block/mq-deadline.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  MQ Deadline i/o scheduler - adaptation of the legacy deadline scheduler,
   4  *  for the blk-mq scheduling framework
   5  *
   6  *  Copyright (C) 2016 Jens Axboe <axboe@kernel.dk>
   7  */
   8 #include <linux/kernel.h>
   9 #include <linux/fs.h>
  10 #include <linux/blkdev.h>
  11 #include <linux/blk-mq.h>
  12 #include <linux/bio.h>
  13 #include <linux/module.h>
  14 #include <linux/slab.h>
  15 #include <linux/init.h>
  16 #include <linux/compiler.h>
  17 #include <linux/rbtree.h>
  18 #include <linux/sbitmap.h>
  19
  20 #include <trace/events/block.h>
  21
  22 #include "elevator.h"
  23 #include "blk.h"
  24 #include "blk-mq.h"
  25 #include "blk-mq-debugfs.h"
  26 #include "blk-mq-sched.h"
  27
  28 /*
  29  * See Documentation/block/deadline-iosched.rst
  30  */
  31 static const int read_expire = HZ / 2;  /* max time before a read is submitted. */
  32 static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
  33 /*
  34  * Time after which to dispatch lower priority requests even if higher
  35  * priority requests are pending.
  36  */
  37 static const int prio_aging_expire = 10 * HZ;
  38 static const int writes_starved = 2;    /* max times reads can starve a write */
  39 static const int fifo_batch = 16;       /* # of sequential requests treated as one
  40                                      by the above parameters. For throughput. */
  41
  42 enum dd_data_dir {
  43         DD_READ         = READ,
  44         DD_WRITE        = WRITE,
  45 };
  46
  47 enum { DD_DIR_COUNT = 2 };
  48
  49 enum dd_prio {
  50         DD_RT_PRIO      = 0,
  51         DD_BE_PRIO      = 1,
  52         DD_IDLE_PRIO    = 2,
  53         DD_PRIO_MAX     = 2,
  54 };
  55
  56 enum { DD_PRIO_COUNT = 3 };
  57
  58 /*
  59  * I/O statistics per I/O priority. It is fine if these counters overflow.
  60  * What matters is that these counters are at least as wide as
  61  * log2(max_outstanding_requests).
  62  */
  63 struct io_stats_per_prio {
  64         uint32_t inserted;
  65         uint32_t merged;
  66         uint32_t dispatched;
  67         atomic_t completed;
  68 };
  69
  70 /*
  71  * Deadline scheduler data per I/O priority (enum dd_prio). Requests are
  72  * present on both sort_list[] and fifo_list[].
  73  */
  74 struct dd_per_prio {
  75         struct list_head dispatch;
  76         struct rb_root sort_list[DD_DIR_COUNT];
  77         struct list_head fifo_list[DD_DIR_COUNT];
  78         /* Next request in FIFO order. Read, write or both are NULL. */
  79         struct request *next_rq[DD_DIR_COUNT];
  80         struct io_stats_per_prio stats;
  81 };
  82
  83 struct deadline_data {
  84         /*
  85          * run time data
  86          */
  87
  88         struct dd_per_prio per_prio[DD_PRIO_COUNT];
  89
  90         /* Data direction of latest dispatched request. */
  91         enum dd_data_dir last_dir;
  92         unsigned int batching;          /* number of sequential requests made */
  93         unsigned int starved;           /* times reads have starved writes */
  94
  95         /*
  96          * settings that change how the i/o scheduler behaves
  97          */
  98         int fifo_expire[DD_DIR_COUNT];
  99         int fifo_batch;
 100         int writes_starved;
 101         int front_merges;
 102         u32 async_depth;
 103         int prio_aging_expire;
 104
 105         spinlock_t lock;
 106         spinlock_t zone_lock;
 107 };
 108
 109 /* Maps an I/O priority class to a deadline scheduler priority. */
 110 static const enum dd_prio ioprio_class_to_prio[] = {
 111         [IOPRIO_CLASS_NONE]     = DD_BE_PRIO,
 112         [IOPRIO_CLASS_RT]       = DD_RT_PRIO,
 113         [IOPRIO_CLASS_BE]       = DD_BE_PRIO,
 114         [IOPRIO_CLASS_IDLE]     = DD_IDLE_PRIO,
 115 };
 116
 117 static inline struct rb_root *
 118 deadline_rb_root(struct dd_per_prio *per_prio, struct request *rq)
 119 {
 120         return &per_prio->sort_list[rq_data_dir(rq)];
 121 }
 122
 123 /*
 124  * Returns the I/O priority class (IOPRIO_CLASS_*) that has been assigned to a
 125  * request.
 126  */
 127 static u8 dd_rq_ioclass(struct request *rq)
 128 {
 129         return IOPRIO_PRIO_CLASS(req_get_ioprio(rq));
 130 }
 131
 132 /*
 133  * get the request before `rq' in sector-sorted order
 134  */
 135 static inline struct request *
 136 deadline_earlier_request(struct request *rq)
 137 {
 138         struct rb_node *node = rb_prev(&rq->rb_node);
 139
 140         if (node)
 141                 return rb_entry_rq(node);
 142
 143         return NULL;
 144 }
 145
 146 /*
 147  * get the request after `rq' in sector-sorted order
 148  */
 149 static inline struct request *
 150 deadline_latter_request(struct request *rq)
 151 {
 152         struct rb_node *node = rb_next(&rq->rb_node);
 153
 154         if (node)
 155                 return rb_entry_rq(node);
 156
 157         return NULL;
 158 }
 159
 160 static void
 161 deadline_add_rq_rb(struct dd_per_prio *per_prio, struct request *rq)
 162 {
 163         struct rb_root *root = deadline_rb_root(per_prio, rq);
 164
 165         elv_rb_add(root, rq);
 166 }
 167
 168 static inline void
 169 deadline_del_rq_rb(struct dd_per_prio *per_prio, struct request *rq)
 170 {
 171         const enum dd_data_dir data_dir = rq_data_dir(rq);
 172
 173         if (per_prio->next_rq[data_dir] == rq)
 174                 per_prio->next_rq[data_dir] = deadline_latter_request(rq);
 175
 176         elv_rb_del(deadline_rb_root(per_prio, rq), rq);
 177 }
 178
 179 /*
 180  * remove rq from rbtree and fifo.
