git.oblomov.eu Git - linux-2.6/blob - 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 *dispatch;     /* driver dispatch queue */
  54         struct list_head *hash;         /* request hash */
  55         unsigned int batching;          /* number of sequential requests made */
  56         sector_t last_sector;           /* head position */
  57         unsigned int starved;           /* times reads have starved writes */
  58
  59         /*
  60          * settings that change how the i/o scheduler behaves
  61          */
  62         int fifo_expire[2];
  63         int fifo_batch;
  64         int writes_starved;
  65         int front_merges;
  66
  67         mempool_t *drq_pool;
  68 };
  69
  70 /*
  71  * pre-request data.
  72  */
  73 struct deadline_rq {
  74         /*
  75          * rbtree index, key is the starting offset
  76          */
  77         struct rb_node rb_node;
  78         sector_t rb_key;
  79
  80         struct request *request;
  81
  82         /*
  83          * request hash, key is the ending offset (for back merge lookup)
  84          */
  85         struct list_head hash;
  86         char on_hash;
  87
  88         /*
  89          * expire fifo
  90          */
  91         struct list_head fifo;
  92         unsigned long expires;
  93 };
  94
  95 static void deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq);
  96
  97 static kmem_cache_t *drq_pool;
  98
  99 #define RQ_DATA(rq)     ((struct deadline_rq *) (rq)->elevator_private)
 100
 101 /*
 102  * the back merge hash support functions
 103  */
 104 static inline void __deadline_del_drq_hash(struct deadline_rq *drq)
 105 {
 106         drq->on_hash = 0;
 107         list_del_init(&drq->hash);
 108 }
 109
 110 static inline void deadline_del_drq_hash(struct deadline_rq *drq)
 111 {
 112         if (ON_HASH(drq))
 113                 __deadline_del_drq_hash(drq);
 114 }
 115
 116 static void
 117 deadline_remove_merge_hints(request_queue_t *q, struct deadline_rq *drq)
 118 {
 119         deadline_del_drq_hash(drq);
 120
 121         if (q->last_merge == drq->request)
 122                 q->last_merge = NULL;
 123 }
 124
 125 static inline void
 126 deadline_add_drq_hash(struct deadline_data *dd, struct deadline_rq *drq)
 127 {
 128         struct request *rq = drq->request;
 129
 130         BUG_ON(ON_HASH(drq));
 131
 132         drq->on_hash = 1;
 133         list_add(&drq->hash, &dd->hash[DL_HASH_FN(rq_hash_key(rq))]);
 134 }
 135
 136 /*
 137  * move hot entry to front of chain
 138  */
 139 static inline void
 140 deadline_hot_drq_hash(struct deadline_data *dd, struct deadline_rq *drq)
 141 {
 142         struct request *rq = drq->request;
 143         struct list_head *head = &dd->hash[DL_HASH_FN(rq_hash_key(rq))];
 144
 145         if (ON_HASH(drq) && drq->hash.prev != head) {
 146                 list_del(&drq->hash);
 147                 list_add(&drq->hash, head);
 148         }
 149 }
 150
 151 static struct request *
 152 deadline_find_drq_hash(struct deadline_data *dd, sector_t offset)
 153 {
 154         struct list_head *hash_list = &dd->hash[DL_HASH_FN(offset)];
 155         struct list_head *entry, *next = hash_list->next;
 156
 157         while ((entry = next) != hash_list) {
 158                 struct deadline_rq *drq = list_entry_hash(entry);
 159                 struct request *__rq = drq->request;
 160
 161                 next = entry->next;
 162
 163                 BUG_ON(!ON_HASH(drq));
 164
 165                 if (!rq_mergeable(__rq)) {
