drivers/block/deadline-iosched.c

   1 /*
   2  *  linux/drivers/block/deadline-iosched.c
   3  *
   4  *  Deadline i/o scheduler.
   5  *
   6  *  Copyright (C) 2002 Jens Axboe <axboe@suse.de>
   7  */
   8 #include <linux/kernel.h>
   9 #include <linux/fs.h>
  10 #include <linux/blkdev.h>
  11 #include <linux/elevator.h>
  12 #include <linux/bio.h>
  13 #include <linux/config.h>
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16 #include <linux/init.h>
  17 #include <linux/compiler.h>
  18 #include <linux/hash.h>
  19 #include <linux/rbtree.h>
  20
  21 /*
  22  * See Documentation/block/deadline-iosched.txt
  23  */
  24 static int read_expire = HZ / 2;  /* max time before a read is submitted. */
  25 static int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
  26 static int writes_starved = 2;    /* max times reads can starve a write */
  27 static int fifo_batch = 16;       /* # of sequential requests treated as one
  28                                      by the above parameters. For throughput. */
  29
  30 static const int deadline_hash_shift = 5;
  31 #define DL_HASH_BLOCK(sec)      ((sec) >> 3)
  32 #define DL_HASH_FN(sec)         (hash_long(DL_HASH_BLOCK((sec)), deadline_hash_shift))
  33 #define DL_HASH_ENTRIES         (1 << deadline_hash_shift)
  34 #define rq_hash_key(rq)         ((rq)->sector + (rq)->nr_sectors)
  35 #define list_entry_hash(ptr)    list_entry((ptr), struct deadline_rq, hash)
  36 #define ON_HASH(drq)            (drq)->on_hash
  37
  38 struct deadline_data {
  39         /*
  40          * run time data
  41          */
  42
  43         /*
  44          * requests (deadline_rq s) are present on both sort_list and fifo_list
  45          */
  46         struct rb_root sort_list[2];
  47         struct list_head fifo_list[2];
  48
  49         /*
  50          * next in sort order. read, write or both are NULL
  51          */
  52         struct deadline_rq *next_drq[2];
  53         struct list_head *hash;         /* request hash */
  54         unsigned int batching;          /* number of sequential requests made */
  55         sector_t last_sector;           /* head position */
  56         unsigned int starved;           /* times reads have starved writes */
  57
  58         /*
  59          * settings that change how the i/o scheduler behaves
  60          */
  61         int fifo_expire[2];
  62         int fifo_batch;
  63         int writes_starved;
  64         int front_merges;
  65
  66         mempool_t *drq_pool;
  67 };
  68
  69 /*
  70  * pre-request data.
  71  */
  72 struct deadline_rq {
  73         /*
  74          * rbtree index, key is the starting offset
  75          */
  76         struct rb_node rb_node;
  77         sector_t rb_key;
  78
  79         struct request *request;
  80
  81         /*
  82          * request hash, key is the ending offset (for back merge lookup)
  83          */
  84         struct list_head hash;
  85         char on_hash;
  86
  87         /*
  88          * expire fifo
  89          */
  90         struct list_head fifo;
  91         unsigned long expires;
  92 };
  93
  94 static void deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq);
  95
  96 static kmem_cache_t *drq_pool;
  97
  98 #define RQ_DATA(rq)     ((struct deadline_rq *) (rq)->elevator_private)
  99
 100 /*
 101  * the back merge hash support functions
 102  */
 103 static inline void __deadline_del_drq_hash(struct deadline_rq *drq)
 104 {
 105         drq->on_hash = 0;
 106         list_del_init(&drq->hash);
 107 }
 108
 109 static inline void deadline_del_drq_hash(struct deadline_rq *drq)
 110 {
 111         if (ON_HASH(drq))
 112                 __deadline_del_drq_hash(drq);
 113 }
 114
 115 static void
 116 deadline_remove_merge_hints(request_queue_t *q, struct deadline_rq *drq)
 117 {
 118         deadline_del_drq_hash(drq);
 119
 120         if (q->last_merge == drq->request)
 121                 q->last_merge = NULL;
 122 }
 123
 124 static inline void
 125 deadline_add_drq_hash(struct deadline_data *dd, struct deadline_rq *drq)
 126 {
 127         struct request *rq = drq->request;
 128
 129         BUG_ON(ON_HASH(drq));
 130
 131         drq->on_hash = 1;
 132         list_add(&drq->hash, &dd->hash[DL_HASH_FN(rq_hash_key(rq))]);
 133 }
 134
 135 /*
 136  * move hot entry to front of chain
 137  */
 138 static inline void
 139 deadline_hot_drq_hash(struct deadline_data *dd, struct deadline_rq *drq)
