block/deadline-iosched.c

   1 /*
   2  *  Deadline i/o scheduler.
   3  *
   4  *  Copyright (C) 2002 Jens Axboe <axboe@suse.de>
   5  */
   6 #include <linux/kernel.h>
   7 #include <linux/fs.h>
   8 #include <linux/blkdev.h>
   9 #include <linux/elevator.h>
  10 #include <linux/bio.h>
  11 #include <linux/config.h>
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <linux/init.h>
  15 #include <linux/compiler.h>
  16 #include <linux/hash.h>
  17 #include <linux/rbtree.h>
  18
  19 /*
  20  * See Documentation/block/deadline-iosched.txt
  21  */
  22 static const int read_expire = HZ / 2;  /* max time before a read is submitted. */
  23 static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
  24 static const int writes_starved = 2;    /* max times reads can starve a write */
  25 static const int fifo_batch = 16;       /* # of sequential requests treated as one
  26                                      by the above parameters. For throughput. */
  27
  28 static const int deadline_hash_shift = 5;
  29 #define DL_HASH_BLOCK(sec)      ((sec) >> 3)
  30 #define DL_HASH_FN(sec)         (hash_long(DL_HASH_BLOCK((sec)), deadline_hash_shift))
  31 #define DL_HASH_ENTRIES         (1 << deadline_hash_shift)
  32 #define rq_hash_key(rq)         ((rq)->sector + (rq)->nr_sectors)
  33 #define ON_HASH(drq)            (!hlist_unhashed(&(drq)->hash))
  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 deadline_rq *next_drq[2];
  50         struct hlist_head *hash;        /* request hash */
  51         unsigned int batching;          /* number of sequential requests made */
  52         sector_t last_sector;           /* head position */
  53         unsigned int starved;           /* times reads have starved writes */
  54
  55         /*
  56          * settings that change how the i/o scheduler behaves
  57          */
  58         int fifo_expire[2];
  59         int fifo_batch;
  60         int writes_starved;
  61         int front_merges;
  62
  63         mempool_t *drq_pool;
  64 };
  65
  66 /*
  67  * pre-request data.
  68  */
  69 struct deadline_rq {
  70         /*
  71          * rbtree index, key is the starting offset
  72          */
  73         struct rb_node rb_node;
  74         sector_t rb_key;
  75
  76         struct request *request;
  77
  78         /*
  79          * request hash, key is the ending offset (for back merge lookup)
  80          */
  81         struct hlist_node hash;
  82
  83         /*
  84          * expire fifo
  85          */
  86         struct list_head fifo;
  87         unsigned long expires;
  88 };
  89
  90 static void deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq);
  91
  92 static kmem_cache_t *drq_pool;
  93
  94 #define RQ_DATA(rq)     ((struct deadline_rq *) (rq)->elevator_private)
  95
  96 /*
  97  * the back merge hash support functions
  98  */
  99 static inline void __deadline_del_drq_hash(struct deadline_rq *drq)
 100 {
 101         hlist_del_init(&drq->hash);
 102 }
 103
 104 static inline void deadline_del_drq_hash(struct deadline_rq *drq)
 105 {
 106         if (ON_HASH(drq))
 107                 __deadline_del_drq_hash(drq);
 108 }
 109
 110 static inline void
 111 deadline_add_drq_hash(struct deadline_data *dd, struct deadline_rq *drq)
 112 {
 113         struct request *rq = drq->request;
 114
 115         BUG_ON(ON_HASH(drq));
 116
 117         hlist_add_head(&drq->hash, &dd->hash[DL_HASH_FN(rq_hash_key(rq))]);
 118 }
 119
 120 /*
 121  * move hot entry to front of chain
 122  */
 123 static inline void
 124 deadline_hot_drq_hash(struct deadline_data *dd, struct deadline_rq *drq)
 125 {
 126         struct request *rq = drq->request;
 127         struct hlist_head *head = &dd->hash[DL_HASH_FN(rq_hash_key(rq))];
 128
 129         if (ON_HASH(drq) && &drq->hash != head->first) {
 130                 hlist_del(&drq->hash);
 131                 hlist_add_head(&drq->hash, head);
