block/mq-deadline.c

   1 /*
   2  *  MQ Deadline i/o scheduler - adaptation of the legacy deadline scheduler,
   3  *  for the blk-mq scheduling framework
   4  *
   5  *  Copyright (C) 2016 Jens Axboe <axboe@kernel.dk>
   6  */
   7 #include <linux/kernel.h>
   8 #include <linux/fs.h>
   9 #include <linux/blkdev.h>
  10 #include <linux/blk-mq.h>
  11 #include <linux/elevator.h>
  12 #include <linux/bio.h>
  13 #include <linux/module.h>
  14 #include <linux/slab.h>
  15 #include <linux/init.h>
  16 #include <linux/compiler.h>
  17 #include <linux/rbtree.h>
  18 #include <linux/sbitmap.h>
  19
  20 #include "blk.h"
  21 #include "blk-mq.h"
  22 #include "blk-mq-debugfs.h"
  23 #include "blk-mq-tag.h"
  24 #include "blk-mq-sched.h"
  25
  26 /*
  27  * See Documentation/block/deadline-iosched.txt
  28  */
  29 static const int read_expire = HZ / 2;  /* max time before a read is submitted. */
  30 static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
  31 static const int writes_starved = 2;    /* max times reads can starve a write */
  32 static const int fifo_batch = 16;       /* # of sequential requests treated as one
  33                                      by the above parameters. For throughput. */
  34
  35 struct deadline_data {
  36         /*
  37          * run time data
  38          */
  39
  40         /*
  41          * requests (deadline_rq s) are present on both sort_list and fifo_list
  42          */
  43         struct rb_root sort_list[2];
  44         struct list_head fifo_list[2];
  45
  46         /*
  47          * next in sort order. read, write or both are NULL
  48          */
  49         struct request *next_rq[2];
  50         unsigned int batching;          /* number of sequential requests made */
  51         unsigned int starved;           /* times reads have starved writes */
  52
  53         /*
  54          * settings that change how the i/o scheduler behaves
  55          */
  56         int fifo_expire[2];
  57         int fifo_batch;
  58         int writes_starved;
  59         int front_merges;
  60
  61         spinlock_t lock;
  62         spinlock_t zone_lock;
  63         struct list_head dispatch;
  64 };
  65
  66 static inline struct rb_root *
  67 deadline_rb_root(struct deadline_data *dd, struct request *rq)
  68 {
  69         return &dd->sort_list[rq_data_dir(rq)];
  70 }
  71
  72 /*
  73  * get the request after `rq' in sector-sorted order
  74  */
  75 static inline struct request *
  76 deadline_latter_request(struct request *rq)
  77 {
  78         struct rb_node *node = rb_next(&rq->rb_node);
  79
  80         if (node)
  81                 return rb_entry_rq(node);
  82
  83         return NULL;
  84 }
  85
  86 static void
  87 deadline_add_rq_rb(struct deadline_data *dd, struct request *rq)
  88 {
  89         struct rb_root *root = deadline_rb_root(dd, rq);
  90
  91         elv_rb_add(root, rq);
  92 }
  93
  94 static inline void
  95 deadline_del_rq_rb(struct deadline_data *dd, struct request *rq)
  96 {
  97         const int data_dir = rq_data_dir(rq);
  98
  99         if (dd->next_rq[data_dir] == rq)
 100                 dd->next_rq[data_dir] = deadline_latter_request(rq);
 101
 102         elv_rb_del(deadline_rb_root(dd, rq), rq);
 103 }
 104
 105 /*
 106  * remove rq from rbtree and fifo.
