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-rw-r--r--block/elevator.c37
1 files changed, 35 insertions, 2 deletions
diff --git a/block/elevator.c b/block/elevator.c
index c5c6214829cb..cca049fb45c8 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -886,15 +886,36 @@ void elv_unregister_queue(struct request_queue *q)
}
EXPORT_SYMBOL(elv_unregister_queue);
-void elv_register(struct elevator_type *e)
+int elv_register(struct elevator_type *e)
{
char *def = "";
+ /* create icq_cache if requested */
+ if (e->icq_size) {
+ if (WARN_ON(e->icq_size < sizeof(struct io_cq)) ||
+ WARN_ON(e->icq_align < __alignof__(struct io_cq)))
+ return -EINVAL;
+
+ snprintf(e->icq_cache_name, sizeof(e->icq_cache_name),
+ "%s_io_cq", e->elevator_name);
+ e->icq_cache = kmem_cache_create(e->icq_cache_name, e->icq_size,
+ e->icq_align, 0, NULL);
+ if (!e->icq_cache)
+ return -ENOMEM;
+ }
+
+ /* register, don't allow duplicate names */
spin_lock(&elv_list_lock);
- BUG_ON(elevator_find(e->elevator_name));
+ if (elevator_find(e->elevator_name)) {
+ spin_unlock(&elv_list_lock);
+ if (e->icq_cache)
+ kmem_cache_destroy(e->icq_cache);
+ return -EBUSY;
+ }
list_add_tail(&e->list, &elv_list);
spin_unlock(&elv_list_lock);
+ /* print pretty message */
if (!strcmp(e->elevator_name, chosen_elevator) ||
(!*chosen_elevator &&
!strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED)))
@@ -902,14 +923,26 @@ void elv_register(struct elevator_type *e)
printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name,
def);
+ return 0;
}
EXPORT_SYMBOL_GPL(elv_register);
void elv_unregister(struct elevator_type *e)
{
+ /* unregister */
spin_lock(&elv_list_lock);
list_del_init(&e->list);
spin_unlock(&elv_list_lock);
+
+ /*
+ * Destroy icq_cache if it exists. icq's are RCU managed. Make
+ * sure all RCU operations are complete before proceeding.
+ */
+ if (e->icq_cache) {
+ rcu_barrier();
+ kmem_cache_destroy(e->icq_cache);
+ e->icq_cache = NULL;
+ }
}
EXPORT_SYMBOL_GPL(elv_unregister);