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