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25#include <linux/kernel.h>
26#include <linux/fs.h>
27#include <linux/blkdev.h>
28#include <linux/elevator.h>
29#include <linux/bio.h>
30#include <linux/module.h>
31#include <linux/slab.h>
32#include <linux/init.h>
33#include <linux/compiler.h>
34#include <linux/blktrace_api.h>
35#include <linux/hash.h>
36#include <linux/uaccess.h>
37#include <linux/pm_runtime.h>
38
39#include <trace/events/block.h>
40
41#include "blk.h"
42#include "blk-cgroup.h"
43
44static DEFINE_SPINLOCK(elv_list_lock);
45static LIST_HEAD(elv_list);
46
47
48
49
50#define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
51
52
53
54
55
56static int elv_iosched_allow_merge(struct request *rq, struct bio *bio)
57{
58 struct request_queue *q = rq->q;
59 struct elevator_queue *e = q->elevator;
60
61 if (e->type->ops.elevator_allow_merge_fn)
62 return e->type->ops.elevator_allow_merge_fn(q, rq, bio);
63
64 return 1;
65}
66
67
68
69
70bool elv_rq_merge_ok(struct request *rq, struct bio *bio)
71{
72 if (!blk_rq_merge_ok(rq, bio))
73 return 0;
74
75 if (!elv_iosched_allow_merge(rq, bio))
76 return 0;
77
78 return 1;
79}
80EXPORT_SYMBOL(elv_rq_merge_ok);
81
82static struct elevator_type *elevator_find(const char *name)
83{
84 struct elevator_type *e;
85
86 list_for_each_entry(e, &elv_list, list) {
87 if (!strcmp(e->elevator_name, name))
88 return e;
89 }
90
91 return NULL;
92}
93
94static void elevator_put(struct elevator_type *e)
95{
96 module_put(e->elevator_owner);
97}
98
99static struct elevator_type *elevator_get(const char *name, bool try_loading)
100{
101 struct elevator_type *e;
102
103 spin_lock(&elv_list_lock);
104
105 e = elevator_find(name);
106 if (!e && try_loading) {
107 spin_unlock(&elv_list_lock);
108 request_module("%s-iosched", name);
109 spin_lock(&elv_list_lock);
110 e = elevator_find(name);
111 }
112
113 if (e && !try_module_get(e->elevator_owner))
114 e = NULL;
115
116 spin_unlock(&elv_list_lock);
117
118 return e;
119}
120
121static char chosen_elevator[ELV_NAME_MAX];
122
123static int __init elevator_setup(char *str)
124{
125
126
127
128
129 strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1);
130 return 1;
131}
132
133__setup("elevator=", elevator_setup);
134
135
136void __init load_default_elevator_module(void)
137{
138 struct elevator_type *e;
139
140 if (!chosen_elevator[0])
141 return;
142
143 spin_lock(&elv_list_lock);
144 e = elevator_find(chosen_elevator);
145 spin_unlock(&elv_list_lock);
146
147 if (!e)
148 request_module("%s-iosched", chosen_elevator);
149}
150
151static struct kobj_type elv_ktype;
152
153struct elevator_queue *elevator_alloc(struct request_queue *q,
154 struct elevator_type *e)
155{
156 struct elevator_queue *eq;
157
158 eq = kzalloc_node(sizeof(*eq), GFP_KERNEL, q->node);
159 if (unlikely(!eq))
160 goto err;
161
162 eq->type = e;
163 kobject_init(&eq->kobj, &elv_ktype);
164 mutex_init(&eq->sysfs_lock);
165 hash_init(eq->hash);
166
167 return eq;
168err:
169 kfree(eq);
170 elevator_put(e);
171 return NULL;
172}
173EXPORT_SYMBOL(elevator_alloc);
174
175static void elevator_release(struct kobject *kobj)
176{
177 struct elevator_queue *e;
178
