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/elevator.h>
  13 #include <linux/bio.h>
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16 #include <linux/init.h>
  17 #include <linux/compiler.h>
  18 #include <linux/rbtree.h>
  19 #include <linux/sbitmap.h>
  20
  21 #include <trace/events/block.h>
  22
  23 #include "blk.h"
  24 #include "blk-mq.h"
  25 #include "blk-mq-debugfs.h"
  26 #include "blk-mq-tag.h"
  27 #include "blk-mq-sched.h"
  28
  29 /*
  30  * See Documentation/block/deadline-iosched.rst
  31  */
  32 static const int read_expire = HZ / 2;  /* max time before a read is submitted. */
  33 static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
  34 static const int writes_starved = 2;    /* max times reads can starve a write */
  35 static const int fifo_batch = 16;       /* # of sequential requests treated as one
  36                                      by the above parameters. For throughput. */
  37
  38 struct deadline_data {
  39         /*
  40          * run time data
  41          */
  42
  43         /*
  44          * requests (deadline_rq s) are present on both sort_list and fifo_list
  45          */
  46         struct rb_root sort_list[2];
  47         struct list_head fifo_list[2];
  48
  49         /*
  50          * next in sort order. read, write or both are NULL
  51          */
  52         struct request *next_rq[2];
  53         unsigned int batching;          /* number of sequential requests made */
  54         unsigned int starved;           /* times reads have starved writes */
  55
  56         /*
  57          * settings that change how the i/o scheduler behaves
  58          */
  59         int fifo_expire[2];
  60         int fifo_batch;
  61         int writes_starved;
  62         int front_merges;
  63
  64         spinlock_t lock;
  65         spinlock_t zone_lock;
  66         struct list_head dispatch;
  67 };
  68
  69 static inline struct rb_root *
  70 deadline_rb_root(struct deadline_data *dd, struct request *rq)
  71 {
  72         return &dd->sort_list[rq_data_dir(rq)];
  73 }
  74
  75 /*
  76  * get the request after `rq' in sector-sorted order
  77  */
  78 static inline struct request *
  79 deadline_latter_request(struct request *rq)
  80 {
  81         struct rb_node *node = rb_next(&rq->rb_node);
  82
  83         if (node)
  84                 return rb_entry_rq(node);
  85
  86         return NULL;
  87 }
  88
  89 static void
  90 deadline_add_rq_rb(struct deadline_data *dd, struct request *rq)
  91 {
  92         struct rb_root *root = deadline_rb_root(dd, rq);
  93
  94         elv_rb_add(root, rq);
  95 }
  96
  97 static inline void
  98 deadline_del_rq_rb(struct deadline_data *dd, struct request *rq)
  99 {
 100         const int data_dir = rq_data_dir(rq);
 101
 102         if (dd->next_rq[data_dir] == rq)
 103                 dd->next_rq[data_dir] = deadline_latter_request(rq);
 104
 105         elv_rb_del(deadline_rb_root(dd, rq), rq);
 106 }
 107
 108 /*
 109  * remove rq from rbtree and fifo.
