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 #ifdef CONFIG_DM_MQ_DEFAULT
  27 static bool use_blk_mq = true;
  28 #else
  29 static bool use_blk_mq = false;
  30 #endif
  31
  32 bool dm_use_blk_mq_default(void)
  33 {
  34         return use_blk_mq;
  35 }
  36
  37 bool dm_use_blk_mq(struct mapped_device *md)
  38 {
  39         return md->use_blk_mq;
  40 }
  41 EXPORT_SYMBOL_GPL(dm_use_blk_mq);
  42
  43 unsigned dm_get_reserved_rq_based_ios(void)
  44 {
  45         return __dm_get_module_param(&reserved_rq_based_ios,
  46                                      RESERVED_REQUEST_BASED_IOS, DM_RESERVED_MAX_IOS);
  47 }
  48 EXPORT_SYMBOL_GPL(dm_get_reserved_rq_based_ios);
  49
  50 static unsigned dm_get_blk_mq_nr_hw_queues(void)
  51 {
  52         return __dm_get_module_param(&dm_mq_nr_hw_queues, 1, 32);
  53 }
  54
  55 static unsigned dm_get_blk_mq_queue_depth(void)
  56 {
  57         return __dm_get_module_param(&dm_mq_queue_depth,
  58                                      DM_MQ_QUEUE_DEPTH, BLK_MQ_MAX_DEPTH);
  59 }
  60
  61 int dm_request_based(struct mapped_device *md)
  62 {
  63         return blk_queue_stackable(md->queue);
  64 }
  65
  66 static void dm_old_start_queue(struct request_queue *q)
  67 {
  68         unsigned long flags;
  69
  70         spin_lock_irqsave(q->queue_lock, flags);
  71         if (blk_queue_stopped(q))
  72                 blk_start_queue(q);
  73         spin_unlock_irqrestore(q->queue_lock, flags);
  74 }
  75
  76 void dm_start_queue(struct request_queue *q)
  77 {
  78         if (!q->mq_ops)
  79                 dm_old_start_queue(q);
  80         else {
  81                 blk_mq_start_stopped_hw_queues(q, true);
  82                 blk_mq_kick_requeue_list(q);
  83         }
  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                 spin_unlock_irqrestore(q->queue_lock, flags);
  93                 return;
  94         }
  95
  96         blk_stop_queue(q);
  97         spin_unlock_irqrestore(q->queue_lock, flags);
  98 }
  99
 100 void dm_stop_queue(struct request_queue *q)
 101 {
 102         if (!q->mq_ops)
 103                 dm_old_stop_queue(q);
 104         else
 105                 blk_mq_stop_hw_queues(q);
 106 }
 107
 108 static struct dm_rq_target_io *alloc_old_rq_tio(struct mapped_device *md,
 109                                                 gfp_t gfp_mask)
 110 {
 111         return mempool_alloc(md->io_pool, gfp_mask);
 112 }
 113
 114 static void free_old_rq_tio(struct dm_rq_target_io *tio)
 115 {
 116         mempool_free(tio, tio->md->io_pool);
 117 }
 118
 119 static struct request *alloc_old_clone_request(struct mapped_device *md,
 120                                                gfp_t gfp_mask)
 121 {
 122         return mempool_alloc(md->rq_pool, gfp_mask);
 123 }
 124
 125 static void free_old_clone_request(struct mapped_device *md, struct request *rq)
 126 {
 127         mempool_free(rq, md->rq_pool);
 128 }
 129
 130 /*
 131  * Partial completion handling for request-based dm
 132  */
 133 static void end_clone_bio(struct bio *clone)
 134 {
 135         struct dm_rq_clone_bio_info *info =
 136                 container_of(clone, struct dm_rq_clone_bio_info, clone);
 137         struct dm_rq_target_io *tio = info->tio;
 138         struct bio *bio = info->orig;
 139         unsigned int nr_bytes = info->orig->bi_iter.bi_size;
 140         int error = clone->bi_error;
 141
 142         bio_put(clone);
 143
 144         if (tio->error)
 145                 /*
 146                  * An error has already been detected on the request.
 147                  * Once error occurred, just let clone->end_io() handle
 148                  * the remainder.
 149                  */
 150                 return;
 151         else if (error) {
 152                 /*
 153                  * Don't notice the error to the upper layer yet.
 154                  * The error handling decision is made by the target driver,
 155                  * when the request is completed.
