[PATCH] usb wifi: zd1201 cleanups
[linux-2.6/mini2440.git] / block / elevator.c
blob8768a367fdded922a17b1c7c47ac24ec993a1628
1 /*
2 * Block device elevator/IO-scheduler.
4 * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
6 * 30042000 Jens Axboe <axboe@suse.de> :
8 * Split the elevator a bit so that it is possible to choose a different
9 * one or even write a new "plug in". There are three pieces:
10 * - elevator_fn, inserts a new request in the queue list
11 * - elevator_merge_fn, decides whether a new buffer can be merged with
12 * an existing request
13 * - elevator_dequeue_fn, called when a request is taken off the active list
15 * 20082000 Dave Jones <davej@suse.de> :
16 * Removed tests for max-bomb-segments, which was breaking elvtune
17 * when run without -bN
19 * Jens:
20 * - Rework again to work with bio instead of buffer_heads
21 * - loose bi_dev comparisons, partition handling is right now
22 * - completely modularize elevator setup and teardown
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/config.h>
31 #include <linux/module.h>
32 #include <linux/slab.h>
33 #include <linux/init.h>
34 #include <linux/compiler.h>
35 #include <linux/delay.h>
36 #include <linux/blktrace_api.h>
38 #include <asm/uaccess.h>
40 static DEFINE_SPINLOCK(elv_list_lock);
41 static LIST_HEAD(elv_list);
44 * can we safely merge with this request?
46 inline int elv_rq_merge_ok(struct request *rq, struct bio *bio)
48 if (!rq_mergeable(rq))
49 return 0;
52 * different data direction or already started, don't merge
54 if (bio_data_dir(bio) != rq_data_dir(rq))
55 return 0;
58 * same device and no special stuff set, merge is ok
60 if (rq->rq_disk == bio->bi_bdev->bd_disk &&
61 !rq->waiting && !rq->special)
62 return 1;
64 return 0;
66 EXPORT_SYMBOL(elv_rq_merge_ok);
68 static inline int elv_try_merge(struct request *__rq, struct bio *bio)
70 int ret = ELEVATOR_NO_MERGE;
73 * we can merge and sequence is ok, check if it's possible
75 if (elv_rq_merge_ok(__rq, bio)) {
76 if (__rq->sector + __rq->nr_sectors == bio->bi_sector)
77 ret = ELEVATOR_BACK_MERGE;
78 else if (__rq->sector - bio_sectors(bio) == bio->bi_sector)
79 ret = ELEVATOR_FRONT_MERGE;
82 return ret;
85 static struct elevator_type *elevator_find(const char *name)
87 struct elevator_type *e = NULL;
88 struct list_head *entry;
90 list_for_each(entry, &elv_list) {
91 struct elevator_type *__e;
93 __e = list_entry(entry, struct elevator_type, list);
95 if (!strcmp(__e->elevator_name, name)) {
96 e = __e;
97 break;
101 return e;
104 static void elevator_put(struct elevator_type *e)
106 module_put(e->elevator_owner);
109 static struct elevator_type *elevator_get(const char *name)
111 struct elevator_type *e;
113 spin_lock_irq(&elv_list_lock);
115 e = elevator_find(name);
116 if (e && !try_module_get(e->elevator_owner))
117 e = NULL;
119 spin_unlock_irq(&elv_list_lock);
121 return e;
124 static int elevator_attach(request_queue_t *q, struct elevator_queue *eq)
126 int ret = 0;
128 q->elevator = eq;
130 if (eq->ops->elevator_init_fn)
131 ret = eq->ops->elevator_init_fn(q, eq);
133 return ret;
136 static char chosen_elevator[16];
138 static int __init elevator_setup(char *str)
141 * Be backwards-compatible with previous kernels, so users
142 * won't get the wrong elevator.
