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/bio.h>
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <linux/init.h>
  15 #include <linux/compiler.h>
  16 #include <linux/rbtree.h>
  17 #include <linux/sbitmap.h>
  18
  19 #include <trace/events/block.h>
  20
  21 #include "elevator.h"
  22 #include "blk.h"
  23 #include "blk-mq.h"
  24 #include "blk-mq-debugfs.h"
  25 #include "blk-mq-sched.h"
  26
  27 /*
  28  * See Documentation/block/deadline-iosched.rst
  29  */
  30 static const int read_expire = HZ / 2;  /* max time before a read is submitted. */
  31 static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
  32 /*
  33  * Time after which to dispatch lower priority requests even if higher
  34  * priority requests are pending.
  35  */
  36 static const int prio_aging_expire = 10 * HZ;
  37 static const int writes_starved = 2;    /* max times reads can starve a write */
  38 static const int fifo_batch = 16;       /* # of sequential requests treated as one
  39                                      by the above parameters. For throughput. */
  40
  41 enum dd_data_dir {
  42         DD_READ         = READ,
  43         DD_WRITE        = WRITE,
  44 };
  45
  46 enum { DD_DIR_COUNT = 2 };
  47
  48 enum dd_prio {
  49         DD_RT_PRIO      = 0,
  50         DD_BE_PRIO      = 1,
  51         DD_IDLE_PRIO    = 2,
  52         DD_PRIO_MAX     = 2,
  53 };
  54
  55 enum { DD_PRIO_COUNT = 3 };
  56
  57 /*
  58  * I/O statistics per I/O priority. It is fine if these counters overflow.
  59  * What matters is that these counters are at least as wide as
  60  * log2(max_outstanding_requests).
  61  */
  62 struct io_stats_per_prio {
  63         uint32_t inserted;
  64         uint32_t merged;
  65         uint32_t dispatched;
  66         atomic_t completed;
  67 };
  68
  69 /*
  70  * Deadline scheduler data per I/O priority (enum dd_prio). Requests are
  71  * present on both sort_list[] and fifo_list[].
  72  */
  73 struct dd_per_prio {
  74         struct list_head dispatch;
  75         struct rb_root sort_list[DD_DIR_COUNT];
  76         struct list_head fifo_list[DD_DIR_COUNT];
  77         /* Position of the most recently dispatched request. */
  78         sector_t latest_pos[DD_DIR_COUNT];
  79         struct io_stats_per_prio stats;
  80 };
  81
  82 struct deadline_data {
  83         /*
  84          * run time data
  85          */
  86
  87         struct dd_per_prio per_prio[DD_PRIO_COUNT];
  88
  89         /* Data direction of latest dispatched request. */
  90         enum dd_data_dir last_dir;
  91         unsigned int batching;          /* number of sequential requests made */
  92         unsigned int starved;           /* times reads have starved writes */
  93
  94         /*
  95          * settings that change how the i/o scheduler behaves
  96          */
  97         int fifo_expire[DD_DIR_COUNT];
  98         int fifo_batch;
  99         int writes_starved;
 100         int front_merges;
 101         u32 async_depth;
 102         int prio_aging_expire;
 103
 104         spinlock_t lock;
 105         spinlock_t zone_lock;
 106 };
 107
 108 /* Maps an I/O priority class to a deadline scheduler priority. */
 109 static const enum dd_prio ioprio_class_to_prio[] = {
 110         [IOPRIO_CLASS_NONE]     = DD_BE_PRIO,
 111         [IOPRIO_CLASS_RT]       = DD_RT_PRIO,
 112         [IOPRIO_CLASS_BE]       = DD_BE_PRIO,
 113         [IOPRIO_CLASS_IDLE]     = DD_IDLE_PRIO,
 114 };
 115
 116 static inline struct rb_root *
 117 deadline_rb_root(struct dd_per_prio *per_prio, struct request *rq)
 118 {
 119         return &per_prio->sort_list[rq_data_dir(rq)];
 120 }
 121
 122 /*
 123  * Returns the I/O priority class (IOPRIO_CLASS_*) that has been assigned to a
 124  * request.
 125  */
 126 static u8 dd_rq_ioclass(struct request *rq)
 127 {
 128         return IOPRIO_PRIO_CLASS(req_get_ioprio(rq));
 129 }
 130
 131 /*
 132  * get the request before `rq' in sector-sorted order
 133  */
 134 static inline struct request *
 135 deadline_earlier_request(struct request *rq)
 136 {
 137         struct rb_node *node = rb_prev(&rq->rb_node);
 138
 139         if (node)
 140                 return rb_entry_rq(node);
 141
 142         return NULL;
 143 }
 144
 145 /*
 146  * get the request after `rq' in sector-sorted order
 147  */
 148 static inline struct request *
 149 deadline_latter_request(struct request *rq)
 150 {
 151         struct rb_node *node = rb_next(&rq->rb_node);
 152
 153         if (node)
 154                 return rb_entry_rq(node);
 155
 156         return NULL;
 157 }
 158
 159 /*
 160  * Return the first request for which blk_rq_pos() >= @pos. For zoned devices,
 161  * return the first request after the start of the zone containing @pos.
 162  */
 163 static inline struct request *deadline_from_pos(struct dd_per_prio *per_prio,
 164                                 enum dd_data_dir data_dir, sector_t pos)
 165 {
 166         struct rb_node *node = per_prio->sort_list[data_dir].rb_node;
 167         struct request *rq, *res = NULL;
 168
 169         if (!node)
 170                 return NULL;
 171
 172         rq = rb_entry_rq(node);
 173         /*
 174          * A zoned write may have been requeued with a starting position that
 175          * is below that of the most recently dispatched request. Hence, for
 176          * zoned writes, start searching from the start of a zone.
 177          */
 178         if (blk_rq_is_seq_zoned_write(rq))
 179                 pos = round_down(pos, rq->q->limits.chunk_sectors);
 180
 181         while (node) {
 182                 rq = rb_entry_rq(node);
 183                 if (blk_rq_pos(rq) >= pos) {
 184                         res = rq;
 185                         node = node->rb_left;
 186                 } else {
 187                         node = node->rb_right;
 188                 }
 189         }
 190         return res;
 191 }
 192
 193 static void
 194 deadline_add_rq_rb(struct dd_per_prio *per_prio, struct request *rq)
 195 {
 196         struct rb_root *root = deadline_rb_root(per_prio, rq);
 197
 198         elv_rb_add(root, rq);
 199 }
 200
 201 static inline void
 202 deadline_del_rq_rb(struct dd_per_prio *per_prio, struct request *rq)
 203 {
 204         elv_rb_del(deadline_rb_root(per_prio, rq), rq);
 205 }
 206
 207 /*
 208  * remove rq from rbtree and fifo.
