elevator: make elevator_init_fn() return 0/-errno

elevator_ops->elevator_init_fn() has a weird return value.  It returns
a void * which the caller should assign to q->elevator->elevator_data
and %NULL return denotes init failure.

Update such that it returns integer 0/-errno and sets elevator_data
directly as necessary.

This makes the interface more conventional and eases further cleanup.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 5 insertions, 3 deletions

diff --git a/block/noop-iosched.c b/block/noop-iosched.c
index 413a0b1d788..5d1bf70e33d 100644
--- a/block/noop-iosched.c
+++ b/block/noop-iosched.c
@@ -59,15 +59,17 @@ noop_latter_request(struct request_queue *q, struct request *rq)
         return list_entry(rq->queuelist.next, struct request, queuelist);
 }
 
-static void *noop_init_queue(struct request_queue *q)
+static int noop_init_queue(struct request_queue *q)
 {
         struct noop_data *nd;
 
         nd = kmalloc_node(sizeof(*nd), GFP_KERNEL, q->node);
         if (!nd)
-                return NULL;
+                return -ENOMEM;
+
         INIT_LIST_HEAD(&nd->queue);
-        return nd;
+        q->elevator->elevator_data = nd;
+        return 0;
 }
 
 static void noop_exit_queue(struct elevator_queue *e)