[PATCH] cfq v2 switch bug

Fix online switching issue with cfq v2.  It does deferred clearing of
e->elevator_data, which screws up the current io scheduler.  It does not
have to, so just remove it.
Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/block/cfq-iosched.c

@@ -1482,7 +1482,6 @@ static int cfq_set_request(request_queue_t *q, struct request *rq, int gfp_mask)
 static void cfq_put_cfqd(struct cfq_data *cfqd)
 {
 	request_queue_t *q = cfqd->queue;
-	elevator_t *e = q->elevator;
 	struct cfq_queue *cfqq;
 
 	if (!atomic_dec_and_test(&cfqd->ref))
@@ -1500,7 +1499,6 @@ static void cfq_put_cfqd(struct cfq_data *cfqd)
 
 	blk_put_queue(q);
 
-	e->elevator_data = NULL;
 	mempool_destroy(cfqd->crq_pool);
 	kfree(cfqd->crq_hash);
 	kfree(cfqd->cfq_hash);