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901 lines
20 KiB
C
901 lines
20 KiB
C
/*
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* Block device elevator/IO-scheduler.
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*
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* Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
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*
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* 30042000 Jens Axboe <axboe@suse.de> :
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*
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* Split the elevator a bit so that it is possible to choose a different
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* one or even write a new "plug in". There are three pieces:
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* - elevator_fn, inserts a new request in the queue list
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* - elevator_merge_fn, decides whether a new buffer can be merged with
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* an existing request
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* - elevator_dequeue_fn, called when a request is taken off the active list
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*
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* 20082000 Dave Jones <davej@suse.de> :
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* Removed tests for max-bomb-segments, which was breaking elvtune
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* when run without -bN
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*
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* Jens:
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* - Rework again to work with bio instead of buffer_heads
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* - loose bi_dev comparisons, partition handling is right now
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* - completely modularize elevator setup and teardown
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*
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*/
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#include <linux/kernel.h>
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#include <linux/fs.h>
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#include <linux/blkdev.h>
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#include <linux/elevator.h>
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#include <linux/bio.h>
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#include <linux/config.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/compiler.h>
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#include <linux/delay.h>
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#include <asm/uaccess.h>
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static DEFINE_SPINLOCK(elv_list_lock);
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static LIST_HEAD(elv_list);
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/*
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* can we safely merge with this request?
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*/
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inline int elv_rq_merge_ok(struct request *rq, struct bio *bio)
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{
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if (!rq_mergeable(rq))
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return 0;
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/*
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* different data direction or already started, don't merge
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*/
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if (bio_data_dir(bio) != rq_data_dir(rq))
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return 0;
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/*
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* same device and no special stuff set, merge is ok
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*/
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if (rq->rq_disk == bio->bi_bdev->bd_disk &&
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!rq->waiting && !rq->special)
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return 1;
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return 0;
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}
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EXPORT_SYMBOL(elv_rq_merge_ok);
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static inline int elv_try_merge(struct request *__rq, struct bio *bio)
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{
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int ret = ELEVATOR_NO_MERGE;
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/*
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* we can merge and sequence is ok, check if it's possible
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*/
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if (elv_rq_merge_ok(__rq, bio)) {
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if (__rq->sector + __rq->nr_sectors == bio->bi_sector)
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ret = ELEVATOR_BACK_MERGE;
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else if (__rq->sector - bio_sectors(bio) == bio->bi_sector)
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ret = ELEVATOR_FRONT_MERGE;
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}
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return ret;
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}
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static struct elevator_type *elevator_find(const char *name)
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{
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struct elevator_type *e = NULL;
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struct list_head *entry;
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list_for_each(entry, &elv_list) {
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struct elevator_type *__e;
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__e = list_entry(entry, struct elevator_type, list);
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if (!strcmp(__e->elevator_name, name)) {
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e = __e;
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break;
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}
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}
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return e;
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}
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static void elevator_put(struct elevator_type *e)
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{
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module_put(e->elevator_owner);
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}
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static struct elevator_type *elevator_get(const char *name)
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{
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struct elevator_type *e;
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spin_lock_irq(&elv_list_lock);
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e = elevator_find(name);
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if (e && !try_module_get(e->elevator_owner))
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e = NULL;
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spin_unlock_irq(&elv_list_lock);
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return e;
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}
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static int elevator_attach(request_queue_t *q, struct elevator_queue *eq)
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{
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int ret = 0;
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q->elevator = eq;
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if (eq->ops->elevator_init_fn)
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ret = eq->ops->elevator_init_fn(q, eq);
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return ret;
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}
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static char chosen_elevator[16];
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static int __init elevator_setup(char *str)
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{
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/*
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* Be backwards-compatible with previous kernels, so users
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* won't get the wrong elevator.
