git.oblomov.eu Git - linux-2.6/blob - 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/module.h>
  12 #include <linux/slab.h>
  13 #include <linux/init.h>
  14 #include <linux/compiler.h>
  15 #include <linux/hash.h>
  16 #include <linux/rbtree.h>
  17
  18 /*
  19  * See Documentation/block/deadline-iosched.txt
  20  */
  21 static const int read_expire = HZ / 2;  /* max time before a read is submitted. */
  22 static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
  23 static const int writes_starved = 2;    /* max times reads can starve a write */
  24 static const int fifo_batch = 16;       /* # of sequential requests treated as one
  25                                      by the above parameters. For throughput. */
  26
  27 static const int deadline_hash_shift = 5;
  28 #define DL_HASH_BLOCK(sec)      ((sec) >> 3)
  29 #define DL_HASH_FN(sec)         (hash_long(DL_HASH_BLOCK((sec)), deadline_hash_shift))
  30 #define DL_HASH_ENTRIES         (1 << deadline_hash_shift)
  31 #define rq_hash_key(rq)         ((rq)->sector + (rq)->nr_sectors)
  32 #define ON_HASH(drq)            (!hlist_unhashed(&(drq)->hash))
  33
  34 struct deadline_data {
  35         /*
  36          * run time data
  37          */
  38
  39         /*
  40          * requests (deadline_rq s) are present on both sort_list and fifo_list
  41          */
  42         struct rb_root sort_list[2];
  43         struct list_head fifo_list[2];
  44
  45         /*
  46          * next in sort order. read, write or both are NULL
  47          */
  48         struct deadline_rq *next_drq[2];
  49         struct hlist_head *hash;        /* request hash */
  50         unsigned int batching;          /* number of sequential requests made */
  51         sector_t last_sector;           /* head position */
  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         mempool_t *drq_pool;
  63 };
  64
  65 /*
  66  * pre-request data.
  67  */
  68 struct deadline_rq {
  69         /*
  70          * rbtree index, key is the starting offset
  71          */
  72         struct rb_node rb_node;
  73         sector_t rb_key;
  74
  75         struct request *request;
  76
  77         /*
  78          * request hash, key is the ending offset (for back merge lookup)
  79          */
  80         struct hlist_node hash;
  81
  82         /*
  83          * expire fifo
  84          */
  85         struct list_head fifo;
  86         unsigned long expires;
  87 };
  88
  89 static void deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq);
  90
  91 static kmem_cache_t *drq_pool;
  92
  93 #define RQ_DATA(rq)     ((struct deadline_rq *) (rq)->elevator_private)
  94
  95 /*
  96  * the back merge hash support functions
  97  */
  98 static inline void __deadline_del_drq_hash(struct deadline_rq *drq)
  99 {
 100         hlist_del_init(&drq->hash);
 101 }
 102
 103 static inline void deadline_del_drq_hash(struct deadline_rq *drq)
 104 {
 105         if (ON_HASH(drq))
 106                 __deadline_del_drq_hash(drq);
 107 }
 108
 109 static inline void
 110 deadline_add_drq_hash(struct deadline_data *dd, struct deadline_rq *drq)
 111 {
 112         struct request *rq = drq->request;
 113
 114         BUG_ON(ON_HASH(drq));
 115
 116         hlist_add_head(&drq->hash, &dd->hash[DL_HASH_FN(rq_hash_key(rq))]);
 117 }
 118
 119 /*
 120  * move hot entry to front of chain
 121  */
 122 static inline void
 123 deadline_hot_drq_hash(struct deadline_data *dd, struct deadline_rq *drq)
 124 {
 125         struct request *rq = drq->request;
 126         struct hlist_head *head = &dd->hash[DL_HASH_FN(rq_hash_key(rq))];
 127
 128         if (ON_HASH(drq) && &drq->hash != head->first) {
 129                 hlist_del(&drq->hash);
 130                 hlist_add_head(&drq->hash, head);
 131         }
 132 }
 133
 134 static struct request *
