlock_irqrestore(q->queue_lock, flags);
  94 }
  95
  96 static void dm_mq_stop_queue(struct request_queue *q)
  97 {
  98         if (blk_mq_queue_stopped(q))
  99                 return;
 100
 101         blk_mq_quiesce_queue(q);
 102 }
 103
 104 void dm_stop_queue(struct request_queue *q)
 105 {
 106         if (!q->mq_ops)
 107                 dm_old_stop_queue(q);
 108         else
 109                 dm_mq_stop_queue(q);
 110 }
 111
 112 /*
 113  * Partial completion handling for request-based dm
 114  */
 115 static void end_clone_bio(struct bio *clone)
 116 {
 117         struct dm_rq_clone_bio_info *info =
 118                 container_of(clone, struct dm_rq_clone_bio_info, clone);
 119         struct dm_rq_target_io *tio = info->tio;
 120         struct bio *bio = info->orig;
 121         unsigned int nr_bytes = info->orig->bi_iter.bi_size;
 122         int error = clone->bi_error;
 123
 124         bio_put(clone);
 125
 126         if (tio->error)
 127                 /*
 128                  * An error has already been detected on the request.
 129                  * Once error occurred, just let clone->end_io() handle
 130                  * the remainder.
 131                  */
 132                 return;
 133         else if (error) {
 134                 /*
 135                  * Don't notice the error to the upper layer yet.
 136                  * The error handling decision is made by the target driver,
 137                  * when the request is completed.
 138                  */
 139                 tio->error = error;
 140                 return;
 141         }
 142
 143         /*
 144          * I/O for the bio successfully completed.
 145          * Notice the data completion to the upper layer.
 146          */
 147
 148         /*
 149          * bios are processed from the head of the list.
 150          * So the completing bio should always be rq->bio.
 151          * If it's not, something wrong is happening.
 152          */
 153         if (tio->orig->bio != bio)
 154                 DMERR("bio completion is going in the middle of the request");
 155
 156         /*
 157          * Update the original request.
 158          * Do not use blk_end_request() here, because it may complete
 159          * the original request before the clone, and break the ordering.
 160          */
 161         blk_update_request(tio->orig, 0, nr_bytes);
 162 }
 163
 164 static struct dm_rq_target_io *tio_from_request(struct request *rq)
 165 {
 166         return blk_mq_rq_to_pdu(rq);
 167 }
 168
 169 static void rq_end_stats(struct mapped_device *md, struct request *orig)
 170 {
 171         if (unlikely(dm_stats_used(&md->stats))) {
 172                 struct dm_rq_target_io *tio = tio_from_request(orig);
 173                 tio->duration_jiffies = jiffies - tio->duration_jiffies;
 174                 dm_stats_account_io(&md->stats, rq_data_dir(orig),
 175                                     blk_rq_pos(orig), tio->n_sectors, true,
 176                                     tio->duration_jiffies, &tio->stats_aux);
 177         }
 178 }
 179
 180 /*
 181  * Don't touch any member of the md after calling this function because
 182  * the md may be freed in dm_put() at the end of this function.
 183  * Or do dm_get() before calling this function and dm_put() later.
 184  */
 185 static void rq_completed(struct mapped_device *md, int rw, bool run_queue)
 186 {
 187         struct request_queue *q = md->queue;
 188         unsigned long flags;
 189
 190         atomic_dec(&md->pending[rw]);
 191
 192         /* nudge anyone waiting on suspend queue */
 193         if (!md_in_flight(md))
 194                 wake_up(&md->wait);
 195
 196         /*
 197          * Run this off this callpath, as drivers could invoke end_io while
 198          * inside their request_fn (and holding the queue lock). Calling
 199          * back into ->request_fn() could deadlock attempting to grab the
 200          * queue lock again.
 201          */
 202         if (!q->mq_ops && run_queue) {
 203                 spin_lock_irqsave(q->queue_lock, flags);
 204                 blk_run_queue_async(q);
 205                 spin_unlock_irqrestore(q->queue_lock, flags);
 206         }
 207
 208         /*
 209          * dm_put() must be at the end of this function. See the comment above
 210          */
 211         dm_put(md);
 212 }
 213
 214 /*
 215  * Complete the clone and the original request.
