block: make blk_init_free_list and elevator_init idempotent

blk_init_allocated_queue_node may fail and the caller _could_ retry.
Accommodate the unlikely event that blk_init_allocated_queue_node is
called on an already initialized (possibly partially) request_queue.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/block/elevator.c b/block/elevator.c
index 0abce473d606..923a9139106c 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -242,9 +242,11 @@ int elevator_init(struct request_queue *q, char *name)
 {
         struct elevator_type *e = NULL;
         struct elevator_queue *eq;
-        int ret = 0;
         void *data;
 
+        if (unlikely(q->elevator))
+                return 0;
+
         INIT_LIST_HEAD(&q->queue_head);
         q->last_merge = NULL;
         q->end_sector = 0;
@@ -284,7 +286,7 @@ int elevator_init(struct request_queue *q, char *name)
         }
 
         elevator_attach(q, eq, data);
-        return ret;
+        return 0;
 }
 EXPORT_SYMBOL(elevator_init);