144 if (!strcmp(str, "as"))
145 strcpy(chosen_elevator, "anticipatory");
146 else
147 strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1);
148 return 1;
151 __setup("elevator=", elevator_setup);
153 static struct kobj_type elv_ktype;
155 static elevator_t *elevator_alloc(struct elevator_type *e)
157 elevator_t *eq = kmalloc(sizeof(elevator_t), GFP_KERNEL);
158 if (eq) {
159 memset(eq, 0, sizeof(*eq));
160 eq->ops = &e->ops;
161 eq->elevator_type = e;
162 kobject_init(&eq->kobj);
163 snprintf(eq->kobj.name, KOBJ_NAME_LEN, "%s", "iosched");
164 eq->kobj.ktype = &elv_ktype;
165 mutex_init(&eq->sysfs_lock);
166 } else {
167 elevator_put(e);
169 return eq;
172 static void elevator_release(struct kobject *kobj)
174 elevator_t *e = container_of(kobj, elevator_t, kobj);
175 elevator_put(e->elevator_type);
176 kfree(e);
179 int elevator_init(request_queue_t *q, char *name)
181 struct elevator_type *e = NULL;
182 struct elevator_queue *eq;
183 int ret = 0;
185 INIT_LIST_HEAD(&q->queue_head);
186 q->last_merge = NULL;
187 q->end_sector = 0;
188 q->boundary_rq = NULL;
190 if (name && !(e = elevator_get(name)))
191 return -EINVAL;
193 if (!e && *chosen_elevator && !(e = elevator_get(chosen_elevator)))
194 printk("I/O scheduler %s not found\n", chosen_elevator);
196 if (!e && !(e = elevator_get(CONFIG_DEFAULT_IOSCHED))) {
197 printk("Default I/O scheduler not found, using no-op\n");
198 e = elevator_get("noop");
201 eq = elevator_alloc(e);
202 if (!eq)
203 return -ENOMEM;
205 ret = elevator_attach(q, eq);
206 if (ret)
207 kobject_put(&eq->kobj);
209 return ret;
212 void elevator_exit(elevator_t *e)
214 mutex_lock(&e->sysfs_lock);
215 if (e->ops->elevator_exit_fn)
216 e->ops->elevator_exit_fn(e);
217 e->ops = NULL;
218 mutex_unlock(&e->sysfs_lock);
220 kobject_put(&e->kobj);
224 * Insert rq into dispatch queue of q. Queue lock must be held on
225 * entry. If sort != 0, rq is sort-inserted; otherwise, rq will be
226 * appended to the dispatch queue. To be used by specific elevators.
228 void elv_dispatch_sort(request_queue_t *q, struct request *rq)
230 sector_t boundary;
231 struct list_head *entry;
233 if (q->last_merge == rq)
234 q->last_merge = NULL;
235 q->nr_sorted--;
237 boundary = q->end_sector;
239 list_for_each_prev(entry, &q->queue_head) {
240 struct request *pos = list_entry_rq(entry);
242 if (pos->flags & (REQ_SOFTBARRIER|REQ_HARDBARRIER|REQ_STARTED))
243 break;
244 if (rq->sector >= boundary) {
245 if (pos->sector < boundary)
246 continue;
247 } else {
248 if (pos->sector >= boundary)
249 break;
251 if (rq->sector >= pos->sector)
252 break;
255 list_add(&rq->queuelist, entry);
258 int elv_merge(request_queue_t *q, struct request **req, struct bio *bio)
260 elevator_t *e = q->elevator;
261 int ret;
263 if (q->last_merge) {
264 ret = elv_try_merge(q->last_merge, bio);
265 if (ret != ELEVATOR_NO_MERGE) {
266 *req = q->last_merge;
267 return ret;
271 if (e->ops->elevator_merge_fn)
272 return e->ops->elevator_merge_fn(q, req, bio);
274 return ELEVATOR_NO_MERGE;
277 void elv_merged_request(request_queue_t *q, struct request *rq)
279 elevator_t *e = q->elevator;