 209  */
 210 static void deadline_remove_request(struct request_queue *q,
 211                                     struct dd_per_prio *per_prio,
 212                                     struct request *rq)
 213 {
 214         list_del_init(&rq->queuelist);
 215
 216         /*
 217          * We might not be on the rbtree, if we are doing an insert merge
 218          */
 219         if (!RB_EMPTY_NODE(&rq->rb_node))
 220                 deadline_del_rq_rb(per_prio, rq);
 221
 222         elv_rqhash_del(q, rq);
 223         if (q->last_merge == rq)
 224                 q->last_merge = NULL;
 225 }
 226
 227 static void dd_request_merged(struct request_queue *q, struct request *req,
 228                               enum elv_merge type)
 229 {
 230         struct deadline_data *dd = q->elevator->elevator_data;
 231         const u8 ioprio_class = dd_rq_ioclass(req);
 232         const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
 233         struct dd_per_prio *per_prio = &dd->per_prio[prio];
 234
 235         /*
 236          * if the merge was a front merge, we need to reposition request
 237          */
 238         if (type == ELEVATOR_FRONT_MERGE) {
 239                 elv_rb_del(deadline_rb_root(per_prio, req), req);
 240                 deadline_add_rq_rb(per_prio, req);
 241         }
 242 }
 243
 244 /*
 245  * Callback function that is invoked after @next has been merged into @req.
 246  */
 247 static void dd_merged_requests(struct request_queue *q, struct request *req,
 248                                struct request *next)
 249 {
 250         struct deadline_data *dd = q->elevator->elevator_data;
 251         const u8 ioprio_class = dd_rq_ioclass(next);
 252         const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
 253
 254         lockdep_assert_held(&dd->lock);
 255
 256         dd->per_prio[prio].stats.merged++;
 257
 258         /*
 259          * if next expires before rq, assign its expire time to rq
 260          * and move into next position (next will be deleted) in fifo
 261          */
 262         if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
 263                 if (time_before((unsigned long)next->fifo_time,
 264                                 (unsigned long)req->fifo_time)) {
 265                         list_move(&req->queuelist, &next->queuelist);
 266                         req->fifo_time = next->fifo_time;
 267                 }
 268         }
 269
 270         /*
 271          * kill knowledge of next, this one is a goner
 272          */
 273         deadline_remove_request(q, &dd->per_prio[prio], next);
 274 }
 275
 276 /*
 277  * move an entry to dispatch queue
 278  */
 279 static void
 280 deadline_move_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
 281                       struct request *rq)
 282 {
 283         /*
 284          * take it off the sort and fifo list
 285          */
 286         deadline_remove_request(rq->q, per_prio, rq);
 287 }
 288
 289 /* Number of requests queued for a given priority level. */
 290 static u32 dd_queued(struct deadline_data *dd, enum dd_prio prio)
 291 {
 292         const struct io_stats_per_prio *stats = &dd->per_prio[prio].stats;
 293
 294         lockdep_assert_held(&dd->lock);
 295
 296         return stats->inserted - atomic_read(&stats->completed);
 297 }
 298
 299 /*
 300  * deadline_check_fifo returns true if and only if there are expired requests
 301  * in the FIFO list. Requires !list_empty(&dd->fifo_list[data_dir]).
 302  */
 303 static inline bool deadline_check_fifo(struct dd_per_prio *per_prio,
 304                                        enum dd_data_dir data_dir)
 305 {
 306         struct request *rq = rq_entry_fifo(per_prio->fifo_list[data_dir].next);
 307
 308         return time_is_before_eq_jiffies((unsigned long)rq->fifo_time);
 309 }
 310
 311 /*
 312  * Check if rq has a sequential request preceding it.
 313  */
 314 static bool deadline_is_seq_write(struct deadline_data *dd, struct request *rq)
 315 {
 316         struct request *prev = deadline_earlier_request(rq);
 317
 318         if (!prev)
 319                 return false;
 320
 321         return blk_rq_pos(prev) + blk_rq_sectors(prev) == blk_rq_pos(rq);
 322 }
 323
 324 /*
 325  * Skip all write requests that are sequential from @rq, even if we cross
 326  * a zone boundary.
 327  */
 328 static struct request *deadline_skip_seq_writes(struct deadline_data *dd,
 329                                                 struct request *rq)
 330 {
 331         sector_t pos = blk_rq_pos(rq);
 332
 333         do {
 334                 pos += blk_rq_sectors(rq);
 335                 rq = deadline_latter_request(rq);
 336         } while (rq && blk_rq_pos(rq) == pos);
 337
 338         return rq;
 339 }
 340
 341 /*
 342  * For the specified data direction, return the next request to
 343  * dispatch using arrival ordered lists.
 344  */
 345 static struct request *
 346 deadline_fifo_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
 347                       enum dd_data_dir data_dir)
 348 {
 349         struct request *rq, *rb_rq, *next;
 350         unsigned long flags;
 351
 352         if (list_empty(&per_prio->fifo_list[data_dir]))
 353                 return NULL;
 354
 355         rq = rq_entry_fifo(per_prio->fifo_list[data_dir].next);
 356         if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q))
 357                 return rq;
 358
 359         /*
 360          * Look for a write request that can be dispatched, that is one with
 361          * an unlocked target zone. For some HDDs, breaking a sequential
 362          * write stream can lead to lower throughput, so make sure to preserve
 363          * sequential write streams, even if that stream crosses into the next
 364          * zones and these zones are unlocked.
 365          */
 366         spin_lock_irqsave(&dd->zone_lock, flags);
 367         list_for_each_entry_safe(rq, next, &per_prio->fifo_list[DD_WRITE],
 368                                  queuelist) {
 369                 /* Check whether a prior request exists for the same zone. */
 370                 rb_rq = deadline_from_pos(per_prio, data_dir, blk_rq_pos(rq));
 371                 if (rb_rq && blk_rq_pos(rb_rq) < blk_rq_pos(rq))
 372                         rq = rb_rq;
 373                 if (blk_req_can_dispatch_to_zone(rq) &&
 374                     (blk_queue_nonrot(rq->q) ||
 375                      !deadline_is_seq_write(dd, rq)))
 376                         goto out;
 377         }
 378         rq = NULL;
 379 out:
 380         spin_unlock_irqrestore(&dd->zone_lock, flags);
 381
 382         return rq;
 383 }
 384
 385 /*
 386  * For the specified data direction, return the next request to
 387  * dispatch using sector position sorted lists.
