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