281 if (e->ops->elevator_merged_fn)
282 e->ops->elevator_merged_fn(q, rq);
284 q->last_merge = rq;
287 void elv_merge_requests(request_queue_t *q, struct request *rq,
288 struct request *next)
290 elevator_t *e = q->elevator;
292 if (e->ops->elevator_merge_req_fn)
293 e->ops->elevator_merge_req_fn(q, rq, next);
294 q->nr_sorted--;
296 q->last_merge = rq;
299 void elv_requeue_request(request_queue_t *q, struct request *rq)
301 elevator_t *e = q->elevator;
304 * it already went through dequeue, we need to decrement the
305 * in_flight count again
307 if (blk_account_rq(rq)) {
308 q->in_flight--;
309 if (blk_sorted_rq(rq) && e->ops->elevator_deactivate_req_fn)
310 e->ops->elevator_deactivate_req_fn(q, rq);
313 rq->flags &= ~REQ_STARTED;
315 elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE);
318 static void elv_drain_elevator(request_queue_t *q)
320 static int printed;
321 while (q->elevator->ops->elevator_dispatch_fn(q, 1))
323 if (q->nr_sorted == 0)
324 return;
325 if (printed++ < 10) {
326 printk(KERN_ERR "%s: forced dispatching is broken "
327 "(nr_sorted=%u), please report this\n",
328 q->elevator->elevator_type->elevator_name, q->nr_sorted);
332 void elv_insert(request_queue_t *q, struct request *rq, int where)
334 struct list_head *pos;
335 unsigned ordseq;
336 int unplug_it = 1;
338 blk_add_trace_rq(q, rq, BLK_TA_INSERT);
340 rq->q = q;
342 switch (where) {
343 case ELEVATOR_INSERT_FRONT:
344 rq->flags |= REQ_SOFTBARRIER;
346 list_add(&rq->queuelist, &q->queue_head);
347 break;
349 case ELEVATOR_INSERT_BACK:
350 rq->flags |= REQ_SOFTBARRIER;
351 elv_drain_elevator(q);
352 list_add_tail(&rq->queuelist, &q->queue_head);
354 * We kick the queue here for the following reasons.
355 * - The elevator might have returned NULL previously
356 * to delay requests and returned them now. As the
357 * queue wasn't empty before this request, ll_rw_blk
358 * won't run the queue on return, resulting in hang.
359 * - Usually, back inserted requests won't be merged
360 * with anything. There's no point in delaying queue
361 * processing.
363 blk_remove_plug(q);
364 q->request_fn(q);
365 break;
367 case ELEVATOR_INSERT_SORT:
368 BUG_ON(!blk_fs_request(rq));
369 rq->flags |= REQ_SORTED;
370 q->nr_sorted++;
371 if (q->last_merge == NULL && rq_mergeable(rq))
372 q->last_merge = rq;
374 * Some ioscheds (cfq) run q->request_fn directly, so
375 * rq cannot be accessed after calling
376 * elevator_add_req_fn.
378 q->elevator->ops->elevator_add_req_fn(q, rq);
379 break;
381 case ELEVATOR_INSERT_REQUEUE:
383 * If ordered flush isn't in progress, we do front
384 * insertion; otherwise, requests should be requeued
385 * in ordseq order.
387 rq->flags |= REQ_SOFTBARRIER;
389 if (q->ordseq == 0) {
390 list_add(&rq->queuelist, &q->queue_head);
391 break;
394 ordseq = blk_ordered_req_seq(rq);
396 list_for_each(pos, &q->queue_head) {
397 struct request *pos_rq = list_entry_rq(pos);
398 if (ordseq <= blk_ordered_req_seq(pos_rq))
399 break;
402 list_add_tail(&rq->queuelist, pos);
404 * most requeues happen because of a busy condition, don't
405 * force unplug of the queue for that case.
