block/mq-deadline.c

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This source file includes following definitions.
deadline_rb_root
deadline_latter_request
deadline_add_rq_rb
deadline_del_rq_rb
deadline_remove_request
dd_request_merged
dd_merged_requests
deadline_move_request
deadline_check_fifo
deadline_fifo_request
deadline_next_request
__dd_dispatch_request
dd_dispatch_request
dd_exit_queue
dd_init_queue
dd_request_merge
dd_bio_merge
dd_insert_request
dd_insert_requests
dd_prepare_request
dd_finish_request
dd_has_work
deadline_var_show
deadline_var_store
DEADLINE_DEBUGFS_DDIR_ATTRS
deadline_starved_show
deadline_dispatch_start
deadline_dispatch_next
deadline_dispatch_stop
deadline_init
deadline_exit
   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 static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
 382 {
 383         struct deadline_data *dd = hctx->queue->elevator->elevator_data;
 384         struct request *rq;
 385 
 386         spin_lock(&dd->lock);
 387         rq = __dd_dispatch_request(dd);
 388         spin_unlock(&dd->lock);
 389 
 390         return rq;
 391 }
 392 
 393 static void dd_exit_queue(struct elevator_queue *e)
 394 {
 395         struct deadline_data *dd = e->elevator_data;
 396 
 397         BUG_ON(!list_empty(&dd->fifo_list[READ]));
 398         BUG_ON(!list_empty(&dd->fifo_list[WRITE]));
 399 
 400         kfree(dd);
 401 }
 402 
 403 /*
 404  * initialize elevator private data (deadline_data).
 405  */
 406 static int dd_init_queue(struct request_queue *q, struct elevator_type *e)
 407 {
 408         struct deadline_data *dd;
 409         struct elevator_queue *eq;
 410 
 411         eq = elevator_alloc(q, e);
 412         if (!eq)
 413                 return -ENOMEM;
 414 
 415         dd = kzalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
 416         if (!dd) {
 417                 kobject_put(&eq->kobj);
 418                 return -ENOMEM;
 419         }
 420         eq->elevator_data = dd;
 421 
 422         INIT_LIST_HEAD(&dd->fifo_list[READ]);
 423         INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
 424         dd->sort_list[READ] = RB_ROOT;
 425         dd->sort_list[WRITE] = RB_ROOT;
 426         dd->fifo_expire[READ] = read_expire;
 427         dd->fifo_expire[WRITE] = write_expire;
 428         dd->writes_starved = writes_starved;
 429         dd->front_merges = 1;
 430         dd->fifo_batch = fifo_batch;
 431         spin_lock_init(&dd->lock);
 432         spin_lock_init(&dd->zone_lock);
 433         INIT_LIST_HEAD(&dd->dispatch);
 434 
 435         q->elevator = eq;
 436         return 0;
 437 }
 438 
 439 static int dd_request_merge(struct request_queue *q, struct request **rq,
 440                             struct bio *bio)
 441 {
 442         struct deadline_data *dd = q->elevator->elevator_data;
 443         sector_t sector = bio_end_sector(bio);
 444         struct request *__rq;
 445 
 446         if (!dd->front_merges)
 447                 return ELEVATOR_NO_MERGE;
 448 
 449         __rq = elv_rb_find(&dd->sort_list[bio_data_dir(bio)], sector);
 450         if (__rq) {
 451                 BUG_ON(sector != blk_rq_pos(__rq));
 452 
 453                 if (elv_bio_merge_ok(__rq, bio)) {
 454                         *rq = __rq;
 455                         return ELEVATOR_FRONT_MERGE;
 456                 }
 457         }
 458 
 459         return ELEVATOR_NO_MERGE;
 460 }
 461 
 462 static bool dd_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio,
 463                 unsigned int nr_segs)
 464 {
 465         struct request_queue *q = hctx->queue;
 466         struct deadline_data *dd = q->elevator->elevator_data;
 467         struct request *free = NULL;
 468         bool ret;
 469 
 470         spin_lock(&dd->lock);
 471         ret = blk_mq_sched_try_merge(q, bio, nr_segs, &free);
 472         spin_unlock(&dd->lock);
 473 
 474         if (free)
 475                 blk_mq_free_request(free);
 476 
 477         return ret;
 478 }
 479 
 480 /*
 481  * add rq to rbtree and fifo
 482  */
 483 static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
 484                               bool at_head)
 485 {
 486         struct request_queue *q = hctx->queue;
 487         struct deadline_data *dd = q->elevator->elevator_data;
 488         const int data_dir = rq_data_dir(rq);
 489 
 490         /*
 491          * This may be a requeue of a write request that has locked its
 492          * target zone. If it is the case, this releases the zone lock.
