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-rw-r--r--block/elevator.c91
1 files changed, 37 insertions, 54 deletions
diff --git a/block/elevator.c b/block/elevator.c
index 6a343e8f8319..a16c2d1713e5 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -168,17 +168,13 @@ static struct elevator_type *elevator_get(const char *name)
return e;
}
-static void *elevator_init_queue(struct request_queue *q,
- struct elevator_queue *eq)
+static int elevator_init_queue(struct request_queue *q,
+ struct elevator_queue *eq)
{
- return eq->ops->elevator_init_fn(q);
-}
-
-static void elevator_attach(struct request_queue *q, struct elevator_queue *eq,
- void *data)
-{
- q->elevator = eq;
- eq->elevator_data = data;
+ eq->elevator_data = eq->ops->elevator_init_fn(q);
+ if (eq->elevator_data)
+ return 0;
+ return -ENOMEM;
}
static char chosen_elevator[ELV_NAME_MAX];
@@ -241,7 +237,7 @@ int elevator_init(struct request_queue *q, char *name)
{
struct elevator_type *e = NULL;
struct elevator_queue *eq;
- void *data;
+ int err;
if (unlikely(q->elevator))
return 0;
@@ -278,13 +274,13 @@ int elevator_init(struct request_queue *q, char *name)
if (!eq)
return -ENOMEM;
- data = elevator_init_queue(q, eq);
- if (!data) {
+ err = elevator_init_queue(q, eq);
+ if (err) {
kobject_put(&eq->kobj);
- return -ENOMEM;
+ return err;
}
- elevator_attach(q, eq, data);
+ q->elevator = eq;
return 0;
}
EXPORT_SYMBOL(elevator_init);
@@ -856,9 +852,8 @@ static struct kobj_type elv_ktype = {
.release = elevator_release,
};
-int elv_register_queue(struct request_queue *q)
+int __elv_register_queue(struct request_queue *q, struct elevator_queue *e)
{
- struct elevator_queue *e = q->elevator;
int error;
error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched");
@@ -876,19 +871,22 @@ int elv_register_queue(struct request_queue *q)
}
return error;
}
-EXPORT_SYMBOL(elv_register_queue);
-static void __elv_unregister_queue(struct elevator_queue *e)
+int elv_register_queue(struct request_queue *q)
{
- kobject_uevent(&e->kobj, KOBJ_REMOVE);
- kobject_del(&e->kobj);
- e->registered = 0;
+ return __elv_register_queue(q, q->elevator);
}
+EXPORT_SYMBOL(elv_register_queue);
void elv_unregister_queue(struct request_queue *q)
{
- if (q)
- __elv_unregister_queue(q->elevator);
+ if (q) {
+ struct elevator_queue *e = q->elevator;
+
+ kobject_uevent(&e->kobj, KOBJ_REMOVE);
+ kobject_del(&e->kobj);
+ e->registered = 0;
+ }
}
EXPORT_SYMBOL(elv_unregister_queue);
@@ -928,50 +926,36 @@ EXPORT_SYMBOL_GPL(elv_unregister);
static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
{
struct elevator_queue *old_elevator, *e;
- void *data;
int err;
- /*
- * Allocate new elevator
- */
+ /* allocate new elevator */
e = elevator_alloc(q, new_e);
if (!e)
return -ENOMEM;
- data = elevator_init_queue(q, e);
- if (!data) {
+ err = elevator_init_queue(q, e);
+ if (err) {
kobject_put(&e->kobj);
- return -ENOMEM;
+ return err;
}
- /*
- * Turn on BYPASS and drain all requests w/ elevator private data
- */
+ /* turn on BYPASS and drain all requests w/ elevator private data */
elv_quiesce_start(q);
- /*
- * Remember old elevator.
- */
- old_elevator = q->elevator;
-
- /*
- * attach and start new elevator
- */
- spin_lock_irq(q->queue_lock);
- elevator_attach(q, e, data);
- spin_unlock_irq(q->queue_lock);
-
- if (old_elevator->registered) {
- __elv_unregister_queue(old_elevator);
-
- err = elv_register_queue(q);
+ /* unregister old queue, register new one and kill old elevator */
+ if (q->elevator->registered) {
+ elv_unregister_queue(q);
+ err = __elv_register_queue(q, e);
if (err)
goto fail_register;
}
- /*
- * finally exit old elevator and turn off BYPASS.
- */
+ /* done, replace the old one with new one and turn off BYPASS */
+ spin_lock_irq(q->queue_lock);
+ old_elevator = q->elevator;
+ q->elevator = e;
+ spin_unlock_irq(q->queue_lock);
+
elevator_exit(old_elevator);
elv_quiesce_end(q);
@@ -985,7 +969,6 @@ fail_register:
* one again (along with re-adding the sysfs dir)
*/
elevator_exit(e);
- q->elevator = old_elevator;
elv_register_queue(q);
elv_quiesce_end(q);