 135 deadline_find_drq_hash(struct deadline_data *dd, sector_t offset)
 136 {
 137         struct hlist_head *hash_list = &dd->hash[DL_HASH_FN(offset)];
 138         struct hlist_node *entry, *next;
 139         struct deadline_rq *drq;
 140
 141         hlist_for_each_entry_safe(drq, entry, next, hash_list, hash) {
 142                 struct request *__rq = drq->request;
 143
 144                 BUG_ON(!ON_HASH(drq));
 145
 146                 if (!rq_mergeable(__rq)) {
 147                         __deadline_del_drq_hash(drq);
 148                         continue;
 149                 }
 150
 151                 if (rq_hash_key(__rq) == offset)
 152                         return __rq;
 153         }
 154
 155         return NULL;
 156 }
 157
 158 /*
 159  * rb tree support functions
 160  */
 161 #define rb_entry_drq(node)      rb_entry((node), struct deadline_rq, rb_node)
 162 #define DRQ_RB_ROOT(dd, drq)    (&(dd)->sort_list[rq_data_dir((drq)->request)])
 163 #define rq_rb_key(rq)           (rq)->sector
 164
 165 static struct deadline_rq *
 166 __deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
 167 {
 168         struct rb_node **p = &DRQ_RB_ROOT(dd, drq)->rb_node;
 169         struct rb_node *parent = NULL;
 170         struct deadline_rq *__drq;
 171
 172         while (*p) {
 173                 parent = *p;
 174                 __drq = rb_entry_drq(parent);
 175
 176                 if (drq->rb_key < __drq->rb_key)
 177                         p = &(*p)->rb_left;
 178                 else if (drq->rb_key > __drq->rb_key)
 179                         p = &(*p)->rb_right;
 180                 else
 181                         return __drq;
 182         }
 183
 184         rb_link_node(&drq->rb_node, parent, p);
 185         return NULL;
 186 }
 187
 188 static void
 189 deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
 190 {
 191         struct deadline_rq *__alias;
 192
 193         drq->rb_key = rq_rb_key(drq->request);
 194
 195 retry:
 196         __alias = __deadline_add_drq_rb(dd, drq);
 197         if (!__alias) {
 198                 rb_insert_color(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
 199                 return;
 200         }
 201
 202         deadline_move_request(dd, __alias);
 203         goto retry;
 204 }
 205
 206 static inline void
 207 deadline_del_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
 208 {
 209         const int data_dir = rq_data_dir(drq->request);
 210
 211         if (dd->next_drq[data_dir] == drq) {
 212                 struct rb_node *rbnext = rb_next(&drq->rb_node);
 213
 214                 dd->next_drq[data_dir] = NULL;
 215                 if (rbnext)
 216                         dd->next_drq[data_dir] = rb_entry_drq(rbnext);
 217         }
 218
 219         BUG_ON(!RB_EMPTY_NODE(&drq->rb_node));
 220         rb_erase(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
 221         RB_CLEAR_NODE(&drq->rb_node);
 222 }
 223
 224 static struct request *
 225 deadline_find_drq_rb(struct deadline_data *dd, sector_t sector, int data_dir)
 226 {
 227         struct rb_node *n = dd->sort_list[data_dir].rb_node;
 228         struct deadline_rq *drq;
 229
 230         while (n) {
 231                 drq = rb_entry_drq(n);
 232
 233                 if (sector < drq->rb_key)
 234                         n = n->rb_left;
 235                 else if (sector > drq->rb_key)
 236                         n = n->rb_right;
 237                 else
 238                         return drq->request;
 239         }
 240
 241         return NULL;
 242 }
 243
 244 /*
 245  * deadline_find_first_drq finds the first (lowest sector numbered) request
 246  * for the specified data_dir. Used to sweep back to the start of the disk
 247  * (1-way elevator) after we process the last (highest sector) request.