 493          */
 494         blk_req_zone_write_unlock(rq);
 495 
 496         if (blk_mq_sched_try_insert_merge(q, rq))
 497                 return;
 498 
 499         blk_mq_sched_request_inserted(rq);
 500 
 501         if (at_head || blk_rq_is_passthrough(rq)) {
 502                 if (at_head)
 503                         list_add(&rq->queuelist, &dd->dispatch);
 504                 else
 505                         list_add_tail(&rq->queuelist, &dd->dispatch);
 506         } else {
 507                 deadline_add_rq_rb(dd, rq);
 508 
 509                 if (rq_mergeable(rq)) {
 510                         elv_rqhash_add(q, rq);
 511                         if (!q->last_merge)
 512                                 q->last_merge = rq;
 513                 }
 514 
 515                 /*
 516                  * set expire time and add to fifo list
 517                  */
 518                 rq->fifo_time = jiffies + dd->fifo_expire[data_dir];
 519                 list_add_tail(&rq->queuelist, &dd->fifo_list[data_dir]);
 520         }
 521 }
 522 
 523 static void dd_insert_requests(struct blk_mq_hw_ctx *hctx,
 524                                struct list_head *list, bool at_head)
 525 {
 526         struct request_queue *q = hctx->queue;
 527         struct deadline_data *dd = q->elevator->elevator_data;
 528 
 529         spin_lock(&dd->lock);
 530         while (!list_empty(list)) {
 531                 struct request *rq;
 532 
 533                 rq = list_first_entry(list, struct request, queuelist);
 534                 list_del_init(&rq->queuelist);
 535                 dd_insert_request(hctx, rq, at_head);
 536         }
 537         spin_unlock(&dd->lock);
 538 }
 539 
 540 /*
 541  * Nothing to do here. This is defined only to ensure that .finish_request
 542  * method is called upon request completion.
 543  */
 544 static void dd_prepare_request(struct request *rq, struct bio *bio)
 545 {
 546 }
 547 
 548 /*
 549  * For zoned block devices, write unlock the target zone of
 550  * completed write requests. Do this while holding the zone lock
 551  * spinlock so that the zone is never unlocked while deadline_fifo_request()
 552  * or deadline_next_request() are executing. This function is called for
 553  * all requests, whether or not these requests complete successfully.
 554  *
 555  * For a zoned block device, __dd_dispatch_request() may have stopped
 556  * dispatching requests if all the queued requests are write requests directed
 557  * at zones that are already locked due to on-going write requests. To ensure
 558  * write request dispatch progress in this case, mark the queue as needing a
 559  * restart to ensure that the queue is run again after completion of the
 560  * request and zones being unlocked.
 561  */
 562 static void dd_finish_request(struct request *rq)
 563 {
 564         struct request_queue *q = rq->q;
 565 
 566         if (blk_queue_is_zoned(q)) {
 567                 struct deadline_data *dd = q->elevator->elevator_data;
 568                 unsigned long flags;
 569 
 570                 spin_lock_irqsave(&dd->zone_lock, flags);
 571                 blk_req_zone_write_unlock(rq);
 572                 if (!list_empty(&dd->fifo_list[WRITE]))
 573                         blk_mq_sched_mark_restart_hctx(rq->mq_hctx);
 574                 spin_unlock_irqrestore(&dd->zone_lock, flags);
 575         }
 576 }
 577 
 578 static bool dd_has_work(struct blk_mq_hw_ctx *hctx)
 579 {
 580         struct deadline_data *dd = hctx->queue->elevator->elevator_data;
 581 
 582         return !list_empty_careful(&dd->dispatch) ||
 583                 !list_empty_careful(&dd->fifo_list[0]) ||
 584                 !list_empty_careful(&dd->fifo_list[1]);
 585 }
 586 
 587 /*
 588  * sysfs parts below
 589  */
 590 static ssize_t
 591 deadline_var_show(int var, char *page)
 592 {
 593         return sprintf(page, "%d\n", var);
 594 }
 595 
 596 static void
 597 deadline_var_store(int *var, const char *page)
 598 {
 599         char *p = (char *) page;
 600 
 601         *var = simple_strtol(p, &p, 10);
 602 }
 603 
 604 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV)                            \
 605 static ssize_t __FUNC(struct elevator_queue *e, char *page)             \
 606 {                                                                       \
 607         struct deadline_data *dd = e->elevator_data;                    \
 608         int __data = __VAR;                                             \
 609         if (__CONV)                                                     \
 610                 __data = jiffies_to_msecs(__data);                      \
 611         return deadline_var_show(__data, (page));                       \
 612 }
 613 SHOW_FUNCTION(deadline_read_expire_show, dd->fifo_expire[READ], 1);
 614 SHOW_FUNCTION(deadline_write_expire_show, dd->fifo_expire[WRITE], 1);