 166                         __deadline_del_drq_hash(drq);
 167                         continue;
 168                 }
 169
 170                 if (rq_hash_key(__rq) == offset)
 171                         return __rq;
 172         }
 173
 174         return NULL;
 175 }
 176
 177 /*
 178  * rb tree support functions
 179  */
 180 #define RB_NONE         (2)
 181 #define RB_EMPTY(root)  ((root)->rb_node == NULL)
 182 #define ON_RB(node)     ((node)->rb_color != RB_NONE)
 183 #define RB_CLEAR(node)  ((node)->rb_color = RB_NONE)
 184 #define rb_entry_drq(node)      rb_entry((node), struct deadline_rq, rb_node)
 185 #define DRQ_RB_ROOT(dd, drq)    (&(dd)->sort_list[rq_data_dir((drq)->request)])
 186 #define rq_rb_key(rq)           (rq)->sector
 187
 188 static struct deadline_rq *
 189 __deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
 190 {
 191         struct rb_node **p = &DRQ_RB_ROOT(dd, drq)->rb_node;
 192         struct rb_node *parent = NULL;
 193         struct deadline_rq *__drq;
 194
 195         while (*p) {
 196                 parent = *p;
 197                 __drq = rb_entry_drq(parent);
 198
 199                 if (drq->rb_key < __drq->rb_key)
 200                         p = &(*p)->rb_left;
 201                 else if (drq->rb_key > __drq->rb_key)
 202                         p = &(*p)->rb_right;
 203                 else
 204                         return __drq;
 205         }
 206
 207         rb_link_node(&drq->rb_node, parent, p);
 208         return NULL;
 209 }
 210
 211 static void
 212 deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
 213 {
 214         struct deadline_rq *__alias;
 215
 216         drq->rb_key = rq_rb_key(drq->request);
 217
 218 retry:
 219         __alias = __deadline_add_drq_rb(dd, drq);
 220         if (!__alias) {
 221                 rb_insert_color(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
 222                 return;
 223         }
 224
 225         deadline_move_request(dd, __alias);
 226         goto retry;
 227 }
 228
 229 static inline void
 230 deadline_del_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
 231 {
 232         const int data_dir = rq_data_dir(drq->request);
 233
 234         if (dd->next_drq[data_dir] == drq) {
 235                 struct rb_node *rbnext = rb_next(&drq->rb_node);
 236
 237                 dd->next_drq[data_dir] = NULL;
 238                 if (rbnext)
 239                         dd->next_drq[data_dir] = rb_entry_drq(rbnext);
 240         }
 241
 242         if (ON_RB(&drq->rb_node)) {
 243                 rb_erase(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
 244                 RB_CLEAR(&drq->rb_node);
 245         }
 246 }
 247
 248 static struct request *
 249 deadline_find_drq_rb(struct deadline_data *dd, sector_t sector, int data_dir)
 250 {
 251         struct rb_node *n = dd->sort_list[data_dir].rb_node;
 252         struct deadline_rq *drq;
 253
 254         while (n) {
 255                 drq = rb_entry_drq(n);
 256
 257                 if (sector < drq->rb_key)
 258                         n = n->rb_left;
 259                 else if (sector > drq->rb_key)
 260                         n = n->rb_right;
 261                 else
 262                         return drq->request;
 263         }
 264
 265         return NULL;
 266 }
 267
 268 /*
 269  * deadline_find_first_drq finds the first (lowest sector numbered) request
 270  * for the specified data_dir. Used to sweep back to the start of the disk
 271  * (1-way elevator) after we process the last (highest sector) request.