 156                  */
 157                 tio->error = error;
 158                 return;
 159         }
 160
 161         /*
 162          * I/O for the bio successfully completed.
 163          * Notice the data completion to the upper layer.
 164          */
 165
 166         /*
 167          * bios are processed from the head of the list.
 168          * So the completing bio should always be rq->bio.
 169          * If it's not, something wrong is happening.
 170          */
 171         if (tio->orig->bio != bio)
 172                 DMERR("bio completion is going in the middle of the request");
 173
 174         /*
 175          * Update the original request.
 176          * Do not use blk_end_request() here, because it may complete
 177          * the original request before the clone, and break the ordering.
 178          */
 179         blk_update_request(tio->orig, 0, nr_bytes);
 180 }
 181
 182 static struct dm_rq_target_io *tio_from_request(struct request *rq)
 183 {
 184         return (rq->q->mq_ops ? blk_mq_rq_to_pdu(rq) : rq->special);
 185 }
 186
 187 static void rq_end_stats(struct mapped_device *md, struct request *orig)
 188 {
 189         if (unlikely(dm_stats_used(&md->stats))) {
 190                 struct dm_rq_target_io *tio = tio_from_request(orig);
 191                 tio->duration_jiffies = jiffies - tio->duration_jiffies;
 192                 dm_stats_account_io(&md->stats, rq_data_dir(orig),
 193                                     blk_rq_pos(orig), tio->n_sectors, true,
 194                                     tio->duration_jiffies, &tio->stats_aux);
 195         }
 196 }
 197
 198 /*
 199  * Don't touch any member of the md after calling this function because
 200  * the md may be freed in dm_put() at the end of this function.
 201  * Or do dm_get() before calling this function and dm_put() later.
 202  */
 203 static void rq_completed(struct mapped_device *md, int rw, bool run_queue)
 204 {
 205         atomic_dec(&md->pending[rw]);
 206
 207         /* nudge anyone waiting on suspend queue */
 208         if (!md_in_flight(md))
 209                 wake_up(&md->wait);
 210
 211         /*
 212          * Run this off this callpath, as drivers could invoke end_io while
 213          * inside their request_fn (and holding the queue lock). Calling
 214          * back into ->request_fn() could deadlock attempting to grab the
 215          * queue lock again.
 216          */
 217         if (!md->queue->mq_ops && run_queue)
 218                 blk_run_queue_async(md->queue);
 219
 220         /*
 221          * dm_put() must be at the end of this function. See the comment above
 222          */
 223         dm_put(md);
 224 }
 225
 226 static void free_rq_clone(struct request *clone)
 227 {
 228         struct dm_rq_target_io *tio = clone->end_io_data;
 229         struct mapped_device *md = tio->md;
 230
 231         blk_rq_unprep_clone(clone);
 232
 233         /*
 234          * It is possible for a clone_old_rq() allocated clone to
 235          * get passed in -- it may not yet have a request_queue.
 236          * This is known to occur if the error target replaces
 237          * a multipath target that has a request_fn queue stacked
 238          * on blk-mq queue(s).
 239          */
 240         if (clone->q && clone->q->mq_ops)
 241                 /* stacked on blk-mq queue(s) */
 242                 tio->ti->type->release_clone_rq(clone);
 243         else if (!md->queue->mq_ops)
 244                 /* request_fn queue stacked on request_fn queue(s) */
 245                 free_old_clone_request(md, clone);
 246
 247         if (!md->queue->mq_ops)
 248                 free_old_rq_tio(tio);
 249 }
 250
 251 /*
 252  * Complete the clone and the original request.
 253  * Must be called without clone's queue lock held,
 254  * see end_clone_request() for more details.
 255  */
 256 static void dm_end_request(struct request *clone, int error)
 257 {
 258         int rw = rq_data_dir(clone);
 259         struct dm_rq_target_io *tio = clone->end_io_data;
 260         struct mapped_device *md = tio->md;
 261         struct request *rq = tio->orig;
 262
 263         if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
 264                 rq->errors = clone->errors;
 265                 rq->resid_len = clone->resid_len;
 266
 267                 if (rq->sense)
 268                         /*
 269                          * We are using the sense buffer of the original
 270                          * request.
 271                          * So setting the length of the sense data is enough.