 107  */
 108 static void deadline_remove_request(struct request_queue *q, struct request *rq)
 109 {
 110         struct deadline_data *dd = q->elevator->elevator_data;
 111
 112         list_del_init(&rq->queuelist);
 113
 114         /*
 115          * We might not be on the rbtree, if we are doing an insert merge
 116          */
 117         if (!RB_EMPTY_NODE(&rq->rb_node))
 118                 deadline_del_rq_rb(dd, rq);
 119
 120         elv_rqhash_del(q, rq);
 121         if (q->last_merge == rq)
 122                 q->last_merge = NULL;
 123 }
 124
 125 static void dd_request_merged(struct request_queue *q, struct request *req,
 126                               enum elv_merge type)
 127 {
 128         struct deadline_data *dd = q->elevator->elevator_data;
 129
 130         /*
 131          * if the merge was a front merge, we need to reposition request
 132          */
 133         if (type == ELEVATOR_FRONT_MERGE) {
 134                 elv_rb_del(deadline_rb_root(dd, req), req);
 135                 deadline_add_rq_rb(dd, req);
 136         }
 137 }
 138
 139 static void dd_merged_requests(struct request_queue *q, struct request *req,
 140                                struct request *next)
 141 {
 142         /*
 143          * if next expires before rq, assign its expire time to rq
 144          * and move into next position (next will be deleted) in fifo
 145          */
 146         if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
 147                 if (time_before((unsigned long)next->fifo_time,
 148                                 (unsigned long)req->fifo_time)) {
 149                         list_move(&req->queuelist, &next->queuelist);
 150                         req->fifo_time = next->fifo_time;
 151                 }
 152         }
 153
 154         /*
 155          * kill knowledge of next, this one is a goner
 156          */
 157         deadline_remove_request(q, next);
 158 }
 159
 160 /*
 161  * move an entry to dispatch queue
 162  */
 163 static void
 164 deadline_move_request(struct deadline_data *dd, struct request *rq)
 165 {
 166         const int data_dir = rq_data_dir(rq);
 167
 168         dd->next_rq[READ] = NULL;
 169         dd->next_rq[WRITE] = NULL;
 170         dd->next_rq[data_dir] = deadline_latter_request(rq);
 171
 172         /*
 173          * take it off the sort and fifo list
 174          */
 175         deadline_remove_request(rq->q, rq);
 176 }
 177
 178 /*
 179  * deadline_check_fifo returns 0 if there are no expired requests on the fifo,
 180  * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
 181  */
 182 static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
 183 {
 184         struct request *rq = rq_entry_fifo(dd->fifo_list[ddir].next);
 185
 186         /*
 187          * rq is expired!
 188          */
 189         if (time_after_eq(jiffies, (unsigned long)rq->fifo_time))
 190                 return 1;
 191
 192         return 0;
 193 }
 194
 195 /*
 196  * For the specified data direction, return the next request to
 197  * dispatch using arrival ordered lists.
 198  */
 199 static struct request *
 200 deadline_fifo_request(struct deadline_data *dd, int data_dir)
 201 {
 202         struct request *rq;
 203         unsigned long flags;
 204
 205         if (WARN_ON_ONCE(data_dir != READ && data_dir != WRITE))
 206                 return NULL;
 207
 208         if (list_empty(&dd->fifo_list[data_dir]))
 209                 return NULL;
 210
 211         rq = rq_entry_fifo(dd->fifo_list[data_dir].next);
 212         if (data_dir == READ || !blk_queue_is_zoned(rq->q))
 213                 return rq;
 214
 215         /*
 216          * Look for a write request that can be dispatched, that is one with
 217          * an unlocked target zone.
 218          */
 219         spin_lock_irqsave(&dd->zone_lock, flags);
 220         list_for_each_entry(rq, &dd->fifo_list[WRITE], queuelist) {
 221                 if (blk_req_can_dispatch_to_zone(rq))
 222                         goto out;
 223         }
 224         rq = NULL;
 225 out:
 226         spin_unlock_irqrestore(&dd->zone_lock, flags);
 227
 228         return rq;
 229 }
 230
 231 /*
 232  * For the specified data direction, return the next request to
 233  * dispatch using sector position sorted lists.
 234  */
 235 static struct request *
 236 deadline_next_request(struct deadline_data *dd, int data_dir)
 237 {
 238         struct request *rq;
 239         unsigned long flags;
 240
 241         if (WARN_ON_ONCE(data_dir != READ && data_dir != WRITE))
 242                 return NULL;
 243
 244         rq = dd->next_rq[data_dir];
 245         if (!rq)
 246                 return NULL;
 247
 248         if (data_dir == READ || !blk_queue_is_zoned(rq->q))
 249                 return rq;
 250
 251         /*
 252          * Look for a write request that can be dispatched, that is one with
 253          * an unlocked target zone.