179 e = container_of(kobj, struct elevator_queue, kobj);
180 elevator_put(e->type);
181 kfree(e);
182}
183
184int elevator_init(struct request_queue *q, char *name)
185{
186 struct elevator_type *e = NULL;
187 int err;
188
189 if (unlikely(q->elevator))
190 return 0;
191
192 INIT_LIST_HEAD(&q->queue_head);
193 q->last_merge = NULL;
194 q->end_sector = 0;
195 q->boundary_rq = NULL;
196
197 if (name) {
198 e = elevator_get(name, true);
199 if (!e)
200 return -EINVAL;
201 }
202
203
204
205
206
207
208 if (!e && *chosen_elevator) {
209 e = elevator_get(chosen_elevator, false);
210 if (!e)
211 printk(KERN_ERR "I/O scheduler %s not found\n",
212 chosen_elevator);
213 }
214
215 if (!e) {
216 e = elevator_get(CONFIG_DEFAULT_IOSCHED, false);
217 if (!e) {
218 printk(KERN_ERR
219 "Default I/O scheduler not found. " \
220 "Using noop.\n");
221 e = elevator_get("noop", false);
222 }
223 }
224
225 err = e->ops.elevator_init_fn(q, e);
226 return 0;
227}
228EXPORT_SYMBOL(elevator_init);
229
230void elevator_exit(struct elevator_queue *e)
231{
232 mutex_lock(&e->sysfs_lock);
233 if (e->type->ops.elevator_exit_fn)
234 e->type->ops.elevator_exit_fn(e);
235 mutex_unlock(&e->sysfs_lock);
236
237 kobject_put(&e->kobj);
238}
239EXPORT_SYMBOL(elevator_exit);
240
241static inline void __elv_rqhash_del(struct request *rq)
242{
243 hash_del(&rq->hash);
244}
245
246static void elv_rqhash_del(struct request_queue *q, struct request *rq)
247{
248 if (ELV_ON_HASH(rq))
249 __elv_rqhash_del(rq);
250}
251
252static void elv_rqhash_add(struct request_queue *q, struct request *rq)
253{
254 struct elevator_queue *e = q->elevator;
255
256 BUG_ON(ELV_ON_HASH(rq));
257 hash_add(e->hash, &rq->hash, rq_hash_key(rq));
258}
259
260static void elv_rqhash_reposition(struct request_queue *q, struct request *rq)
261{
262 __elv_rqhash_del(rq);
263 elv_rqhash_add(q, rq);
264}
265
266static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset)
267{
268 struct elevator_queue *e = q->elevator;
269 struct hlist_node *next;
270 struct request *rq;
271
272 hash_for_each_possible_safe(e->hash, rq, next, hash, offset) {
273 BUG_ON(!ELV_ON_HASH(rq));
274
275 if (unlikely(!rq_mergeable(rq))) {
276 __elv_rqhash_del(rq);
277 continue;
278 }
279
280 if (rq_hash_key(rq) == offset)
281 return rq;
282 }
283
284 return NULL;
285}
286
287
288
289
290
291void elv_rb_add(struct rb_root *root, struct request *rq)
292{
293 struct rb_node **p = &root->rb_node;
294 struct rb_node *parent = NULL;
295 struct request *__rq;
296
297 while (*p) {
298 parent = *p;
299 __rq = rb_entry(parent, struct request, rb_node);
300
301 if (blk_rq_pos(rq) < blk_rq_pos(__rq))
302 p = &(*p)->rb_left;
303 else if (blk_rq_pos(rq) >= blk_rq_pos(__rq))
304 p = &(*p)->rb_right;
305 }
306
307 rb_link_node(&rq->rb_node, parent, p);
308 rb_insert_color(&rq->rb_node, root);
309}
310EXPORT_SYMBOL(elv_rb_add);
311
312void elv_rb_del(struct rb_root *root, struct request *rq)
313{
314 BUG_ON(RB_EMPTY_NODE(&rq->rb_node));
315 rb_erase(&rq->rb_node, root);
316 RB_CLEAR_NODE(&rq->rb_node);
317}
318EXPORT_SYMBOL(elv_rb_del);
319
320struct request *elv_rb_find(struct rb_root *root, sector_t sector)
321{
322 struct rb_node *n = root->rb_node;
323 struct request *rq;
324