 272                          */
 273                         rq->sense_len = clone->sense_len;
 274         }
 275
 276         free_rq_clone(clone);
 277         rq_end_stats(md, rq);
 278         if (!rq->q->mq_ops)
 279                 blk_end_request_all(rq, error);
 280         else
 281                 blk_mq_end_request(rq, error);
 282         rq_completed(md, rw, true);
 283 }
 284
 285 static void dm_unprep_request(struct request *rq)
 286 {
 287         struct dm_rq_target_io *tio = tio_from_request(rq);
 288         struct request *clone = tio->clone;
 289
 290         if (!rq->q->mq_ops) {
 291                 rq->special = NULL;
 292                 rq->cmd_flags &= ~REQ_DONTPREP;
 293         }
 294
 295         if (clone)
 296                 free_rq_clone(clone);
 297         else if (!tio->md->queue->mq_ops)
 298                 free_old_rq_tio(tio);
 299 }
 300
 301 /*
 302  * Requeue the original request of a clone.
 303  */
 304 static void dm_old_requeue_request(struct request *rq)
 305 {
 306         struct request_queue *q = rq->q;
 307         unsigned long flags;
 308
 309         spin_lock_irqsave(q->queue_lock, flags);
 310         blk_requeue_request(q, rq);
 311         blk_run_queue_async(q);
 312         spin_unlock_irqrestore(q->queue_lock, flags);
 313 }
 314
 315 static void dm_mq_requeue_request(struct request *rq)
 316 {
 317         struct request_queue *q = rq->q;
 318         unsigned long flags;
 319
 320         blk_mq_requeue_request(rq);
 321         spin_lock_irqsave(q->queue_lock, flags);
 322         if (!blk_queue_stopped(q))
 323                 blk_mq_kick_requeue_list(q);
 324         spin_unlock_irqrestore(q->queue_lock, flags);
 325 }
 326
 327 static void dm_requeue_original_request(struct mapped_device *md,
 328                                         struct request *rq)
 329 {
 330         int rw = rq_data_dir(rq);
 331
 332         rq_end_stats(md, rq);
 333         dm_unprep_request(rq);
 334
 335         if (!rq->q->mq_ops)
 336                 dm_old_requeue_request(rq);
 337         else
 338                 dm_mq_requeue_request(rq);
 339
 340         rq_completed(md, rw, false);
 341 }
 342
 343 static void dm_done(struct request *clone, int error, bool mapped)
 344 {
 345         int r = error;
 346         struct dm_rq_target_io *tio = clone->end_io_data;
 347         dm_request_endio_fn rq_end_io = NULL;
 348
 349         if (tio->ti) {
 350                 rq_end_io = tio->ti->type->rq_end_io;
 351
 352                 if (mapped && rq_end_io)
 353                         r = rq_end_io(tio->ti, clone, error, &tio->info);
 354         }
 355
 356         if (unlikely(r == -EREMOTEIO && (req_op(clone) == REQ_OP_WRITE_SAME) &&
 357                      !clone->q->limits.max_write_same_sectors))
 358                 disable_write_same(tio->md);
 359
 360         if (r <= 0)
 361                 /* The target wants to complete the I/O */
 362                 dm_end_request(clone, r);
 363         else if (r == DM_ENDIO_INCOMPLETE)
 364                 /* The target will handle the I/O */
 365                 return;
 366         else if (r == DM_ENDIO_REQUEUE)
 367                 /* The target wants to requeue the I/O */
 368                 dm_requeue_original_request(tio->md, tio->orig);
 369         else {
 370                 DMWARN("unimplemented target endio return value: %d", r);
 371                 BUG();
 372         }
 373 }
 374
 375 /*
 376  * Request completion handler for request-based dm
 377  */
 378 static void dm_softirq_done(struct request *rq)
 379 {
 380         bool mapped = true;
 381         struct dm_rq_target_io *tio = tio_from_request(rq);
 382         struct request *clone = tio->clone;
 383         int rw;
 384
 385         if (!clone) {
 386                 rq_end_stats(tio->md, rq);
 387                 rw = rq_data_dir(rq);
 388                 if (!rq->q->mq_ops) {
 389                         blk_end_request_all(rq, tio->error);
 390                         rq_completed(tio->md, rw, false);
 391                         free_old_rq_tio(tio);
 392                 } else {
 393                         blk_mq_end_request(rq, tio->error);
 394                         rq_completed(tio->md, rw, false);
 395                 }
 396                 return;
 397         }
 398
 399         if (rq->cmd_flags & REQ_FAILED)
 400                 mapped = false;
 401
 402         dm_done(clone, tio->error, mapped);
 403 }
 404
 405 /*
 406  * Complete the clone and the original request with the error status
 407  * through softirq context.