 132         }
 133 }
 134
 135 static struct request *
 136 deadline_find_drq_hash(struct deadline_data *dd, sector_t offset)
 137 {
 138         struct hlist_head *hash_list = &dd->hash[DL_HASH_FN(offset)];
 139         struct hlist_node *entry, *next;
 140         struct deadline_rq *drq;
 141
 142         hlist_for_each_entry_safe(drq, entry, next, hash_list, hash) {
 143                 struct request *__rq = drq->request;
 144
 145                 BUG_ON(!ON_HASH(drq));
 146
 147                 if (!rq_mergeable(__rq)) {
 148                         __deadline_del_drq_hash(drq);
 149                         continue;
 150                 }
 151
 152                 if (rq_hash_key(__rq) == offset)
 153                         return __rq;
 154         }
 155
 156         return NULL;
 157 }
 158
 159 /*
 160  * rb tree support functions
 161  */
 162 #define rb_entry_drq(node)      rb_entry((node), struct deadline_rq, rb_node)
 163 #define DRQ_RB_ROOT(dd, drq)    (&(dd)->sort_list[rq_data_dir((drq)->request)])
 164 #define rq_rb_key(rq)           (rq)->sector
 165
 166 static struct deadline_rq *
 167 __deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
 168 {
 169         struct rb_node **p = &DRQ_RB_ROOT(dd, drq)->rb_node;
 170         struct rb_node *parent = NULL;
 171         struct deadline_rq *__drq;
 172
 173         while (*p) {
 174                 parent = *p;
 175                 __drq = rb_entry_drq(parent);
 176
 177                 if (drq->rb_key < __drq->rb_key)
 178                         p = &(*p)->rb_left;
 179                 else if (drq->rb_key > __drq->rb_key)
 180                         p = &(*p)->rb_right;
 181                 else
 182                         return __drq;
 183         }
 184
 185         rb_link_node(&drq->rb_node, parent, p);
 186         return NULL;
 187 }
 188
 189 static void
 190 deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
 191 {
 192         struct deadline_rq *__alias;
 193
 194         drq->rb_key = rq_rb_key(drq->request);
 195
 196 retry:
 197         __alias = __deadline_add_drq_rb(dd, drq);
 198         if (!__alias) {
 199                 rb_insert_color(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
 200                 return;
 201         }
 202
 203         deadline_move_request(dd, __alias);
 204         goto retry;
 205 }
 206
 207 static inline void
 208 deadline_del_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
 209 {
 210         const int data_dir = rq_data_dir(drq->request);
 211
 212         if (dd->next_drq[data_dir] == drq) {
 213                 struct rb_node *rbnext = rb_next(&drq->rb_node);
 214
 215                 dd->next_drq[data_dir] = NULL;
 216                 if (rbnext)
 217                         dd->next_drq[data_dir] = rb_entry_drq(rbnext);
 218         }
 219
 220         BUG_ON(!RB_EMPTY_NODE(&drq->rb_node));
 221         rb_erase(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
 222         RB_CLEAR_NODE(&drq->rb_node);
 223 }
 224
 225 static struct request *
 226 deadline_find_drq_rb(struct deadline_data *dd, sector_t sector, int data_dir)
 227 {
 228         struct rb_node *n = dd->sort_list[data_dir].rb_node;
 229         struct deadline_rq *drq;
 230
 231         while (n) {
 232                 drq = rb_entry_drq(n);
 233
 234                 if (sector < drq->rb_key)
 235                         n = n->rb_left;
 236                 else if (sector > drq->rb_key)
 237                         n = n->rb_right;
 238                 else
 239                         return drq->request;
 240         }
 241
 242         return NULL;
 243 }
 244
 245 /*
 246  * deadline_find_first_drq finds the first (lowest sector numbered) request
 247  * for the specified data_dir. Used to sweep back to the start of the disk
 248  * (1-way elevator) after we process the last (highest sector) request.