 248  */
 249 static struct deadline_rq *
 250 deadline_find_first_drq(struct deadline_data *dd, int data_dir)
 251 {
 252         struct rb_node *n = dd->sort_list[data_dir].rb_node;
 253
 254         for (;;) {
 255                 if (n->rb_left == NULL)
 256                         return rb_entry_drq(n);
 257
 258                 n = n->rb_left;
 259         }
 260 }
 261
 262 /*
 263  * add drq to rbtree and fifo
 264  */
 265 static void
 266 deadline_add_request(struct request_queue *q, struct request *rq)
 267 {
 268         struct deadline_data *dd = q->elevator->elevator_data;
 269         struct deadline_rq *drq = RQ_DATA(rq);
 270
 271         const int data_dir = rq_data_dir(drq->request);
 272
 273         deadline_add_drq_rb(dd, drq);
 274         /*
 275          * set expire time (only used for reads) and add to fifo list
 276          */
 277         drq->expires = jiffies + dd->fifo_expire[data_dir];
 278         list_add_tail(&drq->fifo, &dd->fifo_list[data_dir]);
 279
 280         if (rq_mergeable(rq))
 281                 deadline_add_drq_hash(dd, drq);
 282 }
 283
 284 /*
 285  * remove rq from rbtree, fifo, and hash
 286  */
 287 static void deadline_remove_request(request_queue_t *q, struct request *rq)
 288 {
 289         struct deadline_rq *drq = RQ_DATA(rq);
 290         struct deadline_data *dd = q->elevator->elevator_data;
 291
 292         list_del_init(&drq->fifo);
 293         deadline_del_drq_rb(dd, drq);
 294         deadline_del_drq_hash(drq);
 295 }
 296
 297 static int
 298 deadline_merge(request_queue_t *q, struct request **req, struct bio *bio)
 299 {
 300         struct deadline_data *dd = q->elevator->elevator_data;
 301         struct request *__rq;
 302         int ret;
 303
 304         /*
 305          * see if the merge hash can satisfy a back merge
 306          */
 307         __rq = deadline_find_drq_hash(dd, bio->bi_sector);
 308         if (__rq) {
 309                 BUG_ON(__rq->sector + __rq->nr_sectors != bio->bi_sector);
 310
 311                 if (elv_rq_merge_ok(__rq, bio)) {
 312                         ret = ELEVATOR_BACK_MERGE;
 313                         goto out;
 314                 }
 315         }
 316
 317         /*
 318          * check for front merge
 319          */
 320         if (dd->front_merges) {
 321                 sector_t rb_key = bio->bi_sector + bio_sectors(bio);
 322
 323                 __rq = deadline_find_drq_rb(dd, rb_key, bio_data_dir(bio));
 324                 if (__rq) {
 325                         BUG_ON(rb_key != rq_rb_key(__rq));
 326
 327                         if (elv_rq_merge_ok(__rq, bio)) {
 328                                 ret = ELEVATOR_FRONT_MERGE;
 329                                 goto out;
 330                         }
 331                 }
 332         }
 333
 334         return ELEVATOR_NO_MERGE;
 335 out:
 336         if (ret)
 337                 deadline_hot_drq_hash(dd, RQ_DATA(__rq));
 338         *req = __rq;
 339         return ret;
 340 }
 341
 342 static void deadline_merged_request(request_queue_t *q, struct request *req)
 343 {
 344         struct deadline_data *dd = q->elevator->elevator_data;
 345         struct deadline_rq *drq = RQ_DATA(req);
 346
 347         /*
 348          * hash always needs to be repositioned, key is end sector
 349          */