 408  */
 409 static void dm_complete_request(struct request *rq, int error)
 410 {
 411         struct dm_rq_target_io *tio = tio_from_request(rq);
 412
 413         tio->error = error;
 414         if (!rq->q->mq_ops)
 415                 blk_complete_request(rq);
 416         else
 417                 blk_mq_complete_request(rq, error);
 418 }
 419
 420 /*
 421  * Complete the not-mapped clone and the original request with the error status
 422  * through softirq context.
 423  * Target's rq_end_io() function isn't called.
 424  * This may be used when the target's map_rq() or clone_and_map_rq() functions fail.
 425  */
 426 static void dm_kill_unmapped_request(struct request *rq, int error)
 427 {
 428         rq->cmd_flags |= REQ_FAILED;
 429         dm_complete_request(rq, error);
 430 }
 431
 432 /*
 433  * Called with the clone's queue lock held (in the case of .request_fn)
 434  */
 435 static void end_clone_request(struct request *clone, int error)
 436 {
 437         struct dm_rq_target_io *tio = clone->end_io_data;
 438
 439         if (!clone->q->mq_ops) {
 440                 /*
 441                  * For just cleaning up the information of the queue in which
 442                  * the clone was dispatched.
 443                  * The clone is *NOT* freed actually here because it is alloced
 444                  * from dm own mempool (REQ_ALLOCED isn't set).
 445                  */
 446                 __blk_put_request(clone->q, clone);
 447         }
 448
 449         /*
 450          * Actual request completion is done in a softirq context which doesn't
 451          * hold the clone's queue lock.  Otherwise, deadlock could occur because:
 452          *     - another request may be submitted by the upper level driver
 453          *       of the stacking during the completion
 454          *     - the submission which requires queue lock may be done
 455          *       against this clone's queue
 456          */
 457         dm_complete_request(tio->orig, error);
 458 }
 459
 460 static void dm_dispatch_clone_request(struct request *clone, struct request *rq)
 461 {
 462         int r;
 463
 464         if (blk_queue_io_stat(clone->q))
 465                 clone->cmd_flags |= REQ_IO_STAT;
 466
 467         clone->start_time = jiffies;
 468         r = blk_insert_cloned_request(clone->q, clone);
 469         if (r)
 470                 /* must complete clone in terms of original request */
 471                 dm_complete_request(rq, r);
 472 }
 473
 474 static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
 475                                  void *data)
 476 {
 477         struct dm_rq_target_io *tio = data;
 478         struct dm_rq_clone_bio_info *info =
 479                 container_of(bio, struct dm_rq_clone_bio_info, clone);
 480
 481         info->orig = bio_orig;
 482         info->tio = tio;
 483         bio->bi_end_io = end_clone_bio;
 484
 485         return 0;
 486 }
 487
 488 static int setup_clone(struct request *clone, struct request *rq,
 489                        struct dm_rq_target_io *tio, gfp_t gfp_mask)
 490 {
 491         int r;
 492
 493         r = blk_rq_prep_clone(clone, rq, tio->md->bs, gfp_mask,
 494                               dm_rq_bio_constructor, tio);
 495         if (r)
 496                 return r;
 497
 498         clone->cmd = rq->cmd;
 499         clone->cmd_len = rq->cmd_len;
 500         clone->sense = rq->sense;
 501         clone->end_io = end_clone_request;
 502         clone->end_io_data = tio;
 503
 504         tio->clone = clone;
 505
 506         return 0;
 507 }
 508
 509 static struct request *clone_old_rq(struct request *rq, struct mapped_device *md,
 510                                     struct dm_rq_target_io *tio, gfp_t gfp_mask)
 511 {
 512         /*
 513          * Create clone for use with .request_fn request_queue
 514          */
 515         struct request *clone;
 516
 517         clone = alloc_old_clone_request(md, gfp_mask);
 518         if (!clone)
 519                 return NULL;
 520
 521         blk_rq_init(NULL, clone);
 522         if (setup_clone(clone, rq, tio, gfp_mask)) {
 523                 /* -ENOMEM */