407 unplug_it = 0;
408 break;
410 default:
411 printk(KERN_ERR "%s: bad insertion point %d\n",
412 __FUNCTION__, where);
413 BUG();
416 if (unplug_it && blk_queue_plugged(q)) {
417 int nrq = q->rq.count[READ] + q->rq.count[WRITE]
418 - q->in_flight;
420 if (nrq >= q->unplug_thresh)
421 __generic_unplug_device(q);
425 void __elv_add_request(request_queue_t *q, struct request *rq, int where,
426 int plug)
428 if (q->ordcolor)
429 rq->flags |= REQ_ORDERED_COLOR;
431 if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) {
433 * toggle ordered color
435 if (blk_barrier_rq(rq))
436 q->ordcolor ^= 1;
439 * barriers implicitly indicate back insertion
441 if (where == ELEVATOR_INSERT_SORT)
442 where = ELEVATOR_INSERT_BACK;
445 * this request is scheduling boundary, update
446 * end_sector
448 if (blk_fs_request(rq)) {
449 q->end_sector = rq_end_sector(rq);
450 q->boundary_rq = rq;
452 } else if (!(rq->flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT)
453 where = ELEVATOR_INSERT_BACK;
455 if (plug)
456 blk_plug_device(q);
458 elv_insert(q, rq, where);
461 void elv_add_request(request_queue_t *q, struct request *rq, int where,
462 int plug)
464 unsigned long flags;
466 spin_lock_irqsave(q->queue_lock, flags);
467 __elv_add_request(q, rq, where, plug);
468 spin_unlock_irqrestore(q->queue_lock, flags);
471 static inline struct request *__elv_next_request(request_queue_t *q)
473 struct request *rq;
475 while (1) {
476 while (!list_empty(&q->queue_head)) {
477 rq = list_entry_rq(q->queue_head.next);
478 if (blk_do_ordered(q, &rq))
479 return rq;
482 if (!q->elevator->ops->elevator_dispatch_fn(q, 0))
483 return NULL;
487 struct request *elv_next_request(request_queue_t *q)
489 struct request *rq;
490 int ret;
492 while ((rq = __elv_next_request(q)) != NULL) {
493 if (!(rq->flags & REQ_STARTED)) {
494 elevator_t *e = q->elevator;
497 * This is the first time the device driver
498 * sees this request (possibly after
499 * requeueing). Notify IO scheduler.
501 if (blk_sorted_rq(rq) &&
502 e->ops->elevator_activate_req_fn)
503 e->ops->elevator_activate_req_fn(q, rq);
506 * just mark as started even if we don't start
507 * it, a request that has been delayed should
508 * not be passed by new incoming requests
510 rq->flags |= REQ_STARTED;
511 blk_add_trace_rq(q, rq, BLK_TA_ISSUE);
514 if (!q->boundary_rq || q->boundary_rq == rq) {
515 q->end_sector = rq_end_sector(rq);
516 q->boundary_rq = NULL;
519 if ((rq->flags & REQ_DONTPREP) || !q->prep_rq_fn)
520 break;
522 ret = q->prep_rq_fn(q, rq);
523 if (ret == BLKPREP_OK) {
524 break;
525 } else if (ret == BLKPREP_DEFER) {
527 * the request may have been (partially) prepped.
528 * we need to keep this request in the front to
529 * avoid resource deadlock. REQ_STARTED will
530 * prevent other fs requests from passing this one.
532 rq = NULL;
533 break;
534 } else if (ret == BLKPREP_KILL) {
535 int nr_bytes = rq->hard_nr_sectors << 9;
537 if (!nr_bytes)
538 nr_bytes = rq->data_len;
540 blkdev_dequeue_request(rq);
541 rq->flags |= REQ_QUIET;
542 end_that_request_chunk(rq, 0, nr_bytes);
543 end_that_request_last(rq, 0);
544 } else {
545 printk(KERN_ERR "%s: bad return=%d\n", __FUNCTION__,
546 ret);
547 break;
551 return rq;
554 void elv_dequeue_request(request_queue_t *q, struct request *rq)
556 BUG_ON(list_empty(&rq->queuelist));
558 list_del_init(&rq->queuelist);
561 * the time frame between a request being removed from the lists
562 * and to it is freed is accounted as io that is in progress at
563 * the driver side.
565 if (blk_account_rq(rq))
566 q->in_flight++;
569 int elv_queue_empty(request_queue_t *q)
571 elevator_t *e = q->elevator;
573 if (!list_empty(&q->queue_head))
574 return 0;
576 if (e->ops->elevator_queue_empty_fn)
577 return e->ops->elevator_queue_empty_fn(q);
579 return 1;
582 struct request *elv_latter_request(request_queue_t *q, struct request *rq)
584 elevator_t *e = q->elevator;
586 if (e->ops->elevator_latter_req_fn)
587 return e->ops->elevator_latter_req_fn(q, rq);
588 return NULL;
591 struct request *elv_former_request(request_queue_t *q, struct request *rq)
593 elevator_t *e = q->elevator;
595 if (e->ops->elevator_former_req_fn)
596 return e->ops->elevator_former_req_fn(q, rq);
597 return NULL;
600 int elv_set_request(request_queue_t *q, struct request *rq, struct bio *bio,
601 gfp_t gfp_mask)
603 elevator_t *e = q->elevator;
605 if (e->ops->elevator_set_req_fn)
606 return e->ops->elevator_set_req_fn(q, rq, bio, gfp_mask);
608 rq->elevator_private = NULL;
609 return 0;
612 void elv_put_request(request_queue_t *q, struct request *rq)
614 elevator_t *e = q->elevator;
616 if (e->ops->elevator_put_req_fn)
617 e->ops->elevator_put_req_fn(q, rq);
620 int elv_may_queue(request_queue_t *q, int rw, struct bio *bio)
622 elevator_t *e = q->elevator;
624 if (e->ops->elevator_may_queue_fn)
625 return e->ops->elevator_may_queue_fn(q, rw, bio);
627 return ELV_MQUEUE_MAY;
630 void elv_completed_request(request_queue_t *q, struct request *rq)
632 elevator_t *e = q->elevator;
635 * request is released from the driver, io must be done
637 if (blk_account_rq(rq)) {
638 q->in_flight--;
639 if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn)
640 e->ops->elevator_completed_req_fn(q, rq);
644 * Check if the queue is waiting for fs requests to be
645 * drained for flush sequence.