 350         deadline_del_drq_hash(drq);
 351         deadline_add_drq_hash(dd, drq);
 352
 353         /*
 354          * if the merge was a front merge, we need to reposition request
 355          */
 356         if (rq_rb_key(req) != drq->rb_key) {
 357                 deadline_del_drq_rb(dd, drq);
 358                 deadline_add_drq_rb(dd, drq);
 359         }
 360 }
 361
 362 static void
 363 deadline_merged_requests(request_queue_t *q, struct request *req,
 364                          struct request *next)
 365 {
 366         struct deadline_data *dd = q->elevator->elevator_data;
 367         struct deadline_rq *drq = RQ_DATA(req);
 368         struct deadline_rq *dnext = RQ_DATA(next);
 369
 370         BUG_ON(!drq);
 371         BUG_ON(!dnext);
 372
 373         /*
 374          * reposition drq (this is the merged request) in hash, and in rbtree
 375          * in case of a front merge
 376          */
 377         deadline_del_drq_hash(drq);
 378         deadline_add_drq_hash(dd, drq);
 379
 380         if (rq_rb_key(req) != drq->rb_key) {
 381                 deadline_del_drq_rb(dd, drq);
 382                 deadline_add_drq_rb(dd, drq);
 383         }
 384
 385         /*
 386          * if dnext expires before drq, assign its expire time to drq
 387          * and move into dnext position (dnext will be deleted) in fifo
 388          */
 389         if (!list_empty(&drq->fifo) && !list_empty(&dnext->fifo)) {
 390                 if (time_before(dnext->expires, drq->expires)) {
 391                         list_move(&drq->fifo, &dnext->fifo);
 392                         drq->expires = dnext->expires;
 393                 }
 394         }
 395
 396         /*
 397          * kill knowledge of next, this one is a goner
 398          */
 399         deadline_remove_request(q, next);
 400 }
 401
 402 /*
 403  * move request from sort list to dispatch queue.
 404  */
 405 static inline void
 406 deadline_move_to_dispatch(struct deadline_data *dd, struct deadline_rq *drq)
 407 {
 408         request_queue_t *q = drq->request->q;
 409
 410         deadline_remove_request(q, drq->request);
 411         elv_dispatch_add_tail(q, drq->request);
 412 }
 413
 414 /*
 415  * move an entry to dispatch queue
 416  */
 417 static void
 418 deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq)
 419 {
 420         const int data_dir = rq_data_dir(drq->request);
 421         struct rb_node *rbnext = rb_next(&drq->rb_node);
 422
 423         dd->next_drq[READ] = NULL;
 424         dd->next_drq[WRITE] = NULL;
 425
 426         if (rbnext)
 427                 dd->next_drq[data_dir] = rb_entry_drq(rbnext);
 428
 429         dd->last_sector = drq->request->sector + drq->request->nr_sectors;
 430
 431         /*
 432          * take it off the sort and fifo list, move
 433          * to dispatch queue
 434          */
 435         deadline_move_to_dispatch(dd, drq);
 436 }
 437
 438 #define list_entry_fifo(ptr)    list_entry((ptr), struct deadline_rq, fifo)
 439
 440 /*
 441  * deadline_check_fifo returns 0 if there are no expired reads on the fifo,
 442  * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
 443  */
 444 static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
 445 {
 446         struct deadline_rq *drq = list_entry_fifo(dd->fifo_list[ddir].next);
 447
 448         /*
 449          * drq is expired!
