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