 249  */
 250 static struct deadline_rq *
 251 deadline_find_first_drq(struct deadline_data *dd, int data_dir)
 252 {
 253         struct rb_node *n = dd->sort_list[data_dir].rb_node;
 254
 255         for (;;) {
 256                 if (n->rb_left == NULL)
 257                         return rb_entry_drq(n);
 258
 259                 n = n->rb_left;
 260         }
 261 }
 262
 263 /*
 264  * add drq to rbtree and fifo
 265  */
 266 static void
 267 deadline_add_request(struct request_queue *q, struct request *rq)
 268 {
 269         struct deadline_data *dd = q->elevator->elevator_data;
 270         struct deadline_rq *drq = RQ_DATA(rq);
 271
 272         const int data_dir = rq_data_dir(drq->request);
 273
 274         deadline_add_drq_rb(dd, drq);
 275         /*
 276          * set expire time (only used for reads) and add to fifo list
 277          */
 278         drq->expires = jiffies + dd->fifo_expire[data_dir];
 279         list_add_tail(&drq->fifo, &dd->fifo_list[data_dir]);
 280
 281         if (rq_mergeable(rq))
 282                 deadline_add_drq_hash(dd, drq);
 283 }
 284
 285 /*
 286  * remove rq from rbtree, fifo, and hash
 287  */
 288 static void deadline_remove_request(request_queue_t *q, struct request *rq)
 289 {
 290         struct deadline_rq *drq = RQ_DATA(rq);
 291         struct deadline_data *dd = q->elevator->elevator_data;
 292
 293         list_del_init(&drq->fifo);
 294         deadline_del_drq_rb(dd, drq);
 295         deadline_del_drq_hash(drq);
 296 }
 297
 298 static int
 299 deadline_merge(request_queue_t *q, struct request **req, struct bio *bio)
 300 {
 301         struct deadline_data *dd = q->elevator->elevator_data;
 302         struct request *__rq;
 303         int ret;
 304
 305         /*
 306          * see if the merge hash can satisfy a back merge
 307          */
 308         __rq = deadline_find_drq_hash(dd, bio->bi_sector);
 309         if (__rq) {
 310                 BUG_ON(__rq->sector + __rq->nr_sectors != bio->bi_sector);
 311
 312                 if (elv_rq_merge_ok(__rq, bio)) {
 313                         ret = ELEVATOR_BACK_MERGE;
 314                         goto out;
 315                 }
 316         }
 317
 318         /*
 319          * check for front merge
 320          */
 321         if (dd->front_merges) {
 322                 sector_t rb_key = bio->bi_sector + bio_sectors(bio);
 323
 324                 __rq = deadline_find_drq_rb(dd, rb_key, bio_data_dir(bio));
 325                 if (__rq) {
 326                         BUG_ON(rb_key != rq_rb_key(__rq));
 327
 328                         if (elv_rq_merge_ok(__rq, bio)) {
 329                                 ret = ELEVATOR_FRONT_MERGE;
 330                                 goto out;
 331                         }
 332                 }
 333         }
 334
 335         return ELEVATOR_NO_MERGE;
 336 out:
 337         if (ret)
 338                 deadline_hot_drq_hash(dd, RQ_DATA(__rq));
 339         *req = __rq;
 340         return ret;
 341 }
 342
 343 static void deadline_merged_request(request_queue_t *q, struct request *req)
 344 {
 345         struct deadline_data *dd = q->elevator->elevator_data;
 346         struct deadline_rq *drq = RQ_DATA(req);
 347
 348         /*
 349          * hash always needs to be repositioned, key is end sector
 350          */