 388  */
 389 static struct request *
 390 deadline_next_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
 391                       enum dd_data_dir data_dir)
 392 {
 393         struct request *rq;
 394         unsigned long flags;
 395
 396         rq = deadline_from_pos(per_prio, data_dir,
 397                                per_prio->latest_pos[data_dir]);
 398         if (!rq)
 399                 return NULL;
 400
 401         if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q))
 402                 return rq;
 403
 404         /*
 405          * Look for a write request that can be dispatched, that is one with
 406          * an unlocked target zone. For some HDDs, breaking a sequential
 407          * write stream can lead to lower throughput, so make sure to preserve
 408          * sequential write streams, even if that stream crosses into the next
 409          * zones and these zones are unlocked.
 410          */
 411         spin_lock_irqsave(&dd->zone_lock, flags);
 412         while (rq) {
 413                 if (blk_req_can_dispatch_to_zone(rq))
 414                         break;
 415                 if (blk_queue_nonrot(rq->q))
 416                         rq = deadline_latter_request(rq);
 417                 else
 418                         rq = deadline_skip_seq_writes(dd, rq);
 419         }
 420         spin_unlock_irqrestore(&dd->zone_lock, flags);
 421
 422         return rq;
 423 }
 424
 425 /*
 426  * Returns true if and only if @rq started after @latest_start where
 427  * @latest_start is in jiffies.
 428  */
 429 static bool started_after(struct deadline_data *dd, struct request *rq,
 430                           unsigned long latest_start)
 431 {
 432         unsigned long start_time = (unsigned long)rq->fifo_time;
 433
 434         start_time -= dd->fifo_expire[rq_data_dir(rq)];
 435
 436         return time_after(start_time, latest_start);
 437 }
 438
 439 /*
 440  * deadline_dispatch_requests selects the best request according to
 441  * read/write expire, fifo_batch, etc and with a start time <= @latest_start.
 442  */
 443 static struct request *__dd_dispatch_request(struct deadline_data *dd,
 444                                              struct dd_per_prio *per_prio,
 445                                              unsigned long latest_start)
 446 {
 447         struct request *rq, *next_rq;
 448         enum dd_data_dir data_dir;
 449         enum dd_prio prio;
 450         u8 ioprio_class;
 451
 452         lockdep_assert_held(&dd->lock);
 453
 454         if (!list_empty(&per_prio->dispatch)) {
 455                 rq = list_first_entry(&per_prio->dispatch, struct request,
 456                                       queuelist);
 457                 if (started_after(dd, rq, latest_start))
 458                         return NULL;
 459                 list_del_init(&rq->queuelist);
 460                 data_dir = rq_data_dir(rq);
 461                 goto done;
 462         }
 463
 464         /*
 465          * batches are currently reads XOR writes
 466          */
 467         rq = deadline_next_request(dd, per_prio, dd->last_dir);
 468         if (rq && dd->batching < dd->fifo_batch) {
 469                 /* we have a next request and are still entitled to batch */
 470                 data_dir = rq_data_dir(rq);
 471                 goto dispatch_request;
 472         }
 473
 474         /*
 475          * at this point we are not running a batch. select the appropriate
 476          * data direction (read / write)
 477          */
 478
 479         if (!list_empty(&per_prio->fifo_list[DD_READ])) {
 480                 BUG_ON(RB_EMPTY_ROOT(&per_prio->sort_list[DD_READ]));
 481
 482                 if (deadline_fifo_request(dd, per_prio, DD_WRITE) &&
 483                     (dd->starved++ >= dd->writes_starved))
 484                         goto dispatch_writes;
 485
 486                 data_dir = DD_READ;
 487
 488                 goto dispatch_find_request;
 489         }
 490
 491         /*
 492          * there are either no reads or writes have been starved
 493          */
 494
 495         if (!list_empty(&per_prio->fifo_list[DD_WRITE])) {
 496 dispatch_writes:
 497                 BUG_ON(RB_EMPTY_ROOT(&per_prio->sort_list[DD_WRITE]));
 498
 499                 dd->starved = 0;
 500
 501                 data_dir = DD_WRITE;
 502
 503                 goto dispatch_find_request;
 504         }
 505
 506         return NULL;
 507
 508 dispatch_find_request:
 509         /*
 510          * we are not running a batch, find best request for selected data_dir
 511          */
 512         next_rq = deadline_next_request(dd, per_prio, data_dir);
 513         if (deadline_check_fifo(per_prio, data_dir) || !next_rq) {
 514                 /*
 515                  * A deadline has expired, the last request was in the other
 516                  * direction, or we have run out of higher-sectored requests.
 517                  * Start again from the request with the earliest expiry time.
 518                  */
 519                 rq = deadline_fifo_request(dd, per_prio, data_dir);
 520         } else {
 521                 /*
 522                  * The last req was the same dir and we have a next request in
 523                  * sort order. No expired requests so continue on from here.
 524                  */
 525                 rq = next_rq;
 526         }
 527
 528         /*
 529          * For a zoned block device, if we only have writes queued and none of
 530          * them can be dispatched, rq will be NULL.
 531          */
 532         if (!rq)
 533                 return NULL;
 534
 535         dd->last_dir = data_dir;
 536         dd->batching = 0;
 537
 538 dispatch_request:
 539         if (started_after(dd, rq, latest_start))
 540                 return NULL;
 541
 542         /*
 543          * rq is the selected appropriate request.
 544          */
 545         dd->batching++;
 546         deadline_move_request(dd, per_prio, rq);
 547 done:
 548         ioprio_class = dd_rq_ioclass(rq);
 549         prio = ioprio_class_to_prio[ioprio_class];
 550         dd->per_prio[prio].latest_pos[data_dir] = blk_rq_pos(rq);
 551         dd->per_prio[prio].stats.dispatched++;
 552         /*
 553          * If the request needs its target zone locked, do it.