 254          */
 255         spin_lock_irqsave(&dd->zone_lock, flags);
 256         while (rq) {
 257                 if (blk_req_can_dispatch_to_zone(rq))
 258                         break;
 259                 rq = deadline_latter_request(rq);
 260         }
 261         spin_unlock_irqrestore(&dd->zone_lock, flags);
 262
 263         return rq;
 264 }
 265
 266 /*
 267  * deadline_dispatch_requests selects the best request according to
 268  * read/write expire, fifo_batch, etc
 269  */
 270 static struct request *__dd_dispatch_request(struct deadline_data *dd)
 271 {
 272         struct request *rq, *next_rq;
 273         bool reads, writes;
 274         int data_dir;
 275
 276         if (!list_empty(&dd->dispatch)) {
 277                 rq = list_first_entry(&dd->dispatch, struct request, queuelist);
 278                 list_del_init(&rq->queuelist);
 279                 goto done;
 280         }
 281
 282         reads = !list_empty(&dd->fifo_list[READ]);
 283         writes = !list_empty(&dd->fifo_list[WRITE]);
 284
 285         /*
 286          * batches are currently reads XOR writes
 287          */
 288         rq = deadline_next_request(dd, WRITE);
 289         if (!rq)
 290                 rq = deadline_next_request(dd, READ);
 291
 292         if (rq && dd->batching < dd->fifo_batch)
 293                 /* we have a next request are still entitled to batch */
 294                 goto dispatch_request;
 295
 296         /*
 297          * at this point we are not running a batch. select the appropriate
 298          * data direction (read / write)
 299          */
 300
 301         if (reads) {
 302                 BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[READ]));
 303
 304                 if (deadline_fifo_request(dd, WRITE) &&
 305                     (dd->starved++ >= dd->writes_starved))
 306                         goto dispatch_writes;
 307
 308                 data_dir = READ;
 309
 310                 goto dispatch_find_request;
 311         }
 312
 313         /*
 314          * there are either no reads or writes have been starved
 315          */
 316
 317         if (writes) {
 318 dispatch_writes:
 319                 BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[WRITE]));
 320
 321                 dd->starved = 0;
 322
 323                 data_dir = WRITE;
 324
 325                 goto dispatch_find_request;
 326         }
 327
 328         return NULL;
 329
 330 dispatch_find_request:
 331         /*
 332          * we are not running a batch, find best request for selected data_dir
 333          */
 334         next_rq = deadline_next_request(dd, data_dir);
 335         if (deadline_check_fifo(dd, data_dir) || !next_rq) {
 336                 /*
 337                  * A deadline has expired, the last request was in the other
 338                  * direction, or we have run out of higher-sectored requests.
 339                  * Start again from the request with the earliest expiry time.
 340                  */
 341                 rq = deadline_fifo_request(dd, data_dir);
 342         } else {
 343                 /*
 344                  * The last req was the same dir and we have a next request in
 345                  * sort order. No expired requests so continue on from here.
 346                  */
 347                 rq = next_rq;
 348         }
 349
 350         /*
 351          * For a zoned block device, if we only have writes queued and none of
 352          * them can be dispatched, rq will be NULL.
 353          */
 354         if (!rq)
 355                 return NULL;
 356
 357         dd->batching = 0;
 358
 359 dispatch_request:
 360         /*
 361          * rq is the selected appropriate request.
 362          */
 363         dd->batching++;
 364         deadline_move_request(dd, rq);
 365 done:
 366         /*
 367          * If the request needs its target zone locked, do it.
 368          */
 369         blk_req_zone_write_lock(rq);
 370         rq->rq_flags |= RQF_STARTED;
 371         return rq;
 372 }
 373
 374 /*
 375  * One confusing aspect here is that we get called for a specific
 376  * hardware queue, but we may return a request that is for a
 377  * different hardware queue. This is because mq-deadline has shared
 378  * state for all hardware queues, in terms of sorting, FIFOs, etc.
 379  *
 380  * For a zoned block device, __dd_dispatch_request() may return NULL
 381  * if all the queued write requests are directed at zones that are already
 382  * locked due to on-going write requests. In this case, make sure to mark
 383  * the queue as needing a restart to ensure that the queue is run again
 384  * and the pending writes dispatched once the target zones for the ongoing
 385  * write requests are unlocked in dd_finish_request().