 216  * Must be called without clone's queue lock held,
 217  * see end_clone_request() for more details.
 218  */
 219 static void dm_end_request(struct request *clone, int error)
 220 {
 221         int rw = rq_data_dir(clone);
 222         struct dm_rq_target_io *tio = clone->end_io_data;
 223         struct mapped_device *md = tio->md;
 224         struct request *rq = tio->orig;
 225
 226         blk_rq_unprep_clone(clone);
 227         tio->ti->type->release_clone_rq(clone);
 228
 229         rq_end_stats(md, rq);
 230         if (!rq->q->mq_ops)
 231                 blk_end_request_all(rq, error);
 232         else
 233                 blk_mq_end_request(rq, error);
 234         rq_completed(md, rw, true);
 235 }
 236
 237 /*
 238  * Requeue the original request of a clone.
 239  */
 240 static void dm_old_requeue_request(struct request *rq)
 241 {
 242         struct request_queue *q = rq->q;
 243         unsigned long flags;
 244
 245         spin_lock_irqsave(q->queue_lock, flags);
 246         blk_requeue_request(q, rq);
 247         blk_run_queue_async(q);
 248         spin_unlock_irqrestore(q->queue_lock, flags);
 249 }
 250
 251 static void __dm_mq_kick_requeue_list(struct request_queue *q, unsigned long msecs)
 252 {
 253         blk_mq_delay_kick_requeue_list(q, msecs);
 254 }
 255
 256 void dm_mq_kick_requeue_list(struct mapped_device *md)
 257 {
 258         __dm_mq_kick_requeue_list(dm_get_md_queue(md), 0);
 259 }
 260 EXPORT_SYMBOL(dm_mq_kick_requeue_list);
 261
 262 static void dm_mq_delay_requeue_request(struct request *rq, unsigned long msecs)
 263 {
 264         blk_mq_requeue_request(rq, false);
 265         __dm_mq_kick_requeue_list(rq->q, msecs);
 266 }
 267
 268 static void dm_requeue_original_request(struct dm_rq_target_io *tio, bool delay_requeue)
 269 {
 270         struct mapped_device *md = tio->md;
 271         struct request *rq = tio->orig;
 272         int rw = rq_data_dir(rq);
 273
 274         rq_end_stats(md, rq);
 275         if (tio->clone) {
 276                 blk_rq_unprep_clone(tio->clone);
 277                 tio->ti->type->release_clone_rq(tio->clone);
 278         }
 279
 280         if (!rq->q->mq_ops)
 281                 dm_old_requeue_request(rq);
 282         else
 283                 dm_mq_delay_requeue_request(rq, delay_requeue ? 5000 : 0);
 284
 285         rq_completed(md, rw, false);
 286 }
 287
 288 static void dm_done(struct request *clone, int error, bool mapped)
 289 {
 290         int r = error;
 291         struct dm_rq_target_io *tio = clone->end_io_data;
 292         dm_request_endio_fn rq_end_io = NULL;
 293
 294         if (tio->ti) {
 295                 rq_end_io = tio->ti->type->rq_end_io;
 296
 297                 if (mapped && rq_end_io)
 298                         r = rq_end_io(tio->ti, clone, error, &tio->info);
 299         }
 300
 301         if (unlikely(r == -EREMOTEIO && (req_op(clone) == REQ_OP_WRITE_SAME) &&
 302                      !clone->q->limits.max_write_same_sectors))
 303                 disable_write_same(tio->md);
 304
 305         if (r <= 0)
 306                 /* The target wants to complete the I/O */
 307                 dm_end_request(clone, r);
 308         else if (r == DM_ENDIO_INCOMPLETE)
 309                 /* The target will handle the I/O */
 310                 return;
 311         else if (r == DM_ENDIO_REQUEUE)
 312                 /* The target wants to requeue the I/O */
 313                 dm_requeue_original_request(tio, false);
 314         else {
 315                 DMWARN("unimplemented target endio return value: %d", r);
 316                 BUG();
 317         }
 318 }
 319
 320 /*
 321  * Request completion handler for request-based dm
 322  */
 323 static void dm_softirq_done(struct request *rq)
 324 {
 325         bool mapped = true;
 326         struct dm_rq_target_io *tio = tio_from_request(rq);
 327         struct request *clone = tio->clone;
 328         int rw;
 329
 330         if (!clone) {
 331                 rq_end_stats(tio->md, rq);
 332                 rw = rq_data_dir(rq);
 333                 if (!rq->q->mq_ops)
 334                         blk_end_request_all(rq, tio->error);
 335                 else
 336                         blk_mq_end_request(rq, tio->error);
 337                 rq_completed(tio->md, rw, false);
 338                 return;
 339         }
 340
 341         if (rq->rq_flags & RQF_FAILED)
 342                 mapped = false;
 343
 344         dm_done(clone, tio->error, mapped);
 345 }
 346
 347 /*
 348  * Complete the clone and the original request with the error status
 349  * through softirq context.