 554          */
 555         blk_req_zone_write_lock(rq);
 556         rq->rq_flags |= RQF_STARTED;
 557         return rq;
 558 }
 559
 560 /*
 561  * Check whether there are any requests with priority other than DD_RT_PRIO
 562  * that were inserted more than prio_aging_expire jiffies ago.
 563  */
 564 static struct request *dd_dispatch_prio_aged_requests(struct deadline_data *dd,
 565                                                       unsigned long now)
 566 {
 567         struct request *rq;
 568         enum dd_prio prio;
 569         int prio_cnt;
 570
 571         lockdep_assert_held(&dd->lock);
 572
 573         prio_cnt = !!dd_queued(dd, DD_RT_PRIO) + !!dd_queued(dd, DD_BE_PRIO) +
 574                    !!dd_queued(dd, DD_IDLE_PRIO);
 575         if (prio_cnt < 2)
 576                 return NULL;
 577
 578         for (prio = DD_BE_PRIO; prio <= DD_PRIO_MAX; prio++) {
 579                 rq = __dd_dispatch_request(dd, &dd->per_prio[prio],
 580                                            now - dd->prio_aging_expire);
 581                 if (rq)
 582                         return rq;
 583         }
 584
 585         return NULL;
 586 }
 587
 588 /*
 589  * Called from blk_mq_run_hw_queue() -> __blk_mq_sched_dispatch_requests().
 590  *
 591  * One confusing aspect here is that we get called for a specific
 592  * hardware queue, but we may return a request that is for a
 593  * different hardware queue. This is because mq-deadline has shared
 594  * state for all hardware queues, in terms of sorting, FIFOs, etc.
 595  */
 596 static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
 597 {
 598         struct deadline_data *dd = hctx->queue->elevator->elevator_data;
 599         const unsigned long now = jiffies;
 600         struct request *rq;
 601         enum dd_prio prio;
 602
 603         spin_lock(&dd->lock);
 604         rq = dd_dispatch_prio_aged_requests(dd, now);
 605         if (rq)
 606                 goto unlock;
 607
 608         /*
 609          * Next, dispatch requests in priority order. Ignore lower priority
 610          * requests if any higher priority requests are pending.
 611          */
 612         for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
 613                 rq = __dd_dispatch_request(dd, &dd->per_prio[prio], now);
 614                 if (rq || dd_queued(dd, prio))
 615                         break;
 616         }
 617
 618 unlock:
 619         spin_unlock(&dd->lock);
 620
 621         return rq;
 622 }
 623
 624 /*
 625  * Called by __blk_mq_alloc_request(). The shallow_depth value set by this
 626  * function is used by __blk_mq_get_tag().
 627  */
 628 static void dd_limit_depth(blk_opf_t opf, struct blk_mq_alloc_data *data)
 629 {
 630         struct deadline_data *dd = data->q->elevator->elevator_data;
 631
 632         /* Do not throttle synchronous reads. */
 633         if (op_is_sync(opf) && !op_is_write(opf))
 634                 return;
 635
 636         /*
 637          * Throttle asynchronous requests and writes such that these requests
 638          * do not block the allocation of synchronous requests.
 639          */
 640         data->shallow_depth = dd->async_depth;
 641 }
 642
 643 /* Called by blk_mq_update_nr_requests(). */
 644 static void dd_depth_updated(struct blk_mq_hw_ctx *hctx)
 645 {
 646         struct request_queue *q = hctx->queue;
 647         struct deadline_data *dd = q->elevator->elevator_data;
 648         struct blk_mq_tags *tags = hctx->sched_tags;
 649         unsigned int shift = tags->bitmap_tags.sb.shift;
 650
 651         dd->async_depth = max(1U, 3 * (1U << shift)  / 4);
 652
 653         sbitmap_queue_min_shallow_depth(&tags->bitmap_tags, dd->async_depth);
 654 }
 655
 656 /* Called by blk_mq_init_hctx() and blk_mq_init_sched(). */
 657 static int dd_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
 658 {
 659         dd_depth_updated(hctx);
 660         return 0;
 661 }
 662
 663 static void dd_exit_sched(struct elevator_queue *e)
 664 {
 665         struct deadline_data *dd = e->elevator_data;
 666         enum dd_prio prio;
 667
 668         for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
 669                 struct dd_per_prio *per_prio = &dd->per_prio[prio];
 670                 const struct io_stats_per_prio *stats = &per_prio->stats;
 671                 uint32_t queued;
 672
 673                 WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_READ]));
 674                 WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_WRITE]));
 675
 676                 spin_lock(&dd->lock);
 677                 queued = dd_queued(dd, prio);
 678                 spin_unlock(&dd->lock);
 679
 680                 WARN_ONCE(queued != 0,
 681                           "statistics for priority %d: i %u m %u d %u c %u\n",
 682                           prio, stats->inserted, stats->merged,
 683                           stats->dispatched, atomic_read(&stats->completed));
 684         }
 685
 686         kfree(dd);
 687 }
 688
 689 /*
 690  * initialize elevator private data (deadline_data).
 691  */
 692 static int dd_init_sched(struct request_queue *q, struct elevator_type *e)
 693 {
 694         struct deadline_data *dd;
 695         struct elevator_queue *eq;
 696         enum dd_prio prio;
 697         int ret = -ENOMEM;
 698
 699         eq = elevator_alloc(q, e);
 700         if (!eq)
 701                 return ret;
 702
 703         dd = kzalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
 704         if (!dd)
 705                 goto put_eq;
 706
 707         eq->elevator_data = dd;
 708
 709         for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
 710                 struct dd_per_prio *per_prio = &dd->per_prio[prio];
 711
 712                 INIT_LIST_HEAD(&per_prio->dispatch);
 713                 INIT_LIST_HEAD(&per_prio->fifo_list[DD_READ]);
 714                 INIT_LIST_HEAD(&per_prio->fifo_list[DD_WRITE]);
 715                 per_prio->sort_list[DD_READ] = RB_ROOT;
 716                 per_prio->sort_list[DD_WRITE] = RB_ROOT;
 717         }
 718         dd->fifo_expire[DD_READ] = read_expire;
 719         dd->fifo_expire[DD_WRITE] = write_expire;
 720         dd->writes_starved = writes_starved;
 721         dd->front_merges = 1;
 722         dd->last_dir = DD_WRITE;
 723         dd->fifo_batch = fifo_batch;
 724         dd->prio_aging_expire = prio_aging_expire;
 725         spin_lock_init(&dd->lock);
 726         spin_lock_init(&dd->zone_lock);
 727
 728         /* We dispatch from request queue wide instead of hw queue */
 729         blk_queue_flag_set(QUEUE_FLAG_SQ_SCHED, q);
 730
 731         q->elevator = eq;
 732         return 0;
 733
 734 put_eq:
 735         kobject_put(&eq->kobj);
 736         return ret;
 737 }
 738
 739 /*
 740  * Try to merge @bio into an existing request. If @bio has been merged into
 741  * an existing request, store the pointer to that request into *@rq.