 351         deadline_del_drq_hash(drq);
 352         deadline_add_drq_hash(dd, drq);
 353
 354         /*
 355          * if the merge was a front merge, we need to reposition request
 356          */
 357         if (rq_rb_key(req) != drq->rb_key) {
 358                 deadline_del_drq_rb(dd, drq);
 359                 deadline_add_drq_rb(dd, drq);
 360         }
 361 }
 362
 363 static void
 364 deadline_merged_requests(request_queue_t *q, struct request *req,
 365                          struct request *next)
 366 {
 367         struct deadline_data *dd = q->elevator->elevator_data;
 368         struct deadline_rq *drq = RQ_DATA(req);
 369         struct deadline_rq *dnext = RQ_DATA(next);
 370
 371         BUG_ON(!drq);
 372         BUG_ON(!dnext);
 373
 374         /*
 375          * reposition drq (this is the merged request) in hash, and in rbtree
 376          * in case of a front merge
 377          */
 378         deadline_del_drq_hash(drq);
 379         deadline_add_drq_hash(dd, drq);
 380
 381         if (rq_rb_key(req) != drq->rb_key) {
 382                 deadline_del_drq_rb(dd, drq);
 383                 deadline_add_drq_rb(dd, drq);
 384         }
 385
 386         /*
 387          * if dnext expires before drq, assign its expire time to drq
 388          * and move into dnext position (dnext will be deleted) in fifo
 389          */
 390         if (!list_empty(&drq->fifo) && !list_empty(&dnext->fifo)) {
 391                 if (time_before(dnext->expires, drq->expires)) {
 392                         list_move(&drq->fifo, &dnext->fifo);
 393                         drq->expires = dnext->expires;
 394                 }
 395         }
 396
 397         /*
 398          * kill knowledge of next, this one is a goner
 399          */
 400         deadline_remove_request(q, next);
 401 }
 402
 403 /*
 404  * move request from sort list to dispatch queue.
 405  */
 406 static inline void
 407 deadline_move_to_dispatch(struct deadline_data *dd, struct deadline_rq *drq)
 408 {
 409         request_queue_t *q = drq->request->q;
 410
 411         deadline_remove_request(q, drq->request);
 412         elv_dispatch_add_tail(q, drq->request);
 413 }
 414
 415 /*
 416  * move an entry to dispatch queue
 417  */
 418 static void
 419 deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq)
 420 {
 421         const int data_dir = rq_data_dir(drq->request);
 422         struct rb_node *rbnext = rb_next(&drq->rb_node);
 423
 424         dd->next_drq[READ] = NULL;
 425         dd->next_drq[WRITE] = NULL;
 426
 427         if (rbnext)
 428                 dd->next_drq[data_dir] = rb_entry_drq(rbnext);
 429
 430         dd->last_sector = drq->request->sector + drq->request->nr_sectors;
 431
 432         /*
 433          * take it off the sort and fifo list, move
 434          * to dispatch queue
 435          */
 436         deadline_move_to_dispatch(dd, drq);
 437 }
 438
 439 #define list_entry_fifo(ptr)    list_entry((ptr), struct deadline_rq, fifo)
 440
 441 /*
 442  * deadline_check_fifo returns 0 if there are no expired reads on the fifo,
 443  * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
 444  */
 445 static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
 446 {
 447         struct deadline_rq *drq = list_entry_fifo(dd->fifo_list[ddir].next);
 448
 449         /*
 450          * drq is expired!