325 while (n) {
326 rq = rb_entry(n, struct request, rb_node);
327
328 if (sector < blk_rq_pos(rq))
329 n = n->rb_left;
330 else if (sector > blk_rq_pos(rq))
331 n = n->rb_right;
332 else
333 return rq;
334 }
335
336 return NULL;
337}
338EXPORT_SYMBOL(elv_rb_find);
339
340
341
342
343
344
345void elv_dispatch_sort(struct request_queue *q, struct request *rq)
346{
347 sector_t boundary;
348 struct list_head *entry;
349 int stop_flags;
350
351 if (q->last_merge == rq)
352 q->last_merge = NULL;
353
354 elv_rqhash_del(q, rq);
355
356 q->nr_sorted--;
357
358 boundary = q->end_sector;
359 stop_flags = REQ_SOFTBARRIER | REQ_STARTED;
360 list_for_each_prev(entry, &q->queue_head) {
361 struct request *pos = list_entry_rq(entry);
362
363 if ((rq->cmd_flags & REQ_DISCARD) !=
364 (pos->cmd_flags & REQ_DISCARD))
365 break;
366 if (rq_data_dir(rq) != rq_data_dir(pos))
367 break;
368 if (pos->cmd_flags & stop_flags)
369 break;
370 if (blk_rq_pos(rq) >= boundary) {
371 if (blk_rq_pos(pos) < boundary)
372 continue;
373 } else {
374 if (blk_rq_pos(pos) >= boundary)
375 break;
376 }
377 if (blk_rq_pos(rq) >= blk_rq_pos(pos))
378 break;
379 }
380
381 list_add(&rq->queuelist, entry);
382}
383EXPORT_SYMBOL(elv_dispatch_sort);
384
385
386
387
388
389
390void elv_dispatch_add_tail(struct request_queue *q, struct request *rq)
391{
392 if (q->last_merge == rq)
393 q->last_merge = NULL;
394
395 elv_rqhash_del(q, rq);
396
397 q->nr_sorted--;
398
399 q->end_sector = rq_end_sector(rq);
400 q->boundary_rq = rq;
401 list_add_tail(&rq->queuelist, &q->queue_head);
402}
403EXPORT_SYMBOL(elv_dispatch_add_tail);
404
405int elv_merge(struct request_queue *q, struct request **req, struct bio *bio)
406{
407 struct elevator_queue *e = q->elevator;
408 struct request *__rq;
409 int ret;
410
411
412
413
414
415
416
417 if (blk_queue_nomerges(q))
418 return ELEVATOR_NO_MERGE;
419
420
421
422
423 if (q->last_merge && elv_rq_merge_ok(q->last_merge, bio)) {
424 ret = blk_try_merge(q->last_merge, bio);
425 if (ret != ELEVATOR_NO_MERGE) {
426 *req = q->last_merge;
427 return ret;
428 }
429 }
430
431 if (blk_queue_noxmerges(q))
432 return ELEVATOR_NO_MERGE;
433
434
435
436
437 __rq = elv_rqhash_find(q, bio->bi_sector);
438 if (__rq && elv_rq_merge_ok(__rq, bio)) {
439 *req = __rq;
440 return ELEVATOR_BACK_MERGE;
441 }
442
443 if (e->type->ops.elevator_merge_fn)
444 return e->type->ops.elevator_merge_fn(q, req, bio);
445
446 return ELEVATOR_NO_MERGE;
447}
448
449
450
451
452
453
454
455
456static bool elv_attempt_insert_merge(struct request_queue *q,
457 struct request *rq)
458{
459 struct request *__rq;
460 bool ret;
461
462 if (blk_queue_nomerges(q))
463 return false;
464
465
466
467
468 if (q->last_merge && blk_attempt_req_merge(q, q->last_merge, rq))
469 return true;
470
471 if (blk_queue_noxmerges(q))
472 return false;
473
474 ret = false;
475
476
477
478 while (1) {
479 __rq = elv_rqhash_find(q, blk_rq_pos(rq));
480 if (!__rq || !blk_attempt_req_merge(q, __rq, rq))
481 break;
482
483
484 ret = true;
485 rq = __rq;
486 }
487
488 return ret;
489}
490
491void elv_merged_request(struct request_queue *q, struct request *rq, int type)
492{
493 struct elevator_queue *e = q->elevator;
494