 524                 free_old_clone_request(md, clone);
 525                 return NULL;
 526         }
 527
 528         return clone;
 529 }
 530
 531 static void map_tio_request(struct kthread_work *work);
 532
 533 static void init_tio(struct dm_rq_target_io *tio, struct request *rq,
 534                      struct mapped_device *md)
 535 {
 536         tio->md = md;
 537         tio->ti = NULL;
 538         tio->clone = NULL;
 539         tio->orig = rq;
 540         tio->error = 0;
 541         /*
 542          * Avoid initializing info for blk-mq; it passes
 543          * target-specific data through info.ptr
 544          * (see: dm_mq_init_request)
 545          */
 546         if (!md->init_tio_pdu)
 547                 memset(&tio->info, 0, sizeof(tio->info));
 548         if (md->kworker_task)
 549                 init_kthread_work(&tio->work, map_tio_request);
 550 }
 551
 552 static struct dm_rq_target_io *dm_old_prep_tio(struct request *rq,
 553                                                struct mapped_device *md,
 554                                                gfp_t gfp_mask)
 555 {
 556         struct dm_rq_target_io *tio;
 557         int srcu_idx;
 558         struct dm_table *table;
 559
 560         tio = alloc_old_rq_tio(md, gfp_mask);
 561         if (!tio)
 562                 return NULL;
 563
 564         init_tio(tio, rq, md);
 565
 566         table = dm_get_live_table(md, &srcu_idx);
 567         /*
 568          * Must clone a request if this .request_fn DM device
 569          * is stacked on .request_fn device(s).
 570          */
 571         if (!dm_table_all_blk_mq_devices(table)) {
 572                 if (!clone_old_rq(rq, md, tio, gfp_mask)) {
 573                         dm_put_live_table(md, srcu_idx);
 574                         free_old_rq_tio(tio);
 575                         return NULL;
 576                 }
 577         }
 578         dm_put_live_table(md, srcu_idx);
 579
 580         return tio;
 581 }
 582
 583 /*
 584  * Called with the queue lock held.
 585  */
 586 static int dm_old_prep_fn(struct request_queue *q, struct request *rq)
 587 {
 588         struct mapped_device *md = q->queuedata;
 589         struct dm_rq_target_io *tio;
 590
 591         if (unlikely(rq->special)) {
 592                 DMWARN("Already has something in rq->special.");
 593                 return BLKPREP_KILL;
 594         }
 595
 596         tio = dm_old_prep_tio(rq, md, GFP_ATOMIC);
 597         if (!tio)
 598                 return BLKPREP_DEFER;
 599
 600         rq->special = tio;
 601         rq->cmd_flags |= REQ_DONTPREP;
 602
 603         return BLKPREP_OK;
 604 }
 605
 606 /*
 607  * Returns:
 608  * 0                : the request has been processed
 609  * DM_MAPIO_REQUEUE : the original request needs to be requeued
 610  * < 0              : the request was completed due to failure
 611  */
 612 static int map_request(struct dm_rq_target_io *tio, struct request *rq,
 613                        struct mapped_device *md)
 614 {
 615         int r;
 616         struct dm_target *ti = tio->ti;
 617         struct request *clone = NULL;
 618
 619         if (tio->clone) {
 620                 clone = tio->clone;
 621                 r = ti->type->map_rq(ti, clone, &tio->info);
 622         } else {
 623                 r = ti->type->clone_and_map_rq(ti, rq, &tio->info, &clone);
 624                 if (r < 0) {
 625                         /* The target wants to complete the I/O */
 626                         dm_kill_unmapped_request(rq, r);
 627                         return r;
 628                 }
 629                 if (r != DM_MAPIO_REMAPPED)
 630                         return r;
 631                 if (setup_clone(clone, rq, tio, GFP_ATOMIC)) {
 632                         /* -ENOMEM */
 633                         ti->type->release_clone_rq(clone);
 634                         return DM_MAPIO_REQUEUE;
 635                 }
 636         }
 637
 638         switch (r) {
 639         case DM_MAPIO_SUBMITTED:
 640                 /* The target has taken the I/O to submit by itself later */
 641                 break;
 642         case DM_MAPIO_REMAPPED:
 643                 /* The target has remapped the I/O so dispatch it */
 644                 trace_block_rq_remap(clone->q, clone, disk_devt(dm_disk(md)),
 645                                      blk_rq_pos(rq));
 646                 dm_dispatch_clone_request(clone, rq);
 647                 break;
 648         case DM_MAPIO_REQUEUE:
 649                 /* The target wants to requeue the I/O */
 650                 dm_requeue_original_request(md, tio->orig);
 651                 break;
 652         default:
 653                 if (r > 0) {
 654                         DMWARN("unimplemented target map return value: %d", r);
 655                         BUG();
 656                 }
 657
 658                 /* The target wants to complete the I/O */
 659                 dm_kill_unmapped_request(rq, r);
 660                 return r;
 661         }
 662
 663         return 0;
 664 }
 665
 666 static void dm_start_request(struct mapped_device *md, struct request *orig)
 667 {
 668         if (!orig->q->mq_ops)
 669                 blk_start_request(orig);
 670         else
 671                 blk_mq_start_request(orig);
 672         atomic_inc(&md->pending[rq_data_dir(orig)]);
 673
 674         if (md->seq_rq_merge_deadline_usecs) {
 675                 md->last_rq_pos = rq_end_sector(orig);
 676                 md->last_rq_rw = rq_data_dir(orig);
 677                 md->last_rq_start_time = ktime_get();
 678         }
 679
 680         if (unlikely(dm_stats_used(&md->stats))) {
 681                 struct dm_rq_target_io *tio = tio_from_request(orig);
 682                 tio->duration_jiffies = jiffies;
 683                 tio->n_sectors = blk_rq_sectors(orig);
 684                 dm_stats_account_io(&md->stats, rq_data_dir(orig),
 685                                     blk_rq_pos(orig), tio->n_sectors, false, 0,
 686                                     &tio->stats_aux);
 687         }
 688
 689         /*
 690          * Hold the md reference here for the in-flight I/O.
 691          * We can't rely on the reference count by device opener,
 692          * because the device may be closed during the request completion
 693          * when all bios are completed.
 694          * See the comment in rq_completed() too.
 695          */
 696         dm_get(md);
 697 }
 698
 699 static void map_tio_request(struct kthread_work *work)
 700 {
 701         struct dm_rq_target_io *tio = container_of(work, struct dm_rq_target_io, work);
 702         struct request *rq = tio->orig;
 703         struct mapped_device *md = tio->md;
 704
 705         if (map_request(tio, rq, md) == DM_MAPIO_REQUEUE)
 706                 dm_requeue_original_request(md, rq);
 707 }
 708
 709 ssize_t dm_attr_rq_based_seq_io_merge_deadline_show(struct mapped_device *md, char *buf)
 710 {
 711         return sprintf(buf, "%u\n", md->seq_rq_merge_deadline_usecs);
 712 }
 713
 714 #define MAX_SEQ_RQ_MERGE_DEADLINE_USECS 100000
 715
 716 ssize_t dm_attr_rq_based_seq_io_merge_deadline_store(struct mapped_device *md,
 717                                                      const char *buf, size_t count)
 718 {
 719         unsigned deadline;
 720
 721         if (dm_get_md_type(md) != DM_TYPE_REQUEST_BASED)
 722                 return count;
 723
 724         if (kstrtouint(buf, 10, &deadline))
 725                 return -EINVAL;
 726
 727         if (deadline > MAX_SEQ_RQ_MERGE_DEADLINE_USECS)
 728                 deadline = MAX_SEQ_RQ_MERGE_DEADLINE_USECS;
 729
 730         md->seq_rq_merge_deadline_usecs = deadline;
 731
 732         return count;
 733 }
 734
 735 static bool dm_old_request_peeked_before_merge_deadline(struct mapped_device *md)
 736 {
 737         ktime_t kt_deadline;
 738
 739         if (!md->seq_rq_merge_deadline_usecs)
 740                 return false;
 741
 742         kt_deadline = ns_to_ktime((u64)md->seq_rq_merge_deadline_usecs * NSEC_PER_USEC);
 743         kt_deadline = ktime_add_safe(md->last_rq_start_time, kt_deadline);
 744
 745         return !ktime_after(ktime_get(), kt_deadline);
 746 }
 747
 748 /*
 749  * q->request_fn for old request-based dm.
 750  * Called with the queue lock held.