 140 {
 141         struct request *rq = drq->request;
 142         struct list_head *head = &dd->hash[DL_HASH_FN(rq_hash_key(rq))];
 143
 144         if (ON_HASH(drq) && drq->hash.prev != head) {
 145                 list_del(&drq->hash);
 146                 list_add(&drq->hash, head);
 147         }
 148 }
 149
 150 static struct request *
 151 deadline_find_drq_hash(struct deadline_data *dd, sector_t offset)
 152 {
 153         struct list_head *hash_list = &dd->hash[DL_HASH_FN(offset)];
 154         struct list_head *entry, *next = hash_list->next;
 155
 156         while ((entry = next) != hash_list) {
 157                 struct deadline_rq *drq = list_entry_hash(entry);
 158                 struct request *__rq = drq->request;
 159
 160                 next = entry->next;
 161
 162                 BUG_ON(!ON_HASH(drq));
 163
 164                 if (!rq_mergeable(__rq)) {
 165                         __deadline_del_drq_hash(drq);
 166                         continue;
 167                 }
 168
 169                 if (rq_hash_key(__rq) == offset)
 170                         return __rq;
 171         }
 172
 173         return NULL;
 174 }
 175
 176 /*
 177  * rb tree support functions
 178  */
 179 #define RB_NONE         (2)
 180 #define RB_EMPTY(root)  ((root)->rb_node == NULL)
 181 #define ON_RB(node)     ((node)->rb_color != RB_NONE)
 182 #define RB_CLEAR(node)  ((node)->rb_color = RB_NONE)
 183 #define rb_entry_drq(node)      rb_entry((node), struct deadline_rq, rb_node)
 184 #define DRQ_RB_ROOT(dd, drq)    (&(dd)->sort_list[rq_data_dir((drq)->request)])
 185 #define rq_rb_key(rq)           (rq)->sector
 186
 187 static struct deadline_rq *
 188 __deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
 189 {
 190         struct rb_node **p = &DRQ_RB_ROOT(dd, drq)->rb_node;
 191         struct rb_node *parent = NULL;
 192         struct deadline_rq *__drq;
 193
 194         while (*p) {
 195                 parent = *p;
 196                 __drq = rb_entry_drq(parent);
 197
 198                 if (drq->rb_key < __drq->rb_key)
 199                         p = &(*p)->rb_left;
 200                 else if (drq->rb_key > __drq->rb_key)
 201                         p = &(*p)->rb_right;
 202                 else
 203                         return __drq;
 204         }
 205
 206         rb_link_node(&drq->rb_node, parent, p);
 207         return NULL;
 208 }
 209
 210 static void
 211 deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
 212 {
 213         struct deadline_rq *__alias;
 214
 215         drq->rb_key = rq_rb_key(drq->request);
 216
 217 retry:
 218         __alias = __deadline_add_drq_rb(dd, drq);
 219         if (!__alias) {
 220                 rb_insert_color(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
 221                 return;
 222         }
 223
 224         deadline_move_request(dd, __alias);
 225         goto retry;
 226 }
 227
 228 static inline void
 229 deadline_del_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
 230 {
 231         const int data_dir = rq_data_dir(drq->request);
 232
 233         if (dd->next_drq[data_dir] == drq) {
 234                 struct rb_node *rbnext = rb_next(&drq->rb_node);
 235
 236                 dd->next_drq[data_dir] = NULL;
 237                 if (rbnext)
 238                         dd->next_drq[data_dir] = rb_entry_drq(rbnext);
 239         }
 240
 241         BUG_ON(!ON_RB(&drq->rb_node));
 242         rb_erase(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
 243         RB_CLEAR(&drq->rb_node);
 244 }
 245
 246 static struct request *
 247 deadline_find_drq_rb(struct deadline_data *dd, sector_t sector, int data_dir)
 248 {
 249         struct rb_node *n = dd->sort_list[data_dir].rb_node;
 250         struct deadline_rq *drq;
 251
 252         while (n) {
 253                 drq = rb_entry_drq(n);
 254
 255                 if (sector < drq->rb_key)
 256                         n = n->rb_left;
 257                 else if (sector > drq->rb_key)
 258                         n = n->rb_right;
 259                 else
 260                         return drq->request;
 261         }
 262
 263         return NULL;
 264 }
 265
 266 /*
 267  * deadline_find_first_drq finds the first (lowest sector numbered) request
 268  * for the specified data_dir. Used to sweep back to the start of the disk
 269  * (1-way elevator) after we process the last (highest sector) request.
