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path: root/drivers/block/elevator.c
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Diffstat (limited to 'drivers/block/elevator.c')
-rw-r--r--drivers/block/elevator.c57
1 files changed, 39 insertions, 18 deletions
diff --git a/drivers/block/elevator.c b/drivers/block/elevator.c
index 55621d5c577..d4a49a3df82 100644
--- a/drivers/block/elevator.c
+++ b/drivers/block/elevator.c
@@ -147,24 +147,17 @@ static void elevator_setup_default(void)
struct elevator_type *e;
/*
- * check if default is set and exists
+ * If default has not been set, use the compiled-in selection.
*/
- if (chosen_elevator[0] && (e = elevator_get(chosen_elevator))) {
- elevator_put(e);
- return;
- }
+ if (!chosen_elevator[0])
+ strcpy(chosen_elevator, CONFIG_DEFAULT_IOSCHED);
-#if defined(CONFIG_IOSCHED_AS)
- strcpy(chosen_elevator, "anticipatory");
-#elif defined(CONFIG_IOSCHED_DEADLINE)
- strcpy(chosen_elevator, "deadline");
-#elif defined(CONFIG_IOSCHED_CFQ)
- strcpy(chosen_elevator, "cfq");
-#elif defined(CONFIG_IOSCHED_NOOP)
- strcpy(chosen_elevator, "noop");
-#else
-#error "You must build at least 1 IO scheduler into the kernel"
-#endif
+ /*
+ * If the given scheduler is not available, fall back to no-op.
+ */
+ if (!(e = elevator_find(chosen_elevator)))
+ strcpy(chosen_elevator, "noop");
+ elevator_put(e);
}
static int __init elevator_setup(char *str)
@@ -376,9 +369,14 @@ void __elv_add_request(request_queue_t *q, struct request *rq, int where,
case ELEVATOR_INSERT_SORT:
BUG_ON(!blk_fs_request(rq));
rq->flags |= REQ_SORTED;
- q->elevator->ops->elevator_add_req_fn(q, rq);
if (q->last_merge == NULL && rq_mergeable(rq))
q->last_merge = rq;
+ /*
+ * Some ioscheds (cfq) run q->request_fn directly, so
+ * rq cannot be accessed after calling
+ * elevator_add_req_fn.
+ */
+ q->elevator->ops->elevator_add_req_fn(q, rq);
break;
default:
@@ -642,6 +640,27 @@ 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.
+ */
+ read_lock(&tasklist_lock);
+ do_each_thread(g, p) {
+ struct io_context *ioc = p->io_context;
+ if (ioc && ioc->cic) {
+ ioc->cic->exit(ioc->cic);
+ ioc->cic->dtor(ioc->cic);
+ ioc->cic = NULL;
+ }
+ if (ioc && ioc->aic) {
+ ioc->aic->exit(ioc->aic);
+ ioc->aic->dtor(ioc->aic);
+ ioc->aic = NULL;
+ }
+ } 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);
@@ -739,8 +758,10 @@ ssize_t elv_iosched_store(request_queue_t *q, const char *name, size_t count)
return -EINVAL;
}
- if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name))
+ if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) {
+ elevator_put(e);
return count;
+ }
elevator_switch(q, e);
return count;