 350  */
 351 static void dm_complete_request(struct request *rq, int error)
 352 {
 353         struct dm_rq_target_io *tio = tio_from_request(rq);
 354
 355         tio->error = error;
 356         if (!rq->q->mq_ops)
 357                 blk_complete_request(rq);
 358         else
 359                 blk_mq_complete_request(rq, error);
 360 }
 361
 362 /*
 363  * Complete the not-mapped clone and the original request with the error status
 364  * through softirq context.
 365  * Target's rq_end_io() function isn't called.
 366  * This may be used when the target's map_rq() or clone_and_map_rq() functions fail.
 367  */
 368 static void dm_kill_unmapped_request(struct request *rq, int error)
 369 {
 370         rq->rq_flags |= RQF_FAILED;
 371         dm_complete_request(rq, error);
 372 }
 373
 374 /*
 375  * Called with the clone's queue lock held (in the case of .request_fn)
 376  */
 377 static void end_clone_request(struct request *clone, int error)
 378 {
 379         struct dm_rq_target_io *tio = clone->end_io_data;
 380
 381         /*
 382          * Actual request completion is done in a softirq context which doesn't
 383          * hold the clone's queue lock.  Otherwise, deadlock could occur because:
 384          *     - another request may be submitted by the upper level driver
 385          *       of the stacking during the completion
 386          *     - the submission which requires queue lock may be done
 387          *       against this clone's queue
 388          */
 389         dm_complete_request(tio->orig, error);
 390 }
 391
 392 static void dm_dispatch_clone_request(struct request *clone, struct request *rq)
 393 {
 394         int r;
 395
 396         if (blk_queue_io_stat(clone->q))
 397                 clone->rq_flags |= RQF_IO_STAT;
 398
 399         clone->start_time = jiffies;
 400         r = blk_insert_cloned_request(clone->q, clone);
 401         if (r)
 402                 /* must complete clone in terms of original request */
 403                 dm_complete_request(rq, r);
 404 }
 405
 406 static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
 407                                  void *data)
 408 {
 409         struct dm_rq_target_io *tio = data;
 410         struct dm_rq_clone_bio_info *info =
 411                 container_of(bio, struct dm_rq_clone_bio_info, clone);
 412
 413         info->orig = bio_orig;
 414         info->tio = tio;
 415         bio->bi_end_io = end_clone_bio;
 416
 417         return 0;
 418 }
 419
 420 static int setup_clone(struct request *clone, struct request *rq,
 421                        struct dm_rq_target_io *tio, gfp_t gfp_mask)
 422 {
 423         int r;
 424
 425         r = blk_rq_prep_clone(clone, rq, tio->md->bs, gfp_mask,
 426                               dm_rq_bio_constructor, tio);
 427         if (r)
 428                 return r;
 429
 430         clone->end_io = end_clone_request;
 431         clone->end_io_data = tio;
 432
 433         tio->clone = clone;
 434
 435         return 0;
 436 }
 437
 438 static void map_tio_request(struct kthread_work *work);
 439
 440 static void init_tio(struct dm_rq_target_io *tio, struct request *rq,
 441                      struct mapped_device *md)
 442 {
 443         tio->md = md;
 444         tio->ti = NULL;
 445         tio->clone = NULL;
 446         tio->orig = rq;
 447         tio->error = 0;
 448         /*
 449          * Avoid initializing info for blk-mq; it passes
 450          * target-specific data through info.ptr
 451          * (see: dm_mq_init_request)
 452          */
 453         if (!md->init_tio_pdu)