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*/
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if (!strcmp(str, "as"))
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strcpy(chosen_elevator, "anticipatory");
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else
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strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1);
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return 0;
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}
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__setup("elevator=", elevator_setup);
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static struct kobj_type elv_ktype;
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static elevator_t *elevator_alloc(struct elevator_type *e)
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{
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elevator_t *eq = kmalloc(sizeof(elevator_t), GFP_KERNEL);
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if (eq) {
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memset(eq, 0, sizeof(*eq));
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eq->ops = &e->ops;
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eq->elevator_type = e;
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kobject_init(&eq->kobj);
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snprintf(eq->kobj.name, KOBJ_NAME_LEN, "%s", "iosched");
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eq->kobj.ktype = &elv_ktype;
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mutex_init(&eq->sysfs_lock);
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} else {
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elevator_put(e);
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}
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return eq;
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}
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static void elevator_release(struct kobject *kobj)
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{
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elevator_t *e = container_of(kobj, elevator_t, kobj);
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elevator_put(e->elevator_type);
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kfree(e);
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}
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int elevator_init(request_queue_t *q, char *name)
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{
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struct elevator_type *e = NULL;
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struct elevator_queue *eq;
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int ret = 0;
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INIT_LIST_HEAD(&q->queue_head);
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q->last_merge = NULL;
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q->end_sector = 0;
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q->boundary_rq = NULL;
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if (name && !(e = elevator_get(name)))
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return -EINVAL;
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if (!e && *chosen_elevator && !(e = elevator_get(chosen_elevator)))
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printk("I/O scheduler %s not found\n", chosen_elevator);
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if (!e && !(e = elevator_get(CONFIG_DEFAULT_IOSCHED))) {
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printk("Default I/O scheduler not found, using no-op\n");
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e = elevator_get("noop");
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}
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eq = elevator_alloc(e);
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if (!eq)
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return -ENOMEM;
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ret = elevator_attach(q, eq);
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if (ret)
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kobject_put(&eq->kobj);
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return ret;
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}
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void elevator_exit(elevator_t *e)
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{
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mutex_lock(&e->sysfs_lock);
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if (e->ops->elevator_exit_fn)
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e->ops->elevator_exit_fn(e);
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e->ops = NULL;
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mutex_unlock(&e->sysfs_lock);
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kobject_put(&e->kobj);
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}
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/*
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* Insert rq into dispatch queue of q. Queue lock must be held on
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* entry. If sort != 0, rq is sort-inserted; otherwise, rq will be
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* appended to the dispatch queue. To be used by specific elevators.
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*/
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void elv_dispatch_sort(request_queue_t *q, struct request *rq)
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{
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sector_t boundary;
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struct list_head *entry;
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if (q->last_merge == rq)
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q->last_merge = NULL;
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q->nr_sorted--;
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boundary = q->end_sector;
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list_for_each_prev(entry, &q->queue_head) {
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struct request *pos = list_entry_rq(entry);
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if (pos->flags & (REQ_SOFTBARRIER|REQ_HARDBARRIER|REQ_STARTED))
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break;
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if (rq->sector >= boundary) {
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if (pos->sector < boundary)
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continue;
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} else {
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if (pos->sector >= boundary)
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break;
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}
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if (rq->sector >= pos->sector)
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break;
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}
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list_add(&rq->queuelist, entry);
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}
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int elv_merge(request_queue_t *q, struct request **req, struct bio *bio)
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{
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elevator_t *e = q->elevator;
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int ret;
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if (q->last_merge) {
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ret = elv_try_merge(q->last_merge, bio);