 386  */
 387 static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
 388 {
 389         struct deadline_data *dd = hctx->queue->elevator->elevator_data;
 390         struct request *rq;
 391
 392         spin_lock(&dd->lock);
 393         rq = __dd_dispatch_request(dd);
 394         if (!rq && blk_queue_is_zoned(hctx->queue) &&
 395             !list_empty(&dd->fifo_list[WRITE]))
 396                 blk_mq_sched_mark_restart_hctx(hctx);
 397         spin_unlock(&dd->lock);
 398
 399         return rq;
 400 }
 401
 402 static void dd_exit_queue(struct elevator_queue *e)
 403 {
 404         struct deadline_data *dd = e->elevator_data;
 405
 406         BUG_ON(!list_empty(&dd->fifo_list[READ]));
 407         BUG_ON(!list_empty(&dd->fifo_list[WRITE]));
 408
 409         kfree(dd);
 410 }
 411
 412 /*
 413  * initialize elevator private data (deadline_data).
 414  */
 415 static int dd_init_queue(struct request_queue *q, struct elevator_type *e)
 416 {
 417         struct deadline_data *dd;
 418         struct elevator_queue *eq;
 419
 420         eq = elevator_alloc(q, e);
 421         if (!eq)
 422                 return -ENOMEM;
 423
 424         dd = kzalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
 425         if (!dd) {
 426                 kobject_put(&eq->kobj);
 427                 return -ENOMEM;
 428         }
 429         eq->elevator_data = dd;
 430
 431         INIT_LIST_HEAD(&dd->fifo_list[READ]);
 432         INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
 433         dd->sort_list[READ] = RB_ROOT;
 434         dd->sort_list[WRITE] = RB_ROOT;
 435         dd->fifo_expire[READ] = read_expire;
 436         dd->fifo_expire[WRITE] = write_expire;
 437         dd->writes_starved = writes_starved;
 438         dd->front_merges = 1;
 439         dd->fifo_batch = fifo_batch;
 440         spin_lock_init(&dd->lock);
 441         spin_lock_init(&dd->zone_lock);
 442         INIT_LIST_HEAD(&dd->dispatch);
 443
 444         q->elevator = eq;
 445         return 0;
 446 }
 447
 448 static int dd_request_merge(struct request_queue *q, struct request **rq,
 449                             struct bio *bio)
 450 {
 451         struct deadline_data *dd = q->elevator->elevator_data;
 452         sector_t sector = bio_end_sector(bio);
 453         struct request *__rq;
 454
 455         if (!dd->front_merges)
 456                 return ELEVATOR_NO_MERGE;
 457
 458         __rq = elv_rb_find(&dd->sort_list[bio_data_dir(bio)], sector);
 459         if (__rq) {
 460                 BUG_ON(sector != blk_rq_pos(__rq));
 461
 462                 if (elv_bio_merge_ok(__rq, bio)) {
 463                         *rq = __rq;
 464                         return ELEVATOR_FRONT_MERGE;
 465                 }
 466         }
 467
 468         return ELEVATOR_NO_MERGE;
 469 }
 470
 471 static bool dd_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio)
 472 {
 473         struct request_queue *q = hctx->queue;
 474         struct deadline_data *dd = q->elevator->elevator_data;
 475         struct request *free = NULL;
 476         bool ret;
 477
 478         spin_lock(&dd->lock);
 479         ret = blk_mq_sched_try_merge(q, bio, &free);
 480         spin_unlock(&dd->lock);
 481
 482         if (free)
 483                 blk_mq_free_request(free);
 484
 485         return ret;
 486 }
 487
 488 /*
 489  * add rq to rbtree and fifo
 490  */
 491 static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
 492                               bool at_head)
 493 {
 494         struct request_queue *q = hctx->queue;
 495         struct deadline_data *dd = q->elevator->elevator_data;
 496         const int data_dir = rq_data_dir(rq);
 497
 498         /*
 499          * This may be a requeue of a write request that has locked its
 500          * target zone. If it is the case, this releases the zone lock.