 451          */
 452         if (time_after(jiffies, drq->expires))
 453                 return 1;
 454
 455         return 0;
 456 }
 457
 458 /*
 459  * deadline_dispatch_requests selects the best request according to
 460  * read/write expire, fifo_batch, etc
 461  */
 462 static int deadline_dispatch_requests(request_queue_t *q, int force)
 463 {
 464         struct deadline_data *dd = q->elevator->elevator_data;
 465         const int reads = !list_empty(&dd->fifo_list[READ]);
 466         const int writes = !list_empty(&dd->fifo_list[WRITE]);
 467         struct deadline_rq *drq;
 468         int data_dir;
 469
 470         /*
 471          * batches are currently reads XOR writes
 472          */
 473         if (dd->next_drq[WRITE])
 474                 drq = dd->next_drq[WRITE];
 475         else
 476                 drq = dd->next_drq[READ];
 477
 478         if (drq) {
 479                 /* we have a "next request" */
 480
 481                 if (dd->last_sector != drq->request->sector)
 482                         /* end the batch on a non sequential request */
 483                         dd->batching += dd->fifo_batch;
 484
 485                 if (dd->batching < dd->fifo_batch)
 486                         /* we are still entitled to batch */
 487                         goto dispatch_request;
 488         }
 489
 490         /*
 491          * at this point we are not running a batch. select the appropriate
 492          * data direction (read / write)
 493          */
 494
 495         if (reads) {
 496                 BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[READ]));
 497
 498                 if (writes && (dd->starved++ >= dd->writes_starved))
 499                         goto dispatch_writes;
 500
 501                 data_dir = READ;
 502
 503                 goto dispatch_find_request;
 504         }
 505
 506         /*
 507          * there are either no reads or writes have been starved
 508          */
 509
 510         if (writes) {
 511 dispatch_writes:
 512                 BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[WRITE]));
 513
 514                 dd->starved = 0;
 515
 516                 data_dir = WRITE;
 517
 518                 goto dispatch_find_request;
 519         }
 520
 521         return 0;
 522
 523 dispatch_find_request:
 524         /*
 525          * we are not running a batch, find best request for selected data_dir
 526          */
 527         if (deadline_check_fifo(dd, data_dir)) {
 528                 /* An expired request exists - satisfy it */
 529                 dd->batching = 0;
 530                 drq = list_entry_fifo(dd->fifo_list[data_dir].next);
 531
 532         } else if (dd->next_drq[data_dir]) {
 533                 /*
 534                  * The last req was the same dir and we have a next request in
 535                  * sort order. No expired requests so continue on from here.
 536                  */
 537                 drq = dd->next_drq[data_dir];
 538         } else {
 539                 /*
 540                  * The last req was the other direction or we have run out of
 541                  * higher-sectored requests. Go back to the lowest sectored
 542                  * request (1 way elevator) and start a new batch.
 543                  */
 544                 dd->batching = 0;
 545                 drq = deadline_find_first_drq(dd, data_dir);
 546         }
 547
 548 dispatch_request:
 549         /*
 550          * drq is the selected appropriate request.
 551          */
 552         dd->batching++;
 553         deadline_move_request(dd, drq);
 554
 555         return 1;
 556 }
 557
 558 static int deadline_queue_empty(request_queue_t *q)
 559 {
 560         struct deadline_data *dd = q->elevator->elevator_data;
 561
 562         return list_empty(&dd->fifo_list[WRITE])
 563                 && list_empty(&dd->fifo_list[READ]);
 564 }
 565
 566 static struct request *
 567 deadline_former_request(request_queue_t *q, struct request *rq)
 568 {
 569         struct deadline_rq *drq = RQ_DATA(rq);
 570         struct rb_node *rbprev = rb_prev(&drq->rb_node);
 571
 572         if (rbprev)
 573                 return rb_entry_drq(rbprev)->request;
 574
 575         return NULL;
 576 }
 577
 578 static struct request *
 579 deadline_latter_request(request_queue_t *q, struct request *rq)
 580 {