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if (ret != ELEVATOR_NO_MERGE) {
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*req = q->last_merge;
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return ret;
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}
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}
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if (e->ops->elevator_merge_fn)
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return e->ops->elevator_merge_fn(q, req, bio);
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return ELEVATOR_NO_MERGE;
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}
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void elv_merged_request(request_queue_t *q, struct request *rq)
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{
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elevator_t *e = q->elevator;
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if (e->ops->elevator_merged_fn)
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e->ops->elevator_merged_fn(q, rq);
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q->last_merge = rq;
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}
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void elv_merge_requests(request_queue_t *q, struct request *rq,
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struct request *next)
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{
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elevator_t *e = q->elevator;
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if (e->ops->elevator_merge_req_fn)
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e->ops->elevator_merge_req_fn(q, rq, next);
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q->nr_sorted--;
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q->last_merge = rq;
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}
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void elv_requeue_request(request_queue_t *q, struct request *rq)
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{
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elevator_t *e = q->elevator;
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/*
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* it already went through dequeue, we need to decrement the
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* in_flight count again
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*/
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if (blk_account_rq(rq)) {
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q->in_flight--;
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if (blk_sorted_rq(rq) && e->ops->elevator_deactivate_req_fn)
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e->ops->elevator_deactivate_req_fn(q, rq);
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}
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rq->flags &= ~REQ_STARTED;
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elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE);
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}
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static void elv_drain_elevator(request_queue_t *q)
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{
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static int printed;
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while (q->elevator->ops->elevator_dispatch_fn(q, 1))
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;
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if (q->nr_sorted == 0)
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return;
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if (printed++ < 10) {
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printk(KERN_ERR "%s: forced dispatching is broken "
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"(nr_sorted=%u), please report this\n",
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q->elevator->elevator_type->elevator_name, q->nr_sorted);
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}
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}
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void elv_insert(request_queue_t *q, struct request *rq, int where)
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{
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struct list_head *pos;
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unsigned ordseq;
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rq->q = q;
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switch (where) {
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case ELEVATOR_INSERT_FRONT:
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rq->flags |= REQ_SOFTBARRIER;
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list_add(&rq->queuelist, &q->queue_head);
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break;
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case ELEVATOR_INSERT_BACK:
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rq->flags |= REQ_SOFTBARRIER;
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elv_drain_elevator(q);
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list_add_tail(&rq->queuelist, &q->queue_head);
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/*
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* We kick the queue here for the following reasons.
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* - The elevator might have returned NULL previously
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* to delay requests and returned them now. As the
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* queue wasn't empty before this request, ll_rw_blk
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* won't run the queue on return, resulting in hang.
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* - Usually, back inserted requests won't be merged
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* with anything. There's no point in delaying queue
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* processing.
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*/
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blk_remove_plug(q);
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q->request_fn(q);
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break;
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case ELEVATOR_INSERT_SORT:
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BUG_ON(!blk_fs_request(rq));
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rq->flags |= REQ_SORTED;
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q->nr_sorted++;
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if (q->last_merge == NULL && rq_mergeable(rq))
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q->last_merge = rq;
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/*
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* Some ioscheds (cfq) run q->request_fn directly, so
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* rq cannot be accessed after calling
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* elevator_add_req_fn.
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*/
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q->elevator->ops->elevator_add_req_fn(q, rq);
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break;
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case ELEVATOR_INSERT_REQUEUE:
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/*
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* If ordered flush isn't in progress, we do front
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* insertion; otherwise, requests should be requeued
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* in ordseq order.
