[SCSI] make scsi_requeue_request() use blk_requeue_request()

scsi_requeue_request() used to use blk_insert_request() for requeueing
requests.  This depends on the unobvious behavior of
blk_insert_request() setting REQ_SPECIAL and REQ_SOFTBARRIER when
requeueing.  This patch makes scsi_queue_insert() use
blk_requeue_request().  As REQ_SPECIAL means special requests and
REQ_SOFTBARRIER is automatically handled by blk layer now, no flag
needs to be set.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/scsi_lib.c

@@ -485,8 +485,13 @@ static void scsi_run_queue(struct request_queue *q)
  */
 static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
 {
+	unsigned long flags;
+
 	cmd->request->flags &= ~REQ_DONTPREP;
-	blk_insert_request(q, cmd->request, 1, cmd, 1);
+
+	spin_lock_irqsave(q->queue_lock, flags);
+	blk_requeue_request(q, cmd->request);
+	spin_unlock_irqrestore(q->queue_lock, flags);
 
 	scsi_run_queue(q);
 }