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/deadline-iosched.c b/block/deadline-iosched.c
index 7bf12d793fcd..599b12e5380f 100644
--- a/block/deadline-iosched.c
+++ b/block/deadline-iosched.c
@@ -337,13 +337,13 @@ static void deadline_exit_queue(struct elevator_queue *e)
 /*
  * initialize elevator private data (deadline_data).
  */
-static void *deadline_init_queue(struct request_queue *q)
+static int deadline_init_queue(struct request_queue *q)
 {
         struct deadline_data *dd;
 
         dd = kmalloc_node(sizeof(*dd), GFP_KERNEL | __GFP_ZERO, q->node);
         if (!dd)
-                return NULL;
+                return -ENOMEM;
 
         INIT_LIST_HEAD(&dd->fifo_list[READ]);
         INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
@@ -354,7 +354,9 @@ static void *deadline_init_queue(struct request_queue *q)
         dd->writes_starved = writes_starved;
         dd->front_merges = 1;
         dd->fifo_batch = fifo_batch;
-        return dd;
+
+        q->elevator->elevator_data = dd;
+        return 0;
 }
 
 /*