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*/
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rq->flags |= REQ_SOFTBARRIER;
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if (q->ordseq == 0) {
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list_add(&rq->queuelist, &q->queue_head);
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break;
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}
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ordseq = blk_ordered_req_seq(rq);
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list_for_each(pos, &q->queue_head) {
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struct request *pos_rq = list_entry_rq(pos);
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if (ordseq <= blk_ordered_req_seq(pos_rq))
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break;
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}
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list_add_tail(&rq->queuelist, pos);
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break;
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default:
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printk(KERN_ERR "%s: bad insertion point %d\n",
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__FUNCTION__, where);
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BUG();
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}
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if (blk_queue_plugged(q)) {
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int nrq = q->rq.count[READ] + q->rq.count[WRITE]
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- q->in_flight;
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if (nrq >= q->unplug_thresh)
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__generic_unplug_device(q);
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}
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}
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void __elv_add_request(request_queue_t *q, struct request *rq, int where,
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int plug)
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{
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if (q->ordcolor)
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rq->flags |= REQ_ORDERED_COLOR;
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if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) {
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/*
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* toggle ordered color
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*/
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if (blk_barrier_rq(rq))
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q->ordcolor ^= 1;
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/*
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* barriers implicitly indicate back insertion
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*/
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if (where == ELEVATOR_INSERT_SORT)
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where = ELEVATOR_INSERT_BACK;
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/*
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* this request is scheduling boundary, update
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* end_sector
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*/
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if (blk_fs_request(rq)) {
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q->end_sector = rq_end_sector(rq);
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q->boundary_rq = rq;
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}
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} else if (!(rq->flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT)
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where = ELEVATOR_INSERT_BACK;
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if (plug)
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blk_plug_device(q);
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elv_insert(q, rq, where);
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}
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void elv_add_request(request_queue_t *q, struct request *rq, int where,
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int plug)
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{
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unsigned long flags;
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spin_lock_irqsave(q->queue_lock, flags);
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__elv_add_request(q, rq, where, plug);
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spin_unlock_irqrestore(q->queue_lock, flags);
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}
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static inline struct request *__elv_next_request(request_queue_t *q)
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{
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struct request *rq;
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while (1) {
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while (!list_empty(&q->queue_head)) {
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rq = list_entry_rq(q->queue_head.next);
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if (blk_do_ordered(q, &rq))
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return rq;
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}
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if (!q->elevator->ops->elevator_dispatch_fn(q, 0))
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return NULL;
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}
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}
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struct request *elv_next_request(request_queue_t *q)
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{
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struct request *rq;
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int ret;
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while ((rq = __elv_next_request(q)) != NULL) {
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if (!(rq->flags & REQ_STARTED)) {
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elevator_t *e = q->elevator;
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/*
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* This is the first time the device driver
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* sees this request (possibly after
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* requeueing). Notify IO scheduler.
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*/
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if (blk_sorted_rq(rq) &&
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e->ops->elevator_activate_req_fn)
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e->ops->elevator_activate_req_fn(q, rq);
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/*
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* just mark as started even if we don't start
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* it, a request that has been delayed should
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* not be passed by new incoming requests
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*/
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rq->flags |= REQ_STARTED;
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}
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if (!q->boundary_rq || q->boundary_rq == rq) {
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q->end_sector = rq_end_sector(rq);
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q->boundary_rq = NULL;
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}
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if ((rq->flags & REQ_DONTPREP) || !q->prep_rq_fn)
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break;
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ret = q->prep_rq_fn(q, rq);
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if (ret == BLKPREP_OK) {
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break;
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} else if (ret == BLKPREP_DEFER) {
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/*
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* the request may have been (partially) prepped.
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* we need to keep this request in the front to
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* avoid resource deadlock. REQ_STARTED will
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* prevent other fs requests from passing this one.
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*/
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rq = NULL;
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break;
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} else if (ret == BLKPREP_KILL) {
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int nr_bytes = rq->hard_nr_sectors << 9;
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if (!nr_bytes)
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nr_bytes = rq->data_len;
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blkdev_dequeue_request(rq);
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rq->flags |= REQ_QUIET;
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end_that_request_chunk(rq, 0, nr_bytes);
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end_that_request_last(rq, 0);
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} else {
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printk(KERN_ERR "%s: bad return=%d\n", __FUNCTION__,
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ret);
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break;
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}
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}
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return rq;
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}
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void elv_dequeue_request(request_queue_t *q, struct request *rq)
|
|
{
|
|
BUG_ON(list_empty(&rq->queuelist));
|
|
|
|
list_del_init(&rq->queuelist);
|
|
|
|
/*
|
|
* the time frame between a request being removed from the lists
|
|
* and to it is freed is accounted as io that is in progress at
|
|
* the driver side.