 270  */
 271 static struct deadline_rq *
 272 deadline_find_first_drq(struct deadline_data *dd, int data_dir)
 273 {
 274         struct rb_node *n = dd->sort_list[data_dir].rb_node;
 275
 276         for (;;) {
 277                 if (n->rb_left == NULL)
 278                         return rb_entry_drq(n);
 279
 280                 n = n->rb_left;
 281         }
 282 }
 283
 284 /*
 285  * add drq to rbtree and fifo
 286  */
 287 static void
 288 deadline_add_request(struct request_queue *q, struct request *rq)
 289 {
 290         struct deadline_data *dd = q->elevator->elevator_data;
 291         struct deadline_rq *drq = RQ_DATA(rq);
 292
 293         const int data_dir = rq_data_dir(drq->request);
 294
 295         deadline_add_drq_rb(dd, drq);
 296         /*
 297          * set expire time (only used for reads) and add to fifo list
 298          */
 299         drq->expires = jiffies + dd->fifo_expire[data_dir];
 300         list_add_tail(&drq->fifo, &dd->fifo_list[data_dir]);
 301
 302         if (rq_mergeable(rq)) {
 303                 deadline_add_drq_hash(dd, drq);
 304
 305                 if (!q->last_merge)
 306                         q->last_merge = rq;
 307         }
 308 }
 309
 310 /*
 311  * remove rq from rbtree, fifo, and hash
 312  */
 313 static void deadline_remove_request(request_queue_t *q, struct request *rq)
 314 {
 315         struct deadline_rq *drq = RQ_DATA(rq);
 316         struct deadline_data *dd = q->elevator->elevator_data;
 317
 318         list_del_init(&drq->fifo);
 319         deadline_remove_merge_hints(q, drq);
 320         deadline_del_drq_rb(dd, drq);
 321 }
 322
 323 static int
 324 deadline_merge(request_queue_t *q, struct request **req, struct bio *bio)
 325 {
 326         struct deadline_data *dd = q->elevator->elevator_data;
 327         struct request *__rq;
 328         int ret;
 329
 330         /*
 331          * try last_merge to avoid going to hash
 332          */
 333         ret = elv_try_last_merge(q, bio);
 334         if (ret != ELEVATOR_NO_MERGE) {
 335                 __rq = q->last_merge;
 336                 goto out_insert;
 337         }
 338
 339         /*
 340          * see if the merge hash can satisfy a back merge
 341          */
 342         __rq = deadline_find_drq_hash(dd, bio->bi_sector);
 343         if (__rq) {
 344                 BUG_ON(__rq->sector + __rq->nr_sectors != bio->bi_sector);
 345
 346                 if (elv_rq_merge_ok(__rq, bio)) {
 347                         ret = ELEVATOR_BACK_MERGE;
 348                         goto out;
 349                 }
 350         }
 351
 352         /*
 353          * check for front merge
 354          */
 355         if (dd->front_merges) {
 356                 sector_t rb_key = bio->bi_sector + bio_sectors(bio);
 357
 358                 __rq = deadline_find_drq_rb(dd, rb_key, bio_data_dir(bio));
 359                 if (__rq) {
 360                         BUG_ON(rb_key != rq_rb_key(__rq));
 361
 362                         if (elv_rq_merge_ok(__rq, bio)) {
 363                                 ret = ELEVATOR_FRONT_MERGE;
 364                                 goto out;
 365                         }
 366                 }
 367         }
 368
 369         return ELEVATOR_NO_MERGE;
 370 out:
 371         q->last_merge = __rq;
 372 out_insert:
 373         if (ret)
 374                 deadline_hot_drq_hash(dd, RQ_DATA(__rq));
 375         *req = __rq;
 376         return ret;
 377 }
 378
 379 static void deadline_merged_request(request_queue_t *q, struct request *req)
 380 {
 381         struct deadline_data *dd = q->elevator->elevator_data;
