[BLOCK] Move all core block layer code to new block/ directory
[linux-2.6.git] / 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");