495 if (e->type->ops.elevator_merged_fn)
496 e->type->ops.elevator_merged_fn(q, rq, type);
497
498 if (type == ELEVATOR_BACK_MERGE)
499 elv_rqhash_reposition(q, rq);
500
501 q->last_merge = rq;
502}
503
504void elv_merge_requests(struct request_queue *q, struct request *rq,
505 struct request *next)
506{
507 struct elevator_queue *e = q->elevator;
508 const int next_sorted = next->cmd_flags & REQ_SORTED;
509
510 if (next_sorted && e->type->ops.elevator_merge_req_fn)
511 e->type->ops.elevator_merge_req_fn(q, rq, next);
512
513 elv_rqhash_reposition(q, rq);
514
515 if (next_sorted) {
516 elv_rqhash_del(q, next);
517 q->nr_sorted--;
518 }
519
520 q->last_merge = rq;
521}
522
523void elv_bio_merged(struct request_queue *q, struct request *rq,
524 struct bio *bio)
525{
526 struct elevator_queue *e = q->elevator;
527
528 if (e->type->ops.elevator_bio_merged_fn)
529 e->type->ops.elevator_bio_merged_fn(q, rq, bio);
530}
531
532#ifdef CONFIG_PM_RUNTIME
533static void blk_pm_requeue_request(struct request *rq)
534{
535 if (rq->q->dev && !(rq->cmd_flags & REQ_PM))
536 rq->q->nr_pending--;
537}
538
539static void blk_pm_add_request(struct request_queue *q, struct request *rq)
540{
541 if (q->dev && !(rq->cmd_flags & REQ_PM) && q->nr_pending++ == 0 &&
542 (q->rpm_status == RPM_SUSPENDED || q->rpm_status == RPM_SUSPENDING))
543 pm_request_resume(q->dev);
544}
545#else
546static inline void blk_pm_requeue_request(struct request *rq) {}
547static inline void blk_pm_add_request(struct request_queue *q,
548 struct request *rq)
549{
550}
551#endif
552
553void elv_requeue_request(struct request_queue *q, struct request *rq)
554{
555
556
557
558
559 if (blk_account_rq(rq)) {
560 q->in_flight[rq_is_sync(rq)]--;
561 if (rq->cmd_flags & REQ_SORTED)
562 elv_deactivate_rq(q, rq);
563 }
564
565 rq->cmd_flags &= ~REQ_STARTED;
566
567 blk_pm_requeue_request(rq);
568
569 __elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE);
570}
571
572void elv_drain_elevator(struct request_queue *q)
573{
574 static int printed;
575
576 lockdep_assert_held(q->queue_lock);
577
578 while (q->elevator->type->ops.elevator_dispatch_fn(q, 1))
579 ;
580 if (q->nr_sorted && printed++ < 10) {
581 printk(KERN_ERR "%s: forced dispatching is broken "
582 "(nr_sorted=%u), please report this\n",
583 q->elevator->type->elevator_name, q->nr_sorted);
584 }
585}
586
587void __elv_add_request(struct request_queue *q, struct request *rq, int where)
588{
589 trace_block_rq_insert(q, rq);
590
591 blk_pm_add_request(q, rq);
592
593 rq->q = q;
594
595 if (rq->cmd_flags & REQ_SOFTBARRIER) {
596
597 if (rq->cmd_type == REQ_TYPE_FS) {
598 q->end_sector = rq_end_sector(rq);
599 q->boundary_rq = rq;
600 }
601 } else if (!(rq->cmd_flags & REQ_ELVPRIV) &&
602 (where == ELEVATOR_INSERT_SORT ||
603 where == ELEVATOR_INSERT_SORT_MERGE))
604 where = ELEVATOR_INSERT_BACK;
605
606 switch (where) {
607 case ELEVATOR_INSERT_REQUEUE:
608 case ELEVATOR_INSERT_FRONT:
609 rq->cmd_flags |= REQ_SOFTBARRIER;
610 list_add(&rq->queuelist, &q->queue_head);
611 break;
612
613 case ELEVATOR_INSERT_BACK:
614 rq->cmd_flags |= REQ_SOFTBARRIER;
615 elv_drain_elevator(q);
616 list_add_tail(&rq->queuelist, &q->queue_head);
617
618
619
620
621