 272  */
 273 static struct deadline_rq *
 274 deadline_find_first_drq(struct deadline_data *dd, int data_dir)
 275 {
 276         struct rb_node *n = dd->sort_list[data_dir].rb_node;
 277
 278         for (;;) {
 279                 if (n->rb_left == NULL)
 280                         return rb_entry_drq(n);
 281
 282                 n = n->rb_left;
 283         }
 284 }
 285
 286 /*
 287  * add drq to rbtree and fifo
 288  */
 289 static inline void
 290 deadline_add_request(struct request_queue *q, struct request *rq)
 291 {
 292         struct deadline_data *dd = q->elevator->elevator_data;
 293         struct deadline_rq *drq = RQ_DATA(rq);
 294
 295         const int data_dir = rq_data_dir(drq->request);
 296
 297         deadline_add_drq_rb(dd, drq);
 298         /*
 299          * set expire time (only used for reads) and add to fifo list
 300          */
 301         drq->expires = jiffies + dd->fifo_expire[data_dir];
 302         list_add_tail(&drq->fifo, &dd->fifo_list[data_dir]);
 303
 304         if (rq_mergeable(rq)) {
 305                 deadline_add_drq_hash(dd, drq);
 306
 307                 if (!q->last_merge)
 308                         q->last_merge = rq;
 309         }
 310 }
 311
 312 /*
 313  * remove rq from rbtree, fifo, and hash
 314  */
 315 static void deadline_remove_request(request_queue_t *q, struct request *rq)
 316 {
 317         struct deadline_rq *drq = RQ_DATA(rq);
 318
 319         if (drq) {
 320                 struct deadline_data *dd = q->elevator->elevator_data;
 321
 322                 list_del_init(&drq->fifo);
 323                 deadline_remove_merge_hints(q, drq);
 324                 deadline_del_drq_rb(dd, drq);
 325         }
 326 }
 327
 328 static int
 329 deadline_merge(request_queue_t *q, struct request **req, struct bio *bio)
 330 {
 331         struct deadline_data *dd = q->elevator->elevator_data;
 332         struct request *__rq;
 333         int ret;
 334
 335         /*
 336          * try last_merge to avoid going to hash
 337          */
 338         ret = elv_try_last_merge(q, bio);
 339         if (ret != ELEVATOR_NO_MERGE) {
 340                 __rq = q->last_merge;
 341                 goto out_insert;
 342         }
 343
 344         /*
 345          * see if the merge hash can satisfy a back merge
 346          */
 347         __rq = deadline_find_drq_hash(dd, bio->bi_sector);
 348         if (__rq) {
 349                 BUG_ON(__rq->sector + __rq->nr_sectors != bio->bi_sector);
 350
 351                 if (elv_rq_merge_ok(__rq, bio)) {
 352                         ret = ELEVATOR_BACK_MERGE;
 353                         goto out;
 354                 }
 355         }
 356
 357         /*
 358          * check for front merge
 359          */
 360         if (dd->front_merges) {
 361                 sector_t rb_key = bio->bi_sector + bio_sectors(bio);
 362
 363                 __rq = deadline_find_drq_rb(dd, rb_key, bio_data_dir(bio));
 364                 if (__rq) {
 365                         BUG_ON(rb_key != rq_rb_key(__rq));
 366
 367                         if (elv_rq_merge_ok(__rq, bio)) {
 368                                 ret = ELEVATOR_FRONT_MERGE;
 369                                 goto out;
 370                         }
 371                 }
 372         }
 373
 374         return ELEVATOR_NO_MERGE;
 375 out:
 376         q->last_merge = __rq;
 377 out_insert:
 378         if (ret)
 379                 deadline_hot_drq_hash(dd, RQ_DATA(__rq));
 380         *req = __rq;
 381         return ret;
 382 }
 383
 384 static void deadline_merged_request(request_queue_t *q, struct request *req)
 385 {
 386         struct deadline_data *dd = q->elevator->elevator_data;
 387         struct deadline_rq *drq = RQ_DATA(req);
 388
 389         /*
 390          * hash always needs to be repositioned, key is end sector
 391          */
 392         deadline_del_drq_hash(drq);
 393         deadline_add_drq_hash(dd, drq);
 394
 395         /*
 396          * if the merge was a front merge, we need to reposition request
 397          */
 398         if (rq_rb_key(req) != drq->rb_key) {
 399                 deadline_del_drq_rb(dd, drq);
 400                 deadline_add_drq_rb(dd, drq);
 401         }
 402
 403         q->last_merge = req;
 404 }
 405
 406 static void
 407 deadline_merged_requests(request_queue_t *q, struct request *req,
 408                          struct request *next)
 409 {
 410         struct deadline_data *dd = q->elevator->elevator_data;
 411         struct deadline_rq *drq = RQ_DATA(req);
 412         struct deadline_rq *dnext = RQ_DATA(next);
 413
 414         BUG_ON(!drq);
 415         BUG_ON(!dnext);
 416
 417         /*
 418          * reposition drq (this is the merged request) in hash, and in rbtree
 419          * in case of a front merge
 420          */
 421         deadline_del_drq_hash(drq);
 422         deadline_add_drq_hash(dd, drq);
 423
 424         if (rq_rb_key(req) != drq->rb_key) {
 425                 deadline_del_drq_rb(dd, drq);
 426                 deadline_add_drq_rb(dd, drq);
 427         }
 428
 429         /*
 430          * if dnext expires before drq, assign its expire time to drq
 431          * and move into dnext position (dnext will be deleted) in fifo
 432          */
 433         if (!list_empty(&drq->fifo) && !list_empty(&dnext->fifo)) {
 434                 if (time_before(dnext->expires, drq->expires)) {
 435                         list_move(&drq->fifo, &dnext->fifo);
 436                         drq->expires = dnext->expires;
 437                 }
 438         }
 439
 440         /*
 441          * kill knowledge of next, this one is a goner
 442          */
 443         deadline_remove_request(q, next);
 444 }
 445
 446 /*
 447  * move request from sort list to dispatch queue.