 615 SHOW_FUNCTION(deadline_writes_starved_show, dd->writes_starved, 0);
 616 SHOW_FUNCTION(deadline_front_merges_show, dd->front_merges, 0);
 617 SHOW_FUNCTION(deadline_fifo_batch_show, dd->fifo_batch, 0);
 618 #undef SHOW_FUNCTION
 619 
 620 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)                 \
 621 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
 622 {                                                                       \
 623         struct deadline_data *dd = e->elevator_data;                    \
 624         int __data;                                                     \
 625         deadline_var_store(&__data, (page));                            \
 626         if (__data < (MIN))                                             \
 627                 __data = (MIN);                                         \
 628         else if (__data > (MAX))                                        \
 629                 __data = (MAX);                                         \
 630         if (__CONV)                                                     \
 631                 *(__PTR) = msecs_to_jiffies(__data);                    \
 632         else                                                            \
 633                 *(__PTR) = __data;                                      \
 634         return count;                                                   \
 635 }
 636 STORE_FUNCTION(deadline_read_expire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1);
 637 STORE_FUNCTION(deadline_write_expire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1);
 638 STORE_FUNCTION(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0);
 639 STORE_FUNCTION(deadline_front_merges_store, &dd->front_merges, 0, 1, 0);
 640 STORE_FUNCTION(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX, 0);
 641 #undef STORE_FUNCTION
 642 
 643 #define DD_ATTR(name) \
 644         __ATTR(name, 0644, deadline_##name##_show, deadline_##name##_store)
 645 
 646 static struct elv_fs_entry deadline_attrs[] = {
 647         DD_ATTR(read_expire),
 648         DD_ATTR(write_expire),
 649         DD_ATTR(writes_starved),
 650         DD_ATTR(front_merges),
 651         DD_ATTR(fifo_batch),
 652         __ATTR_NULL
 653 };
 654 
 655 #ifdef CONFIG_BLK_DEBUG_FS
 656 #define DEADLINE_DEBUGFS_DDIR_ATTRS(ddir, name)                         \
 657 static void *deadline_##name##_fifo_start(struct seq_file *m,           \
 658                                           loff_t *pos)                  \
 659         __acquires(&dd->lock)                                           \
 660 {                                                                       \
 661         struct request_queue *q = m->private;                           \
 662         struct deadline_data *dd = q->elevator->elevator_data;          \
 663                                                                         \
 664         spin_lock(&dd->lock);                                           \
 665         return seq_list_start(&dd->fifo_list[ddir], *pos);              \
 666 }                                                                       \
 667                                                                         \
 668 static void *deadline_##name##_fifo_next(struct seq_file *m, void *v,   \
 669                                          loff_t *pos)                   \
 670 {                                                                       \
 671         struct request_queue *q = m->private;                           \
 672         struct deadline_data *dd = q->elevator->elevator_data;          \
 673                                                                         \
 674         return seq_list_next(v, &dd->fifo_list[ddir], pos);             \
 675 }                                                                       \
 676                                                                         \
 677 static void deadline_##name##_fifo_stop(struct seq_file *m, void *v)    \
 678         __releases(&dd->lock)                                           \
 679 {                                                                       \
 680         struct request_queue *q = m->private;                           \
 681         struct deadline_data *dd = q->elevator->elevator_data;          \
 682                                                                         \
 683         spin_unlock(&dd->lock);                                         \
 684 }                                                                       \
 685                                                                         \
 686 static const struct seq_operations deadline_##name##_fifo_seq_ops = {   \
 687         .start  = deadline_##name##_fifo_start,                         \
 688         .next   = deadline_##name##_fifo_next,                          \