 751  */
 752 static void dm_old_request_fn(struct request_queue *q)
 753 {
 754         struct mapped_device *md = q->queuedata;
 755         struct dm_target *ti = md->immutable_target;
 756         struct request *rq;
 757         struct dm_rq_target_io *tio;
 758         sector_t pos = 0;
 759
 760         if (unlikely(!ti)) {
 761                 int srcu_idx;
 762                 struct dm_table *map = dm_get_live_table(md, &srcu_idx);
 763
 764                 ti = dm_table_find_target(map, pos);
 765                 dm_put_live_table(md, srcu_idx);
 766         }
 767
 768         /*
 769          * For suspend, check blk_queue_stopped() and increment
 770          * ->pending within a single queue_lock not to increment the
 771          * number of in-flight I/Os after the queue is stopped in
 772          * dm_suspend().
 773          */
 774         while (!blk_queue_stopped(q)) {
 775                 rq = blk_peek_request(q);
 776                 if (!rq)
 777                         return;
 778
 779                 /* always use block 0 to find the target for flushes for now */
 780                 pos = 0;
 781                 if (req_op(rq) != REQ_OP_FLUSH)
 782                         pos = blk_rq_pos(rq);
 783
 784                 if ((dm_old_request_peeked_before_merge_deadline(md) &&
 785                      md_in_flight(md) && rq->bio && rq->bio->bi_vcnt == 1 &&
 786                      md->last_rq_pos == pos && md->last_rq_rw == rq_data_dir(rq)) ||
 787                     (ti->type->busy && ti->type->busy(ti))) {
 788                         blk_delay_queue(q, 10);
 789                         return;
 790                 }
 791
 792                 dm_start_request(md, rq);
 793
 794                 tio = tio_from_request(rq);
 795                 /* Establish tio->ti before queuing work (map_tio_request) */
 796                 tio->ti = ti;
 797                 queue_kthread_work(&md->kworker, &tio->work);
 798                 BUG_ON(!irqs_disabled());
 799         }
 800 }
 801
 802 /*
 803  * Fully initialize a .request_fn request-based queue.
 804  */
 805 int dm_old_init_request_queue(struct mapped_device *md)
 806 {
 807         /* Fully initialize the queue */
 808         if (!blk_init_allocated_queue(md->queue, dm_old_request_fn, NULL))
 809                 return -EINVAL;
 810
 811         /* disable dm_old_request_fn's merge heuristic by default */
 812         md->seq_rq_merge_deadline_usecs = 0;
 813
 814         dm_init_normal_md_queue(md);
 815         blk_queue_softirq_done(md->queue, dm_softirq_done);
 816         blk_queue_prep_rq(md->queue, dm_old_prep_fn);
 817
 818         /* Initialize the request-based DM worker thread */
 819         init_kthread_worker(&md->kworker);
 820         md->kworker_task = kthread_run(kthread_worker_fn, &md->kworker,
 821                                        "kdmwork-%s", dm_device_name(md));
 822         if (IS_ERR(md->kworker_task))
 823                 return PTR_ERR(md->kworker_task);
 824
 825         elv_register_queue(md->queue);
 826
 827         return 0;
 828 }
 829
 830 static int dm_mq_init_request(void *data, struct request *rq,
 831                        unsigned int hctx_idx, unsigned int request_idx,
 832                        unsigned int numa_node)
 833 {
 834         struct mapped_device *md = data;
 835         struct dm_rq_target_io *tio = blk_mq_rq_to_pdu(rq);
 836
 837         /*
 838          * Must initialize md member of tio, otherwise it won't
 839          * be available in dm_mq_queue_rq.
 840          */
 841         tio->md = md;
 842
 843         if (md->init_tio_pdu) {
 844                 /* target-specific per-io data is immediately after the tio */
 845                 tio->info.ptr = tio + 1;
 846         }
 847
 848         return 0;
 849 }
 850
 851 static int dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
 852                           const struct blk_mq_queue_data *bd)
 853 {
 854         struct request *rq = bd->rq;
 855         struct dm_rq_target_io *tio = blk_mq_rq_to_pdu(rq);
 856         struct mapped_device *md = tio->md;
 857         struct dm_target *ti = md->immutable_target;
 858
 859         if (unlikely(!ti)) {
 860                 int srcu_idx;
 861                 struct dm_table *map = dm_get_live_table(md, &srcu_idx);
 862
 863                 ti = dm_table_find_target(map, 0);
 864                 dm_put_live_table(md, srcu_idx);
 865         }
 866
 867         if (ti->type->busy && ti->type->busy(ti))
 868                 return BLK_MQ_RQ_QUEUE_BUSY;
 869
 870         dm_start_request(md, rq);
 871
 872         /* Init tio using md established in .init_request */
 873         init_tio(tio, rq, md);
 874
 875         /*
 876          * Establish tio->ti before calling map_request().