 742  */
 743 static int dd_request_merge(struct request_queue *q, struct request **rq,
 744                             struct bio *bio)
 745 {
 746         struct deadline_data *dd = q->elevator->elevator_data;
 747         const u8 ioprio_class = IOPRIO_PRIO_CLASS(bio->bi_ioprio);
 748         const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
 749         struct dd_per_prio *per_prio = &dd->per_prio[prio];
 750         sector_t sector = bio_end_sector(bio);
 751         struct request *__rq;
 752
 753         if (!dd->front_merges)
 754                 return ELEVATOR_NO_MERGE;
 755
 756         __rq = elv_rb_find(&per_prio->sort_list[bio_data_dir(bio)], sector);
 757         if (__rq) {
 758                 BUG_ON(sector != blk_rq_pos(__rq));
 759
 760                 if (elv_bio_merge_ok(__rq, bio)) {
 761                         *rq = __rq;
 762                         if (blk_discard_mergable(__rq))
 763                                 return ELEVATOR_DISCARD_MERGE;
 764                         return ELEVATOR_FRONT_MERGE;
 765                 }
 766         }
 767
 768         return ELEVATOR_NO_MERGE;
 769 }
 770
 771 /*
 772  * Attempt to merge a bio into an existing request. This function is called
 773  * before @bio is associated with a request.
 774  */
 775 static bool dd_bio_merge(struct request_queue *q, struct bio *bio,
 776                 unsigned int nr_segs)
 777 {
 778         struct deadline_data *dd = q->elevator->elevator_data;
 779         struct request *free = NULL;
 780         bool ret;
 781
 782         spin_lock(&dd->lock);
 783         ret = blk_mq_sched_try_merge(q, bio, nr_segs, &free);
 784         spin_unlock(&dd->lock);
 785
 786         if (free)
 787                 blk_mq_free_request(free);
 788
 789         return ret;
 790 }
 791
 792 /*
 793  * add rq to rbtree and fifo
 794  */
 795 static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
 796                               blk_insert_t flags, struct list_head *free)
 797 {
 798         struct request_queue *q = hctx->queue;
 799         struct deadline_data *dd = q->elevator->elevator_data;
 800         const enum dd_data_dir data_dir = rq_data_dir(rq);
 801         u16 ioprio = req_get_ioprio(rq);
 802         u8 ioprio_class = IOPRIO_PRIO_CLASS(ioprio);
 803         struct dd_per_prio *per_prio;
 804         enum dd_prio prio;
 805
 806         lockdep_assert_held(&dd->lock);
 807
 808         /*
 809          * This may be a requeue of a write request that has locked its
 810          * target zone. If it is the case, this releases the zone lock.
 811          */
 812         blk_req_zone_write_unlock(rq);
 813
 814         prio = ioprio_class_to_prio[ioprio_class];
 815         per_prio = &dd->per_prio[prio];
 816         if (!rq->elv.priv[0]) {
 817                 per_prio->stats.inserted++;
 818                 rq->elv.priv[0] = (void *)(uintptr_t)1;
 819         }
 820
 821         if (blk_mq_sched_try_insert_merge(q, rq, free))
 822                 return;
 823
 824         trace_block_rq_insert(rq);
 825
 826         if (flags & BLK_MQ_INSERT_AT_HEAD) {
 827                 list_add(&rq->queuelist, &per_prio->dispatch);
 828                 rq->fifo_time = jiffies;
 829         } else {
 830                 struct list_head *insert_before;
 831
 832                 deadline_add_rq_rb(per_prio, rq);
 833
 834                 if (rq_mergeable(rq)) {
 835                         elv_rqhash_add(q, rq);
 836                         if (!q->last_merge)
 837                                 q->last_merge = rq;
 838                 }
 839
 840                 /*
 841                  * set expire time and add to fifo list
 842                  */
 843                 rq->fifo_time = jiffies + dd->fifo_expire[data_dir];
 844                 insert_before = &per_prio->fifo_list[data_dir];
 845 #ifdef CONFIG_BLK_DEV_ZONED
 846                 /*
 847                  * Insert zoned writes such that requests are sorted by
 848                  * position per zone.
 849                  */
 850                 if (blk_rq_is_seq_zoned_write(rq)) {
 851                         struct request *rq2 = deadline_latter_request(rq);
 852
 853                         if (rq2 && blk_rq_zone_no(rq2) == blk_rq_zone_no(rq))
 854                                 insert_before = &rq2->queuelist;
 855                 }
 856 #endif
 857                 list_add_tail(&rq->queuelist, insert_before);
 858         }
 859 }
 860
 861 /*
 862  * Called from blk_mq_insert_request() or blk_mq_dispatch_plug_list().
 863  */
 864 static void dd_insert_requests(struct blk_mq_hw_ctx *hctx,
 865                                struct list_head *list,
 866                                blk_insert_t flags)
 867 {
 868         struct request_queue *q = hctx->queue;
 869         struct deadline_data *dd = q->elevator->elevator_data;
 870         LIST_HEAD(free);
 871
 872         spin_lock(&dd->lock);
 873         while (!list_empty(list)) {
 874                 struct request *rq;
 875
 876                 rq = list_first_entry(list, struct request, queuelist);
 877                 list_del_init(&rq->queuelist);
 878                 dd_insert_request(hctx, rq, flags, &free);
 879         }
 880         spin_unlock(&dd->lock);
 881
 882         blk_mq_free_requests(&free);
 883 }
 884
 885 /* Callback from inside blk_mq_rq_ctx_init(). */
 886 static void dd_prepare_request(struct request *rq)
 887 {
 888         rq->elv.priv[0] = NULL;
 889 }
 890
 891 static bool dd_has_write_work(struct blk_mq_hw_ctx *hctx)
 892 {
 893         struct deadline_data *dd = hctx->queue->elevator->elevator_data;
 894         enum dd_prio p;
 895
 896         for (p = 0; p <= DD_PRIO_MAX; p++)
 897                 if (!list_empty_careful(&dd->per_prio[p].fifo_list[DD_WRITE]))
 898                         return true;
 899
 900         return false;
 901 }
 902
 903 /*
 904  * Callback from inside blk_mq_free_request().