 181  */
 182 static void deadline_remove_request(struct request_queue *q,
 183                                     struct dd_per_prio *per_prio,
 184                                     struct request *rq)
 185 {
 186         list_del_init(&rq->queuelist);
 187
 188         /*
 189          * We might not be on the rbtree, if we are doing an insert merge
 190          */
 191         if (!RB_EMPTY_NODE(&rq->rb_node))
 192                 deadline_del_rq_rb(per_prio, rq);
 193
 194         elv_rqhash_del(q, rq);
 195         if (q->last_merge == rq)
 196                 q->last_merge = NULL;
 197 }
 198
 199 static void dd_request_merged(struct request_queue *q, struct request *req,
 200                               enum elv_merge type)
 201 {
 202         struct deadline_data *dd = q->elevator->elevator_data;
 203         const u8 ioprio_class = dd_rq_ioclass(req);
 204         const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
 205         struct dd_per_prio *per_prio = &dd->per_prio[prio];
 206
 207         /*
 208          * if the merge was a front merge, we need to reposition request
 209          */
 210         if (type == ELEVATOR_FRONT_MERGE) {
 211                 elv_rb_del(deadline_rb_root(per_prio, req), req);
 212                 deadline_add_rq_rb(per_prio, req);
 213         }
 214 }
 215
 216 /*
 217  * Callback function that is invoked after @next has been merged into @req.
 218  */
 219 static void dd_merged_requests(struct request_queue *q, struct request *req,
 220                                struct request *next)
 221 {
 222         struct deadline_data *dd = q->elevator->elevator_data;
 223         const u8 ioprio_class = dd_rq_ioclass(next);
 224         const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
 225
 226         lockdep_assert_held(&dd->lock);
 227
 228         dd->per_prio[prio].stats.merged++;
 229
 230         /*
 231          * if next expires before rq, assign its expire time to rq
 232          * and move into next position (next will be deleted) in fifo
 233          */
 234         if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
 235                 if (time_before((unsigned long)next->fifo_time,
 236                                 (unsigned long)req->fifo_time)) {
 237                         list_move(&req->queuelist, &next->queuelist);
 238                         req->fifo_time = next->fifo_time;
 239                 }
 240         }
 241
 242         /*
 243          * kill knowledge of next, this one is a goner
 244          */
 245         deadline_remove_request(q, &dd->per_prio[prio], next);
 246 }
 247
 248 /*
 249  * move an entry to dispatch queue
 250  */
 251 static void
 252 deadline_move_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
 253                       struct request *rq)
 254 {
 255         const enum dd_data_dir data_dir = rq_data_dir(rq);
 256
 257         per_prio->next_rq[data_dir] = deadline_latter_request(rq);
 258
 259         /*
 260          * take it off the sort and fifo list
 261          */
 262         deadline_remove_request(rq->q, per_prio, rq);
 263 }
 264
 265 /* Number of requests queued for a given priority level. */
 266 static u32 dd_queued(struct deadline_data *dd, enum dd_prio prio)
 267 {
 268         const struct io_stats_per_prio *stats = &dd->per_prio[prio].stats;
 269
 270         lockdep_assert_held(&dd->lock);
 271
 272         return stats->inserted - atomic_read(&stats->completed);
 273 }
 274
 275 /*
 276  * deadline_check_fifo returns 0 if there are no expired requests on the fifo,
 277  * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
 278  */
 279 static inline int deadline_check_fifo(struct dd_per_prio *per_prio,
 280                                       enum dd_data_dir data_dir)
 281 {
 282         struct request *rq = rq_entry_fifo(per_prio->fifo_list[data_dir].next);
 283
 284         /*
 285          * rq is expired!
 286          */
 287         if (time_after_eq(jiffies, (unsigned long)rq->fifo_time))
 288                 return 1;
 289
 290         return 0;
 291 }
 292
 293 /*
 294  * Check if rq has a sequential request preceding it.
 295  */
 296 static bool deadline_is_seq_write(struct deadline_data *dd, struct request *rq)
 297 {
 298         struct request *prev = deadline_earlier_request(rq);
 299
 300         if (!prev)
 301                 return false;
 302
 303         return blk_rq_pos(prev) + blk_rq_sectors(prev) == blk_rq_pos(rq);
 304 }
 305
 306 /*
 307  * Skip all write requests that are sequential from @rq, even if we cross
 308  * a zone boundary.
 309  */
 310 static struct request *deadline_skip_seq_writes(struct deadline_data *dd,
 311                                                 struct request *rq)
 312 {
 313         sector_t pos = blk_rq_pos(rq);
 314         sector_t skipped_sectors = 0;
 315
 316         while (rq) {
 317                 if (blk_rq_pos(rq) != pos + skipped_sectors)
 318                         break;
 319                 skipped_sectors += blk_rq_sectors(rq);
 320                 rq = deadline_latter_request(rq);
 321         }
 322
 323         return rq;
 324 }
 325
 326 /*
 327  * For the specified data direction, return the next request to
 328  * dispatch using arrival ordered lists.
 329  */
 330 static struct request *
 331 deadline_fifo_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
 332                       enum dd_data_dir data_dir)
 333 {
 334         struct request *rq;
 335         unsigned long flags;
 336
 337         if (list_empty(&per_prio->fifo_list[data_dir]))
 338                 return NULL;
 339
 340         rq = rq_entry_fifo(per_prio->fifo_list[data_dir].next);
 341         if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q))
 342                 return rq;
 343
 344         /*
 345          * Look for a write request that can be dispatched, that is one with
 346          * an unlocked target zone. For some HDDs, breaking a sequential
 347          * write stream can lead to lower throughput, so make sure to preserve
 348          * sequential write streams, even if that stream crosses into the next
 349          * zones and these zones are unlocked.