 450          */
 451         if (time_after(jiffies, drq->expires))
 452                 return 1;
 453
 454         return 0;
 455 }
 456
 457 /*
 458  * deadline_dispatch_requests selects the best request according to
 459  * read/write expire, fifo_batch, etc
 460  */
 461 static int deadline_dispatch_requests(request_queue_t *q, int force)
 462 {
 463         struct deadline_data *dd = q->elevator->elevator_data;
 464         const int reads = !list_empty(&dd->fifo_list[READ]);
 465         const int writes = !list_empty(&dd->fifo_list[WRITE]);
 466         struct deadline_rq *drq;
 467         int data_dir;
 468
 469         /*
 470          * batches are currently reads XOR writes
 471          */
 472         if (dd->next_drq[WRITE])
 473                 drq = dd->next_drq[WRITE];
 474         else
 475                 drq = dd->next_drq[READ];
 476
 477         if (drq) {
 478                 /* we have a "next request" */
 479
 480                 if (dd->last_sector != drq->request->sector)
 481                         /* end the batch on a non sequential request */
 482                         dd->batching += dd->fifo_batch;
 483
 484                 if (dd->batching < dd->fifo_batch)
 485                         /* we are still entitled to batch */
 486                         goto dispatch_request;
 487         }
 488
 489         /*
 490          * at this point we are not running a batch. select the appropriate
 491          * data direction (read / write)
 492          */
 493
 494         if (reads) {
 495                 BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[READ]));
 496
 497                 if (writes && (dd->starved++ >= dd->writes_starved))
 498                         goto dispatch_writes;
 499
 500                 data_dir = READ;
 501
 502                 goto dispatch_find_request;
 503         }
 504
 505         /*
 506          * there are either no reads or writes have been starved
 507          */
 508
 509         if (writes) {
 510 dispatch_writes:
 511                 BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[WRITE]));
 512
 513                 dd->starved = 0;
 514
 515                 data_dir = WRITE;
 516
 517                 goto dispatch_find_request;
 518         }
 519
 520         return 0;
 521
 522 dispatch_find_request:
 523         /*
 524          * we are not running a batch, find best request for selected data_dir
 525          */
 526         if (deadline_check_fifo(dd, data_dir)) {
 527                 /* An expired request exists - satisfy it */
 528                 dd->batching = 0;
 529                 drq = list_entry_fifo(dd->fifo_list[data_dir].next);
 530
 531         } else if (dd->next_drq[data_dir]) {
 532                 /*
 533                  * The last req was the same dir and we have a next request in
 534                  * sort order. No expired requests so continue on from here.
 535                  */
 536                 drq = dd->next_drq[data_dir];
 537         } else {
 538                 /*
 539                  * The last req was the other direction or we have run out of
 540                  * higher-sectored requests. Go back to the lowest sectored
 541                  * request (1 way elevator) and start a new batch.
 542                  */
 543                 dd->batching = 0;
 544                 drq = deadline_find_first_drq(dd, data_dir);
 545         }
 546
 547 dispatch_request:
 548         /*
 549          * drq is the selected appropriate request.
 550          */
 551         dd->batching++;
 552         deadline_move_request(dd, drq);
 553
 554         return 1;
 555 }
 556
 557 static int deadline_queue_empty(request_queue_t *q)
 558 {
 559         struct deadline_data *dd = q->elevator->elevator_data;
 560
 561         return list_empty(&dd->fifo_list[WRITE])
 562                 && list_empty(&dd->fifo_list[READ]);
 563 }
 564
 565 static struct request *
 566 deadline_former_request(request_queue_t *q, struct request *rq)
 567 {
 568         struct deadline_rq *drq = RQ_DATA(rq);
 569         struct rb_node *rbprev = rb_prev(&drq->rb_node);
 570
 571         if (rbprev)
 572                 return rb_entry_drq(rbprev)->request;
 573
 574         return NULL;
 575 }
 576
 577 static struct request *
 578 deadline_latter_request(request_queue_t *q, struct request *rq)
 579 {