 110  */
 111 static void deadline_remove_request(struct request_queue *q, struct request *rq)
 112 {
 113         struct deadline_data *dd = q->elevator->elevator_data;
 114
 115         list_del_init(&rq->queuelist);
 116
 117         /*
 118          * We might not be on the rbtree, if we are doing an insert merge
 119          */
 120         if (!RB_EMPTY_NODE(&rq->rb_node))
 121                 deadline_del_rq_rb(dd, rq);
 122
 123         elv_rqhash_del(q, rq);
 124         if (q->last_merge == rq)
 125                 q->last_merge = NULL;
 126 }
 127
 128 static void dd_request_merged(struct request_queue *q, struct request *req,
 129                               enum elv_merge type)
 130 {
 131         struct deadline_data *dd = q->elevator->elevator_data;
 132
 133         /*
 134          * if the merge was a front merge, we need to reposition request
 135          */
 136         if (type == ELEVATOR_FRONT_MERGE) {
 137                 elv_rb_del(deadline_rb_root(dd, req), req);
 138                 deadline_add_rq_rb(dd, req);
 139         }
 140 }
 141
 142 static void dd_merged_requests(struct request_queue *q, struct request *req,
 143                                struct request *next)
 144 {
 145         /*
 146          * if next expires before rq, assign its expire time to rq
 147          * and move into next position (next will be deleted) in fifo
 148          */
 149         if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
 150                 if (time_before((unsigned long)next->fifo_time,
 151                                 (unsigned long)req->fifo_time)) {
 152                         list_move(&req->queuelist, &next->queuelist);
 153                         req->fifo_time = next->fifo_time;
 154                 }
 155         }
 156
 157         /*
 158          * kill knowledge of next, this one is a goner
 159          */
 160         deadline_remove_request(q, next);
 161 }
 162
 163 /*
 164  * move an entry to dispatch queue
 165  */
 166 static void
 167 deadline_move_request(struct deadline_data *dd, struct request *rq)
 168 {
 169         const int data_dir = rq_data_dir(rq);
 170
 171         dd->next_rq[READ] = NULL;
 172         dd->next_rq[WRITE] = NULL;
 173         dd->next_rq[data_dir] = deadline_latter_request(rq);
 174
 175         /*
 176          * take it off the sort and fifo list
 177          */
 178         deadline_remove_request(rq->q, rq);
 179 }
 180
 181 /*
 182  * deadline_check_fifo returns 0 if there are no expired requests on the fifo,
 183  * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
 184  */
 185 static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
 186 {
 187         struct request *rq = rq_entry_fifo(dd->fifo_list[ddir].next);
 188
 189         /*
 190          * rq is expired!
 191          */
 192         if (time_after_eq(jiffies, (unsigned long)rq->fifo_time))
 193                 return 1;
 194
 195         return 0;
 196 }
 197
 198 /*
 199  * For the specified data direction, return the next request to
 200  * dispatch using arrival ordered lists.
 201  */
 202 static struct request *
 203 deadline_fifo_request(struct deadline_data *dd, int data_dir)
 204 {
 205         struct request *rq;
 206         unsigned long flags;
 207
 208         if (WARN_ON_ONCE(data_dir != READ && data_dir != WRITE))
 209                 return NULL;
 210
 211         if (list_empty(&dd->fifo_list[data_dir]))
 212                 return NULL;
 213
 214         rq = rq_entry_fifo(dd->fifo_list[data_dir].next);
 215         if (data_dir == READ || !blk_queue_is_zoned(rq->q))
 216                 return rq;
 217
 218         /*
 219          * Look for a write request that can be dispatched, that is one with
 220          * an unlocked target zone.
 221          */
 222         spin_lock_irqsave(&dd->zone_lock, flags);
 223         list_for_each_entry(rq, &dd->fifo_list[WRITE], queuelist) {
 224                 if (blk_req_can_dispatch_to_zone(rq))
 225                         goto out;
 226         }
 227         rq = NULL;
 228 out:
 229         spin_unlock_irqrestore(&dd->zone_lock, flags);
 230
 231         return rq;
 232 }
 233
 234 /*
 235  * For the specified data direction, return the next request to
 236  * dispatch using sector position sorted lists.
 237  */
 238 static struct request *
 239 deadline_next_request(struct deadline_data *dd, int data_dir)
 240 {
 241         struct request *rq;
 242         unsigned long flags;
 243
 244         if (WARN_ON_ONCE(data_dir != READ && data_dir != WRITE))
 245                 return NULL;
 246
 247         rq = dd->next_rq[data_dir];
 248         if (!rq)
 249                 return NULL;
 250
 251         if (data_dir == READ || !blk_queue_is_zoned(rq->q))
 252                 return rq;
 253
 254         /*
 255          * Look for a write request that can be dispatched, that is one with
 256          * an unlocked target zone.