 448  */
 449 static inline void
 450 deadline_move_to_dispatch(struct deadline_data *dd, struct deadline_rq *drq)
 451 {
 452         request_queue_t *q = drq->request->q;
 453
 454         deadline_remove_request(q, drq->request);
 455         list_add_tail(&drq->request->queuelist, dd->dispatch);
 456 }
 457
 458 /*
 459  * move an entry to dispatch queue
 460  */
 461 static void
 462 deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq)
 463 {
 464         const int data_dir = rq_data_dir(drq->request);
 465         struct rb_node *rbnext = rb_next(&drq->rb_node);
 466
 467         dd->next_drq[READ] = NULL;
 468         dd->next_drq[WRITE] = NULL;
 469
 470         if (rbnext)
 471                 dd->next_drq[data_dir] = rb_entry_drq(rbnext);
 472
 473         dd->last_sector = drq->request->sector + drq->request->nr_sectors;
 474
 475         /*
 476          * take it off the sort and fifo list, move
 477          * to dispatch queue
 478          */
 479         deadline_move_to_dispatch(dd, drq);
 480 }
 481
 482 #define list_entry_fifo(ptr)    list_entry((ptr), struct deadline_rq, fifo)
 483
 484 /*
 485  * deadline_check_fifo returns 0 if there are no expired reads on the fifo,
 486  * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
 487  */
 488 static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
 489 {
 490         struct deadline_rq *drq = list_entry_fifo(dd->fifo_list[ddir].next);
 491
 492         /*
 493          * drq is expired!
 494          */
 495         if (time_after(jiffies, drq->expires))
 496                 return 1;
 497
 498         return 0;
 499 }
 500
 501 /*
 502  * deadline_dispatch_requests selects the best request according to
 503  * read/write expire, fifo_batch, etc
 504  */
 505 static int deadline_dispatch_requests(struct deadline_data *dd)
 506 {
 507         const int reads = !list_empty(&dd->fifo_list[READ]);
 508         const int writes = !list_empty(&dd->fifo_list[WRITE]);
 509         struct deadline_rq *drq;
 510         int data_dir;
 511
 512         /*
 513          * batches are currently reads XOR writes
 514          */
 515         if (dd->next_drq[WRITE])
 516                 drq = dd->next_drq[WRITE];
 517         else
 518                 drq = dd->next_drq[READ];
 519
 520         if (drq) {
 521                 /* we have a "next request" */
 522
 523                 if (dd->last_sector != drq->request->sector)
 524                         /* end the batch on a non sequential request */
 525                         dd->batching += dd->fifo_batch;
 526
 527                 if (dd->batching < dd->fifo_batch)
 528                         /* we are still entitled to batch */
 529                         goto dispatch_request;
 530         }
 531
 532         /*
 533          * at this point we are not running a batch. select the appropriate
 534          * data direction (read / write)
 535          */
 536
 537         if (reads) {
 538                 BUG_ON(RB_EMPTY(&dd->sort_list[READ]));
 539
 540                 if (writes && (dd->starved++ >= dd->writes_starved))
 541                         goto dispatch_writes;
 542
 543                 data_dir = READ;
 544
 545                 goto dispatch_find_request;
 546         }
 547
 548         /*
 549          * there are either no reads or writes have been starved
 550          */
 551
 552         if (writes) {
 553 dispatch_writes:
 554                 BUG_ON(RB_EMPTY(&dd->sort_list[WRITE]));
 555
 556                 dd->starved = 0;
 557
 558                 data_dir = WRITE;
 559
 560                 goto dispatch_find_request;
 561         }
 562
 563         return 0;
 564
 565 dispatch_find_request:
 566         /*
 567          * we are not running a batch, find best request for selected data_dir
 568          */
