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>

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index b220c686089d82b5ffc41eada6efd59c7f7ca7e5..2d19f0cc47f272c5ae4f96ee97ea34a1bce5a407 100644 (file)
--- 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);