 581         struct deadline_rq *drq = RQ_DATA(rq);
 582         struct rb_node *rbnext = rb_next(&drq->rb_node);
 583
 584         if (rbnext)
 585                 return rb_entry_drq(rbnext)->request;
 586
 587         return NULL;
 588 }
 589
 590 static void deadline_exit_queue(elevator_t *e)
 591 {
 592         struct deadline_data *dd = e->elevator_data;
 593
 594         BUG_ON(!list_empty(&dd->fifo_list[READ]));
 595         BUG_ON(!list_empty(&dd->fifo_list[WRITE]));
 596
 597         mempool_destroy(dd->drq_pool);
 598         kfree(dd->hash);
 599         kfree(dd);
 600 }
 601
 602 /*
 603  * initialize elevator private data (deadline_data), and alloc a drq for
 604  * each request on the free lists
 605  */
 606 static void *deadline_init_queue(request_queue_t *q, elevator_t *e)
 607 {
 608         struct deadline_data *dd;
 609         int i;
 610
 611         if (!drq_pool)
 612                 return NULL;
 613
 614         dd = kmalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
 615         if (!dd)
 616                 return NULL;
 617         memset(dd, 0, sizeof(*dd));
 618
 619         dd->hash = kmalloc_node(sizeof(struct hlist_head)*DL_HASH_ENTRIES,
 620                                 GFP_KERNEL, q->node);
 621         if (!dd->hash) {
 622                 kfree(dd);
 623                 return NULL;
 624         }
 625
 626         dd->drq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
 627                                         mempool_free_slab, drq_pool, q->node);
 628         if (!dd->drq_pool) {
 629                 kfree(dd->hash);
 630                 kfree(dd);
 631                 return NULL;
 632         }
 633
 634         for (i = 0; i < DL_HASH_ENTRIES; i++)
 635                 INIT_HLIST_HEAD(&dd->hash[i]);
 636
 637         INIT_LIST_HEAD(&dd->fifo_list[READ]);
 638         INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
 639         dd->sort_list[READ] = RB_ROOT;
 640         dd->sort_list[WRITE] = RB_ROOT;
 641         dd->fifo_expire[READ] = read_expire;
 642         dd->fifo_expire[WRITE] = write_expire;
 643         dd->writes_starved = writes_starved;
 644         dd->front_merges = 1;
 645         dd->fifo_batch = fifo_batch;
 646         return dd;
 647 }
 648
 649 static void deadline_put_request(request_queue_t *q, struct request *rq)
 650 {
 651         struct deadline_data *dd = q->elevator->elevator_data;
 652         struct deadline_rq *drq = RQ_DATA(rq);
 653
 654         mempool_free(drq, dd->drq_pool);
 655         rq->elevator_private = NULL;
 656 }
 657
 658 static int
 659 deadline_set_request(request_queue_t *q, struct request *rq, struct bio *bio,
 660                      gfp_t gfp_mask)
 661 {
 662         struct deadline_data *dd = q->elevator->elevator_data;
 663         struct deadline_rq *drq;
 664
 665         drq = mempool_alloc(dd->drq_pool, gfp_mask);
 666         if (drq) {
 667                 memset(drq, 0, sizeof(*drq));
 668                 RB_CLEAR_NODE(&drq->rb_node);
 669                 drq->request = rq;
 670
 671                 INIT_HLIST_NODE(&drq->hash);
 672
 673                 INIT_LIST_HEAD(&drq->fifo);
 674
 675                 rq->elevator_private = drq;
 676                 return 0;
 677         }
 678
 679         return 1;
 680 }
 681
 682 /*
 683  * sysfs parts below
 684  */
 685
 686 static ssize_t
 687 deadline_var_show(int var, char *page)
 688 {
 689         return sprintf(page, "%d\n", var);
 690 }
 691
 692 static ssize_t
 693 deadline_var_store(int *var, const char *page, size_t count)
 694 {
 695         char *p = (char *) page;
 696
 697         *var = simple_strtol(p, &p, 10);
 698         return count;
 699 }
 700
 701 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV)                            \
 702 static ssize_t __FUNC(elevator_t *e, char *page)                        \
 703 {                                                                       \
 704         struct deadline_data *dd = e->elevator_data;                    \
 705         int __data = __VAR;                                             \
 706         if (__CONV)                                                     \
 707                 __data = jiffies_to_msecs(__data);                      \
 708         return deadline_var_show(__data, (page));                       \
 709 }
 710 SHOW_FUNCTION(deadline_read_expire_show, dd->fifo_expire[READ], 1);