 350          */
 351         spin_lock_irqsave(&dd->zone_lock, flags);
 352         list_for_each_entry(rq, &per_prio->fifo_list[DD_WRITE], queuelist) {
 353                 if (blk_req_can_dispatch_to_zone(rq) &&
 354                     (blk_queue_nonrot(rq->q) ||
 355                      !deadline_is_seq_write(dd, rq)))
 356                         goto out;
 357         }
 358         rq = NULL;
 359 out:
 360         spin_unlock_irqrestore(&dd->zone_lock, flags);
 361
 362         return rq;
 363 }
 364
 365 /*
 366  * For the specified data direction, return the next request to
 367  * dispatch using sector position sorted lists.
 368  */
 369 static struct request *
 370 deadline_next_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
 371                       enum dd_data_dir data_dir)
 372 {
 373         struct request *rq;
 374         unsigned long flags;
 375
 376         rq = per_prio->next_rq[data_dir];
 377         if (!rq)
 378                 return NULL;
 379
 380         if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q))
 381                 return rq;
 382
 383         /*
 384          * Look for a write request that can be dispatched, that is one with
 385          * an unlocked target zone. For some HDDs, breaking a sequential
 386          * write stream can lead to lower throughput, so make sure to preserve
 387          * sequential write streams, even if that stream crosses into the next
 388          * zones and these zones are unlocked.
 389          */
 390         spin_lock_irqsave(&dd->zone_lock, flags);
 391         while (rq) {
 392                 if (blk_req_can_dispatch_to_zone(rq))
 393                         break;
 394                 if (blk_queue_nonrot(rq->q))
 395                         rq = deadline_latter_request(rq);
 396                 else
 397                         rq = deadline_skip_seq_writes(dd, rq);
 398         }
 399         spin_unlock_irqrestore(&dd->zone_lock, flags);
 400
 401         return rq;
 402 }
 403
 404 /*
 405  * Returns true if and only if @rq started after @latest_start where
 406  * @latest_start is in jiffies.
 407  */
 408 static bool started_after(struct deadline_data *dd, struct request *rq,
 409                           unsigned long latest_start)
 410 {
 411         unsigned long start_time = (unsigned long)rq->fifo_time;
 412
 413         start_time -= dd->fifo_expire[rq_data_dir(rq)];
 414
 415         return time_after(start_time, latest_start);
 416 }
 417
 418 /*
 419  * deadline_dispatch_requests selects the best request according to
 420  * read/write expire, fifo_batch, etc and with a start time <= @latest_start.
 421  */
 422 static struct request *__dd_dispatch_request(struct deadline_data *dd,
 423                                              struct dd_per_prio *per_prio,
 424                                              unsigned long latest_start)
 425 {
 426         struct request *rq, *next_rq;
 427         enum dd_data_dir data_dir;
 428         enum dd_prio prio;
 429         u8 ioprio_class;
 430
 431         lockdep_assert_held(&dd->lock);
 432
 433         if (!list_empty(&per_prio->dispatch)) {
 434                 rq = list_first_entry(&per_prio->dispatch, struct request,
 435                                       queuelist);
 436                 if (started_after(dd, rq, latest_start))
 437                         return NULL;
 438                 list_del_init(&rq->queuelist);
 439                 goto done;
 440         }
 441
 442         /*
 443          * batches are currently reads XOR writes
 444          */
 445         rq = deadline_next_request(dd, per_prio, dd->last_dir);
 446         if (rq && dd->batching < dd->fifo_batch)
 447                 /* we have a next request are still entitled to batch */
 448                 goto dispatch_request;
 449
 450         /*
 451          * at this point we are not running a batch. select the appropriate
 452          * data direction (read / write)
 453          */
 454
 455         if (!list_empty(&per_prio->fifo_list[DD_READ])) {
 456                 BUG_ON(RB_EMPTY_ROOT(&per_prio->sort_list[DD_READ]));
 457
 458                 if (deadline_fifo_request(dd, per_prio, DD_WRITE) &&
 459                     (dd->starved++ >= dd->writes_starved))
 460                         goto dispatch_writes;
 461
 462                 data_dir = DD_READ;
 463
 464                 goto dispatch_find_request;
 465         }
 466
 467         /*
 468          * there are either no reads or writes have been starved
 469          */
 470
 471         if (!list_empty(&per_prio->fifo_list[DD_WRITE])) {
 472 dispatch_writes:
 473                 BUG_ON(RB_EMPTY_ROOT(&per_prio->sort_list[DD_WRITE]));
 474
 475                 dd->starved = 0;
 476
 477                 data_dir = DD_WRITE;
 478
 479                 goto dispatch_find_request;
 480         }
 481
 482         return NULL;
 483
 484 dispatch_find_request:
 485         /*
 486          * we are not running a batch, find best request for selected data_dir
 487          */
 488         next_rq = deadline_next_request(dd, per_prio, data_dir);
 489         if (deadline_check_fifo(per_prio, data_dir) || !next_rq) {
 490                 /*
 491                  * A deadline has expired, the last request was in the other
 492                  * direction, or we have run out of higher-sectored requests.
 493                  * Start again from the request with the earliest expiry time.
 494                  */
 495                 rq = deadline_fifo_request(dd, per_prio, data_dir);
 496         } else {
 497                 /*
 498                  * The last req was the same dir and we have a next request in
 499                  * sort order. No expired requests so continue on from here.
 500                  */
 501                 rq = next_rq;
 502         }
 503
 504         /*
 505          * For a zoned block device, if we only have writes queued and none of
 506          * them can be dispatched, rq will be NULL.
 507          */
 508         if (!rq)
 509                 return NULL;
 510
 511         dd->last_dir = data_dir;
 512         dd->batching = 0;
 513
 514 dispatch_request:
 515         if (started_after(dd, rq, latest_start))
 516                 return NULL;
 517
 518         /*
 519          * rq is the selected appropriate request.
 520          */
 521         dd->batching++;
 522         deadline_move_request(dd, per_prio, rq);
 523 done:
 524         ioprio_class = dd_rq_ioclass(rq);
 525         prio = ioprio_class_to_prio[ioprio_class];
 526         dd->per_prio[prio].stats.dispatched++;
 527         /*
 528          * If the request needs its target zone locked, do it.
 529          */
 530         blk_req_zone_write_lock(rq);
 531         rq->rq_flags |= RQF_STARTED;
 532         return rq;
 533 }
 534
 535 /*
 536  * Check whether there are any requests with priority other than DD_RT_PRIO
 537  * that were inserted more than prio_aging_expire jiffies ago.