 905  *
 906  * For zoned block devices, write unlock the target zone of
 907  * completed write requests. Do this while holding the zone lock
 908  * spinlock so that the zone is never unlocked while deadline_fifo_request()
 909  * or deadline_next_request() are executing. This function is called for
 910  * all requests, whether or not these requests complete successfully.
 911  *
 912  * For a zoned block device, __dd_dispatch_request() may have stopped
 913  * dispatching requests if all the queued requests are write requests directed
 914  * at zones that are already locked due to on-going write requests. To ensure
 915  * write request dispatch progress in this case, mark the queue as needing a
 916  * restart to ensure that the queue is run again after completion of the
 917  * request and zones being unlocked.
 918  */
 919 static void dd_finish_request(struct request *rq)
 920 {
 921         struct request_queue *q = rq->q;
 922         struct deadline_data *dd = q->elevator->elevator_data;
 923         const u8 ioprio_class = dd_rq_ioclass(rq);
 924         const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
 925         struct dd_per_prio *per_prio = &dd->per_prio[prio];
 926
 927         /*
 928          * The block layer core may call dd_finish_request() without having
 929          * called dd_insert_requests(). Skip requests that bypassed I/O
 930          * scheduling. See also blk_mq_request_bypass_insert().
 931          */
 932         if (!rq->elv.priv[0])
 933                 return;
 934
 935         atomic_inc(&per_prio->stats.completed);
 936
 937         if (blk_queue_is_zoned(q)) {
 938                 unsigned long flags;
 939
 940                 spin_lock_irqsave(&dd->zone_lock, flags);
 941                 blk_req_zone_write_unlock(rq);
 942                 spin_unlock_irqrestore(&dd->zone_lock, flags);
 943
 944                 if (dd_has_write_work(rq->mq_hctx))
 945                         blk_mq_sched_mark_restart_hctx(rq->mq_hctx);
 946         }
 947 }
 948
 949 static bool dd_has_work_for_prio(struct dd_per_prio *per_prio)
 950 {
 951         return !list_empty_careful(&per_prio->dispatch) ||
 952                 !list_empty_careful(&per_prio->fifo_list[DD_READ]) ||
 953                 !list_empty_careful(&per_prio->fifo_list[DD_WRITE]);
 954 }
 955
 956 static bool dd_has_work(struct blk_mq_hw_ctx *hctx)
 957 {
 958         struct deadline_data *dd = hctx->queue->elevator->elevator_data;
 959         enum dd_prio prio;
 960
 961         for (prio = 0; prio <= DD_PRIO_MAX; prio++)
 962                 if (dd_has_work_for_prio(&dd->per_prio[prio]))
 963                         return true;
 964
 965         return false;
 966 }
 967
 968 /*
 969  * sysfs parts below
 970  */
 971 #define SHOW_INT(__FUNC, __VAR)                                         \
 972 static ssize_t __FUNC(struct elevator_queue *e, char *page)             \
 973 {                                                                       \
 974         struct deadline_data *dd = e->elevator_data;                    \
 975                                                                         \
 976         return sysfs_emit(page, "%d\n", __VAR);                         \
 977 }
 978 #define SHOW_JIFFIES(__FUNC, __VAR) SHOW_INT(__FUNC, jiffies_to_msecs(__VAR))
 979 SHOW_JIFFIES(deadline_read_expire_show, dd->fifo_expire[DD_READ]);
 980 SHOW_JIFFIES(deadline_write_expire_show, dd->fifo_expire[DD_WRITE]);
 981 SHOW_JIFFIES(deadline_prio_aging_expire_show, dd->prio_aging_expire);
 982 SHOW_INT(deadline_writes_starved_show, dd->writes_starved);
 983 SHOW_INT(deadline_front_merges_show, dd->front_merges);
 984 SHOW_INT(deadline_async_depth_show, dd->async_depth);
 985 SHOW_INT(deadline_fifo_batch_show, dd->fifo_batch);
 986 #undef SHOW_INT
 987 #undef SHOW_JIFFIES
 988
 989 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)                 \
 990 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
 991 {                                                                       \
 992         struct deadline_data *dd = e->elevator_data;                    \
 993         int __data, __ret;                                              \
 994                                                                         \
 995         __ret = kstrtoint(page, 0, &__data);                            \
 996         if (__ret < 0)                                                  \
 997                 return __ret;                                           \
 998         if (__data < (MIN))                                             \
 999                 __data = (MIN);                                         \
1000         else if (__data > (MAX))                                        \
1001                 __data = (MAX);                                         \
1002         *(__PTR) = __CONV(__data);                                      \
1003         return count;                                                   \
1004 }
1005 #define STORE_INT(__FUNC, __PTR, MIN, MAX)                              \
1006         STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, )
1007 #define STORE_JIFFIES(__FUNC, __PTR, MIN, MAX)                          \
1008         STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, msecs_to_jiffies)
1009 STORE_JIFFIES(deadline_read_expire_store, &dd->fifo_expire[DD_READ], 0, INT_MAX);
1010 STORE_JIFFIES(deadline_write_expire_store, &dd->fifo_expire[DD_WRITE], 0, INT_MAX);
1011 STORE_JIFFIES(deadline_prio_aging_expire_store, &dd->prio_aging_expire, 0, INT_MAX);
1012 STORE_INT(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX);
1013 STORE_INT(deadline_front_merges_store, &dd->front_merges, 0, 1);
1014 STORE_INT(deadline_async_depth_store, &dd->async_depth, 1, INT_MAX);
1015 STORE_INT(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX);
1016 #undef STORE_FUNCTION
1017 #undef STORE_INT
1018 #undef STORE_JIFFIES
1019
1020 #define DD_ATTR(name) \
1021         __ATTR(name, 0644, deadline_##name##_show, deadline_##name##_store)
1022
1023 static struct elv_fs_entry deadline_attrs[] = {
1024         DD_ATTR(read_expire),
1025         DD_ATTR(write_expire),
1026         DD_ATTR(writes_starved),
1027         DD_ATTR(front_merges),
1028         DD_ATTR(async_depth),
1029         DD_ATTR(fifo_batch),
1030         DD_ATTR(prio_aging_expire),
1031         __ATTR_NULL
1032 };
1033
1034 #ifdef CONFIG_BLK_DEBUG_FS
1035 #define DEADLINE_DEBUGFS_DDIR_ATTRS(prio, data_dir, name)               \
1036 static void *deadline_##name##_fifo_start(struct seq_file *m,           \
1037                                           loff_t *pos)                  \