 257          */
 258         spin_lock_irqsave(&dd->zone_lock, flags);
 259         while (rq) {
 260                 if (blk_req_can_dispatch_to_zone(rq))
 261                         break;
 262                 rq = deadline_latter_request(rq);
 263         }
 264         spin_unlock_irqrestore(&dd->zone_lock, flags);
 265
 266         return rq;
 267 }
 268
 269 /*
 270  * deadline_dispatch_requests selects the best request according to
 271  * read/write expire, fifo_batch, etc
 272  */
 273 static struct request *__dd_dispatch_request(struct deadline_data *dd)
 274 {
 275         struct request *rq, *next_rq;
 276         bool reads, writes;
 277         int data_dir;
 278
 279         if (!list_empty(&dd->dispatch)) {
 280                 rq = list_first_entry(&dd->dispatch, struct request, queuelist);
 281                 list_del_init(&rq->queuelist);
 282                 goto done;
 283         }
 284
 285         reads = !list_empty(&dd->fifo_list[READ]);
 286         writes = !list_empty(&dd->fifo_list[WRITE]);
 287
 288         /*
 289          * batches are currently reads XOR writes
 290          */
 291         rq = deadline_next_request(dd, WRITE);
 292         if (!rq)
 293                 rq = deadline_next_request(dd, READ);
 294
 295         if (rq && dd->batching < dd->fifo_batch)
 296                 /* we have a next request are still entitled to batch */
 297                 goto dispatch_request;
 298
 299         /*
 300          * at this point we are not running a batch. select the appropriate
 301          * data direction (read / write)
 302          */
 303
 304         if (reads) {
 305                 BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[READ]));
 306
 307                 if (deadline_fifo_request(dd, WRITE) &&
 308                     (dd->starved++ >= dd->writes_starved))
 309                         goto dispatch_writes;
 310
 311                 data_dir = READ;
 312
 313                 goto dispatch_find_request;
 314         }
 315
 316         /*
 317          * there are either no reads or writes have been starved
 318          */
 319
 320         if (writes) {
 321 dispatch_writes:
 322                 BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[WRITE]));
 323
 324                 dd->starved = 0;
 325
 326                 data_dir = WRITE;
 327
 328                 goto dispatch_find_request;
 329         }
 330
 331         return NULL;
 332
 333 dispatch_find_request:
 334         /*
 335          * we are not running a batch, find best request for selected data_dir
 336          */
 337         next_rq = deadline_next_request(dd, data_dir);
 338         if (deadline_check_fifo(dd, data_dir) || !next_rq) {
 339                 /*
 340                  * A deadline has expired, the last request was in the other
 341                  * direction, or we have run out of higher-sectored requests.
 342                  * Start again from the request with the earliest expiry time.
 343                  */
 344                 rq = deadline_fifo_request(dd, data_dir);
 345         } else {
 346                 /*
 347                  * The last req was the same dir and we have a next request in
 348                  * sort order. No expired requests so continue on from here.
 349                  */
 350                 rq = next_rq;
 351         }
 352
 353         /*
 354          * For a zoned block device, if we only have writes queued and none of
 355          * them can be dispatched, rq will be NULL.
 356          */
 357         if (!rq)
 358                 return NULL;
 359
 360         dd->batching = 0;
 361
 362 dispatch_request:
 363         /*
 364          * rq is the selected appropriate request.
 365          */
 366         dd->batching++;
 367         deadline_move_request(dd, rq);
 368 done:
 369         /*
 370          * If the request needs its target zone locked, do it.
 371          */
 372         blk_req_zone_write_lock(rq);
 373         rq->rq_flags |= RQF_STARTED;
 374         return rq;
 375 }
 376
 377 /*
 378  * One confusing aspect here is that we get called for a specific
 379  * hardware queue, but we may return a request that is for a
 380  * different hardware queue. This is because mq-deadline has shared
 381  * state for all hardware queues, in terms of sorting, FIFOs, etc.
 382  */
 383 static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
 384 {
 385         struct deadline_data *dd = hctx->queue->elevator->elevator_data;
 386         struct request *rq;
 387
 388         spin_lock(&dd->lock);
 389         rq = __dd_dispatch_request(dd);
 390         spin_unlock(&dd->lock);
 391
 392         return rq;
 393 }
 394
 395 static void dd_exit_queue(struct elevator_queue *e)
 396 {
 397         struct deadline_data *dd = e->elevator_data;
 398
 399         BUG_ON(!list_empty(&dd->fifo_list[READ]));
 400         BUG_ON(!list_empty(&dd->fifo_list[WRITE]));
 401
 402         kfree(dd);
 403 }
 404
 405 /*
 406  * initialize elevator private data (deadline_data).