 501          */
 502         blk_req_zone_write_unlock(rq);
 503
 504         if (blk_mq_sched_try_insert_merge(q, rq))
 505                 return;
 506
 507         blk_mq_sched_request_inserted(rq);
 508
 509         if (at_head || blk_rq_is_passthrough(rq)) {
 510                 if (at_head)
 511                         list_add(&rq->queuelist, &dd->dispatch);
 512                 else
 513                         list_add_tail(&rq->queuelist, &dd->dispatch);
 514         } else {
 515                 deadline_add_rq_rb(dd, rq);
 516
 517                 if (rq_mergeable(rq)) {
 518                         elv_rqhash_add(q, rq);
 519                         if (!q->last_merge)
 520                                 q->last_merge = rq;
 521                 }
 522
 523                 /*
 524                  * set expire time and add to fifo list
 525                  */
 526                 rq->fifo_time = jiffies + dd->fifo_expire[data_dir];
 527                 list_add_tail(&rq->queuelist, &dd->fifo_list[data_dir]);
 528         }
 529 }
 530
 531 static void dd_insert_requests(struct blk_mq_hw_ctx *hctx,
 532                                struct list_head *list, bool at_head)
 533 {
 534         struct request_queue *q = hctx->queue;
 535         struct deadline_data *dd = q->elevator->elevator_data;
 536
 537         spin_lock(&dd->lock);
 538         while (!list_empty(list)) {
 539                 struct request *rq;
 540
 541                 rq = list_first_entry(list, struct request, queuelist);
 542                 list_del_init(&rq->queuelist);
 543                 dd_insert_request(hctx, rq, at_head);
 544         }
 545         spin_unlock(&dd->lock);
 546 }
 547
 548 /*
 549  * Nothing to do here. This is defined only to ensure that .finish_request
 550  * method is called upon request completion.
 551  */
 552 static void dd_prepare_request(struct request *rq, struct bio *bio)
 553 {
 554 }
 555
 556 /*
 557  * For zoned block devices, write unlock the target zone of
 558  * completed write requests. Do this while holding the zone lock
 559  * spinlock so that the zone is never unlocked while deadline_fifo_request()
 560  * or deadline_next_request() are executing. This function is called for
 561  * all requests, whether or not these requests complete successfully.
 562  */
 563 static void dd_finish_request(struct request *rq)
 564 {
 565         struct request_queue *q = rq->q;
 566
 567         if (blk_queue_is_zoned(q)) {
 568                 struct deadline_data *dd = q->elevator->elevator_data;
 569                 unsigned long flags;
 570
 571                 spin_lock_irqsave(&dd->zone_lock, flags);
 572                 blk_req_zone_write_unlock(rq);
 573                 spin_unlock_irqrestore(&dd->zone_lock, flags);
 574         }
 575 }
 576
 577 static bool dd_has_work(struct blk_mq_hw_ctx *hctx)
 578 {
 579         struct deadline_data *dd = hctx->queue->elevator->elevator_data;
 580
 581         return !list_empty_careful(&dd->dispatch) ||
 582                 !list_empty_careful(&dd->fifo_list[0]) ||
 583                 !list_empty_careful(&dd->fifo_list[1]);
 584 }
 585
 586 /*
 587  * sysfs parts below
 588  */
 589 static ssize_t
 590 deadline_var_show(int var, char *page)
 591 {
 592         return sprintf(page, "%d\n", var);
 593 }
 594
 595 static void
 596 deadline_var_store(int *var, const char *page)
 597 {
 598         char *p = (char *) page;
 599
 600         *var = simple_strtol(p, &p, 10);
 601 }
 602
 603 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV)                            \
 604 static ssize_t __FUNC(struct elevator_queue *e, char *page)             \
 605 {                                                                       \
 606         struct deadline_data *dd = e->elevator_data;                    \
 607         int __data = __VAR;                                             \
 608         if (__CONV)                                                     \
 609                 __data = jiffies_to_msecs(__data);                      \
 610         return deadline_var_show(__data, (page));                       \
 611 }
 612 SHOW_FUNCTION(deadline_read_expire_show, dd->fifo_expire[READ], 1);
 613 SHOW_FUNCTION(deadline_write_expire_show, dd->fifo_expire[WRITE], 1);
 614 SHOW_FUNCTION(deadline_writes_starved_show, dd->writes_starved, 0);
 615 SHOW_FUNCTION(deadline_front_merges_show, dd->front_merges, 0);
 616 SHOW_FUNCTION(deadline_fifo_batch_show, dd->fifo_batch, 0);
 617 #undef SHOW_FUNCTION
 618
 619 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)                 \
 620 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
 621 {                                                                       \
 622         struct deadline_data *dd = e->elevator_data;                    \