|
|
*/
|
|
if (blk_account_rq(rq))
|
|
q->in_flight++;
|
|
}
|
|
|
|
int elv_queue_empty(request_queue_t *q)
|
|
{
|
|
elevator_t *e = q->elevator;
|
|
|
|
if (!list_empty(&q->queue_head))
|
|
return 0;
|
|
|
|
if (e->ops->elevator_queue_empty_fn)
|
|
return e->ops->elevator_queue_empty_fn(q);
|
|
|
|
return 1;
|
|
}
|
|
|
|
struct request *elv_latter_request(request_queue_t *q, struct request *rq)
|
|
{
|
|
elevator_t *e = q->elevator;
|
|
|
|
if (e->ops->elevator_latter_req_fn)
|
|
return e->ops->elevator_latter_req_fn(q, rq);
|
|
return NULL;
|
|
}
|
|
|
|
struct request *elv_former_request(request_queue_t *q, struct request *rq)
|
|
{
|
|
elevator_t *e = q->elevator;
|
|
|
|
if (e->ops->elevator_former_req_fn)
|
|
return e->ops->elevator_former_req_fn(q, rq);
|
|
return NULL;
|
|
}
|
|
|
|
int elv_set_request(request_queue_t *q, struct request *rq, struct bio *bio,
|
|
gfp_t gfp_mask)
|
|
{
|
|
elevator_t *e = q->elevator;
|
|
|
|
if (e->ops->elevator_set_req_fn)
|
|
return e->ops->elevator_set_req_fn(q, rq, bio, gfp_mask);
|
|
|
|
rq->elevator_private = NULL;
|
|
return 0;
|
|
}
|
|
|
|
void elv_put_request(request_queue_t *q, struct request *rq)
|
|
{
|
|
elevator_t *e = q->elevator;
|
|
|
|
if (e->ops->elevator_put_req_fn)
|
|
e->ops->elevator_put_req_fn(q, rq);
|
|
}
|
|
|
|
int elv_may_queue(request_queue_t *q, int rw, struct bio *bio)
|
|
{
|
|
elevator_t *e = q->elevator;
|
|
|
|
if (e->ops->elevator_may_queue_fn)
|
|
return e->ops->elevator_may_queue_fn(q, rw, bio);
|
|
|
|
return ELV_MQUEUE_MAY;
|
|
}
|
|
|
|
void elv_completed_request(request_queue_t *q, struct request *rq)
|
|
{
|
|
elevator_t *e = q->elevator;
|
|
|
|
/*
|
|
* request is released from the driver, io must be done
|
|
*/
|
|
if (blk_account_rq(rq)) {
|
|
q->in_flight--;
|
|
if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn)
|
|
e->ops->elevator_completed_req_fn(q, rq);
|
|
}
|
|
|
|
/*
|
|
* Check if the queue is waiting for fs requests to be
|
|
* drained for flush sequence.
|
|
*/
|
|
if (unlikely(q->ordseq)) {
|
|
struct request *first_rq = list_entry_rq(q->queue_head.next);
|
|
if (q->in_flight == 0 &&
|
|
blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN &&
|
|
blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) {
|
|
blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0);
|
|
q->request_fn(q);
|
|
}
|
|
}
|
|
}
|
|
|
|
#define to_elv(atr) container_of((atr), struct elv_fs_entry, attr)
|
|
|
|
static ssize_t
|
|
elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
|
|
{
|
|
elevator_t *e = container_of(kobj, elevator_t, kobj);
|
|
struct elv_fs_entry *entry = to_elv(attr);
|
|
ssize_t error;
|
|
|
|
if (!entry->show)
|
|
return -EIO;
|
|
|
|
mutex_lock(&e->sysfs_lock);
|
|
error = e->ops ? entry->show(e, page) : -ENOENT;
|
|