 580         struct deadline_rq *drq = RQ_DATA(rq);
 581         struct rb_node *rbnext = rb_next(&drq->rb_node);
 582
 583         if (rbnext)
 584                 return rb_entry_drq(rbnext)->request;
 585
 586         return NULL;
 587 }
 588
 589 static void deadline_exit_queue(elevator_t *e)
 590 {
 591         struct deadline_data *dd = e->elevator_data;
 592
 593         BUG_ON(!list_empty(&dd->fifo_list[READ]));
 594         BUG_ON(!list_empty(&dd->fifo_list[WRITE]));
 595
 596         mempool_destroy(dd->drq_pool);
 597         kfree(dd->hash);
 598         kfree(dd);
 599 }
 600
 601 /*
 602  * initialize elevator private data (deadline_data), and alloc a drq for
 603  * each request on the free lists
 604  */
 605 static void *deadline_init_queue(request_queue_t *q, elevator_t *e)
 606 {
 607         struct deadline_data *dd;
 608         int i;
 609
 610         if (!drq_pool)
 611                 return NULL;
 612
 613         dd = kmalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
 614         if (!dd)
 615                 return NULL;
 616         memset(dd, 0, sizeof(*dd));
 617
 618         dd->hash = kmalloc_node(sizeof(struct hlist_head)*DL_HASH_ENTRIES,
 619                                 GFP_KERNEL, q->node);
 620         if (!dd->hash) {
 621                 kfree(dd);
 622                 return NULL;
 623         }
 624
 625         dd->drq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
 626                                         mempool_free_slab, drq_pool, q->node);
 627         if (!dd->drq_pool) {
 628                 kfree(dd->hash);
 629                 kfree(dd);
 630                 return NULL;
 631         }
 632
 633         for (i = 0; i < DL_HASH_ENTRIES; i++)
 634                 INIT_HLIST_HEAD(&dd->hash[i]);
 635
 636         INIT_LIST_HEAD(&dd->fifo_list[READ]);
 637         INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
 638         dd->sort_list[READ] = RB_ROOT;
 639         dd->sort_list[WRITE] = RB_ROOT;
 640         dd->fifo_expire[READ] = read_expire;
 641         dd->fifo_expire[WRITE] = write_expire;
 642         dd->writes_starved = writes_starved;
 643         dd->front_merges = 1;
 644         dd->fifo_batch = fifo_batch;
 645         return dd;
 646 }
 647
 648 static void deadline_put_request(request_queue_t *q, struct request *rq)
 649 {
 650         struct deadline_data *dd = q->elevator->elevator_data;
 651         struct deadline_rq *drq = RQ_DATA(rq);
 652
 653         mempool_free(drq, dd->drq_pool);
 654         rq->elevator_private = NULL;
 655 }
 656
 657 static int
 658 deadline_set_request(request_queue_t *q, struct request *rq, struct bio *bio,
 659                      gfp_t gfp_mask)
 660 {
 661         struct deadline_data *dd = q->elevator->elevator_data;
 662         struct deadline_rq *drq;
 663
 664         drq = mempool_alloc(dd->drq_pool, gfp_mask);
 665         if (drq) {
 666                 memset(drq, 0, sizeof(*drq));
 667                 RB_CLEAR_NODE(&drq->rb_node);
 668                 drq->request = rq;
 669
 670                 INIT_HLIST_NODE(&drq->hash);
 671
 672                 INIT_LIST_HEAD(&drq->fifo);
 673
 674                 rq->elevator_private = drq;
 675                 return 0;
 676         }
 677
 678         return 1;
 679 }
 680
 681 /*
 682  * sysfs parts below
 683  */
 684
 685 static ssize_t
 686 deadline_var_show(int var, char *page)
 687 {
 688         return sprintf(page, "%d\n", var);
 689 }
 690
 691 static ssize_t
 692 deadline_var_store(int *var, const char *page, size_t count)
 693 {
 694         char *p = (char *) page;
 695
 696         *var = simple_strtol(p, &p, 10);
 697         return count;
 698 }
 699
 700 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV)                            \
 701 static ssize_t __FUNC(elevator_t *e, char *page)                        \
 702 {                                                                       \
 703         struct deadline_data *dd = e->elevator_data;                    \
 704         int __data = __VAR;                                             \
 705         if (__CONV)                                                     \
 706                 __data = jiffies_to_msecs(__data);                      \
 707         return deadline_var_show(__data, (page));                       \
 708 }
 709 SHOW_FUNCTION(deadline_read_expire_show, dd->fifo_expire[READ], 1);