 623         int __data;                                                     \
 624         deadline_var_store(&__data, (page));                            \
 625         if (__data < (MIN))                                             \
 626                 __data = (MIN);                                         \
 627         else if (__data > (MAX))                                        \
 628                 __data = (MAX);                                         \
 629         if (__CONV)                                                     \
 630                 *(__PTR) = msecs_to_jiffies(__data);                    \
 631         else                                                            \
 632                 *(__PTR) = __data;                                      \
 633         return count;                                                   \
 634 }
 635 STORE_FUNCTION(deadline_read_expire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1);
 636 STORE_FUNCTION(deadline_write_expire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1);
 637 STORE_FUNCTION(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0);
 638 STORE_FUNCTION(deadline_front_merges_store, &dd->front_merges, 0, 1, 0);
 639 STORE_FUNCTION(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX, 0);
 640 #undef STORE_FUNCTION
 641
 642 #define DD_ATTR(name) \
 643         __ATTR(name, 0644, deadline_##name##_show, deadline_##name##_store)
 644
 645 static struct elv_fs_entry deadline_attrs[] = {
 646         DD_ATTR(read_expire),
 647         DD_ATTR(write_expire),
 648         DD_ATTR(writes_starved),
 649         DD_ATTR(front_merges),
 650         DD_ATTR(fifo_batch),
 651         __ATTR_NULL
 652 };
 653
 654 #ifdef CONFIG_BLK_DEBUG_FS
 655 #define DEADLINE_DEBUGFS_DDIR_ATTRS(ddir, name)                         \
 656 static void *deadline_##name##_fifo_start(struct seq_file *m,           \
 657                                           loff_t *pos)                  \
 658         __acquires(&dd->lock)                                           \
 659 {                                                                       \
 660         struct request_queue *q = m->private;                           \
 661         struct deadline_data *dd = q->elevator->elevator_data;          \
 662                                                                         \
 663         spin_lock(&dd->lock);                                           \
 664         return seq_list_start(&dd->fifo_list[ddir], *pos);              \
 665 }                                                                       \
 666                                                                         \
 667 static void *deadline_##name##_fifo_next(struct seq_file *m, void *v,   \
 668                                          loff_t *pos)                   \
 669 {                                                                       \
 670         struct request_queue *q = m->private;                           \
 671         struct deadline_data *dd = q->elevator->elevator_data;          \
 672                                                                         \
 673         return seq_list_next(v, &dd->fifo_list[ddir], pos);             \
 674 }                                                                       \
 675                                                                         \
 676 static void deadline_##name##_fifo_stop(struct seq_file *m, void *v)    \
 677         __releases(&dd->lock)                                           \
 678 {                                                                       \
 679         struct request_queue *q = m->private;                           \
 680         struct deadline_data *dd = q->elevator->elevator_data;          \
 681                                                                         \
 682         spin_unlock(&dd->lock);                                         \
 683 }                                                                       \
 684                                                                         \
 685 static const struct seq_operations deadline_##name##_fifo_seq_ops = {   \
 686         .start  = deadline_##name##_fifo_start,                         \
 687         .next   = deadline_##name##_fifo_next,                          \
 688         .stop   = deadline_##name##_fifo_stop,                          \
 689         .show   = blk_mq_debugfs_rq_show,                               \
 690 };                                                                      \
 691                                                                         \
 692 static int deadline_##name##_next_rq_show(void *data,                   \
 693                                           struct seq_file *m)           \
 694 {                                                                       \