 382         struct deadline_rq *drq = RQ_DATA(req);
 383
 384         /*
 385          * hash always needs to be repositioned, key is end sector
 386          */
 387         deadline_del_drq_hash(drq);
 388         deadline_add_drq_hash(dd, drq);
 389
 390         /*
 391          * if the merge was a front merge, we need to reposition request
 392          */
 393         if (rq_rb_key(req) != drq->rb_key) {
 394                 deadline_del_drq_rb(dd, drq);
 395                 deadline_add_drq_rb(dd, drq);
 396         }
 397
 398         q->last_merge = req;
 399 }
 400
 401 static void
 402 deadline_merged_requests(request_queue_t *q, struct request *req,
 403                          struct request *next)
 404 {
 405         struct deadline_data *dd = q->elevator->elevator_data;
 406         struct deadline_rq *drq = RQ_DATA(req);
 407         struct deadline_rq *dnext = RQ_DATA(next);
 408
 409         BUG_ON(!drq);
 410         BUG_ON(!dnext);
 411
 412         /*
 413          * reposition drq (this is the merged request) in hash, and in rbtree
 414          * in case of a front merge
 415          */
 416         deadline_del_drq_hash(drq);
 417         deadline_add_drq_hash(dd, drq);
 418
 419         if (rq_rb_key(req) != drq->rb_key) {
 420                 deadline_del_drq_rb(dd, drq);
 421                 deadline_add_drq_rb(dd, drq);
 422         }
 423
 424         /*
 425          * if dnext expires before drq, assign its expire time to drq
 426          * and move into dnext position (dnext will be deleted) in fifo
 427          */
 428         if (!list_empty(&drq->fifo) && !list_empty(&dnext->fifo)) {
 429                 if (time_before(dnext->expires, drq->expires)) {
 430                         list_move(&drq->fifo, &dnext->fifo);
 431                         drq->expires = dnext->expires;
 432                 }
 433         }
 434
 435         /*
 436          * kill knowledge of next, this one is a goner
 437          */
 438         deadline_remove_request(q, next);
 439 }
 440
 441 /*
 442  * move request from sort list to dispatch queue.
 443  */
 444 static inline void
 445 deadline_move_to_dispatch(struct deadline_data *dd, struct deadline_rq *drq)
 446 {
 447         request_queue_t *q = drq->request->q;
 448
 449         deadline_remove_request(q, drq->request);
 450         elv_dispatch_add_tail(q, drq->request);
 451 }
 452
 453 /*
 454  * move an entry to dispatch queue
 455  */
 456 static void
 457 deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq)
 458 {
 459         const int data_dir = rq_data_dir(drq->request);
 460         struct rb_node *rbnext = rb_next(&drq->rb_node);
 461
 462         dd->next_drq[READ] = NULL;
 463         dd->next_drq[WRITE] = NULL;
 464
 465         if (rbnext)
 466                 dd->next_drq[data_dir] = rb_entry_drq(rbnext);
 467
 468         dd->last_sector = drq->request->sector + drq->request->nr_sectors;
 469
 470         /*
 471          * take it off the sort and fifo list, move
 472          * to dispatch queue
 473          */
 474         deadline_move_to_dispatch(dd, drq);
 475 }
 476
 477 #define list_entry_fifo(ptr)    list_entry((ptr), struct deadline_rq, fifo)
 478
 479 /*
 480  * deadline_check_fifo returns 0 if there are no expired reads on the fifo,
 481  * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
 482  */
 483 static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
 484 {
 485         struct deadline_rq *drq = list_entry_fifo(dd->fifo_list[ddir].next);
 486
 487         /*
 488          * drq is expired!