 454                 memset(&tio->info, 0, sizeof(tio->info));
 455         if (md->kworker_task)
 456                 kthread_init_work(&tio->work, map_tio_request);
 457 }
 458
 459 /*
 460  * Returns:
 461  * DM_MAPIO_*       : the request has been processed as indicated
 462  * DM_MAPIO_REQUEUE : the original request needs to be immediately requeued
 463  * < 0              : the request was completed due to failure
 464  */
 465 static int map_request(struct dm_rq_target_io *tio)
 466 {
 467         int r;
 468         struct dm_target *ti = tio->ti;
 469         struct mapped_device *md = tio->md;
 470         struct request *rq = tio->orig;
 471         struct request *clone = NULL;
 472
 473         r = ti->type->clone_and_map_rq(ti, rq, &tio->info, &clone);
 474         switch (r) {
 475         case DM_MAPIO_SUBMITTED:
 476                 /* The target has taken the I/O to submit by itself later */
 477                 break;
 478         case DM_MAPIO_REMAPPED:
 479                 if (setup_clone(clone, rq, tio, GFP_ATOMIC)) {
 480                         /* -ENOMEM */
 481                         ti->type->release_clone_rq(clone);
 482                         return DM_MAPIO_REQUEUE;
 483                 }
 484
 485                 /* The target has remapped the I/O so dispatch it */
 486                 trace_block_rq_remap(clone->q, clone, disk_devt(dm_disk(md)),
 487                                      blk_rq_pos(rq));
 488                 dm_dispatch_clone_request(clone, rq);
 489                 break;
 490         case DM_MAPIO_REQUEUE:
 491                 /* The target wants to requeue the I/O */
 492                 break;
 493         case DM_MAPIO_DELAY_REQUEUE:
 494                 /* The target wants to requeue the I/O after a delay */
 495                 dm_requeue_original_request(tio, true);
 496                 break;
 497         default:
 498                 if (r > 0) {
 499                         DMWARN("unimplemented target map return value: %d", r);
 500                         BUG();
 501                 }
 502
 503                 /* The target wants to complete the I/O */
 504                 dm_kill_unmapped_request(rq, r);
 505         }
 506
 507         return r;
 508 }
 509
 510 static void dm_start_request(struct mapped_device *md, struct request *orig)
 511 {
 512         if (!orig->q->mq_ops)
 513                 blk_start_request(orig);
 514         else
 515                 blk_mq_start_request(orig);
 516         atomic_inc(&md->pending[rq_data_dir(orig)]);
 517
 518         if (md->seq_rq_merge_deadline_usecs) {
 519                 md->last_rq_pos = rq_end_sector(orig);
 520                 md->last_rq_rw = rq_data_dir(orig);
 521                 md->last_rq_start_time = ktime_get();
 522         }
 523
 524         if (unlikely(dm_stats_used(&md->stats))) {
 525                 struct dm_rq_target_io *tio = tio_from_request(orig);
 526                 tio->duration_jiffies = jiffies;
 527                 tio->n_sectors = blk_rq_sectors(orig);
 528                 dm_stats_account_io(&md->stats, rq_data_dir(orig),
 529                                     blk_rq_pos(orig), tio->n_sectors, false, 0,
 530                                     &tio->stats_aux);
 531         }
 532
 533         /*
 534          * Hold the md reference here for the in-flight I/O.
 535          * We can't rely on the reference count by device opener,
 536          * because the device may be closed during the request completion
 537          * when all bios are completed.
 538          * See the comment in rq_completed() too.