 538  */
 539 static struct request *dd_dispatch_prio_aged_requests(struct deadline_data *dd,
 540                                                       unsigned long now)
 541 {
 542         struct request *rq;
 543         enum dd_prio prio;
 544         int prio_cnt;
 545
 546         lockdep_assert_held(&dd->lock);
 547
 548         prio_cnt = !!dd_queued(dd, DD_RT_PRIO) + !!dd_queued(dd, DD_BE_PRIO) +
 549                    !!dd_queued(dd, DD_IDLE_PRIO);
 550         if (prio_cnt < 2)
 551                 return NULL;
 552
 553         for (prio = DD_BE_PRIO; prio <= DD_PRIO_MAX; prio++) {
 554                 rq = __dd_dispatch_request(dd, &dd->per_prio[prio],
 555                                            now - dd->prio_aging_expire);
 556                 if (rq)
 557                         return rq;
 558         }
 559
 560         return NULL;
 561 }
 562
 563 /*
 564  * Called from blk_mq_run_hw_queue() -> __blk_mq_sched_dispatch_requests().
 565  *
 566  * One confusing aspect here is that we get called for a specific
 567  * hardware queue, but we may return a request that is for a
 568  * different hardware queue. This is because mq-deadline has shared
 569  * state for all hardware queues, in terms of sorting, FIFOs, etc.
 570  */
 571 static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
 572 {
 573         struct deadline_data *dd = hctx->queue->elevator->elevator_data;
 574         const unsigned long now = jiffies;
 575         struct request *rq;
 576         enum dd_prio prio;
 577
 578         spin_lock(&dd->lock);
 579         rq = dd_dispatch_prio_aged_requests(dd, now);
 580         if (rq)
 581                 goto unlock;
 582
 583         /*
 584          * Next, dispatch requests in priority order. Ignore lower priority
 585          * requests if any higher priority requests are pending.
 586          */
 587         for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
 588                 rq = __dd_dispatch_request(dd, &dd->per_prio[prio], now);
 589                 if (rq || dd_queued(dd, prio))
 590                         break;
 591         }
 592
 593 unlock:
 594         spin_unlock(&dd->lock);
 595
 596         return rq;
 597 }
 598
 599 /*
 600  * Called by __blk_mq_alloc_request(). The shallow_depth value set by this
 601  * function is used by __blk_mq_get_tag().
 602  */
 603 static void dd_limit_depth(blk_opf_t opf, struct blk_mq_alloc_data *data)
 604 {
 605         struct deadline_data *dd = data->q->elevator->elevator_data;
 606
 607         /* Do not throttle synchronous reads. */
 608         if (op_is_sync(opf) && !op_is_write(opf))
 609                 return;
 610
 611         /*
 612          * Throttle asynchronous requests and writes such that these requests
 613          * do not block the allocation of synchronous requests.
 614          */
 615         data->shallow_depth = dd->async_depth;
 616 }
 617
 618 /* Called by blk_mq_update_nr_requests(). */
 619 static void dd_depth_updated(struct blk_mq_hw_ctx *hctx)
 620 {
 621         struct request_queue *q = hctx->queue;
 622         struct deadline_data *dd = q->elevator->elevator_data;
 623         struct blk_mq_tags *tags = hctx->sched_tags;
 624
 625         dd->async_depth = max(1UL, 3 * q->nr_requests / 4);
 626
 627         sbitmap_queue_min_shallow_depth(&tags->bitmap_tags, dd->async_depth);
 628 }
 629
 630 /* Called by blk_mq_init_hctx() and blk_mq_init_sched(). */
 631 static int dd_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
 632 {
 633         dd_depth_updated(hctx);
 634         return 0;
 635 }
 636
 637 static void dd_exit_sched(struct elevator_queue *e)
 638 {
 639         struct deadline_data *dd = e->elevator_data;
 640         enum dd_prio prio;
 641
 642         for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
 643                 struct dd_per_prio *per_prio = &dd->per_prio[prio];
 644                 const struct io_stats_per_prio *stats = &per_prio->stats;
 645                 uint32_t queued;
 646
 647                 WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_READ]));
 648                 WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_WRITE]));
 649
 650                 spin_lock(&dd->lock);
 651                 queued = dd_queued(dd, prio);
 652                 spin_unlock(&dd->lock);
 653
 654                 WARN_ONCE(queued != 0,
 655                           "statistics for priority %d: i %u m %u d %u c %u\n",
 656                           prio, stats->inserted, stats->merged,
 657                           stats->dispatched, atomic_read(&stats->completed));
 658         }
 659
 660         kfree(dd);
 661 }
 662
 663 /*
 664  * initialize elevator private data (deadline_data).
 665  */
 666 static int dd_init_sched(struct request_queue *q, struct elevator_type *e)
 667 {
 668         struct deadline_data *dd;
 669         struct elevator_queue *eq;
 670         enum dd_prio prio;
 671         int ret = -ENOMEM;
 672
 673         eq = elevator_alloc(q, e);
 674         if (!eq)
 675                 return ret;
 676
 677         dd = kzalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
 678         if (!dd)
 679                 goto put_eq;
 680
 681         eq->elevator_data = dd;
 682
 683         for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
 684                 struct dd_per_prio *per_prio = &dd->per_prio[prio];
 685
 686                 INIT_LIST_HEAD(&per_prio->dispatch);
 687                 INIT_LIST_HEAD(&per_prio->fifo_list[DD_READ]);
 688                 INIT_LIST_HEAD(&per_prio->fifo_list[DD_WRITE]);
 689                 per_prio->sort_list[DD_READ] = RB_ROOT;
 690                 per_prio->sort_list[DD_WRITE] = RB_ROOT;
 691         }
 692         dd->fifo_expire[DD_READ] = read_expire;
 693         dd->fifo_expire[DD_WRITE] = write_expire;
 694         dd->writes_starved = writes_starved;
 695         dd->front_merges = 1;
 696         dd->last_dir = DD_WRITE;
 697         dd->fifo_batch = fifo_batch;
 698         dd->prio_aging_expire = prio_aging_expire;
 699         spin_lock_init(&dd->lock);
 700         spin_lock_init(&dd->zone_lock);
 701
 702         /* We dispatch from request queue wide instead of hw queue */
 703         blk_queue_flag_set(QUEUE_FLAG_SQ_SCHED, q);
 704
 705         q->elevator = eq;
 706         return 0;
 707
 708 put_eq:
 709         kobject_put(&eq->kobj);
 710         return ret;
 711 }
 712
 713 /*
 714  * Try to merge @bio into an existing request. If @bio has been merged into
 715  * an existing request, store the pointer to that request into *@rq.