 489          */
 490         if (time_after(jiffies, drq->expires))
 491                 return 1;
 492
 493         return 0;
 494 }
 495
 496 /*
 497  * deadline_dispatch_requests selects the best request according to
 498  * read/write expire, fifo_batch, etc
 499  */
 500 static int deadline_dispatch_requests(request_queue_t *q, int force)
 501 {
 502         struct deadline_data *dd = q->elevator->elevator_data;
 503         const int reads = !list_empty(&dd->fifo_list[READ]);
 504         const int writes = !list_empty(&dd->fifo_list[WRITE]);
 505         struct deadline_rq *drq;
 506         int data_dir;
 507
 508         /*
 509          * batches are currently reads XOR writes
 510          */
 511         if (dd->next_drq[WRITE])
 512                 drq = dd->next_drq[WRITE];
 513         else
 514                 drq = dd->next_drq[READ];
 515
 516         if (drq) {
 517                 /* we have a "next request" */
 518
 519                 if (dd->last_sector != drq->request->sector)
 520                         /* end the batch on a non sequential request */
 521                         dd->batching += dd->fifo_batch;
 522
 523                 if (dd->batching < dd->fifo_batch)
 524                         /* we are still entitled to batch */
 525                         goto dispatch_request;
 526         }
 527
 528         /*
 529          * at this point we are not running a batch. select the appropriate
 530          * data direction (read / write)
 531          */
 532
 533         if (reads) {
 534                 BUG_ON(RB_EMPTY(&dd->sort_list[READ]));
 535
 536                 if (writes && (dd->starved++ >= dd->writes_starved))
 537                         goto dispatch_writes;
 538
 539                 data_dir = READ;
 540
 541                 goto dispatch_find_request;
 542         }
 543
 544         /*
 545          * there are either no reads or writes have been starved
 546          */
 547
 548         if (writes) {
 549 dispatch_writes:
 550                 BUG_ON(RB_EMPTY(&dd->sort_list[WRITE]));
 551
 552                 dd->starved = 0;
 553
 554                 data_dir = WRITE;
 555
 556                 goto dispatch_find_request;
 557         }
 558
 559         return 0;
 560
 561 dispatch_find_request:
 562         /*
 563          * we are not running a batch, find best request for selected data_dir
 564          */
 565         if (deadline_check_fifo(dd, data_dir)) {
 566                 /* An expired request exists - satisfy it */
 567                 dd->batching = 0;
 568                 drq = list_entry_fifo(dd->fifo_list[data_dir].next);
 569
 570         } else if (dd->next_drq[data_dir]) {
 571                 /*
 572                  * The last req was the same dir and we have a next request in
 573                  * sort order. No expired requests so continue on from here.
 574                  */
 575                 drq = dd->next_drq[data_dir];
 576         } else {
 577                 /*
 578                  * The last req was the other direction or we have run out of
 579                  * higher-sectored requests. Go back to the lowest sectored
 580                  * request (1 way elevator) and start a new batch.
 581                  */
 582                 dd->batching = 0;
 583                 drq = deadline_find_first_drq(dd, data_dir);
 584         }
 585
 586 dispatch_request:
 587         /*
 588          * drq is the selected appropriate request.