 407  */
 408 static int dd_init_queue(struct request_queue *q, struct elevator_type *e)
 409 {
 410         struct deadline_data *dd;
 411         struct elevator_queue *eq;
 412
 413         eq = elevator_alloc(q, e);
 414         if (!eq)
 415                 return -ENOMEM;
 416
 417         dd = kzalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
 418         if (!dd) {
 419                 kobject_put(&eq->kobj);
 420                 return -ENOMEM;
 421         }
 422         eq->elevator_data = dd;
 423
 424         INIT_LIST_HEAD(&dd->fifo_list[READ]);
 425         INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
 426         dd->sort_list[READ] = RB_ROOT;
 427         dd->sort_list[WRITE] = RB_ROOT;
 428         dd->fifo_expire[READ] = read_expire;
 429         dd->fifo_expire[WRITE] = write_expire;
 430         dd->writes_starved = writes_starved;
 431         dd->front_merges = 1;
 432         dd->fifo_batch = fifo_batch;
 433         spin_lock_init(&dd->lock);
 434         spin_lock_init(&dd->zone_lock);
 435         INIT_LIST_HEAD(&dd->dispatch);
 436
 437         q->elevator = eq;
 438         return 0;
 439 }
 440
 441 static int dd_request_merge(struct request_queue *q, struct request **rq,
 442                             struct bio *bio)
 443 {
 444         struct deadline_data *dd = q->elevator->elevator_data;
 445         sector_t sector = bio_end_sector(bio);
 446         struct request *__rq;
 447
 448         if (!dd->front_merges)
 449                 return ELEVATOR_NO_MERGE;
 450
 451         __rq = elv_rb_find(&dd->sort_list[bio_data_dir(bio)], sector);
 452         if (__rq) {
 453                 BUG_ON(sector != blk_rq_pos(__rq));
 454
 455                 if (elv_bio_merge_ok(__rq, bio)) {
 456                         *rq = __rq;
 457                         return ELEVATOR_FRONT_MERGE;
 458                 }
 459         }
 460
 461         return ELEVATOR_NO_MERGE;
 462 }
 463
 464 static bool dd_bio_merge(struct request_queue *q, struct bio *bio,
 465                 unsigned int nr_segs)
 466 {
 467         struct deadline_data *dd = q->elevator->elevator_data;
 468         struct request *free = NULL;
 469         bool ret;
 470
 471         spin_lock(&dd->lock);
 472         ret = blk_mq_sched_try_merge(q, bio, nr_segs, &free);
 473         spin_unlock(&dd->lock);
 474
 475         if (free)
 476                 blk_mq_free_request(free);
 477
 478         return ret;
 479 }
 480
 481 /*
 482  * add rq to rbtree and fifo
 483  */
 484 static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
 485                               bool at_head)
 486 {
 487         struct request_queue *q = hctx->queue;
 488         struct deadline_data *dd = q->elevator->elevator_data;
 489         const int data_dir = rq_data_dir(rq);
 490
 491         /*
 492          * This may be a requeue of a write request that has locked its
 493          * target zone. If it is the case, this releases the zone lock.
 494          */
 495         blk_req_zone_write_unlock(rq);
 496
 497         if (blk_mq_sched_try_insert_merge(q, rq))
 498                 return;
 499
 500         trace_block_rq_insert(rq);
 501
 502         if (at_head) {
 503                 list_add(&rq->queuelist, &dd->dispatch);
 504         } else {
 505                 deadline_add_rq_rb(dd, rq);
 506
 507                 if (rq_mergeable(rq)) {
 508                         elv_rqhash_add(q, rq);
 509                         if (!q->last_merge)
 510                                 q->last_merge = rq;
 511                 }
 512
 513                 /*
 514                  * set expire time and add to fifo list
 515                  */
 516                 rq->fifo_time = jiffies + dd->fifo_expire[data_dir];
 517                 list_add_tail(&rq->queuelist, &dd->fifo_list[data_dir]);
 518         }
 519 }
 520
 521 static void dd_insert_requests(struct blk_mq_hw_ctx *hctx,
 522                                struct list_head *list, bool at_head)
 523 {
 524         struct request_queue *q = hctx->queue;
 525         struct deadline_data *dd = q->elevator->elevator_data;
 526
 527         spin_lock(&dd->lock);
 528         while (!list_empty(list)) {
 529                 struct request *rq;
 530
 531                 rq = list_first_entry(list, struct request, queuelist);
 532                 list_del_init(&rq->queuelist);
 533                 dd_insert_request(hctx, rq, at_head);
 534         }
 535         spin_unlock(&dd->lock);
 536 }
 537
 538 /*
 539  * Nothing to do here. This is defined only to ensure that .finish_request
 540  * method is called upon request completion.