 716  */
 717 static int dd_request_merge(struct request_queue *q, struct request **rq,
 718                             struct bio *bio)
 719 {
 720         struct deadline_data *dd = q->elevator->elevator_data;
 721         const u8 ioprio_class = IOPRIO_PRIO_CLASS(bio->bi_ioprio);
 722         const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
 723         struct dd_per_prio *per_prio = &dd->per_prio[prio];
 724         sector_t sector = bio_end_sector(bio);
 725         struct request *__rq;
 726
 727         if (!dd->front_merges)
 728                 return ELEVATOR_NO_MERGE;
 729
 730         __rq = elv_rb_find(&per_prio->sort_list[bio_data_dir(bio)], sector);
 731         if (__rq) {
 732                 BUG_ON(sector != blk_rq_pos(__rq));
 733
 734                 if (elv_bio_merge_ok(__rq, bio)) {
 735                         *rq = __rq;
 736                         if (blk_discard_mergable(__rq))
 737                                 return ELEVATOR_DISCARD_MERGE;
 738                         return ELEVATOR_FRONT_MERGE;
 739                 }
 740         }
 741
 742         return ELEVATOR_NO_MERGE;
 743 }
 744
 745 /*
 746  * Attempt to merge a bio into an existing request. This function is called
 747  * before @bio is associated with a request.
 748  */
 749 static bool dd_bio_merge(struct request_queue *q, struct bio *bio,
 750                 unsigned int nr_segs)
 751 {
 752         struct deadline_data *dd = q->elevator->elevator_data;
 753         struct request *free = NULL;
 754         bool ret;
 755
 756         spin_lock(&dd->lock);
 757         ret = blk_mq_sched_try_merge(q, bio, nr_segs, &free);
 758         spin_unlock(&dd->lock);
 759
 760         if (free)
 761                 blk_mq_free_request(free);
 762
 763         return ret;
 764 }
 765
 766 /*
 767  * add rq to rbtree and fifo
 768  */
 769 static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
 770                               bool at_head)
 771 {
 772         struct request_queue *q = hctx->queue;
 773         struct deadline_data *dd = q->elevator->elevator_data;
 774         const enum dd_data_dir data_dir = rq_data_dir(rq);
 775         u16 ioprio = req_get_ioprio(rq);
 776         u8 ioprio_class = IOPRIO_PRIO_CLASS(ioprio);
 777         struct dd_per_prio *per_prio;
 778         enum dd_prio prio;
 779         LIST_HEAD(free);
 780
 781         lockdep_assert_held(&dd->lock);
 782
 783         /*
 784          * This may be a requeue of a write request that has locked its
 785          * target zone. If it is the case, this releases the zone lock.
 786          */
 787         blk_req_zone_write_unlock(rq);
 788
 789         prio = ioprio_class_to_prio[ioprio_class];
 790         per_prio = &dd->per_prio[prio];
 791         if (!rq->elv.priv[0]) {
 792                 per_prio->stats.inserted++;
 793                 rq->elv.priv[0] = (void *)(uintptr_t)1;
 794         }
 795
 796         if (blk_mq_sched_try_insert_merge(q, rq, &free)) {
 797                 blk_mq_free_requests(&free);
 798                 return;
 799         }
 800
 801         trace_block_rq_insert(rq);
 802
 803         if (at_head) {
 804                 list_add(&rq->queuelist, &per_prio->dispatch);
 805                 rq->fifo_time = jiffies;
 806         } else {
 807                 deadline_add_rq_rb(per_prio, rq);
 808
 809                 if (rq_mergeable(rq)) {
 810                         elv_rqhash_add(q, rq);
 811                         if (!q->last_merge)
 812                                 q->last_merge = rq;
 813                 }
 814
 815                 /*
 816                  * set expire time and add to fifo list
 817                  */
 818                 rq->fifo_time = jiffies + dd->fifo_expire[data_dir];
 819                 list_add_tail(&rq->queuelist, &per_prio->fifo_list[data_dir]);
 820         }
 821 }
 822
 823 /*
 824  * Called from blk_mq_sched_insert_request() or blk_mq_sched_insert_requests().
 825  */
 826 static void dd_insert_requests(struct blk_mq_hw_ctx *hctx,
 827                                struct list_head *list, bool at_head)
 828 {
 829         struct request_queue *q = hctx->queue;
 830         struct deadline_data *dd = q->elevator->elevator_data;
 831
 832         spin_lock(&dd->lock);
 833         while (!list_empty(list)) {
 834                 struct request *rq;
 835
 836                 rq = list_first_entry(list, struct request, queuelist);
 837                 list_del_init(&rq->queuelist);
 838                 dd_insert_request(hctx, rq, at_head);
 839         }
 840         spin_unlock(&dd->lock);
 841 }
 842
 843 /* Callback from inside blk_mq_rq_ctx_init(). */
 844 static void dd_prepare_request(struct request *rq)
 845 {
 846         rq->elv.priv[0] = NULL;
 847 }
 848
 849 static bool dd_has_write_work(struct blk_mq_hw_ctx *hctx)
 850 {
 851         struct deadline_data *dd = hctx->queue->elevator->elevator_data;
 852         enum dd_prio p;
 853
 854         for (p = 0; p <= DD_PRIO_MAX; p++)
 855                 if (!list_empty_careful(&dd->per_prio[p].fifo_list[DD_WRITE]))
 856                         return true;
 857
 858         return false;
 859 }
 860
 861 /*
 862  * Callback from inside blk_mq_free_request().
 863  *
 864  * For zoned block devices, write unlock the target zone of
 865  * completed write requests. Do this while holding the zone lock
 866  * spinlock so that the zone is never unlocked while deadline_fifo_request()
 867  * or deadline_next_request() are executing. This function is called for
 868  * all requests, whether or not these requests complete successfully.