mutex_unlock(&e->sysfs_lock);
|
|
return error;
|
|
}
|
|
|
|
static ssize_t
|
|
elv_attr_store(struct kobject *kobj, struct attribute *attr,
|
|
const char *page, size_t length)
|
|
{
|
|
elevator_t *e = container_of(kobj, elevator_t, kobj);
|
|
struct elv_fs_entry *entry = to_elv(attr);
|
|
ssize_t error;
|
|
|
|
if (!entry->store)
|
|
return -EIO;
|
|
|
|
mutex_lock(&e->sysfs_lock);
|
|
error = e->ops ? entry->store(e, page, length) : -ENOENT;
|
|
mutex_unlock(&e->sysfs_lock);
|
|
return error;
|
|
}
|
|
|
|
static struct sysfs_ops elv_sysfs_ops = {
|
|
.show = elv_attr_show,
|
|
.store = elv_attr_store,
|
|
};
|
|
|
|
static struct kobj_type elv_ktype = {
|
|
.sysfs_ops = &elv_sysfs_ops,
|
|
.release = elevator_release,
|
|
};
|
|
|
|
int elv_register_queue(struct request_queue *q)
|
|
{
|
|
elevator_t *e = q->elevator;
|
|
int error;
|
|
|
|
e->kobj.parent = &q->kobj;
|
|
|
|
error = kobject_add(&e->kobj);
|
|
if (!error) {
|
|
struct elv_fs_entry *attr = e->elevator_type->elevator_attrs;
|
|
if (attr) {
|
|
while (attr->attr.name) {
|
|
if (sysfs_create_file(&e->kobj, &attr->attr))
|
|
break;
|
|
attr++;
|
|
}
|
|
}
|
|
kobject_uevent(&e->kobj, KOBJ_ADD);
|
|
}
|
|
return error;
|
|
}
|
|
|
|
void elv_unregister_queue(struct request_queue *q)
|
|
{
|
|
if (q) {
|
|
elevator_t *e = q->elevator;
|
|
kobject_uevent(&e->kobj, KOBJ_REMOVE);
|
|
kobject_del(&e->kobj);
|
|
}
|
|
}
|
|
|
|
int elv_register(struct elevator_type *e)
|
|
{
|
|
spin_lock_irq(&elv_list_lock);
|
|
if (elevator_find(e->elevator_name))
|
|
BUG();
|
|
list_add_tail(&e->list, &elv_list);
|
|
spin_unlock_irq(&elv_list_lock);
|
|
|
|
printk(KERN_INFO "io scheduler %s registered", e->elevator_name);
|
|
if (!strcmp(e->elevator_name, chosen_elevator) ||
|
|
(!*chosen_elevator &&
|
|
!strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED)))
|
|
printk(" (default)");
|
|
printk("\n");
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(elv_register);
|
|
|
|
void elv_unregister(struct elevator_type *e)
|
|
{
|
|
struct task_struct *g, *p;
|
|
|
|
/*
|
|
* Iterate every thread in the process to remove the io contexts.
|
|
*/
|
|
if (e->ops.trim) {
|
|
read_lock(&tasklist_lock);
|
|
do_each_thread(g, p) {
|
|
task_lock(p);
|
|
e->ops.trim(p->io_context);
|
|
task_unlock(p);
|
|
} while_each_thread(g, p);
|
|
read_unlock(&tasklist_lock);
|
|
}
|
|
|
|
spin_lock_irq(&elv_list_lock);
|
|
list_del_init(&e->list);
|
|
spin_unlock_irq(&elv_list_lock);
|
|
}
|
|
EXPORT_SYMBOL_GPL(elv_unregister);
|
|
|
|
/*
|
|
* switch to new_e io scheduler. be careful not to introduce deadlocks -
|
|
* we don't free the old io scheduler, before we have allocated what we
|
|
* need for the new one. this way we have a chance of going back to the old
|
|
* one, if the new one fails init for some reason.