 710 SHOW_FUNCTION(deadline_write_expire_show, dd->fifo_expire[WRITE], 1);
 711 SHOW_FUNCTION(deadline_writes_starved_show, dd->writes_starved, 0);
 712 SHOW_FUNCTION(deadline_front_merges_show, dd->front_merges, 0);
 713 SHOW_FUNCTION(deadline_fifo_batch_show, dd->fifo_batch, 0);
 714 #undef SHOW_FUNCTION
 715
 716 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)                 \
 717 static ssize_t __FUNC(elevator_t *e, const char *page, size_t count)    \
 718 {                                                                       \
 719         struct deadline_data *dd = e->elevator_data;                    \
 720         int __data;                                                     \
 721         int ret = deadline_var_store(&__data, (page), count);           \
 722         if (__data < (MIN))                                             \
 723                 __data = (MIN);                                         \
 724         else if (__data > (MAX))                                        \
 725                 __data = (MAX);                                         \
 726         if (__CONV)                                                     \
 727                 *(__PTR) = msecs_to_jiffies(__data);                    \
 728         else                                                            \
 729                 *(__PTR) = __data;                                      \
 730         return ret;                                                     \
 731 }
 732 STORE_FUNCTION(deadline_read_expire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1);
 733 STORE_FUNCTION(deadline_write_expire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1);
 734 STORE_FUNCTION(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0);
 735 STORE_FUNCTION(deadline_front_merges_store, &dd->front_merges, 0, 1, 0);
 736 STORE_FUNCTION(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX, 0);
 737 #undef STORE_FUNCTION
 738
 739 #define DD_ATTR(name) \
 740         __ATTR(name, S_IRUGO|S_IWUSR, deadline_##name##_show, \
 741                                       deadline_##name##_store)
 742
 743 static struct elv_fs_entry deadline_attrs[] = {
 744         DD_ATTR(read_expire),
 745         DD_ATTR(write_expire),
 746         DD_ATTR(writes_starved),
 747         DD_ATTR(front_merges),
 748         DD_ATTR(fifo_batch),
 749         __ATTR_NULL
 750 };
 751
 752 static struct elevator_type iosched_deadline = {
 753         .ops = {
 754                 .elevator_merge_fn =            deadline_merge,
 755                 .elevator_merged_fn =           deadline_merged_request,
 756                 .elevator_merge_req_fn =        deadline_merged_requests,
 757                 .elevator_dispatch_fn =         deadline_dispatch_requests,
 758                 .elevator_add_req_fn =          deadline_add_request,
 759                 .elevator_queue_empty_fn =      deadline_queue_empty,
 760                 .elevator_former_req_fn =       deadline_former_request,
 761                 .elevator_latter_req_fn =       deadline_latter_request,
 762                 .elevator_set_req_fn =          deadline_set_request,
 763                 .elevator_put_req_fn =          deadline_put_request,
 764                 .elevator_init_fn =             deadline_init_queue,
 765                 .elevator_exit_fn =             deadline_exit_queue,
 766         },
 767
 768         .elevator_attrs = deadline_attrs,
 769         .elevator_name = "deadline",
 770         .elevator_owner = THIS_MODULE,
 771 };
 772
 773 static int __init deadline_init(void)
 774 {
 775         int ret;
 776
 777         drq_pool = kmem_cache_create("deadline_drq", sizeof(struct deadline_rq),
 778                                      0, 0, NULL, NULL);
 779
 780         if (!drq_pool)
 781                 return -ENOMEM;
 782
 783         ret = elv_register(&iosched_deadline);
 784         if (ret)
 785                 kmem_cache_destroy(drq_pool);
 786
 787         return ret;
 788 }
 789
 790 static void __exit deadline_exit(void)
 791 {
 792         kmem_cache_destroy(drq_pool);
 793         elv_unregister(&iosched_deadline);
 794 }
 795
 796 module_init(deadline_init);
 797 module_exit(deadline_exit);
 798
 799 MODULE_AUTHOR("Jens Axboe");
 800 MODULE_LICENSE("GPL");
 801 MODULE_DESCRIPTION("deadline IO scheduler");