 869  *
 870  * For a zoned block device, __dd_dispatch_request() may have stopped
 871  * dispatching requests if all the queued requests are write requests directed
 872  * at zones that are already locked due to on-going write requests. To ensure
 873  * write request dispatch progress in this case, mark the queue as needing a
 874  * restart to ensure that the queue is run again after completion of the
 875  * request and zones being unlocked.
 876  */
 877 static void dd_finish_request(struct request *rq)
 878 {
 879         struct request_queue *q = rq->q;
 880         struct deadline_data *dd = q->elevator->elevator_data;
 881         const u8 ioprio_class = dd_rq_ioclass(rq);
 882         const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
 883         struct dd_per_prio *per_prio = &dd->per_prio[prio];
 884
 885         /*
 886          * The block layer core may call dd_finish_request() without having
 887          * called dd_insert_requests(). Skip requests that bypassed I/O
 888          * scheduling. See also blk_mq_request_bypass_insert().
 889          */
 890         if (!rq->elv.priv[0])
 891                 return;
 892
 893         atomic_inc(&per_prio->stats.completed);
 894
 895         if (blk_queue_is_zoned(q)) {
 896                 unsigned long flags;
 897
 898                 spin_lock_irqsave(&dd->zone_lock, flags);
 899                 blk_req_zone_write_unlock(rq);
 900                 spin_unlock_irqrestore(&dd->zone_lock, flags);
 901
 902                 if (dd_has_write_work(rq->mq_hctx))
 903                         blk_mq_sched_mark_restart_hctx(rq->mq_hctx);
 904         }
 905 }
 906
 907 static bool dd_has_work_for_prio(struct dd_per_prio *per_prio)
 908 {
 909         return !list_empty_careful(&per_prio->dispatch) ||
 910                 !list_empty_careful(&per_prio->fifo_list[DD_READ]) ||
 911                 !list_empty_careful(&per_prio->fifo_list[DD_WRITE]);
 912 }
 913
 914 static bool dd_has_work(struct blk_mq_hw_ctx *hctx)
 915 {
 916         struct deadline_data *dd = hctx->queue->elevator->elevator_data;
 917         enum dd_prio prio;
 918
 919         for (prio = 0; prio <= DD_PRIO_MAX; prio++)
 920                 if (dd_has_work_for_prio(&dd->per_prio[prio]))
 921                         return true;
 922
 923         return false;
 924 }
 925
 926 /*
 927  * sysfs parts below
 928  */
 929 #define SHOW_INT(__FUNC, __VAR)                                         \
 930 static ssize_t __FUNC(struct elevator_queue *e, char *page)             \
 931 {                                                                       \
 932         struct deadline_data *dd = e->elevator_data;                    \
 933                                                                         \
 934         return sysfs_emit(page, "%d\n", __VAR);                         \
 935 }
 936 #define SHOW_JIFFIES(__FUNC, __VAR) SHOW_INT(__FUNC, jiffies_to_msecs(__VAR))
 937 SHOW_JIFFIES(deadline_read_expire_show, dd->fifo_expire[DD_READ]);
 938 SHOW_JIFFIES(deadline_write_expire_show, dd->fifo_expire[DD_WRITE]);
 939 SHOW_JIFFIES(deadline_prio_aging_expire_show, dd->prio_aging_expire);
 940 SHOW_INT(deadline_writes_starved_show, dd->writes_starved);
 941 SHOW_INT(deadline_front_merges_show, dd->front_merges);
 942 SHOW_INT(deadline_async_depth_show, dd->async_depth);
 943 SHOW_INT(deadline_fifo_batch_show, dd->fifo_batch);
 944 #undef SHOW_INT
 945 #undef SHOW_JIFFIES
 946
 947 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)                 \
 948 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
 949 {                                                                       \
 950         struct deadline_data *dd = e->elevator_data;                    \
 951         int __data, __ret;                                              \
 952                                                                         \
 953         __ret = kstrtoint(page, 0, &__data);                            \
 954         if (__ret < 0)                                                  \
 955                 return __ret;                                           \
 956         if (__data < (MIN))                                             \
 957                 __data = (MIN);                                         \
 958         else if (__data > (MAX))                                        \
 959                 __data = (MAX);                                         \
 960         *(__PTR) = __CONV(__data);                                      \
 961         return count;                                                   \
 962 }
 963 #define STORE_INT(__FUNC, __PTR, MIN, MAX)                              \
 964         STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, )
 965 #define STORE_JIFFIES(__FUNC, __PTR, MIN, MAX)                          \
 966         STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, msecs_to_jiffies)
 967 STORE_JIFFIES(deadline_read_expire_store, &dd->fifo_expire[DD_READ], 0, INT_MAX);
 968 STORE_JIFFIES(deadline_write_expire_store, &dd->fifo_expire[DD_WRITE], 0, INT_MAX);
 969 STORE_JIFFIES(deadline_prio_aging_expire_store, &dd->prio_aging_expire, 0, INT_MAX);
 970 STORE_INT(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX);
 971 STORE_INT(deadline_front_merges_store, &dd->front_merges, 0, 1);
 972 STORE_INT(deadline_async_depth_store, &dd->async_depth, 1, INT_MAX);
 973 STORE_INT(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX);
 974 #undef STORE_FUNCTION
 975 #undef STORE_INT
 976 #undef STORE_JIFFIES
 977
 978 #define DD_ATTR(name) \
 979         __ATTR(name, 0644, deadline_##name##_show, deadline_##name##_store)
 980
 981 static struct elv_fs_entry deadline_attrs[] = {
 982         DD_ATTR(read_expire),
 983         DD_ATTR(write_expire),
 984         DD_ATTR(writes_starved),
 985         DD_ATTR(front_merges),
 986         DD_ATTR(async_depth),
 987         DD_ATTR(fifo_batch),
 988         DD_ATTR(prio_aging_expire),
 989         __ATTR_NULL
 990 };
 991
 992 #ifdef CONFIG_BLK_DEBUG_FS
 993 #define DEADLINE_DEBUGFS_DDIR_ATTRS(prio, data_dir, name)               \
 994 static void *deadline_##name##_fifo_start(struct seq_file *m,           \
 995                                           loff_t *pos)                  \
 996         __acquires(&dd->lock)                                           \
 997 {                                                                       \