1038         __acquires(&dd->lock)                                           \
1039 {                                                                       \
1040         struct request_queue *q = m->private;                           \
1041         struct deadline_data *dd = q->elevator->elevator_data;          \
1042         struct dd_per_prio *per_prio = &dd->per_prio[prio];             \
1043                                                                         \
1044         spin_lock(&dd->lock);                                           \
1045         return seq_list_start(&per_prio->fifo_list[data_dir], *pos);    \
1046 }                                                                       \
1047                                                                         \
1048 static void *deadline_##name##_fifo_next(struct seq_file *m, void *v,   \
1049                                          loff_t *pos)                   \
1050 {                                                                       \
1051         struct request_queue *q = m->private;                           \
1052         struct deadline_data *dd = q->elevator->elevator_data;          \
1053         struct dd_per_prio *per_prio = &dd->per_prio[prio];             \
1054                                                                         \
1055         return seq_list_next(v, &per_prio->fifo_list[data_dir], pos);   \
1056 }                                                                       \
1057                                                                         \
1058 static void deadline_##name##_fifo_stop(struct seq_file *m, void *v)    \
1059         __releases(&dd->lock)                                           \
1060 {                                                                       \
1061         struct request_queue *q = m->private;                           \
1062         struct deadline_data *dd = q->elevator->elevator_data;          \
1063                                                                         \
1064         spin_unlock(&dd->lock);                                         \
1065 }                                                                       \
1066                                                                         \
1067 static const struct seq_operations deadline_##name##_fifo_seq_ops = {   \
1068         .start  = deadline_##name##_fifo_start,                         \
1069         .next   = deadline_##name##_fifo_next,                          \
1070         .stop   = deadline_##name##_fifo_stop,                          \
1071         .show   = blk_mq_debugfs_rq_show,                               \
1072 };                                                                      \
1073                                                                         \
1074 static int deadline_##name##_next_rq_show(void *data,                   \
1075                                           struct seq_file *m)           \
1076 {                                                                       \
1077         struct request_queue *q = data;                                 \
1078         struct deadline_data *dd = q->elevator->elevator_data;          \
1079         struct dd_per_prio *per_prio = &dd->per_prio[prio];             \
1080         struct request *rq;                                             \
1081                                                                         \
1082         rq = deadline_from_pos(per_prio, data_dir,                      \
1083                                per_prio->latest_pos[data_dir]);         \
1084         if (rq)                                                         \
1085                 __blk_mq_debugfs_rq_show(m, rq);                        \
1086         return 0;                                                       \
1087 }
1088
1089 DEADLINE_DEBUGFS_DDIR_ATTRS(DD_RT_PRIO, DD_READ, read0);
1090 DEADLINE_DEBUGFS_DDIR_ATTRS(DD_RT_PRIO, DD_WRITE, write0);
1091 DEADLINE_DEBUGFS_DDIR_ATTRS(DD_BE_PRIO, DD_READ, read1);
1092 DEADLINE_DEBUGFS_DDIR_ATTRS(DD_BE_PRIO, DD_WRITE, write1);
1093 DEADLINE_DEBUGFS_DDIR_ATTRS(DD_IDLE_PRIO, DD_READ, read2);
1094 DEADLINE_DEBUGFS_DDIR_ATTRS(DD_IDLE_PRIO, DD_WRITE, write2);
1095 #undef DEADLINE_DEBUGFS_DDIR_ATTRS
1096
1097 static int deadline_batching_show(void *data, struct seq_file *m)
1098 {
1099         struct request_queue *q = data;
1100         struct deadline_data *dd = q->elevator->elevator_data;
1101
1102         seq_printf(m, "%u\n", dd->batching);
1103         return 0;
1104 }
1105
1106 static int deadline_starved_show(void *data, struct seq_file *m)
1107 {
1108         struct request_queue *q = data;
1109         struct deadline_data *dd = q->elevator->elevator_data;
1110
1111         seq_printf(m, "%u\n", dd->starved);
1112         return 0;
1113 }
1114
1115 static int dd_async_depth_show(void *data, struct seq_file *m)
1116 {
1117         struct request_queue *q = data;
1118         struct deadline_data *dd = q->elevator->elevator_data;
1119
1120         seq_printf(m, "%u\n", dd->async_depth);
1121         return 0;
1122 }
1123
1124 static int dd_queued_show(void *data, struct seq_file *m)
1125 {
1126         struct request_queue *q = data;
1127         struct deadline_data *dd = q->elevator->elevator_data;
1128         u32 rt, be, idle;
1129
1130         spin_lock(&dd->lock);
1131         rt = dd_queued(dd, DD_RT_PRIO);
1132         be = dd_queued(dd, DD_BE_PRIO);
1133         idle = dd_queued(dd, DD_IDLE_PRIO);
1134         spin_unlock(&dd->lock);
1135
1136         seq_printf(m, "%u %u %u\n", rt, be, idle);
1137
1138         return 0;
1139 }
1140
1141 /* Number of requests owned by the block driver for a given priority. */
1142 static u32 dd_owned_by_driver(struct deadline_data *dd, enum dd_prio prio)
1143 {
1144         const struct io_stats_per_prio *stats = &dd->per_prio[prio].stats;
1145
1146         lockdep_assert_held(&dd->lock);
1147
1148         return stats->dispatched + stats->merged -
1149                 atomic_read(&stats->completed);
1150 }
1151
1152 static int dd_owned_by_driver_show(void *data, struct seq_file *m)
1153 {
1154         struct request_queue *q = data;
1155         struct deadline_data *dd = q->elevator->elevator_data;
1156         u32 rt, be, idle;
1157
1158         spin_lock(&dd->lock);
1159         rt = dd_owned_by_driver(dd, DD_RT_PRIO);
1160         be = dd_owned_by_driver(dd, DD_BE_PRIO);
1161         idle = dd_owned_by_driver(dd, DD_IDLE_PRIO);
1162         spin_unlock(&dd->lock);
1163
1164         seq_printf(m, "%u %u %u\n", rt, be, idle);