647 if (unlikely(q->ordseq)) {
648 struct request *first_rq = list_entry_rq(q->queue_head.next);
649 if (q->in_flight == 0 &&
650 blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN &&
651 blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) {
652 blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0);
653 q->request_fn(q);
658 #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr)
660 static ssize_t
661 elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
663 elevator_t *e = container_of(kobj, elevator_t, kobj);
664 struct elv_fs_entry *entry = to_elv(attr);
665 ssize_t error;
667 if (!entry->show)
668 return -EIO;
670 mutex_lock(&e->sysfs_lock);
671 error = e->ops ? entry->show(e, page) : -ENOENT;
672 mutex_unlock(&e->sysfs_lock);
673 return error;
676 static ssize_t
677 elv_attr_store(struct kobject *kobj, struct attribute *attr,
678 const char *page, size_t length)
680 elevator_t *e = container_of(kobj, elevator_t, kobj);
681 struct elv_fs_entry *entry = to_elv(attr);
682 ssize_t error;
684 if (!entry->store)
685 return -EIO;
687 mutex_lock(&e->sysfs_lock);
688 error = e->ops ? entry->store(e, page, length) : -ENOENT;
689 mutex_unlock(&e->sysfs_lock);
690 return error;
693 static struct sysfs_ops elv_sysfs_ops = {
694 .show = elv_attr_show,
695 .store = elv_attr_store,
698 static struct kobj_type elv_ktype = {
699 .sysfs_ops = &elv_sysfs_ops,
700 .release = elevator_release,
703 int elv_register_queue(struct request_queue *q)
705 elevator_t *e = q->elevator;
706 int error;
708 e->kobj.parent = &q->kobj;
710 error = kobject_add(&e->kobj);
711 if (!error) {
712 struct elv_fs_entry *attr = e->elevator_type->elevator_attrs;
713 if (attr) {
714 while (attr->attr.name) {
715 if (sysfs_create_file(&e->kobj, &attr->attr))
716 break;
717 attr++;
720 kobject_uevent(&e->kobj, KOBJ_ADD);
722 return error;
725 void elv_unregister_queue(struct request_queue *q)
727 if (q) {
728 elevator_t *e = q->elevator;
729 kobject_uevent(&e->kobj, KOBJ_REMOVE);
730 kobject_del(&e->kobj);
734 int elv_register(struct elevator_type *e)
736 spin_lock_irq(&elv_list_lock);
737 BUG_ON(elevator_find(e->elevator_name));
738 list_add_tail(&e->list, &elv_list);
739 spin_unlock_irq(&elv_list_lock);
741 printk(KERN_INFO "io scheduler %s registered", e->elevator_name);
742 if (!strcmp(e->elevator_name, chosen_elevator) ||
743 (!*chosen_elevator &&
744 !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED)))
745 printk(" (default)");
746 printk("\n");
747 return 0;
749 EXPORT_SYMBOL_GPL(elv_register);
751 void elv_unregister(struct elevator_type *e)
753 struct task_struct *g, *p;
756 * Iterate every thread in the process to remove the io contexts.