 998         struct request_queue *q = m->private;                           \
 999         struct deadline_data *dd = q->elevator->elevator_data;          \
1000         struct dd_per_prio *per_prio = &dd->per_prio[prio];             \
1001                                                                         \
1002         spin_lock(&dd->lock);                                           \
1003         return seq_list_start(&per_prio->fifo_list[data_dir], *pos);    \
1004 }                                                                       \
1005                                                                         \
1006 static void *deadline_##name##_fifo_next(struct seq_file *m, void *v,   \
1007                                          loff_t *pos)                   \
1008 {                                                                       \
1009         struct request_queue *q = m->private;                           \
1010         struct deadline_data *dd = q->elevator->elevator_data;          \
1011         struct dd_per_prio *per_prio = &dd->per_prio[prio];             \
1012                                                                         \
1013         return seq_list_next(v, &per_prio->fifo_list[data_dir], pos);   \
1014 }                                                                       \
1015                                                                         \
1016 static void deadline_##name##_fifo_stop(struct seq_file *m, void *v)    \
1017         __releases(&dd->lock)                                           \
1018 {                                                                       \
1019         struct request_queue *q = m->private;                           \
1020         struct deadline_data *dd = q->elevator->elevator_data;          \
1021                                                                         \
1022         spin_unlock(&dd->lock);                                         \
1023 }                                                                       \
1024                                                                         \
1025 static const struct seq_operations deadline_##name##_fifo_seq_ops = {   \
1026         .start  = deadline_##name##_fifo_start,                         \
1027         .next   = deadline_##name##_fifo_next,                          \
1028         .stop   = deadline_##name##_fifo_stop,                          \
1029         .show   = blk_mq_debugfs_rq_show,                               \
1030 };                                                                      \
1031                                                                         \
1032 static int deadline_##name##_next_rq_show(void *data,                   \
1033                                           struct seq_file *m)           \
1034 {                                                                       \
1035         struct request_queue *q = data;                                 \
1036         struct deadline_data *dd = q->elevator->elevator_data;          \
1037         struct dd_per_prio *per_prio = &dd->per_prio[prio];             \
1038         struct request *rq = per_prio->next_rq[data_dir];               \
1039                                                                         \
1040         if (rq)                                                         \
1041                 __blk_mq_debugfs_rq_show(m, rq);                        \
1042         return 0;                                                       \
1043 }
1044
1045 DEADLINE_DEBUGFS_DDIR_ATTRS(DD_RT_PRIO, DD_READ, read0);
1046 DEADLINE_DEBUGFS_DDIR_ATTRS(DD_RT_PRIO, DD_WRITE, write0);
1047 DEADLINE_DEBUGFS_DDIR_ATTRS(DD_BE_PRIO, DD_READ, read1);
1048 DEADLINE_DEBUGFS_DDIR_ATTRS(DD_BE_PRIO, DD_WRITE, write1);
1049 DEADLINE_DEBUGFS_DDIR_ATTRS(DD_IDLE_PRIO, DD_READ, read2);
1050 DEADLINE_DEBUGFS_DDIR_ATTRS(DD_IDLE_PRIO, DD_WRITE, write2);
1051 #undef DEADLINE_DEBUGFS_DDIR_ATTRS
1052
1053 static int deadline_batching_show(void *data, struct seq_file *m)
1054 {
1055         struct request_queue *q = data;
1056         struct deadline_data *dd = q->elevator->elevator_data;
1057
1058         seq_printf(m, "%u\n", dd->batching);
1059         return 0;
1060 }
1061
1062 static int deadline_starved_show(void *data, struct seq_file *m)
1063 {
1064         struct request_queue *q = data;
1065         struct deadline_data *dd = q->elevator->elevator_data;
1066
1067         seq_printf(m, "%u\n", dd->starved);
1068         return 0;
1069 }
1070
1071 static int dd_async_depth_show(void *data, struct seq_file *m)
1072 {
1073         struct request_queue *q = data;
1074         struct deadline_data *dd = q->elevator->elevator_data;
1075
1076         seq_printf(m, "%u\n", dd->async_depth);
1077         return 0;
1078 }
1079
1080 static int dd_queued_show(void *data, struct seq_file *m)
1081 {
1082         struct request_queue *q = data;
1083         struct deadline_data *dd = q->elevator->elevator_data;
1084         u32 rt, be, idle;
1085
1086         spin_lock(&dd->lock);
1087         rt = dd_queued(dd, DD_RT_PRIO);
1088         be = dd_queued(dd, DD_BE_PRIO);
1089         idle = dd_queued(dd, DD_IDLE_PRIO);
1090         spin_unlock(&dd->lock);
1091
1092         seq_printf(m, "%u %u %u\n", rt, be, idle);
1093
1094         return 0;
1095 }
1096
1097 /* Number of requests owned by the block driver for a given priority. */
1098 static u32 dd_owned_by_driver(struct deadline_data *dd, enum dd_prio prio)
1099 {
1100         const struct io_stats_per_prio *stats = &dd->per_prio[prio].stats;
1101
1102         lockdep_assert_held(&dd->lock);
1103
1104         return stats->dispatched + stats->merged -
1105                 atomic_read(&stats->completed);
1106 }
1107
1108 static int dd_owned_by_driver_show(void *data, struct seq_file *m)
1109 {
1110         struct request_queue *q = data;
1111         struct deadline_data *dd = q->elevator->elevator_data;
1112         u32 rt, be, idle;
1113
1114         spin_lock(&dd->lock);
1115         rt = dd_owned_by_driver(dd, DD_RT_PRIO);
1116         be = dd_owned_by_driver(dd, DD_BE_PRIO);
1117         idle = dd_owned_by_driver(dd, DD_IDLE_PRIO);
1118         spin_unlock(&dd->lock);
1119
1120         seq_printf(m, "%u %u %u\n", rt, be, idle);
1121
1122         return 0;
1123 }
1124
1125 #define DEADLINE_DISPATCH_ATTR(prio)                                    \
1126 static void *deadline_dispatch##prio##_start(struct seq_file *m,        \