 569         if (deadline_check_fifo(dd, data_dir)) {
 570                 /* An expired request exists - satisfy it */
 571                 dd->batching = 0;
 572                 drq = list_entry_fifo(dd->fifo_list[data_dir].next);
 573
 574         } else if (dd->next_drq[data_dir]) {
 575                 /*
 576                  * The last req was the same dir and we have a next request in
 577                  * sort order. No expired requests so continue on from here.
 578                  */
 579                 drq = dd->next_drq[data_dir];
 580         } else {
 581                 /*
 582                  * The last req was the other direction or we have run out of
 583                  * higher-sectored requests. Go back to the lowest sectored
 584                  * request (1 way elevator) and start a new batch.
 585                  */
 586                 dd->batching = 0;
 587                 drq = deadline_find_first_drq(dd, data_dir);
 588         }
 589
 590 dispatch_request:
 591         /*
 592          * drq is the selected appropriate request.
 593          */
 594         dd->batching++;
 595         deadline_move_request(dd, drq);
 596
 597         return 1;
 598 }
 599
 600 static struct request *deadline_next_request(request_queue_t *q)
 601 {
 602         struct deadline_data *dd = q->elevator->elevator_data;
 603         struct request *rq;
 604
 605         /*
 606          * if there are still requests on the dispatch queue, grab the first one
 607          */
 608         if (!list_empty(dd->dispatch)) {
 609 dispatch:
 610                 rq = list_entry_rq(dd->dispatch->next);
 611                 return rq;
 612         }
 613
 614         if (deadline_dispatch_requests(dd))
 615                 goto dispatch;
 616
 617         return NULL;
 618 }
 619
 620 static void
 621 deadline_insert_request(request_queue_t *q, struct request *rq, int where)
 622 {
 623         struct deadline_data *dd = q->elevator->elevator_data;
 624
 625         /* barriers must flush the reorder queue */
 626         if (unlikely(rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)
 627                         && where == ELEVATOR_INSERT_SORT))
 628                 where = ELEVATOR_INSERT_BACK;
 629
 630         switch (where) {
 631                 case ELEVATOR_INSERT_BACK:
 632                         while (deadline_dispatch_requests(dd))
 633                                 ;
 634                         list_add_tail(&rq->queuelist, dd->dispatch);
 635                         break;
 636                 case ELEVATOR_INSERT_FRONT:
 637                         list_add(&rq->queuelist, dd->dispatch);
 638                         break;
 639                 case ELEVATOR_INSERT_SORT:
 640                         BUG_ON(!blk_fs_request(rq));
 641                         deadline_add_request(q, rq);
 642                         break;
 643                 default:
 644                         printk("%s: bad insert point %d\n", __FUNCTION__,where);
 645                         return;
 646         }
 647 }
 648
 649 static int deadline_queue_empty(request_queue_t *q)
 650 {
 651         struct deadline_data *dd = q->elevator->elevator_data;
 652
 653         if (!list_empty(&dd->fifo_list[WRITE])
 654             || !list_empty(&dd->fifo_list[READ])
 655             || !list_empty(dd->dispatch))
 656                 return 0;
 657
 658         return 1;
 659 }
 660
 661 static struct request *
 662 deadline_former_request(request_queue_t *q, struct request *rq)
 663 {
 664         struct deadline_rq *drq = RQ_DATA(rq);
 665         struct rb_node *rbprev = rb_prev(&drq->rb_node);
 666
 667         if (rbprev)
 668                 return rb_entry_drq(rbprev)->request;
 669
 670         return NULL;
 671 }
 672
 673 static struct request *