758 if (e->ops.trim) {
759 read_lock(&tasklist_lock);
760 do_each_thread(g, p) {
761 task_lock(p);
762 e->ops.trim(p->io_context);
763 task_unlock(p);
764 } while_each_thread(g, p);
765 read_unlock(&tasklist_lock);
768 spin_lock_irq(&elv_list_lock);
769 list_del_init(&e->list);
770 spin_unlock_irq(&elv_list_lock);
772 EXPORT_SYMBOL_GPL(elv_unregister);
775 * switch to new_e io scheduler. be careful not to introduce deadlocks -
776 * we don't free the old io scheduler, before we have allocated what we
777 * need for the new one. this way we have a chance of going back to the old
778 * one, if the new one fails init for some reason.
780 static int elevator_switch(request_queue_t *q, struct elevator_type *new_e)
782 elevator_t *old_elevator, *e;
785 * Allocate new elevator
787 e = elevator_alloc(new_e);
788 if (!e)
789 return 0;
792 * Turn on BYPASS and drain all requests w/ elevator private data
794 spin_lock_irq(q->queue_lock);
796 set_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
798 elv_drain_elevator(q);
800 while (q->rq.elvpriv) {
801 blk_remove_plug(q);
802 q->request_fn(q);
803 spin_unlock_irq(q->queue_lock);
804 msleep(10);
805 spin_lock_irq(q->queue_lock);
806 elv_drain_elevator(q);
809 spin_unlock_irq(q->queue_lock);
812 * unregister old elevator data
814 elv_unregister_queue(q);
815 old_elevator = q->elevator;
818 * attach and start new elevator
820 if (elevator_attach(q, e))
821 goto fail;
823 if (elv_register_queue(q))
824 goto fail_register;
827 * finally exit old elevator and turn off BYPASS.
829 elevator_exit(old_elevator);
830 clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
831 return 1;
833 fail_register:
835 * switch failed, exit the new io scheduler and reattach the old
836 * one again (along with re-adding the sysfs dir)
838 elevator_exit(e);
839 e = NULL;
840 fail:
841 q->elevator = old_elevator;
842 elv_register_queue(q);
843 clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
844 if (e)
845 kobject_put(&e->kobj);
846 return 0;
849 ssize_t elv_iosched_store(request_queue_t *q, const char *name, size_t count)
851 char elevator_name[ELV_NAME_MAX];
852 size_t len;
853 struct elevator_type *e;
855 elevator_name[sizeof(elevator_name) - 1] = '\0';
856 strncpy(elevator_name, name, sizeof(elevator_name) - 1);
857 len = strlen(elevator_name);
859 if (len && elevator_name[len - 1] == '\n')
860 elevator_name[len - 1] = '\0';
862 e = elevator_get(elevator_name);
863 if (!e) {
864 printk(KERN_ERR "elevator: type %s not found\n", elevator_name);
865 return -EINVAL;
868 if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) {
869 elevator_put(e);
870 return count;
873 if (!elevator_switch(q, e))
874 printk(KERN_ERR "elevator: switch to %s failed\n",elevator_name);
875 return count;
878 ssize_t elv_iosched_show(request_queue_t *q, char *name)
880 elevator_t *e = q->elevator;
881 struct elevator_type *elv = e->elevator_type;
882 struct list_head *entry;
883 int len = 0;
885 spin_lock_irq(q->queue_lock);
886 list_for_each(entry, &elv_list) {
887 struct elevator_type *__e;
889 __e = list_entry(entry, struct elevator_type, list);
890 if (!strcmp(elv->elevator_name, __e->elevator_name))
891 len += sprintf(name+len, "[%s] ", elv->elevator_name);
892 else
893 len += sprintf(name+len, "%s ", __e->elevator_name);
895 spin_unlock_irq(q->queue_lock);
897 len += sprintf(len+name, "\n");
898 return len;
901 EXPORT_SYMBOL(elv_dispatch_sort);
902 EXPORT_SYMBOL(elv_add_request);
903 EXPORT_SYMBOL(__elv_add_request);
904 EXPORT_SYMBOL(elv_next_request);
905 EXPORT_SYMBOL(elv_dequeue_request);
906 EXPORT_SYMBOL(elv_queue_empty);
907 EXPORT_SYMBOL(elevator_exit);
908 EXPORT_SYMBOL(elevator_init);