1127                                              loff_t *pos)               \
1128         __acquires(&dd->lock)                                           \
1129 {                                                                       \
1130         struct request_queue *q = m->private;                           \
1131         struct deadline_data *dd = q->elevator->elevator_data;          \
1132         struct dd_per_prio *per_prio = &dd->per_prio[prio];             \
1133                                                                         \
1134         spin_lock(&dd->lock);                                           \
1135         return seq_list_start(&per_prio->dispatch, *pos);               \
1136 }                                                                       \
1137                                                                         \
1138 static void *deadline_dispatch##prio##_next(struct seq_file *m,         \
1139                                             void *v, loff_t *pos)       \
1140 {                                                                       \
1141         struct request_queue *q = m->private;                           \
1142         struct deadline_data *dd = q->elevator->elevator_data;          \
1143         struct dd_per_prio *per_prio = &dd->per_prio[prio];             \
1144                                                                         \
1145         return seq_list_next(v, &per_prio->dispatch, pos);              \
1146 }                                                                       \
1147                                                                         \
1148 static void deadline_dispatch##prio##_stop(struct seq_file *m, void *v) \
1149         __releases(&dd->lock)                                           \
1150 {                                                                       \
1151         struct request_queue *q = m->private;                           \
1152         struct deadline_data *dd = q->elevator->elevator_data;          \
1153                                                                         \
1154         spin_unlock(&dd->lock);                                         \
1155 }                                                                       \
1156                                                                         \
1157 static const struct seq_operations deadline_dispatch##prio##_seq_ops = { \
1158         .start  = deadline_dispatch##prio##_start,                      \
1159         .next   = deadline_dispatch##prio##_next,                       \
1160         .stop   = deadline_dispatch##prio##_stop,                       \
1161         .show   = blk_mq_debugfs_rq_show,                               \
1162 }
1163
1164 DEADLINE_DISPATCH_ATTR(0);
1165 DEADLINE_DISPATCH_ATTR(1);
1166 DEADLINE_DISPATCH_ATTR(2);
1167 #undef DEADLINE_DISPATCH_ATTR
1168
1169 #define DEADLINE_QUEUE_DDIR_ATTRS(name)                                 \
1170         {#name "_fifo_list", 0400,                                      \
1171                         .seq_ops = &deadline_##name##_fifo_seq_ops}
1172 #define DEADLINE_NEXT_RQ_ATTR(name)                                     \
1173         {#name "_next_rq", 0400, deadline_##name##_next_rq_show}
1174 static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = {
1175         DEADLINE_QUEUE_DDIR_ATTRS(read0),
1176         DEADLINE_QUEUE_DDIR_ATTRS(write0),
1177         DEADLINE_QUEUE_DDIR_ATTRS(read1),
1178         DEADLINE_QUEUE_DDIR_ATTRS(write1),
1179         DEADLINE_QUEUE_DDIR_ATTRS(read2),
1180         DEADLINE_QUEUE_DDIR_ATTRS(write2),
1181         DEADLINE_NEXT_RQ_ATTR(read0),
1182         DEADLINE_NEXT_RQ_ATTR(write0),
1183         DEADLINE_NEXT_RQ_ATTR(read1),
1184         DEADLINE_NEXT_RQ_ATTR(write1),
1185         DEADLINE_NEXT_RQ_ATTR(read2),
1186         DEADLINE_NEXT_RQ_ATTR(write2),
1187         {"batching", 0400, deadline_batching_show},
1188         {"starved", 0400, deadline_starved_show},
1189         {"async_depth", 0400, dd_async_depth_show},
1190         {"dispatch0", 0400, .seq_ops = &deadline_dispatch0_seq_ops},
1191         {"dispatch1", 0400, .seq_ops = &deadline_dispatch1_seq_ops},
1192         {"dispatch2", 0400, .seq_ops = &deadline_dispatch2_seq_ops},
1193         {"owned_by_driver", 0400, dd_owned_by_driver_show},
1194         {"queued", 0400, dd_queued_show},
1195         {},
1196 };
1197 #undef DEADLINE_QUEUE_DDIR_ATTRS
1198 #endif
1199
1200 static struct elevator_type mq_deadline = {
1201         .ops = {
1202                 .depth_updated          = dd_depth_updated,
1203                 .limit_depth            = dd_limit_depth,
1204                 .insert_requests        = dd_insert_requests,
1205                 .dispatch_request       = dd_dispatch_request,
1206                 .prepare_request        = dd_prepare_request,
1207                 .finish_request         = dd_finish_request,
1208                 .next_request           = elv_rb_latter_request,
1209                 .former_request         = elv_rb_former_request,
1210                 .bio_merge              = dd_bio_merge,
1211                 .request_merge          = dd_request_merge,
1212                 .requests_merged        = dd_merged_requests,
1213                 .request_merged         = dd_request_merged,
1214                 .has_work               = dd_has_work,
1215                 .init_sched             = dd_init_sched,
1216                 .exit_sched             = dd_exit_sched,
1217                 .init_hctx              = dd_init_hctx,
1218         },
1219
1220 #ifdef CONFIG_BLK_DEBUG_FS
1221         .queue_debugfs_attrs = deadline_queue_debugfs_attrs,
1222 #endif
1223         .elevator_attrs = deadline_attrs,
1224         .elevator_name = "mq-deadline",
1225         .elevator_alias = "deadline",
1226         .elevator_features = ELEVATOR_F_ZBD_SEQ_WRITE,
1227         .elevator_owner = THIS_MODULE,
1228 };
1229 MODULE_ALIAS("mq-deadline-iosched");
1230
1231 static int __init deadline_init(void)
1232 {
1233         return elv_register(&mq_deadline);
1234 }
1235
1236 static void __exit deadline_exit(void)
1237 {
1238         elv_unregister(&mq_deadline);
1239 }
1240
1241 module_init(deadline_init);
1242 module_exit(deadline_exit);
1243
1244 MODULE_AUTHOR("Jens Axboe, Damien Le Moal and Bart Van Assche");
1245 MODULE_LICENSE("GPL");
1246 MODULE_DESCRIPTION("MQ deadline IO scheduler");