 541  */
 542 static void dd_prepare_request(struct request *rq)
 543 {
 544 }
 545
 546 /*
 547  * For zoned block devices, write unlock the target zone of
 548  * completed write requests. Do this while holding the zone lock
 549  * spinlock so that the zone is never unlocked while deadline_fifo_request()
 550  * or deadline_next_request() are executing. This function is called for
 551  * all requests, whether or not these requests complete successfully.
 552  *
 553  * For a zoned block device, __dd_dispatch_request() may have stopped
 554  * dispatching requests if all the queued requests are write requests directed
 555  * at zones that are already locked due to on-going write requests. To ensure
 556  * write request dispatch progress in this case, mark the queue as needing a
 557  * restart to ensure that the queue is run again after completion of the
 558  * request and zones being unlocked.
 559  */
 560 static void dd_finish_request(struct request *rq)
 561 {
 562         struct request_queue *q = rq->q;
 563
 564         if (blk_queue_is_zoned(q)) {
 565                 struct deadline_data *dd = q->elevator->elevator_data;
 566                 unsigned long flags;
 567
 568                 spin_lock_irqsave(&dd->zone_lock, flags);
 569                 blk_req_zone_write_unlock(rq);
 570                 if (!list_empty(&dd->fifo_list[WRITE]))
 571                         blk_mq_sched_mark_restart_hctx(rq->mq_hctx);
 572                 spin_unlock_irqrestore(&dd->zone_lock, flags);
 573         }
 574 }
 575
 576 static bool dd_has_work(struct blk_mq_hw_ctx *hctx)
 577 {
 578         struct deadline_data *dd = hctx->queue->elevator->elevator_data;
 579
 580         return !list_empty_careful(&dd->dispatch) ||
 581                 !list_empty_careful(&dd->fifo_list[0]) ||
 582                 !list_empty_careful(&dd->fifo_list[1]);
 583 }
 584
 585 /*
 586  * sysfs parts below
 587  */
 588 static ssize_t
 589 deadline_var_show(int var, char *page)
 590 {
 591         return sprintf(page, "%d\n", var);
 592 }
 593
 594 static void
 595 deadline_var_store(int *var, const char *page)
 596 {
 597         char *p = (char *) page;
 598
 599         *var = simple_strtol(p, &p, 10);
 600 }
 601
 602 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV)                            \
 603 static ssize_t __FUNC(struct elevator_queue *e, char *page)             \
 604 {                                                                       \
 605         struct deadline_data *dd = e->elevator_data;                    \
 606         int __data = __VAR;                                             \
 607         if (__CONV)                                                     \
 608                 __data = jiffies_to_msecs(__data);                      \
 609         return deadline_var_show(__data, (page));                       \
 610 }
 611 SHOW_FUNCTION(deadline_read_expire_show, dd->fifo_expire[READ], 1);
 612 SHOW_FUNCTION(deadline_write_expire_show, dd->fifo_expire[WRITE], 1);
 613 SHOW_FUNCTION(deadline_writes_starved_show, dd->writes_starved, 0);
 614 SHOW_FUNCTION(deadline_front_merges_show, dd->front_merges, 0);
 615 SHOW_FUNCTION(deadline_fifo_batch_show, dd->fifo_batch, 0);
 616 #undef SHOW_FUNCTION
 617
 618 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)                 \
 619 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
 620 {                                                                       \
 621         struct deadline_data *dd = e->elevator_data;                    \
 622         int __data;                                                     \
 623         deadline_var_store(&__data, (page));                            \
 624         if (__data < (MIN))                                             \
 625                 __data = (MIN);                                         \
 626         else if (__data > (MAX))                                        \
 627                 __data = (MAX);                                         \
 628         if (__CONV)                                                     \
 629                 *(__PTR) = msecs_to_jiffies(__data);                    \
 630         else                                                            \
 631                 *(__PTR) = __data;                                      \
 632         return count;                                                   \
 633 }
