1 files changed, 34 insertions, 21 deletions

diff --git a/block/elevator.c b/block/elevator.c
index 8768a367fdde..a0afdd317cef 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -121,16 +121,16 @@ static struct elevator_type *elevator_get(const char *name)
         return e;
 }
 
-static int elevator_attach(request_queue_t *q, struct elevator_queue *eq)
+static void *elevator_init_queue(request_queue_t *q, struct elevator_queue *eq)
 {
-        int ret = 0;
+        return eq->ops->elevator_init_fn(q, eq);
+}
 
+static void elevator_attach(request_queue_t *q, struct elevator_queue *eq,
+                           void *data)
+{
         q->elevator = eq;
-
-        if (eq->ops->elevator_init_fn)
-                ret = eq->ops->elevator_init_fn(q, eq);
-
-        return ret;
+        eq->elevator_data = data;
 }
 
 static char chosen_elevator[16];
@@ -181,6 +181,7 @@ int elevator_init(request_queue_t *q, char *name)
         struct elevator_type *e = NULL;
         struct elevator_queue *eq;
         int ret = 0;
+        void *data;
 
         INIT_LIST_HEAD(&q->queue_head);
         q->last_merge = NULL;
@@ -202,10 +203,13 @@ int elevator_init(request_queue_t *q, char *name)
         if (!eq)
                 return -ENOMEM;
 
-        ret = elevator_attach(q, eq);
-        if (ret)
+        data = elevator_init_queue(q, eq);
+        if (!data) {
                 kobject_put(&eq->kobj);
+                return -ENOMEM;
+        }
 
+        elevator_attach(q, eq, data);
         return ret;
 }
 
@@ -722,13 +726,16 @@ int elv_register_queue(struct request_queue *q)
         return error;
 }
 
+static void __elv_unregister_queue(elevator_t *e)
+{
+        kobject_uevent(&e->kobj, KOBJ_REMOVE);
+        kobject_del(&e->kobj);
+}
+
 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);
-        }
+        if (q)
+                __elv_unregister_queue(q->elevator);
 }
 
 int elv_register(struct elevator_type *e)
@@ -780,6 +787,7 @@ EXPORT_SYMBOL_GPL(elv_unregister);
 static int elevator_switch(request_queue_t *q, struct elevator_type *new_e)
 {
         elevator_t *old_elevator, *e;
+        void *data;
 
         /*
          * Allocate new elevator
@@ -788,6 +796,12 @@ static int elevator_switch(request_queue_t *q, struct elevator_type *new_e)
         if (!e)
                 return 0;
 
+        data = elevator_init_queue(q, e);
+        if (!data) {
+                kobject_put(&e->kobj);
+                return 0;
+        }
+
         /*
          * Turn on BYPASS and drain all requests w/ elevator private data
          */
@@ -806,19 +820,19 @@ static int elevator_switch(request_queue_t *q, struct elevator_type *new_e)
                 elv_drain_elevator(q);
         }
 
-        spin_unlock_irq(q->queue_lock);
-
         /*
-         * unregister old elevator data
+         * Remember old elevator.
          */
-        elv_unregister_queue(q);
         old_elevator = q->elevator;
 
         /*
          * attach and start new elevator
          */
-        if (elevator_attach(q, e))
-                goto fail;
+        elevator_attach(q, e, data);
+
+        spin_unlock_irq(q->queue_lock);
+
+        __elv_unregister_queue(old_elevator);
 
         if (elv_register_queue(q))
                 goto fail_register;
@@ -837,7 +851,6 @@ fail_register:
          */
         elevator_exit(e);
         e = NULL;
-fail:
         q->elevator = old_elevator;
         elv_register_queue(q);
         clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);