 695         struct request_queue *q = data;                                 \
 696         struct deadline_data *dd = q->elevator->elevator_data;          \
 697         struct request *rq = dd->next_rq[ddir];                         \
 698                                                                         \
 699         if (rq)                                                         \
 700                 __blk_mq_debugfs_rq_show(m, rq);                        \
 701         return 0;                                                       \
 702 }
 703 DEADLINE_DEBUGFS_DDIR_ATTRS(READ, read)
 704 DEADLINE_DEBUGFS_DDIR_ATTRS(WRITE, write)
 705 #undef DEADLINE_DEBUGFS_DDIR_ATTRS
 706
 707 static int deadline_batching_show(void *data, struct seq_file *m)
 708 {
 709         struct request_queue *q = data;
 710         struct deadline_data *dd = q->elevator->elevator_data;
 711
 712         seq_printf(m, "%u\n", dd->batching);
 713         return 0;
 714 }
 715
 716 static int deadline_starved_show(void *data, struct seq_file *m)
 717 {
 718         struct request_queue *q = data;
 719         struct deadline_data *dd = q->elevator->elevator_data;
 720
 721         seq_printf(m, "%u\n", dd->starved);
 722         return 0;
 723 }
 724
 725 static void *deadline_dispatch_start(struct seq_file *m, loff_t *pos)
 726         __acquires(&dd->lock)
 727 {
 728         struct request_queue *q = m->private;
 729         struct deadline_data *dd = q->elevator->elevator_data;
 730
 731         spin_lock(&dd->lock);
 732         return seq_list_start(&dd->dispatch, *pos);
 733 }
 734
 735 static void *deadline_dispatch_next(struct seq_file *m, void *v, loff_t *pos)
 736 {
 737         struct request_queue *q = m->private;
 738         struct deadline_data *dd = q->elevator->elevator_data;
 739
 740         return seq_list_next(v, &dd->dispatch, pos);
 741 }
 742
 743 static void deadline_dispatch_stop(struct seq_file *m, void *v)
 744         __releases(&dd->lock)
 745 {
 746         struct request_queue *q = m->private;
 747         struct deadline_data *dd = q->elevator->elevator_data;
 748
 749         spin_unlock(&dd->lock);
 750 }
 751
 752 static const struct seq_operations deadline_dispatch_seq_ops = {
 753         .start  = deadline_dispatch_start,
 754         .next   = deadline_dispatch_next,
 755         .stop   = deadline_dispatch_stop,
 756         .show   = blk_mq_debugfs_rq_show,
 757 };
 758
 759 #define DEADLINE_QUEUE_DDIR_ATTRS(name)                                         \
 760         {#name "_fifo_list", 0400, .seq_ops = &deadline_##name##_fifo_seq_ops}, \
 761         {#name "_next_rq", 0400, deadline_##name##_next_rq_show}
 762 static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = {
 763         DEADLINE_QUEUE_DDIR_ATTRS(read),
 764         DEADLINE_QUEUE_DDIR_ATTRS(write),
 765         {"batching", 0400, deadline_batching_show},
 766         {"starved", 0400, deadline_starved_show},
 767         {"dispatch", 0400, .seq_ops = &deadline_dispatch_seq_ops},
 768         {},
 769 };
 770 #undef DEADLINE_QUEUE_DDIR_ATTRS
 771 #endif
 772
 773 static struct elevator_type mq_deadline = {
 774         .ops.mq = {
 775                 .insert_requests        = dd_insert_requests,
 776                 .dispatch_request       = dd_dispatch_request,
 777                 .prepare_request        = dd_prepare_request,
 778                 .finish_request         = dd_finish_request,
 779                 .next_request           = elv_rb_latter_request,
 780                 .former_request         = elv_rb_former_request,
 781                 .bio_merge              = dd_bio_merge,
 782                 .request_merge          = dd_request_merge,
 783                 .requests_merged        = dd_merged_requests,
 784                 .request_merged         = dd_request_merged,
 785                 .has_work               = dd_has_work,
 786                 .init_sched             = dd_init_queue,
 787                 .exit_sched             = dd_exit_queue,
 788         },
 789
 790         .uses_mq        = true,
 791 #ifdef CONFIG_BLK_DEBUG_FS
 792         .queue_debugfs_attrs = deadline_queue_debugfs_attrs,
 793 #endif
 794         .elevator_attrs = deadline_attrs,
 795         .elevator_name = "mq-deadline",
 796         .elevator_alias = "deadline",
 797         .elevator_owner = THIS_MODULE,
 798 };
 799 MODULE_ALIAS("mq-deadline-iosched");
 800
 801 static int __init deadline_init(void)
 802 {
 803         return elv_register(&mq_deadline);
 804 }
 805
 806 static void __exit deadline_exit(void)
 807 {
 808         elv_unregister(&mq_deadline);
 809 }
 810
 811 module_init(deadline_init);
 812 module_exit(deadline_exit);
 813
 814 MODULE_AUTHOR("Jens Axboe");
 815 MODULE_LICENSE("GPL");
 816 MODULE_DESCRIPTION("MQ deadline IO scheduler");