 674 deadline_latter_request(request_queue_t *q, struct request *rq)
 675 {
 676         struct deadline_rq *drq = RQ_DATA(rq);
 677         struct rb_node *rbnext = rb_next(&drq->rb_node);
 678
 679         if (rbnext)
 680                 return rb_entry_drq(rbnext)->request;
 681
 682         return NULL;
 683 }
 684
 685 static void deadline_exit_queue(elevator_t *e)
 686 {
 687         struct deadline_data *dd = e->elevator_data;
 688
 689         BUG_ON(!list_empty(&dd->fifo_list[READ]));
 690         BUG_ON(!list_empty(&dd->fifo_list[WRITE]));
 691
 692         mempool_destroy(dd->drq_pool);
 693         kfree(dd->hash);
 694         kfree(dd);
 695 }
 696
 697 /*
 698  * initialize elevator private data (deadline_data), and alloc a drq for
 699  * each request on the free lists
 700  */
 701 static int deadline_init_queue(request_queue_t *q, elevator_t *e)
 702 {
 703         struct deadline_data *dd;
 704         int i;
 705
 706         if (!drq_pool)
 707                 return -ENOMEM;
 708
 709         dd = kmalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
 710         if (!dd)
 711                 return -ENOMEM;
 712         memset(dd, 0, sizeof(*dd));
 713
 714         dd->hash = kmalloc_node(sizeof(struct list_head)*DL_HASH_ENTRIES,
 715                                 GFP_KERNEL, q->node);
 716         if (!dd->hash) {
 717                 kfree(dd);
 718                 return -ENOMEM;
 719         }
 720
 721         dd->drq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
 722                                         mempool_free_slab, drq_pool, q->node);
 723         if (!dd->drq_pool) {
 724                 kfree(dd->hash);
 725                 kfree(dd);
 726                 return -ENOMEM;
 727         }
 728
 729         for (i = 0; i < DL_HASH_ENTRIES; i++)
 730                 INIT_LIST_HEAD(&dd->hash[i]);
 731
 732         INIT_LIST_HEAD(&dd->fifo_list[READ]);
 733         INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
 734         dd->sort_list[READ] = RB_ROOT;
 735         dd->sort_list[WRITE] = RB_ROOT;
 736         dd->dispatch = &q->queue_head;
 737         dd->fifo_expire[READ] = read_expire;
 738         dd->fifo_expire[WRITE] = write_expire;
 739         dd->writes_starved = writes_starved;
 740         dd->front_merges = 1;
 741         dd->fifo_batch = fifo_batch;
 742         e->elevator_data = dd;
 743         return 0;
 744 }
 745
 746 static void deadline_put_request(request_queue_t *q, struct request *rq)
 747 {
 748         struct deadline_data *dd = q->elevator->elevator_data;
 749         struct deadline_rq *drq = RQ_DATA(rq);
 750
 751         if (drq) {
 752                 mempool_free(drq, dd->drq_pool);
 753                 rq->elevator_private = NULL;
 754         }
 755 }
 756
 757 static int
 758 deadline_set_request(request_queue_t *q, struct request *rq, struct bio *bio,
 759                      int gfp_mask)
 760 {
 761         struct deadline_data *dd = q->elevator->elevator_data;
 762         struct deadline_rq *drq;
 763
 764         drq = mempool_alloc(dd->drq_pool, gfp_mask);
 765         if (drq) {
 766                 memset(drq, 0, sizeof(*drq));
 767                 RB_CLEAR(&drq->rb_node);
 768                 drq->request = rq;
 769
 770                 INIT_LIST_HEAD(&drq->hash);
 771                 drq->on_hash = 0;
 772
 773                 INIT_LIST_HEAD(&drq->fifo);
 774
 775                 rq->elevator_private = drq;
 776                 return 0;
 777         }
 778
 779         return 1;
 780 }
 781
 782 /*
 783  * sysfs parts below
 784  */
 785 struct deadline_fs_entry {
 786         struct attribute attr;
 787         ssize_t (*show)(struct deadline_data *, char *);
 788         ssize_t (*store)(struct deadline_data *, const char *, size_t);
 789 };
 790
 791 static ssize_t