 634 STORE_FUNCTION(deadline_read_expire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1);
 635 STORE_FUNCTION(deadline_write_expire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1);
 636 STORE_FUNCTION(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0);
 637 STORE_FUNCTION(deadline_front_merges_store, &dd->front_merges, 0, 1, 0);
 638 STORE_FUNCTION(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX, 0);
 639 #undef STORE_FUNCTION
 640
 641 #define DD_ATTR(name) \
 642         __ATTR(name, 0644, deadline_##name##_show, deadline_##name##_store)
 643
 644 static struct elv_fs_entry deadline_attrs[] = {
 645         DD_ATTR(read_expire),
 646         DD_ATTR(write_expire),
 647         DD_ATTR(writes_starved),
 648         DD_ATTR(front_merges),
 649         DD_ATTR(fifo_batch),
 650         __ATTR_NULL
 651 };
 652
 653 #ifdef CONFIG_BLK_DEBUG_FS
 654 #define DEADLINE_DEBUGFS_DDIR_ATTRS(ddir, name)                         \
 655 static void *deadline_##name##_fifo_start(struct seq_file *m,           \
 656                                           loff_t *pos)                  \
 657         __acquires(&dd->lock)                                           \
 658 {                                                                       \
 659         struct request_queue *q = m->private;                           \
 660         struct deadline_data *dd = q->elevator->elevator_data;          \
 661                                                                         \
 662         spin_lock(&dd->lock);                                           \
 663         return seq_list_start(&dd->fifo_list[ddir], *pos);              \
 664 }                                                                       \
 665                                                                         \
 666 static void *deadline_##name##_fifo_next(struct seq_file *m, void *v,   \
 667                                          loff_t *pos)                   \
 668 {                                                                       \
 669         struct request_queue *q = m->private;                           \
 670         struct deadline_data *dd = q->elevator->elevator_data;          \
 671                                                                         \
 672         return seq_list_next(v, &dd->fifo_list[ddir], pos);             \
 673 }                                                                       \
 674                                                                         \
 675 static void deadline_##name##_fifo_stop(struct seq_file *m, void *v)    \
 676         __releases(&dd->lock)                                           \
 677 {                                                                       \
 678         struct request_queue *q = m->private;                           \
 679         struct deadline_data *dd = q->elevator->elevator_data;          \
 680                                                                         \
 681         spin_unlock(&dd->lock);                                         \
 682 }                                                                       \
 683                                                                         \
 684 static const struct seq_operations deadline_##name##_fifo_seq_ops = {   \
 685         .start  = deadline_##name##_fifo_start,                         \
 686         .next   = deadline_##name##_fifo_next,                          \
 687         .stop   = deadline_##name##_fifo_stop,                          \
 688         .show   = blk_mq_debugfs_rq_show,                               \
 689 };                                                                      \
 690                                                                         \
 691 static int deadline_##name##_next_rq_show(void *data,                   \
 692                                           struct seq_file *m)           \
 693 {                                                                       \
 694         struct request_queue *q = data;                                 \
 695         struct deadline_data *dd = q->elevator->elevator_data;          \
 696         struct request *rq = dd->next_rq[ddir];                         \
 697                                                                         \
 698         if (rq)                                                         \