 877          */
 878         tio->ti = ti;
 879
 880         /* Direct call is fine since .queue_rq allows allocations */
 881         if (map_request(tio, rq, md) == DM_MAPIO_REQUEUE) {
 882                 /* Undo dm_start_request() before requeuing */
 883                 rq_end_stats(md, rq);
 884                 rq_completed(md, rq_data_dir(rq), false);
 885                 return BLK_MQ_RQ_QUEUE_BUSY;
 886         }
 887
 888         return BLK_MQ_RQ_QUEUE_OK;
 889 }
 890
 891 static struct blk_mq_ops dm_mq_ops = {
 892         .queue_rq = dm_mq_queue_rq,
 893         .map_queue = blk_mq_map_queue,
 894         .complete = dm_softirq_done,
 895         .init_request = dm_mq_init_request,
 896 };
 897
 898 int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t)
 899 {
 900         struct request_queue *q;
 901         struct dm_target *immutable_tgt;
 902         int err;
 903
 904         if (!dm_table_all_blk_mq_devices(t)) {
 905                 DMERR("request-based dm-mq may only be stacked on blk-mq device(s)");
 906                 return -EINVAL;
 907         }
 908
 909         md->tag_set = kzalloc_node(sizeof(struct blk_mq_tag_set), GFP_KERNEL, md->numa_node_id);
 910         if (!md->tag_set)
 911                 return -ENOMEM;
 912
 913         md->tag_set->ops = &dm_mq_ops;
 914         md->tag_set->queue_depth = dm_get_blk_mq_queue_depth();
 915         md->tag_set->numa_node = md->numa_node_id;
 916         md->tag_set->flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
 917         md->tag_set->nr_hw_queues = dm_get_blk_mq_nr_hw_queues();
 918         md->tag_set->driver_data = md;
 919
 920         md->tag_set->cmd_size = sizeof(struct dm_rq_target_io);
 921         immutable_tgt = dm_table_get_immutable_target(t);
 922         if (immutable_tgt && immutable_tgt->per_io_data_size) {
 923                 /* any target-specific per-io data is immediately after the tio */
 924                 md->tag_set->cmd_size += immutable_tgt->per_io_data_size;
 925                 md->init_tio_pdu = true;
 926         }
 927
 928         err = blk_mq_alloc_tag_set(md->tag_set);
 929         if (err)
 930                 goto out_kfree_tag_set;
 931
 932         q = blk_mq_init_allocated_queue(md->tag_set, md->queue);
 933         if (IS_ERR(q)) {
 934                 err = PTR_ERR(q);
 935                 goto out_tag_set;
 936         }
 937         dm_init_md_queue(md);
 938
 939         /* backfill 'mq' sysfs registration normally done in blk_register_queue */
 940         blk_mq_register_disk(md->disk);
 941
 942         return 0;
 943
 944 out_tag_set:
 945         blk_mq_free_tag_set(md->tag_set);
 946 out_kfree_tag_set:
 947         kfree(md->tag_set);
 948
 949         return err;
 950 }
 951
 952 void dm_mq_cleanup_mapped_device(struct mapped_device *md)
 953 {
 954         if (md->tag_set) {
 955                 blk_mq_free_tag_set(md->tag_set);
 956                 kfree(md->tag_set);
 957         }
 958 }
 959
 960 module_param(reserved_rq_based_ios, uint, S_IRUGO | S_IWUSR);
 961 MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools");
 962
 963 module_param(use_blk_mq, bool, S_IRUGO | S_IWUSR);
 964 MODULE_PARM_DESC(use_blk_mq, "Use block multiqueue for request-based DM devices");
 965
 966 module_param(dm_mq_nr_hw_queues, uint, S_IRUGO | S_IWUSR);
 967 MODULE_PARM_DESC(dm_mq_nr_hw_queues, "Number of hardware queues for request-based dm-mq devices");
 968
 969 module_param(dm_mq_queue_depth, uint, S_IRUGO | S_IWUSR);
 970 MODULE_PARM_DESC(dm_mq_queue_depth, "Queue depth for request-based dm-mq devices");