Merge branch 'for-3.9/core' of git://git.kernel.dk/linux-block

[firefly-linux-kernel-4.4.55.git] / block / elevator.c

diff --git a/block/elevator.c b/block/elevator.c
index 11683bb10b7b75e6f94d1124d91fe549a8934a65..a0ffdd943c98aa5e0f39f102b98f1bc4cf9777f5 100644 (file)
--- 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;