 539          */
 540         dm_get(md);
 541 }
 542
 543 static int __dm_rq_init_rq(struct mapped_device *md, struct request *rq)
 544 {
 545         struct dm_rq_target_io *tio = blk_mq_rq_to_pdu(rq);
 546
 547         /*
 548          * Must initialize md member of tio, otherwise it won't
 549          * be available in dm_mq_queue_rq.
 550          */
 551         tio->md = md;
 552
 553         if (md->init_tio_pdu) {
 554                 /* target-specific per-io data is immediately after the tio */
 555                 tio->info.ptr = tio + 1;
 556         }
 557
 558         return 0;
 559 }
 560
 561 static int dm_rq_init_rq(struct request_queue *q, struct request *rq, gfp_t gfp)
 562 {
 563         return __dm_rq_init_rq(q->rq_alloc_data, rq);
 564 }
 565
 566 static void map_tio_request(struct kthread_work *work)
 567 {
 568         struct dm_rq_target_io *tio = container_of(work, struct dm_rq_target_io, work);
 569
 570         if (map_request(tio) == DM_MAPIO_REQUEUE)
 571                 dm_requeue_original_request(tio, false);
 572 }
 573
 574 ssize_t dm_attr_rq_based_seq_io_merge_deadline_show(struct mapped_device *md, char *buf)
 575 {
 576         return sprintf(buf, "%u\n", md->seq_rq_merge_deadline_usecs);
 577 }
 578
 579 #define MAX_SEQ_RQ_MERGE_DEADLINE_USECS 100000
 580
 581 ssize_t dm_attr_rq_based_seq_io_merge_deadline_store(struct mapped_device *md,
 582                                                      const char *buf, size_t count)
 583 {
 584         unsigned deadline;
 585
 586         if (dm_get_md_type(md) != DM_TYPE_REQUEST_BASED)
 587                 return count;
 588
 589         if (kstrtouint(buf, 10, &deadline))
 590                 return -EINVAL;
 591
 592         if (deadline > MAX_SEQ_RQ_MERGE_DEADLINE_USECS)
 593                 deadline = MAX_SEQ_RQ_MERGE_DEADLINE_USECS;
 594
 595         md->seq_rq_merge_deadline_usecs = deadline;
 596
 597         return count;
 598 }
 599
 600 static bool dm_old_request_peeked_before_merge_deadline(struct mapped_device *md)
 601 {
 602         ktime_t kt_deadline;
 603
 604         if (!md->seq_rq_merge_deadline_usecs)
 605                 return false;
 606
 607         kt_deadline = ns_to_ktime((u64)md->seq_rq_merge_deadline_usecs * NSEC_PER_USEC);
 608         kt_deadline = ktime_add_safe(md->last_rq_start_time, kt_deadline);
 609
 610         return !ktime_after(ktime_get(), kt_deadline);
 611 }
 612
 613 /*
 614  * q->request_fn for old request-based dm.
 615  * Called with the queue lock held.
 616  */
 617 static void dm_old_request_fn(struct request_queue *q)
 618 {
 619         struct mapped_device *md = q->queuedata;
 620         struct dm_target *ti = md->immutable_target;
 621         struct request *rq;
 622         struct dm_rq_target_io *tio;
 623         sector_t pos = 0;
 624
 625         if (unlikely(!ti)) {
 626                 int srcu_idx;
 627                 struct dm_table *map = dm_get_live_table(md, &srcu_idx);
 628
 629                 if (unlikely(!map)) {
 630                         dm_put_live_table(md, srcu_idx);
 631                         return;
 632                 }
 633                 ti = dm_table_find_target(map, pos);
 634                 dm_put_live_table(md, srcu_idx);
 635         }
 636
 637         /*
 638          * For suspend, check blk_queue_stopped() and increment
 639          * ->pending within a single queue_lock not to increment the
 640          * number of in-flight I/Os after the queue is stopped in
 641          * dm_suspend().
