/*
- * linux/drivers/block/elevator.c
- *
* Block device elevator/IO-scheduler.
*
* Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
if (q->last_merge == rq)
q->last_merge = NULL;
+ q->nr_sorted--;
boundary = q->end_sector;
if (e->ops->elevator_merge_req_fn)
e->ops->elevator_merge_req_fn(q, rq, next);
+ q->nr_sorted--;
q->last_merge = rq;
}
__elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0);
}
+static void elv_drain_elevator(request_queue_t *q)
+{
+ static int printed;
+ while (q->elevator->ops->elevator_dispatch_fn(q, 1))
+ ;
+ if (q->nr_sorted == 0)
+ return;
+ if (printed++ < 10) {
+ printk(KERN_ERR "%s: forced dispatching is broken "
+ "(nr_sorted=%u), please report this\n",
+ q->elevator->elevator_type->elevator_name, q->nr_sorted);
+ }
+}
+
void __elv_add_request(request_queue_t *q, struct request *rq, int where,
int plug)
{
case ELEVATOR_INSERT_BACK:
rq->flags |= REQ_SOFTBARRIER;
-
- while (q->elevator->ops->elevator_dispatch_fn(q, 1))
- ;
+ elv_drain_elevator(q);
list_add_tail(&rq->queuelist, &q->queue_head);
/*
* We kick the queue here for the following reasons.
case ELEVATOR_INSERT_SORT:
BUG_ON(!blk_fs_request(rq));
rq->flags |= REQ_SORTED;
+ q->nr_sorted++;
if (q->last_merge == NULL && rq_mergeable(rq))
q->last_merge = rq;
/*
struct request *elv_latter_request(request_queue_t *q, struct request *rq)
{
- struct list_head *next;
-
elevator_t *e = q->elevator;
if (e->ops->elevator_latter_req_fn)
return e->ops->elevator_latter_req_fn(q, rq);
-
- next = rq->queuelist.next;
- if (next != &q->queue_head && next != &rq->queuelist)
- return list_entry_rq(next);
-
return NULL;
}
struct request *elv_former_request(request_queue_t *q, struct request *rq)
{
- struct list_head *prev;
-
elevator_t *e = q->elevator;
if (e->ops->elevator_former_req_fn)
return e->ops->elevator_former_req_fn(q, rq);
-
- prev = rq->queuelist.prev;
- if (prev != &q->queue_head && prev != &rq->queuelist)
- return list_entry_rq(prev);
-
return NULL;
}
set_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
- while (q->elevator->ops->elevator_dispatch_fn(q, 1))
- ;
+ elv_drain_elevator(q);
while (q->rq.elvpriv) {
blk_remove_plug(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);
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;
- memset(elevator_name, 0, sizeof(elevator_name));
- strncpy(elevator_name, name, sizeof(elevator_name));
+ elevator_name[sizeof(elevator_name) - 1] = '\0';
+ strncpy(elevator_name, name, sizeof(elevator_name) - 1);
+ len = strlen(elevator_name);
- if (elevator_name[strlen(elevator_name) - 1] == '\n')
- elevator_name[strlen(elevator_name) - 1] = '\0';
+ if (len && elevator_name[len - 1] == '\n')
+ elevator_name[len - 1] = '\0';
e = elevator_get(elevator_name);
if (!e) {