1 files changed, 33 insertions, 17 deletions

diff --git a/drivers/block/elevator.c b/drivers/block/elevator.c
index 55621d5c5774..36f1057084b0 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)
@@ -642,6 +635,27 @@ 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 +753,10 @@ 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;