 642          */
 643         while (!blk_queue_stopped(q)) {
 644                 rq = blk_peek_request(q);
 645                 if (!rq)
 646                         return;
 647
 648                 /* always use block 0 to find the target for flushes for now */
 649                 pos = 0;
 650                 if (req_op(rq) != REQ_OP_FLUSH)
 651                         pos = blk_rq_pos(rq);
 652
 653                 if ((dm_old_request_peeked_before_merge_deadline(md) &&
 654                      md_in_flight(md) && rq->bio && !bio_multiple_segments(rq->bio) &&
 655                      md->last_rq_pos == pos && md->last_rq_rw == rq_data_dir(rq)) ||
 656                     (ti->type->busy && ti->type->busy(ti))) {
 657                         blk_delay_queue(q, 10);
 658                         return;
 659                 }
 660
 661                 dm_start_request(md, rq);
 662
 663                 tio = tio_from_request(rq);
 664                 init_tio(tio, rq, md);
 665                 /* Establish tio->ti before queuing work (map_tio_request) */
 666                 tio->ti = ti;
 667                 kthread_queue_work(&md->kworker, &tio->work);
 668                 BUG_ON(!irqs_disabled());
 669         }
 670 }
 671
 672 /*
 673  * Fully initialize a .request_fn request-based queue.
 674  */
 675 int dm_old_init_request_queue(struct mapped_device *md, struct dm_table *t)
 676 {
 677         struct dm_target *immutable_tgt;
 678
 679         /* Fully initialize the queue */
 680         md->queue->cmd_size = sizeof(struct dm_rq_target_io);
 681         md->queue->rq_alloc_data = md;
 682         md->queue->request_fn = dm_old_request_fn;
 683         md->queue->init_rq_fn = dm_rq_init_rq;
 684
 685         immutable_tgt = dm_table_get_immutable_target(t);
 686         if (immutable_tgt && immutable_tgt->per_io_data_size) {
 687                 /* any target-specific per-io data is immediately after the tio */
 688                 md->queue->cmd_size += immutable_tgt->per_io_data_size;
 689                 md->init_tio_pdu = true;
 690         }
 691         if (blk_init_allocated_queue(md->queue) < 0)
 692                 return -EINVAL;
 693
 694         /* disable dm_old_request_fn's merge heuristic by default */
 695         md->seq_rq_merge_deadline_usecs = 0;
 696
 697         dm_init_normal_md_queue(md);
 698         blk_queue_softirq_done(md->queue, dm_softirq_done);
 699
 700         /* Initialize the request-based DM worker thread */
 701         kthread_init_worker(&md->kworker);
 702         md->kworker_task = kthread_run(kthread_worker_fn, &md->kworker,
 703                                        "kdmwork-%s", dm_device_name(md));
 704         if (IS_ERR(md->kworker_task)) {
 705                 int error = PTR_ERR(md->kworker_task);
 706                 md->kworker_task = NULL;
 707                 return error;
 708         }
 709
 710         elv_register_queue(md->queue);
 711
 712         return 0;
 713 }
 714
 715 static int dm_mq_init_request(void *data, struct request *rq,
 716                        unsigned int hctx_idx, unsigned int request_idx,
 717                        unsigned int numa_node)
 718 {
 719         return __dm_rq_init_rq(data, rq);
 720 }
 721
 722 static int dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
 723                           const struct blk_mq_queue_data *bd)
 724 {
 725         struct request *rq = bd->rq;
 726         struct dm_rq_target_io *tio = blk_mq_rq_to_pdu(rq);
 727         struct mapped_device *md = tio->md;
 728         struct dm_target *ti = md->immutable_target;
 729
 730         if (unlikely(!ti)) {
 731                 int srcu_idx;
 732                 struct dm_table *map = dm_get_live_table(md, &srcu_idx);
 733
 734                 ti = dm_table_find_target(map, 0);
 735                 dm_put_live_table(md, srcu_idx);
 736         }
 737
 738         if (ti->type->busy && ti->type->busy(ti))
 739                 return BLK_MQ_RQ_QUEUE_BUSY;
 740
 741         dm_start_request(md, rq);
 742
 743         /* Init tio using md established in .init_request */
 744         init_tio(tio, rq, md);
 745
 746         /*
 747          * Establish tio->ti before calling map_request().