622
623
624
625
626
627 __blk_run_queue(q);
628 break;
629
630 case ELEVATOR_INSERT_SORT_MERGE:
631
632
633
634
635
636 if (elv_attempt_insert_merge(q, rq))
637 break;
638 case ELEVATOR_INSERT_SORT:
639 BUG_ON(rq->cmd_type != REQ_TYPE_FS);
640 rq->cmd_flags |= REQ_SORTED;
641 q->nr_sorted++;
642 if (rq_mergeable(rq)) {
643 elv_rqhash_add(q, rq);
644 if (!q->last_merge)
645 q->last_merge = rq;
646 }
647
648
649
650
651
652
653 q->elevator->type->ops.elevator_add_req_fn(q, rq);
654 break;
655
656 case ELEVATOR_INSERT_FLUSH:
657 rq->cmd_flags |= REQ_SOFTBARRIER;
658 blk_insert_flush(rq);
659 break;
660 default:
661 printk(KERN_ERR "%s: bad insertion point %d\n",
662 __func__, where);
663 BUG();
664 }
665}
666EXPORT_SYMBOL(__elv_add_request);
667
668void elv_add_request(struct request_queue *q, struct request *rq, int where)
669{
670 unsigned long flags;
671
672 spin_lock_irqsave(q->queue_lock, flags);
673 __elv_add_request(q, rq, where);
674 spin_unlock_irqrestore(q->queue_lock, flags);
675}
676EXPORT_SYMBOL(elv_add_request);
677
678struct request *elv_latter_request(struct request_queue *q, struct request *rq)
679{
680 struct elevator_queue *e = q->elevator;
681
682 if (e->type->ops.elevator_latter_req_fn)
683 return e->type->ops.elevator_latter_req_fn(q, rq);
684 return NULL;
685}
686
687struct request *elv_former_request(struct request_queue *q, struct request *rq)
688{
689 struct elevator_queue *e = q->elevator;
690
691 if (e->type->ops.elevator_former_req_fn)
692 return e->type->ops.elevator_former_req_fn(q, rq);
693 return NULL;
694}
695
696int elv_set_request(struct request_queue *q, struct request *rq,
697 struct bio *bio, gfp_t gfp_mask)
698{
699 struct elevator_queue *e = q->elevator;
700
701 if (e->type->ops.elevator_set_req_fn)
702 return e->type->ops.elevator_set_req_fn(q, rq, bio, gfp_mask);
703 return 0;
704}
705
706void elv_put_request(struct request_queue *q, struct request *rq)
707{
708 struct elevator_queue *e = q->elevator;
709
710 if (e->type->ops.elevator_put_req_fn)
711 e->type->ops.elevator_put_req_fn(rq);
712}
713
714int elv_may_queue(struct request_queue *q, int rw)
715{
716 struct elevator_queue *e = q->elevator;
717
718 if (e->type->ops.elevator_may_queue_fn)
719 return e->type->ops.elevator_may_queue_fn(q, rw);
720
721 return ELV_MQUEUE_MAY;
722}
723
724void elv_abort_queue(struct request_queue *q)
725{
726 struct request *rq;
727
728 blk_abort_flushes(q);
729
730 while (!list_empty(&q->queue_head)) {
731 rq = list_entry_rq(q->queue_head.next);
732 rq->cmd_flags |= REQ_QUIET;
733 trace_block_rq_abort(q, rq);
734
735
736
737
738 blk_start_request(rq);
739 __blk_end_request_all(rq, -EIO);
740 }
741}
742EXPORT_SYMBOL(elv_abort_queue);
743
744void elv_completed_request(struct request_queue *q, struct request *rq)
745{
746 struct elevator_queue *e = q->elevator;
747
748
749
750
751 if (blk_account_rq(rq)) {
752 q->in_flight[rq_is_sync(rq)]--;
753 if ((rq->cmd_flags & REQ_SORTED) &&
754 e->type->ops.elevator_completed_req_fn)
755 e->type->ops.elevator_completed_req_fn(q, rq);
756 }
757}
758
759#define to_elv(atr) container_of((atr), struct elv_fs_entry, attr)
760
761static ssize_t
762elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