1165
1166         return 0;
1167 }
1168
1169 #define DEADLINE_DISPATCH_ATTR(prio)                                    \
1170 static void *deadline_dispatch##prio##_start(struct seq_file *m,        \
1171                                              loff_t *pos)               \
1172         __acquires(&dd->lock)                                           \
1173 {                                                                       \
1174         struct request_queue *q = m->private;                           \
1175         struct deadline_data *dd = q->elevator->elevator_data;          \
1176         struct dd_per_prio *per_prio = &dd->per_prio[prio];             \
1177                                                                         \
1178         spin_lock(&dd->lock);                                           \
1179         return seq_list_start(&per_prio->dispatch, *pos);               \
1180 }                                                                       \
1181                                                                         \
1182 static void *deadline_dispatch##prio##_next(struct seq_file *m,         \
1183                                             void *v, loff_t *pos)       \
1184 {                                                                       \
1185         struct request_queue *q = m->private;                           \
1186         struct deadline_data *dd = q->elevator->elevator_data;          \
1187         struct dd_per_prio *per_prio = &dd->per_prio[prio];             \
1188                                                                         \
1189         return seq_list_next(v, &per_prio->dispatch, pos);              \
1190 }                                                                       \
1191                                                                         \
1192 static void deadline_dispatch##prio##_stop(struct seq_file *m, void *v) \
1193         __releases(&dd->lock)                                           \
1194 {                                                                       \
1195         struct request_queue *q = m->private;                           \
1196         struct deadline_data *dd = q->elevator->elevator_data;          \
1197                                                                         \
1198         spin_unlock(&dd->lock);                                         \
1199 }                                                                       \
1200                                                                         \
1201 static const struct seq_operations deadline_dispatch##prio##_seq_ops = { \
1202         .start  = deadline_dispatch##prio##_start,                      \
1203         .next   = deadline_dispatch##prio##_next,                       \
1204         .stop   = deadline_dispatch##prio##_stop,                       \
1205         .show   = blk_mq_debugfs_rq_show,                               \
1206 }
1207
1208 DEADLINE_DISPATCH_ATTR(0);
1209 DEADLINE_DISPATCH_ATTR(1);
1210 DEADLINE_DISPATCH_ATTR(2);
1211 #undef DEADLINE_DISPATCH_ATTR
1212
1213 #define DEADLINE_QUEUE_DDIR_ATTRS(name)                                 \
1214         {#name "_fifo_list", 0400,                                      \
1215                         .seq_ops = &deadline_##name##_fifo_seq_ops}
1216 #define DEADLINE_NEXT_RQ_ATTR(name)                                     \
1217         {#name "_next_rq", 0400, deadline_##name##_next_rq_show}
1218 static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = {
1219         DEADLINE_QUEUE_DDIR_ATTRS(read0),
1220         DEADLINE_QUEUE_DDIR_ATTRS(write0),
1221         DEADLINE_QUEUE_DDIR_ATTRS(read1),
1222         DEADLINE_QUEUE_DDIR_ATTRS(write1),
1223         DEADLINE_QUEUE_DDIR_ATTRS(read2),
1224         DEADLINE_QUEUE_DDIR_ATTRS(write2),
1225         DEADLINE_NEXT_RQ_ATTR(read0),
1226         DEADLINE_NEXT_RQ_ATTR(write0),
1227         DEADLINE_NEXT_RQ_ATTR(read1),
1228         DEADLINE_NEXT_RQ_ATTR(write1),
1229         DEADLINE_NEXT_RQ_ATTR(read2),
1230         DEADLINE_NEXT_RQ_ATTR(write2),
1231         {"batching", 0400, deadline_batching_show},
1232         {"starved", 0400, deadline_starved_show},
1233         {"async_depth", 0400, dd_async_depth_show},
1234         {"dispatch0", 0400, .seq_ops = &deadline_dispatch0_seq_ops},
1235         {"dispatch1", 0400, .seq_ops = &deadline_dispatch1_seq_ops},
1236         {"dispatch2", 0400, .seq_ops = &deadline_dispatch2_seq_ops},
1237         {"owned_by_driver", 0400, dd_owned_by_driver_show},
1238         {"queued", 0400, dd_queued_show},
1239         {},
1240 };
1241 #undef DEADLINE_QUEUE_DDIR_ATTRS
1242 #endif
1243
1244 static struct elevator_type mq_deadline = {
1245         .ops = {
1246                 .depth_updated          = dd_depth_updated,
1247                 .limit_depth            = dd_limit_depth,
1248                 .insert_requests        = dd_insert_requests,
1249                 .dispatch_request       = dd_dispatch_request,
1250                 .prepare_request        = dd_prepare_request,
1251                 .finish_request         = dd_finish_request,
1252                 .next_request           = elv_rb_latter_request,
1253                 .former_request         = elv_rb_former_request,
1254                 .bio_merge              = dd_bio_merge,
1255                 .request_merge          = dd_request_merge,
1256                 .requests_merged        = dd_merged_requests,
1257                 .request_merged         = dd_request_merged,
1258                 .has_work               = dd_has_work,
1259                 .init_sched             = dd_init_sched,
1260                 .exit_sched             = dd_exit_sched,
1261                 .init_hctx              = dd_init_hctx,
1262         },
1263
1264 #ifdef CONFIG_BLK_DEBUG_FS
1265         .queue_debugfs_attrs = deadline_queue_debugfs_attrs,
1266 #endif
1267         .elevator_attrs = deadline_attrs,
1268         .elevator_name = "mq-deadline",
1269         .elevator_alias = "deadline",
1270         .elevator_features = ELEVATOR_F_ZBD_SEQ_WRITE,
1271         .elevator_owner = THIS_MODULE,
1272 };
1273 MODULE_ALIAS("mq-deadline-iosched");
1274
1275 static int __init deadline_init(void)
1276 {
1277         return elv_register(&mq_deadline);
1278 }
1279
1280 static void __exit deadline_exit(void)
1281 {
1282         elv_unregister(&mq_deadline);
1283 }
1284
1285 module_init(deadline_init);
1286 module_exit(deadline_exit);
1287
1288 MODULE_AUTHOR("Jens Axboe, Damien Le Moal and Bart Van Assche");
1289 MODULE_LICENSE("GPL");
1290 MODULE_DESCRIPTION("MQ deadline IO scheduler");