Release old elevator on change elevator

We should release old elevator when change to use a new one.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index b220c686089d..2d19f0cc47f2 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -338,12 +338,18 @@ wait:
 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
 {
         struct request_queue *rq;
+        elevator_t *old_e;
 
         rq = blk_init_queue(do_blkif_request, &blkif_io_lock);
         if (rq == NULL)
                 return -1;
 
-        elevator_init(rq, "noop");
+        old_e = rq->elevator;
+        if (IS_ERR_VALUE(elevator_init(rq, "noop")))
+                printk(KERN_WARNING
+                        "blkfront: Switch elevator failed, use default\n");
+        else
+                elevator_exit(old_e);
 
         /* Hard sector size and max sectors impersonate the equiv. hardware. */
         blk_queue_hardsect_size(rq, sector_size);