 748          */
 749         tio->ti = ti;
 750
 751         /* Direct call is fine since .queue_rq allows allocations */
 752         if (map_request(tio) == DM_MAPIO_REQUEUE) {
 753                 /* Undo dm_start_request() before requeuing */
 754                 rq_end_stats(md, rq);
 755                 rq_completed(md, rq_data_dir(rq), false);
 756                 return BLK_MQ_RQ_QUEUE_BUSY;
 757         }
 758
 759         return BLK_MQ_RQ_QUEUE_OK;
 760 }
 761
 762 static struct blk_mq_ops dm_mq_ops = {
 763         .queue_rq = dm_mq_queue_rq,
 764         .complete = dm_softirq_done,
 765         .init_request = dm_mq_init_request,
 766 };
 767
 768 int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t)
 769 {
 770         struct request_queue *q;
 771         struct dm_target *immutable_tgt;
 772         int err;
 773
 774         if (!dm_table_all_blk_mq_devices(t)) {
 775                 DMERR("request-based dm-mq may only be stacked on blk-mq device(s)");
 776                 return -EINVAL;
 777         }
 778
 779         md->tag_set = kzalloc_node(sizeof(struct blk_mq_tag_set), GFP_KERNEL, md->numa_node_id);
 780         if (!md->tag_set)
 781                 return -ENOMEM;
 782
 783         md->tag_set->ops = &dm_mq_ops;
 784         md->tag_set->queue_depth = dm_get_blk_mq_queue_depth();
 785         md->tag_set->numa_node = md->numa_node_id;
 786         md->tag_set->flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
 787         md->tag_set->nr_hw_queues = dm_get_blk_mq_nr_hw_queues();
 788         md->tag_set->driver_data = md;
 789
 790         md->tag_set->cmd_size = sizeof(struct dm_rq_target_io);
 791         immutable_tgt = dm_table_get_immutable_target(t);
 792         if (immutable_tgt && immutable_tgt->per_io_data_size) {
 793                 /* any target-specific per-io data is immediately after the tio */
 794                 md->tag_set->cmd_size += immutable_tgt->per_io_data_size;
 795                 md->init_tio_pdu = true;
 796         }
 797
 798         err = blk_mq_alloc_tag_set(md->tag_set);
 799         if (err)
 800                 goto out_kfree_tag_set;
 801
 802         q = blk_mq_init_allocated_queue(md->tag_set, md->queue);
 803         if (IS_ERR(q)) {
 804                 err = PTR_ERR(q);
 805                 goto out_tag_set;
 806         }
 807         dm_init_md_queue(md);
 808
 809         /* backfill 'mq' sysfs registration normally done in blk_register_queue */
 810         blk_mq_register_dev(disk_to_dev(md->disk), q);
 811
 812         return 0;
 813
 814 out_tag_set:
 815         blk_mq_free_tag_set(md->tag_set);
 816 out_kfree_tag_set:
 817         kfree(md->tag_set);
 818
 819         return err;
 820 }
 821
 822 void dm_mq_cleanup_mapped_device(struct mapped_device *md)
 823 {
 824         if (md->tag_set) {
 825                 blk_mq_free_tag_set(md->tag_set);
 826                 kfree(md->tag_set);
 827         }
 828 }
 829
 830 module_param(reserved_rq_based_ios, uint, S_IRUGO | S_IWUSR);
 831 MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools");
 832
 833 module_param(use_blk_mq, bool, S_IRUGO | S_IWUSR);
 834 MODULE_PARM_DESC(use_blk_mq, "Use block multiqueue for request-based DM devices");
 835
 836 module_param(dm_mq_nr_hw_queues, uint, S_IRUGO | S_IWUSR);
 837 MODULE_PARM_DESC(dm_mq_nr_hw_queues, "Number of hardware queues for request-based dm-mq devices");
 838
 839 module_param(dm_mq_queue_depth, uint, S_IRUGO | S_IWUSR);
 840 MODULE_PARM_DESC(dm_mq_queue_depth, "Queue depth for request-based dm-mq devices");