763{
764 struct elv_fs_entry *entry = to_elv(attr);
765 struct elevator_queue *e;
766 ssize_t error;
767
768 if (!entry->show)
769 return -EIO;
770
771 e = container_of(kobj, struct elevator_queue, kobj);
772 mutex_lock(&e->sysfs_lock);
773 error = e->type ? entry->show(e, page) : -ENOENT;
774 mutex_unlock(&e->sysfs_lock);
775 return error;
776}
777
778static ssize_t
779elv_attr_store(struct kobject *kobj, struct attribute *attr,
780 const char *page, size_t length)
781{
782 struct elv_fs_entry *entry = to_elv(attr);
783 struct elevator_queue *e;
784 ssize_t error;
785
786 if (!entry->store)
787 return -EIO;
788
789 e = container_of(kobj, struct elevator_queue, kobj);
790 mutex_lock(&e->sysfs_lock);
791 error = e->type ? entry->store(e, page, length) : -ENOENT;
792 mutex_unlock(&e->sysfs_lock);
793 return error;
794}
795
796static const struct sysfs_ops elv_sysfs_ops = {
797 .show = elv_attr_show,
798 .store = elv_attr_store,
799};
800
801static struct kobj_type elv_ktype = {
802 .sysfs_ops = &elv_sysfs_ops,
803 .release = elevator_release,
804};
805
806int elv_register_queue(struct request_queue *q)
807{
808 struct elevator_queue *e = q->elevator;
809 int error;
810
811 error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched");
812 if (!error) {
813 struct elv_fs_entry *attr = e->type->elevator_attrs;
814 if (attr) {
815 while (attr->attr.name) {
816 if (sysfs_create_file(&e->kobj, &attr->attr))
817 break;
818 attr++;
819 }
820 }
821 kobject_uevent(&e->kobj, KOBJ_ADD);
822 e->registered = 1;
823 }
824 return error;
825}
826EXPORT_SYMBOL(elv_register_queue);
827
828void elv_unregister_queue(struct request_queue *q)
829{
830 if (q) {
831 struct elevator_queue *e = q->elevator;
832
833 kobject_uevent(&e->kobj, KOBJ_REMOVE);
834 kobject_del(&e->kobj);
835 e->registered = 0;
836 }
837}
838EXPORT_SYMBOL(elv_unregister_queue);
839
840int elv_register(struct elevator_type *e)
841{
842 char *def = "";
843
844
845 if (e->icq_size) {
846 if (WARN_ON(e->icq_size < sizeof(struct io_cq)) ||
847 WARN_ON(e->icq_align < __alignof__(struct io_cq)))
848 return -EINVAL;
849
850 snprintf(e->icq_cache_name, sizeof(e->icq_cache_name),
851 "%s_io_cq", e->elevator_name);
852 e->icq_cache = kmem_cache_create(e->icq_cache_name, e->icq_size,
853 e->icq_align, 0, NULL);
854 if (!e->icq_cache)
855 return -ENOMEM;
856 }
857
858
859 spin_lock(&elv_list_lock);
860 if (elevator_find(e->elevator_name)) {
861 spin_unlock(&elv_list_lock);
862 if (e->icq_cache)
863 kmem_cache_destroy(e->icq_cache);
864 return -EBUSY;
865 }
866 list_add_tail(&e->list, &elv_list);
867 spin_unlock(&elv_list_lock);
868
869
870 if (!strcmp(e->elevator_name, chosen_elevator) ||
871 (!*chosen_elevator &&
872 !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED)))
873 def = " (default)";
874
875 printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name,
876 def);
877 return 0;
878}
879EXPORT_SYMBOL_GPL(elv_register);
880
881void elv_unregister(struct elevator_type *e)
882{
883
884 spin_lock(&elv_list_lock);
885 list_del_init(&e->list);
886 spin_unlock(&elv_list_lock);
887
888
889
890
891
892 if (e->icq_cache) {
893 rcu_barrier();
894 kmem_cache_destroy(e->icq_cache);