 699                 __blk_mq_debugfs_rq_show(m, rq);                        \
 700         return 0;                                                       \
 701 }
 702 DEADLINE_DEBUGFS_DDIR_ATTRS(READ, read)
 703 DEADLINE_DEBUGFS_DDIR_ATTRS(WRITE, write)
 704 #undef DEADLINE_DEBUGFS_DDIR_ATTRS
 705
 706 static int deadline_batching_show(void *data, struct seq_file *m)
 707 {
 708         struct request_queue *q = data;
 709         struct deadline_data *dd = q->elevator->elevator_data;
 710
 711         seq_printf(m, "%u\n", dd->batching);
 712         return 0;
 713 }
 714
 715 static int deadline_starved_show(void *data, struct seq_file *m)
 716 {
 717         struct request_queue *q = data;
 718         struct deadline_data *dd = q->elevator->elevator_data;
 719
 720         seq_printf(m, "%u\n", dd->starved);
 721         return 0;
 722 }
 723
 724 static void *deadline_dispatch_start(struct seq_file *m, loff_t *pos)
 725         __acquires(&dd->lock)
 726 {
 727         struct request_queue *q = m->private;
 728         struct deadline_data *dd = q->elevator->elevator_data;
 729
 730         spin_lock(&dd->lock);
 731         return seq_list_start(&dd->dispatch, *pos);
 732 }
 733
 734 static void *deadline_dispatch_next(struct seq_file *m, void *v, loff_t *pos)
 735 {
 736         struct request_queue *q = m->private;
 737         struct deadline_data *dd = q->elevator->elevator_data;
 738
 739         return seq_list_next(v, &dd->dispatch, pos);
 740 }
 741
 742 static void deadline_dispatch_stop(struct seq_file *m, void *v)
 743         __releases(&dd->lock)
 744 {
 745         struct request_queue *q = m->private;
 746         struct deadline_data *dd = q->elevator->elevator_data;
 747
 748         spin_unlock(&dd->lock);
 749 }
 750
 751 static const struct seq_operations deadline_dispatch_seq_ops = {
 752         .start  = deadline_dispatch_start,
 753         .next   = deadline_dispatch_next,
 754         .stop   = deadline_dispatch_stop,
 755         .show   = blk_mq_debugfs_rq_show,
 756 };
 757
 758 #define DEADLINE_QUEUE_DDIR_ATTRS(name)                                         \
 759         {#name "_fifo_list", 0400, .seq_ops = &deadline_##name##_fifo_seq_ops}, \
 760         {#name "_next_rq", 0400, deadline_##name##_next_rq_show}
 761 static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = {
 762         DEADLINE_QUEUE_DDIR_ATTRS(read),
 763         DEADLINE_QUEUE_DDIR_ATTRS(write),
 764         {"batching", 0400, deadline_batching_show},
 765         {"starved", 0400, deadline_starved_show},
 766         {"dispatch", 0400, .seq_ops = &deadline_dispatch_seq_ops},
 767         {},
 768 };
 769 #undef DEADLINE_QUEUE_DDIR_ATTRS
 770 #endif
 771
 772 static struct elevator_type mq_deadline = {
 773         .ops = {
 774                 .insert_requests        = dd_insert_requests,
 775                 .dispatch_request       = dd_dispatch_request,
 776                 .prepare_request        = dd_prepare_request,
 777                 .finish_request         = dd_finish_request,
 778                 .next_request           = elv_rb_latter_request,
 779                 .former_request         = elv_rb_former_request,
 780                 .bio_merge              = dd_bio_merge,
 781                 .request_merge          = dd_request_merge,
 782                 .requests_merged        = dd_merged_requests,
 783                 .request_merged         = dd_request_merged,
 784                 .has_work               = dd_has_work,
 785                 .init_sched             = dd_init_queue,
 786                 .exit_sched             = dd_exit_queue,
 787         },
 788
 789 #ifdef CONFIG_BLK_DEBUG_FS
 790         .queue_debugfs_attrs = deadline_queue_debugfs_attrs,
 791 #endif
 792         .elevator_attrs = deadline_attrs,
 793         .elevator_name = "mq-deadline",
 794         .elevator_alias = "deadline",
 795         .elevator_features = ELEVATOR_F_ZBD_SEQ_WRITE,
 796         .elevator_owner = THIS_MODULE,
 797 };
 798 MODULE_ALIAS("mq-deadline-iosched");
 799
 800 static int __init deadline_init(void)
 801 {
 802         return elv_register(&mq_deadline);
 803 }
 804
 805 static void __exit deadline_exit(void)
 806 {
 807         elv_unregister(&mq_deadline);
 808 }
 809
 810 module_init(deadline_init);
 811 module_exit(deadline_exit);
 812
 813 MODULE_AUTHOR("Jens Axboe");
 814 MODULE_LICENSE("GPL");
 815 MODULE_DESCRIPTION("MQ deadline IO scheduler");