 792 deadline_var_show(int var, char *page)
 793 {
 794         return sprintf(page, "%d\n", var);
 795 }
 796
 797 static ssize_t
 798 deadline_var_store(int *var, const char *page, size_t count)
 799 {
 800         char *p = (char *) page;
 801
 802         *var = simple_strtol(p, &p, 10);
 803         return count;
 804 }
 805
 806 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV)                            \
 807 static ssize_t __FUNC(struct deadline_data *dd, char *page)             \
 808 {                                                                       \
 809         int __data = __VAR;                                     \
 810         if (__CONV)                                                     \
 811                 __data = jiffies_to_msecs(__data);                      \
 812         return deadline_var_show(__data, (page));                       \
 813 }
 814 SHOW_FUNCTION(deadline_readexpire_show, dd->fifo_expire[READ], 1);
 815 SHOW_FUNCTION(deadline_writeexpire_show, dd->fifo_expire[WRITE], 1);
 816 SHOW_FUNCTION(deadline_writesstarved_show, dd->writes_starved, 0);
 817 SHOW_FUNCTION(deadline_frontmerges_show, dd->front_merges, 0);
 818 SHOW_FUNCTION(deadline_fifobatch_show, dd->fifo_batch, 0);
 819 #undef SHOW_FUNCTION
 820
 821 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)                 \
 822 static ssize_t __FUNC(struct deadline_data *dd, const char *page, size_t count) \
 823 {                                                                       \
 824         int __data;                                                     \
 825         int ret = deadline_var_store(&__data, (page), count);           \
 826         if (__data < (MIN))                                             \
 827                 __data = (MIN);                                         \
 828         else if (__data > (MAX))                                        \
 829                 __data = (MAX);                                         \
 830         if (__CONV)                                                     \
 831                 *(__PTR) = msecs_to_jiffies(__data);                    \
 832         else                                                            \
 833                 *(__PTR) = __data;                                      \
 834         return ret;                                                     \
 835 }
 836 STORE_FUNCTION(deadline_readexpire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1);
 837 STORE_FUNCTION(deadline_writeexpire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1);
 838 STORE_FUNCTION(deadline_writesstarved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0);
 839 STORE_FUNCTION(deadline_frontmerges_store, &dd->front_merges, 0, 1, 0);
 840 STORE_FUNCTION(deadline_fifobatch_store, &dd->fifo_batch, 0, INT_MAX, 0);
 841 #undef STORE_FUNCTION
 842
 843 static struct deadline_fs_entry deadline_readexpire_entry = {
 844         .attr = {.name = "read_expire", .mode = S_IRUGO | S_IWUSR },
 845         .show = deadline_readexpire_show,
 846         .store = deadline_readexpire_store,
 847 };
 848 static struct deadline_fs_entry deadline_writeexpire_entry = {
 849         .attr = {.name = "write_expire", .mode = S_IRUGO | S_IWUSR },
 850         .show = deadline_writeexpire_show,
 851         .store = deadline_writeexpire_store,
 852 };
 853 static struct deadline_fs_entry deadline_writesstarved_entry = {
 854         .attr = {.name = "writes_starved", .mode = S_IRUGO | S_IWUSR },
 855         .show = deadline_writesstarved_show,
 856         .store = deadline_writesstarved_store,
 857 };
 858 static struct deadline_fs_entry deadline_frontmerges_entry = {
 859         .attr = {.name = "front_merges", .mode = S_IRUGO | S_IWUSR },
 860         .show = deadline_frontmerges_show,
 861         .store = deadline_frontmerges_store,