 711 SHOW_FUNCTION(deadline_write_expire_show, dd->fifo_expire[WRITE], 1);
 712 SHOW_FUNCTION(deadline_writes_starved_show, dd->writes_starved, 0);
 713 SHOW_FUNCTION(deadline_front_merges_show, dd->front_merges, 0);
 714 SHOW_FUNCTION(deadline_fifo_batch_show, dd->fifo_batch, 0);
 715 #undef SHOW_FUNCTION
 716
 717 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)                 \
 718 static ssize_t __FUNC(elevator_t *e, const char *page, size_t count)    \
 719 {                                                                       \
 720         struct deadline_data *dd = e->elevator_data;                    \
 721         int __data;                                                     \
 722         int ret = deadline_var_store(&__data, (page), count);           \
 723         if (__data < (MIN))                                             \
 724                 __data = (MIN);                                         \
 725         else if (__data > (MAX))                                        \
 726                 __data = (MAX);                                         \
 727         if (__CONV)                                                     \
 728                 *(__PTR) = msecs_to_jiffies(__data);                    \
 729         else                                                            \
 730                 *(__PTR) = __data;                                      \
 731         return ret;                                                     \
 732 }
 733 STORE_FUNCTION(deadline_read_expire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1);
 734 STORE_FUNCTION(deadline_write_expire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1);
 735 STORE_FUNCTION(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0);
 736 STORE_FUNCTION(deadline_front_merges_store, &dd->front_merges, 0, 1, 0);
 737 STORE_FUNCTION(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX, 0);
 738 #undef STORE_FUNCTION
 739
 740 #define DD_ATTR(name) \
 741         __ATTR(name, S_IRUGO|S_IWUSR, deadline_##name##_show, \
 742                                       deadline_##name##_store)
 743
 744 static struct elv_fs_entry deadline_attrs[] = {
 745         DD_ATTR(read_expire),
 746         DD_ATTR(write_expire),
 747         DD_ATTR(writes_starved),
 748         DD_ATTR(front_merges),
 749         DD_ATTR(fifo_batch),
 750         __ATTR_NULL
 751 };
 752
 753 static struct elevator_type iosched_deadline = {
 754         .ops = {
 755                 .elevator_merge_fn =            deadline_merge,
 756                 .elevator_merged_fn =           deadline_merged_request,
 757                 .elevator_merge_req_fn =        deadline_merged_requests,
 758                 .elevator_dispatch_fn =         deadline_dispatch_requests,
 759                 .elevator_add_req_fn =          deadline_add_request,
 760                 .elevator_queue_empty_fn =      deadline_queue_empty,
 761                 .elevator_former_req_fn =       deadline_former_request,
 762                 .elevator_latter_req_fn =       deadline_latter_request,
 763                 .elevator_set_req_fn =          deadline_set_request,
 764                 .elevator_put_req_fn =          deadline_put_request,
 765                 .elevator_init_fn =             deadline_init_queue,
 766                 .elevator_exit_fn =             deadline_exit_queue,
 767         },
 768
 769         .elevator_attrs = deadline_attrs,
 770         .elevator_name = "deadline",
 771         .elevator_owner = THIS_MODULE,
 772 };
 773
 774 static int __init deadline_init(void)
 775 {
 776         int ret;
 777
 778         drq_pool = kmem_cache_create("deadline_drq", sizeof(struct deadline_rq),
 779                                      0, 0, NULL, NULL);
 780
 781         if (!drq_pool)
 782                 return -ENOMEM;
 783
 784         ret = elv_register(&iosched_deadline);
 785         if (ret)
 786                 kmem_cache_destroy(drq_pool);
 787
 788         return ret;
 789 }
 790
 791 static void __exit deadline_exit(void)
 792 {
 793         kmem_cache_destroy(drq_pool);
 794         elv_unregister(&iosched_deadline);
 795 }
 796
 797 module_init(deadline_init);
 798 module_exit(deadline_exit);
 799
 800 MODULE_AUTHOR("Jens Axboe");
 801 MODULE_LICENSE("GPL");
 802 MODULE_DESCRIPTION("deadline IO scheduler");