 589          */
 590         dd->batching++;
 591         deadline_move_request(dd, drq);
 592
 593         return 1;
 594 }
 595
 596 static int deadline_queue_empty(request_queue_t *q)
 597 {
 598         struct deadline_data *dd = q->elevator->elevator_data;
 599
 600         return list_empty(&dd->fifo_list[WRITE])
 601                 && list_empty(&dd->fifo_list[READ]);
 602 }
 603
 604 static struct request *
 605 deadline_former_request(request_queue_t *q, struct request *rq)
 606 {
 607         struct deadline_rq *drq = RQ_DATA(rq);
 608         struct rb_node *rbprev = rb_prev(&drq->rb_node);
 609
 610         if (rbprev)
 611                 return rb_entry_drq(rbprev)->request;
 612
 613         return NULL;
 614 }
 615
 616 static struct request *
 617 deadline_latter_request(request_queue_t *q, struct request *rq)
 618 {
 619         struct deadline_rq *drq = RQ_DATA(rq);
 620         struct rb_node *rbnext = rb_next(&drq->rb_node);
 621
 622         if (rbnext)
 623                 return rb_entry_drq(rbnext)->request;
 624
 625         return NULL;
 626 }
 627
 628 static void deadline_exit_queue(elevator_t *e)
 629 {
 630         struct deadline_data *dd = e->elevator_data;
 631
 632         BUG_ON(!list_empty(&dd->fifo_list[READ]));
 633         BUG_ON(!list_empty(&dd->fifo_list[WRITE]));
 634
 635         mempool_destroy(dd->drq_pool);
 636         kfree(dd->hash);
 637         kfree(dd);
 638 }
 639
 640 /*
 641  * initialize elevator private data (deadline_data), and alloc a drq for
 642  * each request on the free lists
 643  */
 644 static int deadline_init_queue(request_queue_t *q, elevator_t *e)
 645 {
 646         struct deadline_data *dd;
 647         int i;
 648
 649         if (!drq_pool)
 650                 return -ENOMEM;
 651
 652         dd = kmalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
 653         if (!dd)
 654                 return -ENOMEM;
 655         memset(dd, 0, sizeof(*dd));
 656
 657         dd->hash = kmalloc_node(sizeof(struct list_head)*DL_HASH_ENTRIES,
 658                                 GFP_KERNEL, q->node);
 659         if (!dd->hash) {
 660                 kfree(dd);
 661                 return -ENOMEM;
 662         }
 663
 664         dd->drq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
 665                                         mempool_free_slab, drq_pool, q->node);
 666         if (!dd->drq_pool) {
 667                 kfree(dd->hash);
 668                 kfree(dd);
 669                 return -ENOMEM;
 670         }
 671
 672         for (i = 0; i < DL_HASH_ENTRIES; i++)
 673                 INIT_LIST_HEAD(&dd->hash[i]);
 674
 675         INIT_LIST_HEAD(&dd->fifo_list[READ]);
 676         INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
 677         dd->sort_list[READ] = RB_ROOT;
 678         dd->sort_list[WRITE] = RB_ROOT;
 679         dd->fifo_expire[READ] = read_expire;
 680         dd->fifo_expire[WRITE] = write_expire;
 681         dd->writes_starved = writes_starved;
 682         dd->front_merges = 1;
 683         dd->fifo_batch = fifo_batch;
 684         e->elevator_data = dd;
 685         return 0;
 686 }
 687
 688 static void deadline_put_request(request_queue_t *q, struct request *rq)
 689 {
 690         struct deadline_data *dd = q->elevator->elevator_data;
 691         struct deadline_rq *drq = RQ_DATA(rq);
 692
 693         mempool_free(drq, dd->drq_pool);
 694         rq->elevator_private = NULL;
 695 }
 696
 697 static int
 698 deadline_set_request(request_queue_t *q, struct request *rq, struct bio *bio,
 699                      int gfp_mask)
 700 {
 701         struct deadline_data *dd = q->elevator->elevator_data;
 702         struct deadline_rq *drq;
 703
 704         drq = mempool_alloc(dd->drq_pool, gfp_mask);
 705         if (drq) {
 706                 memset(drq, 0, sizeof(*drq));
 707                 RB_CLEAR(&drq->rb_node);
 708                 drq->request = rq;
 709
 710                 INIT_LIST_HEAD(&drq->hash);
 711                 drq->on_hash = 0;