|
|
*/
|
|
static int elevator_switch(request_queue_t *q, struct elevator_type *new_e)
|
|
{
|
|
elevator_t *old_elevator, *e;
|
|
|
|
/*
|
|
* Allocate new elevator
|
|
*/
|
|
e = elevator_alloc(new_e);
|
|
if (!e)
|
|
return 0;
|
|
|
|
/*
|
|
* Turn on BYPASS and drain all requests w/ elevator private data
|
|
*/
|
|
spin_lock_irq(q->queue_lock);
|
|
|
|
set_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
|
|
|
|
elv_drain_elevator(q);
|
|
|
|
while (q->rq.elvpriv) {
|
|
blk_remove_plug(q);
|
|
q->request_fn(q);
|
|
spin_unlock_irq(q->queue_lock);
|
|
msleep(10);
|
|
spin_lock_irq(q->queue_lock);
|
|
elv_drain_elevator(q);
|
|
}
|
|
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
/*
|
|
* unregister old elevator data
|
|
*/
|
|
elv_unregister_queue(q);
|
|
old_elevator = q->elevator;
|
|
|
|
/*
|
|
* attach and start new elevator
|
|
*/
|
|
if (elevator_attach(q, e))
|
|
goto fail;
|
|
|
|
if (elv_register_queue(q))
|
|
goto fail_register;
|
|
|
|
/*
|
|
* finally exit old elevator and turn off BYPASS.
|
|
*/
|
|
elevator_exit(old_elevator);
|
|
clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
|
|
return 1;
|
|
|
|
fail_register:
|
|
/*
|
|
* switch failed, exit the new io scheduler and reattach the old
|
|
* one again (along with re-adding the sysfs dir)
|
|
*/
|
|
elevator_exit(e);
|
|
e = NULL;
|
|
fail:
|
|
q->elevator = old_elevator;
|
|
elv_register_queue(q);
|
|
clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
|
|
if (e)
|
|
kobject_put(&e->kobj);
|
|
return 0;
|
|
}
|
|
|
|
ssize_t elv_iosched_store(request_queue_t *q, const char *name, size_t count)
|
|
{
|
|
char elevator_name[ELV_NAME_MAX];
|
|
size_t len;
|
|
struct elevator_type *e;
|
|
|
|
elevator_name[sizeof(elevator_name) - 1] = '\0';
|
|
strncpy(elevator_name, name, sizeof(elevator_name) - 1);
|
|
len = strlen(elevator_name);
|
|
|
|
if (len && elevator_name[len - 1] == '\n')
|
|
elevator_name[len - 1] = '\0';
|
|
|
|
e = elevator_get(elevator_name);
|
|
if (!e) {
|
|
printk(KERN_ERR "elevator: type %s not found\n", elevator_name);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) {
|
|
elevator_put(e);
|
|
return count;
|
|
}
|
|
|
|
if (!elevator_switch(q, e))
|
|
printk(KERN_ERR "elevator: switch to %s failed\n",elevator_name);
|
|
return count;
|
|
}
|
|
|
|
ssize_t elv_iosched_show(request_queue_t *q, char *name)
|
|
{
|
|
elevator_t *e = q->elevator;
|
|
struct elevator_type *elv = e->elevator_type;
|
|
struct list_head *entry;
|
|
int len = 0;
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
list_for_each(entry, &elv_list) {
|
|
struct elevator_type *__e;
|
|
|
|
__e = list_entry(entry, struct elevator_type, list);
|
|
if (!strcmp(elv->elevator_name, __e->elevator_name))
|
|
len += sprintf(name+len, "[%s] ", elv->elevator_name);
|
|
else
|
|
len += sprintf(name+len, "%s ", __e->elevator_name);
|
|
}
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
len += sprintf(len+name, "\n");
|
|
return len;
|
|
}
|
|
|
|
EXPORT_SYMBOL(elv_dispatch_sort);
|
|
EXPORT_SYMBOL(elv_add_request);
|
|
EXPORT_SYMBOL(__elv_add_request);
|
|
EXPORT_SYMBOL(elv_requeue_request);
|
|
EXPORT_SYMBOL(elv_next_request);
|
|
EXPORT_SYMBOL(elv_dequeue_request);
|
|
EXPORT_SYMBOL(elv_queue_empty);
|
|
EXPORT_SYMBOL(elv_completed_request);
|
|
EXPORT_SYMBOL(elevator_exit);
|
|
EXPORT_SYMBOL(elevator_init);
|