 689         .stop   = deadline_##name##_fifo_stop,                          \
 690         .show   = blk_mq_debugfs_rq_show,                               \
 691 };                                                                      \
 692                                                                         \
 693 static int deadline_##name##_next_rq_show(void *data,                   \
 694                                           struct seq_file *m)           \
 695 {                                                                       \
 696         struct request_queue *q = data;                                 \
 697         struct deadline_data *dd = q->elevator->elevator_data;          \
 698         struct request *rq = dd->next_rq[ddir];                         \
 699                                                                         \
 700         if (rq)                                                         \
 701                 __blk_mq_debugfs_rq_show(m, rq);                        \
 702         return 0;                                                       \
 703 }
 704 DEADLINE_DEBUGFS_DDIR_ATTRS(READ, read)
 705 DEADLINE_DEBUGFS_DDIR_ATTRS(WRITE, write)
 706 #undef DEADLINE_DEBUGFS_DDIR_ATTRS
 707 
 708 static int deadline_batching_show(void *data, struct seq_file *m)
 709 {
 710         struct request_queue *q = data;
 711         struct deadline_data *dd = q->elevator->elevator_data;
 712 
 713         seq_printf(m, "%u\n", dd->batching);
 714         return 0;
 715 }
 716 
 717 static int deadline_starved_show(void *data, struct seq_file *m)
 718 {
 719         struct request_queue *q = data;
 720         struct deadline_data *dd = q->elevator->elevator_data;
 721 
 722         seq_printf(m, "%u\n", dd->starved);
 723         return 0;
 724 }
 725 
 726 static void *deadline_dispatch_start(struct seq_file *m, loff_t *pos)
 727         __acquires(&dd->lock)
 728 {
 729         struct request_queue *q = m->private;
 730         struct deadline_data *dd = q->elevator->elevator_data;
 731 
 732         spin_lock(&dd->lock);
 733         return seq_list_start(&dd->dispatch, *pos);
 734 }
 735 
 736 static void *deadline_dispatch_next(struct seq_file *m, void *v, loff_t *pos)
 737 {
 738         struct request_queue *q = m->private;
 739         struct deadline_data *dd = q->elevator->elevator_data;
 740 
 741         return seq_list_next(v, &dd->dispatch, pos);
 742 }
 743 
 744 static void deadline_dispatch_stop(struct seq_file *m, void *v)
 745         __releases(&dd->lock)
 746 {
 747         struct request_queue *q = m->private;
 748         struct deadline_data *dd = q->elevator->elevator_data;
 749 
 750         spin_unlock(&dd->lock);
 751 }
 752 
 753 static const struct seq_operations deadline_dispatch_seq_ops = {
 754         .start  = deadline_dispatch_start,
 755         .next   = deadline_dispatch_next,
 756         .stop   = deadline_dispatch_stop,
 757         .show   = blk_mq_debugfs_rq_show,
 758 };
 759 
 760 #define DEADLINE_QUEUE_DDIR_ATTRS(name)                                         \
 761         {#name "_fifo_list", 0400, .seq_ops = &deadline_##name##_fifo_seq_ops}, \
 762         {#name "_next_rq", 0400, deadline_##name##_next_rq_show}
 763 static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = {
 764         DEADLINE_QUEUE_DDIR_ATTRS(read),
 765         DEADLINE_QUEUE_DDIR_ATTRS(write),
 766         {"batching", 0400, deadline_batching_show},
 767         {"starved", 0400, deadline_starved_show},
 768         {"dispatch", 0400, .seq_ops = &deadline_dispatch_seq_ops},
 769         {},
 770 };
 771 #undef DEADLINE_QUEUE_DDIR_ATTRS
 772 #endif
 773 
 774 static struct elevator_type mq_deadline = {
 775         .ops = {
 776                 .insert_requests        = dd_insert_requests,
 777                 .dispatch_request       = dd_dispatch_request,
 778                 .prepare_request        = dd_prepare_request,
 779                 .finish_request         = dd_finish_request,
 780                 .next_request           = elv_rb_latter_request,
 781                 .former_request         = elv_rb_former_request,
 782                 .bio_merge              = dd_bio_merge,
 783                 .request_merge          = dd_request_merge,
 784                 .requests_merged        = dd_merged_requests,
 785                 .request_merged         = dd_request_merged,
 786                 .has_work               = dd_has_work,
 787                 .init_sched             = dd_init_queue,
 788                 .exit_sched             = dd_exit_queue,
 789         },
 790 
 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_features = ELEVATOR_F_ZBD_SEQ_WRITE,
 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");
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root/block/mq-deadline.c

DEFINITIONS