 712
 713                 INIT_LIST_HEAD(&drq->fifo);
 714
 715                 rq->elevator_private = drq;
 716                 return 0;
 717         }
 718
 719         return 1;
 720 }
 721
 722 /*
 723  * sysfs parts below
 724  */
 725 struct deadline_fs_entry {
 726         struct attribute attr;
 727         ssize_t (*show)(struct deadline_data *, char *);
 728         ssize_t (*store)(struct deadline_data *, const char *, size_t);
 729 };
 730
 731 static ssize_t
 732 deadline_var_show(int var, char *page)
 733 {
 734         return sprintf(page, "%d\n", var);
 735 }
 736
 737 static ssize_t
 738 deadline_var_store(int *var, const char *page, size_t count)
 739 {
 740         char *p = (char *) page;
 741
 742         *var = simple_strtol(p, &p, 10);
 743         return count;
 744 }
 745
 746 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV)                            \
 747 static ssize_t __FUNC(struct deadline_data *dd, char *page)             \
 748 {                                                                       \
 749         int __data = __VAR;                                     \
 750         if (__CONV)                                                     \
 751                 __data = jiffies_to_msecs(__data);                      \
 752         return deadline_var_show(__data, (page));                       \
 753 }
 754 SHOW_FUNCTION(deadline_readexpire_show, dd->fifo_expire[READ], 1);
 755 SHOW_FUNCTION(deadline_writeexpire_show, dd->fifo_expire[WRITE], 1);
 756 SHOW_FUNCTION(deadline_writesstarved_show, dd->writes_starved, 0);
 757 SHOW_FUNCTION(deadline_frontmerges_show, dd->front_merges, 0);
 758 SHOW_FUNCTION(deadline_fifobatch_show, dd->fifo_batch, 0);
 759 #undef SHOW_FUNCTION
 760
 761 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)                 \
 762 static ssize_t __FUNC(struct deadline_data *dd, const char *page, size_t count) \
 763 {                                                                       \
 764         int __data;                                                     \
 765         int ret = deadline_var_store(&__data, (page), count);           \
 766         if (__data < (MIN))                                             \
 767                 __data = (MIN);                                         \
 768         else if (__data > (MAX))                                        \
 769                 __data = (MAX);                                         \
 770         if (__CONV)                                                     \
 771                 *(__PTR) = msecs_to_jiffies(__data);                    \
 772         else                                                            \
 773                 *(__PTR) = __data;                                      \
 774         return ret;                                                     \
 775 }
 776 STORE_FUNCTION(deadline_readexpire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1);
 777 STORE_FUNCTION(deadline_writeexpire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1);
 778 STORE_FUNCTION(deadline_writesstarved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0);
 779 STORE_FUNCTION(deadline_frontmerges_store, &dd->front_merges, 0, 1, 0);
 780 STORE_FUNCTION(deadline_fifobatch_store, &dd->fifo_batch, 0, INT_MAX, 0);
 781 #undef STORE_FUNCTION
 782
 783 static struct deadline_fs_entry deadline_readexpire_entry = {
 784         .attr = {.name = "read_expire", .mode = S_IRUGO | S_IWUSR },
 785         .show = deadline_readexpire_show,
 786         .store = deadline_readexpire_store,
 787 };
 788 static struct deadline_fs_entry deadline_writeexpire_entry = {
 789         .attr = {.name = "write_expire", .mode = S_IRUGO | S_IWUSR },
 790         .show = deadline_writeexpire_show,
 791         .store = deadline_writeexpire_store,
 792 };
 793 static struct deadline_fs_entry deadline_writesstarved_entry = {
 794         .attr = {.name = "writes_starved", .mode = S_IRUGO | S_IWUSR },
 795         .show = deadline_writesstarved_show,