 862 };
 863 static struct deadline_fs_entry deadline_fifobatch_entry = {
 864         .attr = {.name = "fifo_batch", .mode = S_IRUGO | S_IWUSR },
 865         .show = deadline_fifobatch_show,
 866         .store = deadline_fifobatch_store,
 867 };
 868
 869 static struct attribute *default_attrs[] = {
 870         &deadline_readexpire_entry.attr,
 871         &deadline_writeexpire_entry.attr,
 872         &deadline_writesstarved_entry.attr,
 873         &deadline_frontmerges_entry.attr,
 874         &deadline_fifobatch_entry.attr,
 875         NULL,
 876 };
 877
 878 #define to_deadline(atr) container_of((atr), struct deadline_fs_entry, attr)
 879
 880 static ssize_t
 881 deadline_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
 882 {
 883         elevator_t *e = container_of(kobj, elevator_t, kobj);
 884         struct deadline_fs_entry *entry = to_deadline(attr);
 885
 886         if (!entry->show)
 887                 return -EIO;
 888
 889         return entry->show(e->elevator_data, page);
 890 }
 891
 892 static ssize_t
 893 deadline_attr_store(struct kobject *kobj, struct attribute *attr,
 894                     const char *page, size_t length)
 895 {
 896         elevator_t *e = container_of(kobj, elevator_t, kobj);
 897         struct deadline_fs_entry *entry = to_deadline(attr);
 898
 899         if (!entry->store)
 900                 return -EIO;
 901
 902         return entry->store(e->elevator_data, page, length);
 903 }
 904
 905 static struct sysfs_ops deadline_sysfs_ops = {
 906         .show   = deadline_attr_show,
 907         .store  = deadline_attr_store,
 908 };
 909
 910 static struct kobj_type deadline_ktype = {
 911         .sysfs_ops      = &deadline_sysfs_ops,
 912         .default_attrs  = default_attrs,
 913 };
 914
 915 static struct elevator_type iosched_deadline = {
 916         .ops = {
 917                 .elevator_merge_fn =            deadline_merge,
 918                 .elevator_merged_fn =           deadline_merged_request,
 919                 .elevator_merge_req_fn =        deadline_merged_requests,
 920                 .elevator_next_req_fn =         deadline_next_request,
 921                 .elevator_add_req_fn =          deadline_insert_request,
 922                 .elevator_remove_req_fn =       deadline_remove_request,
 923                 .elevator_queue_empty_fn =      deadline_queue_empty,
 924                 .elevator_former_req_fn =       deadline_former_request,
 925                 .elevator_latter_req_fn =       deadline_latter_request,
 926                 .elevator_set_req_fn =          deadline_set_request,
 927                 .elevator_put_req_fn =          deadline_put_request,
 928                 .elevator_init_fn =             deadline_init_queue,
 929                 .elevator_exit_fn =             deadline_exit_queue,
 930         },
 931
 932         .elevator_ktype = &deadline_ktype,
 933         .elevator_name = "deadline",
 934         .elevator_owner = THIS_MODULE,
 935 };
 936
 937 static int __init deadline_init(void)
 938 {
 939         int ret;
 940
 941         drq_pool = kmem_cache_create("deadline_drq", sizeof(struct deadline_rq),
 942                                      0, 0, NULL, NULL);
 943
 944         if (!drq_pool)
 945                 return -ENOMEM;
 946
 947         ret = elv_register(&iosched_deadline);
 948         if (ret)
 949                 kmem_cache_destroy(drq_pool);
 950
 951         return ret;
 952 }
 953
 954 static void __exit deadline_exit(void)
 955 {
 956         kmem_cache_destroy(drq_pool);
 957         elv_unregister(&iosched_deadline);
 958 }
 959
 960 module_init(deadline_init);
 961 module_exit(deadline_exit);
 962
 963 MODULE_AUTHOR("Jens Axboe");
 964 MODULE_LICENSE("GPL");
 965 MODULE_DESCRIPTION("deadline IO scheduler");