1 files changed, 30 insertions, 9 deletions

diff --git a/block/elevator.c b/block/elevator.c
index 11683bb10b7b..a0ffdd943c98 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -95,14 +95,14 @@ static void elevator_put(struct elevator_type *e)
 	module_put(e->elevator_owner);
 }
 
-static struct elevator_type *elevator_get(const char *name)
+static struct elevator_type *elevator_get(const char *name, bool try_loading)
 {
 	struct elevator_type *e;
 
 	spin_lock(&elv_list_lock);
 
 	e = elevator_find(name);
-	if (!e) {
+	if (!e && try_loading) {
 		spin_unlock(&elv_list_lock);
 		request_module("%s-iosched", name);
 		spin_lock(&elv_list_lock);
@@ -131,6 +131,22 @@ static int __init elevator_setup(char *str)
 
 __setup("elevator=", elevator_setup);
 
+/* called during boot to load the elevator chosen by the elevator param */
+void __init load_default_elevator_module(void)
+{
+	struct elevator_type *e;
+
+	if (!chosen_elevator[0])
+		return;
+
+	spin_lock(&elv_list_lock);
+	e = elevator_find(chosen_elevator);
+	spin_unlock(&elv_list_lock);
+
+	if (!e)
+		request_module("%s-iosched", chosen_elevator);
+}
+
 static struct kobj_type elv_ktype;
 
 static struct elevator_queue *elevator_alloc(struct request_queue *q,
@@ -177,25 +193,30 @@ int elevator_init(struct request_queue *q, char *name)
 	q->boundary_rq = NULL;
 
 	if (name) {
-		e = elevator_get(name);
+		e = elevator_get(name, true);
 		if (!e)
 			return -EINVAL;
 	}
 
+	/*
+	 * Use the default elevator specified by config boot param or
+	 * config option.  Don't try to load modules as we could be running
+	 * off async and request_module() isn't allowed from async.
+	 */
 	if (!e && *chosen_elevator) {
-		e = elevator_get(chosen_elevator);
+		e = elevator_get(chosen_elevator, false);
 		if (!e)
 			printk(KERN_ERR "I/O scheduler %s not found\n",
 							chosen_elevator);
 	}
 
 	if (!e) {
-		e = elevator_get(CONFIG_DEFAULT_IOSCHED);
+		e = elevator_get(CONFIG_DEFAULT_IOSCHED, false);
 		if (!e) {
 			printk(KERN_ERR
 				"Default I/O scheduler not found. " \
 				"Using noop.\n");
-			e = elevator_get("noop");
+			e = elevator_get("noop", false);
 		}
 	}
 
@@ -252,10 +273,10 @@ static void elv_rqhash_reposition(struct request_queue *q, struct request *rq)
 static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset)
 {
 	struct elevator_queue *e = q->elevator;
-	struct hlist_node *entry, *next;
+	struct hlist_node *next;
 	struct request *rq;
 
-	hash_for_each_possible_safe(e->hash, rq, entry, next, hash, offset) {
+	hash_for_each_possible_safe(e->hash, rq, next, hash, offset) {
 		BUG_ON(!ELV_ON_HASH(rq));
 
 		if (unlikely(!rq_mergeable(rq))) {
@@ -936,7 +957,7 @@ int elevator_change(struct request_queue *q, const char *name)
 		return -ENXIO;
 
 	strlcpy(elevator_name, name, sizeof(elevator_name));
-	e = elevator_get(strstrip(elevator_name));
+	e = elevator_get(strstrip(elevator_name), true);
 	if (!e) {
 		printk(KERN_ERR "elevator: type %s not found\n", elevator_name);
 		return -EINVAL;