 796         .store = deadline_writesstarved_store,
 797 };
 798 static struct deadline_fs_entry deadline_frontmerges_entry = {
 799         .attr = {.name = "front_merges", .mode = S_IRUGO | S_IWUSR },
 800         .show = deadline_frontmerges_show,
 801         .store = deadline_frontmerges_store,
 802 };
 803 static struct deadline_fs_entry deadline_fifobatch_entry = {
 804         .attr = {.name = "fifo_batch", .mode = S_IRUGO | S_IWUSR },
 805         .show = deadline_fifobatch_show,
 806         .store = deadline_fifobatch_store,
 807 };
 808
 809 static struct attribute *default_attrs[] = {
 810         &deadline_readexpire_entry.attr,
 811         &deadline_writeexpire_entry.attr,
 812         &deadline_writesstarved_entry.attr,
 813         &deadline_frontmerges_entry.attr,
 814         &deadline_fifobatch_entry.attr,
 815         NULL,
 816 };
 817
 818 #define to_deadline(atr) container_of((atr), struct deadline_fs_entry, attr)
 819
 820 static ssize_t
 821 deadline_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
 822 {
 823         elevator_t *e = container_of(kobj, elevator_t, kobj);
 824         struct deadline_fs_entry *entry = to_deadline(attr);
 825
 826         if (!entry->show)
 827                 return -EIO;
 828
 829         return entry->show(e->elevator_data, page);
 830 }
 831
 832 static ssize_t
 833 deadline_attr_store(struct kobject *kobj, struct attribute *attr,
 834                     const char *page, size_t length)
 835 {
 836         elevator_t *e = container_of(kobj, elevator_t, kobj);
 837         struct deadline_fs_entry *entry = to_deadline(attr);
 838
 839         if (!entry->store)
 840                 return -EIO;
 841
 842         return entry->store(e->elevator_data, page, length);
 843 }
 844
 845 static struct sysfs_ops deadline_sysfs_ops = {
 846         .show   = deadline_attr_show,
 847         .store  = deadline_attr_store,
 848 };
 849
 850 static struct kobj_type deadline_ktype = {
 851         .sysfs_ops      = &deadline_sysfs_ops,
 852         .default_attrs  = default_attrs,
 853 };
 854
 855 static struct elevator_type iosched_deadline = {
 856         .ops = {
 857                 .elevator_merge_fn =            deadline_merge,
 858                 .elevator_merged_fn =           deadline_merged_request,
 859                 .elevator_merge_req_fn =        deadline_merged_requests,
 860                 .elevator_dispatch_fn =         deadline_dispatch_requests,
 861                 .elevator_add_req_fn =          deadline_add_request,
 862                 .elevator_queue_empty_fn =      deadline_queue_empty,
 863                 .elevator_former_req_fn =       deadline_former_request,
 864                 .elevator_latter_req_fn =       deadline_latter_request,
 865                 .elevator_set_req_fn =          deadline_set_request,
 866                 .elevator_put_req_fn =          deadline_put_request,
 867                 .elevator_init_fn =             deadline_init_queue,
 868                 .elevator_exit_fn =             deadline_exit_queue,
 869         },
 870
 871         .elevator_ktype = &deadline_ktype,
 872         .elevator_name = "deadline",
 873         .elevator_owner = THIS_MODULE,
 874 };
 875
 876 static int __init deadline_init(void)
 877 {
 878         int ret;
 879
 880         drq_pool = kmem_cache_create("deadline_drq", sizeof(struct deadline_rq),
 881                                      0, 0, NULL, NULL);
 882
 883         if (!drq_pool)
 884                 return -ENOMEM;
 885
 886         ret = elv_register(&iosched_deadline);
 887         if (ret)
 888                 kmem_cache_destroy(drq_pool);
 889
 890         return ret;
 891 }
 892
 893 static void __exit deadline_exit(void)
 894 {
 895         kmem_cache_destroy(drq_pool);
 896         elv_unregister(&iosched_deadline);
 897 }
 898
 899 module_init(deadline_init);
 900 module_exit(deadline_exit);
 901
 902 MODULE_AUTHOR("Jens Axboe");
 903 MODULE_LICENSE("GPL");
 904 MODULE_DESCRIPTION("deadline IO scheduler");