diff options
| -rw-r--r-- | block/elevator.c | 90 |
1 files changed, 45 insertions, 45 deletions
diff --git a/block/elevator.c b/block/elevator.c index f016855a46b..f8c08e1bff2 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -121,11 +121,10 @@ static struct elevator_type *elevator_get(const char *name) return e; } -static int elevator_init_queue(struct request_queue *q, - struct elevator_queue *eq) +static int elevator_init_queue(struct request_queue *q) { - eq->elevator_data = eq->type->ops.elevator_init_fn(q); - if (eq->elevator_data) + q->elevator->elevator_data = q->elevator->type->ops.elevator_init_fn(q); + if (q->elevator->elevator_data) return 0; return -ENOMEM; } @@ -188,7 +187,6 @@ static void elevator_release(struct kobject *kobj) int elevator_init(struct request_queue *q, char *name) { struct elevator_type *e = NULL; - struct elevator_queue *eq; int err; if (unlikely(q->elevator)) @@ -222,17 +220,16 @@ int elevator_init(struct request_queue *q, char *name) } } - eq = elevator_alloc(q, e); - if (!eq) + q->elevator = elevator_alloc(q, e); + if (!q->elevator) return -ENOMEM; - err = elevator_init_queue(q, eq); + err = elevator_init_queue(q); if (err) { - kobject_put(&eq->kobj); + kobject_put(&q->elevator->kobj); return err; } - q->elevator = eq; return 0; } EXPORT_SYMBOL(elevator_init); @@ -801,8 +798,9 @@ static struct kobj_type elv_ktype = { .release = elevator_release, }; -int __elv_register_queue(struct request_queue *q, struct elevator_queue *e) +int elv_register_queue(struct request_queue *q) { + struct elevator_queue *e = q->elevator; int error; error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); @@ -820,11 +818,6 @@ int __elv_register_queue(struct request_queue *q, struct elevator_queue *e) } return error; } - -int elv_register_queue(struct request_queue *q) -{ - return __elv_register_queue(q, q->elevator); -} EXPORT_SYMBOL(elv_register_queue); void elv_unregister_queue(struct request_queue *q) @@ -907,51 +900,58 @@ EXPORT_SYMBOL_GPL(elv_unregister); */ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) { - struct elevator_queue *old_elevator, *e; + struct elevator_queue *old = q->elevator; + bool registered = old->registered; int err; - /* allocate new elevator */ - e = elevator_alloc(q, new_e); - if (!e) - return -ENOMEM; - - err = elevator_init_queue(q, e); - if (err) { - kobject_put(&e->kobj); - return err; - } - - /* turn on BYPASS and drain all requests w/ elevator private data */ + /* + * Turn on BYPASS and drain all requests w/ elevator private data. + * Block layer doesn't call into a quiesced elevator - all requests + * are directly put on the dispatch list without elevator data + * using INSERT_BACK. All requests have SOFTBARRIER set and no + * merge happens either. + */ elv_quiesce_start(q); - /* unregister old queue, register new one and kill old elevator */ - if (q->elevator->registered) { + /* unregister and clear all auxiliary data of the old elevator */ + if (registered) elv_unregister_queue(q); - err = __elv_register_queue(q, e); - if (err) - goto fail_register; - } - /* done, clear io_cq's, switch elevators and turn off BYPASS */ spin_lock_irq(q->queue_lock); ioc_clear_queue(q); - old_elevator = q->elevator; - q->elevator = e; spin_unlock_irq(q->queue_lock); - elevator_exit(old_elevator); + /* allocate, init and register new elevator */ + err = -ENOMEM; + q->elevator = elevator_alloc(q, new_e); + if (!q->elevator) + goto fail_init; + + err = elevator_init_queue(q); + if (err) { + kobject_put(&q->elevator->kobj); + goto fail_init; + } + + if (registered) { + err = elv_register_queue(q); + if (err) + goto fail_register; + } + + /* done, kill the old one and finish */ + elevator_exit(old); elv_quiesce_end(q); - blk_add_trace_msg(q, "elv switch: %s", e->type->elevator_name); + blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name); return 0; 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); + elevator_exit(q->elevator); +fail_init: + /* switch failed, restore and re-register old elevator */ + q->elevator = old; elv_register_queue(q); elv_quiesce_end(q); |