895 e->icq_cache = NULL;
896 }
897}
898EXPORT_SYMBOL_GPL(elv_unregister);
899
900
901
902
903
904
905
906static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
907{
908 struct elevator_queue *old = q->elevator;
909 bool registered = old->registered;
910 int err;
911
912
913
914
915
916
917
918
919 blk_queue_bypass_start(q);
920
921
922 if (registered)
923 elv_unregister_queue(q);
924
925 spin_lock_irq(q->queue_lock);
926 ioc_clear_queue(q);
927 spin_unlock_irq(q->queue_lock);
928
929
930 err = new_e->ops.elevator_init_fn(q, new_e);
931 if (err)
932 goto fail_init;
933
934 if (registered) {
935 err = elv_register_queue(q);
936 if (err)
937 goto fail_register;
938 }
939
940
941 elevator_exit(old);
942 blk_queue_bypass_end(q);
943
944 blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name);
945
946 return 0;
947
948fail_register:
949 elevator_exit(q->elevator);
950fail_init:
951
952 q->elevator = old;
953 elv_register_queue(q);
954 blk_queue_bypass_end(q);
955
956 return err;
957}
958
959
960
961
962int elevator_change(struct request_queue *q, const char *name)
963{
964 char elevator_name[ELV_NAME_MAX];
965 struct elevator_type *e;
966
967 if (!q->elevator)
968 return -ENXIO;
969
970 strlcpy(elevator_name, name, sizeof(elevator_name));
971 e = elevator_get(strstrip(elevator_name), true);
972 if (!e) {
973 printk(KERN_ERR "elevator: type %s not found\n", elevator_name);
974 return -EINVAL;
975 }
976
977 if (!strcmp(elevator_name, q->elevator->type->elevator_name)) {
978 elevator_put(e);
979 return 0;
980 }
981
982 return elevator_switch(q, e);
983}
984EXPORT_SYMBOL(elevator_change);
985
986ssize_t elv_iosched_store(struct request_queue *q, const char *name,
987 size_t count)
988{
989 int ret;
990
991 if (!q->elevator)
992 return count;
993
994 ret = elevator_change(q, name);
995 if (!ret)
996 return count;
997
998 printk(KERN_ERR "elevator: switch to %s failed\n", name);
999 return ret;
1000}
1001
1002ssize_t elv_iosched_show(struct request_queue *q, char *name)
1003{
1004 struct elevator_queue *e = q->elevator;
1005 struct elevator_type *elv;
1006 struct elevator_type *__e;
1007 int len = 0;
1008
1009 if (!q->elevator || !blk_queue_stackable(q))
1010 return sprintf(name, "none\n");
1011
1012 elv = e->type;
1013
1014 spin_lock(&elv_list_lock);
1015 list_for_each_entry(__e, &elv_list, list) {
1016 if (!strcmp(elv->elevator_name, __e->elevator_name))
1017 len += sprintf(name+len, "[%s] ", elv->elevator_name);
1018 else
1019 len += sprintf(name+len, "%s ", __e->elevator_name);
1020 }
1021 spin_unlock(&elv_list_lock);
1022
1023 len += sprintf(len+name, "\n");
1024 return len;
1025}
1026
1027struct request *elv_rb_former_request(struct request_queue *q,
1028 struct request *rq)
1029{
1030 struct rb_node *rbprev = rb_prev(&rq->rb_node);
1031
1032 if (rbprev)
1033 return rb_entry_rq(rbprev);
1034
1035 return NULL;
1036}
1037EXPORT_SYMBOL(elv_rb_former_request);
1038
1039struct request *elv_rb_latter_request(struct request_queue *q,
1040 struct request *rq)
1041{
1042 struct rb_node *rbnext = rb_next(&rq->rb_node);
1043
1044 if (rbnext)
1045 return rb_entry_rq(rbnext);
1046
1047 return NULL;
1048}
1049EXPORT_SYMBOL(elv_rb_latter_request);
1050