loop: don't try to use AIO for discards

Christoph Hellwig · axboe · commit f0225cacfe7e · 2016-08-04T14:19:16.000-06:00
Fix a fat-fingered conversion to the req_op accessors, and also
use a switch statement to make it more obvious what is being checked.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reported-by: Dave Chinner &lt;david@fromorbit.com&gt;
Fixes: c2df40 ("drivers: use req op accessor");
Reviewed-by: Ming Lei &lt;ming.lei@canonical.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@fb.com&gt;
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
@@ -1659,11 +1659,15 @@ static int loop_queue_rq(struct blk_mq_hw_ctx *hctx,
 	if (lo->lo_state != Lo_bound)
 		return -EIO;
 
-	if (lo->use_dio && (req_op(cmd->rq) != REQ_OP_FLUSH ||
-	    req_op(cmd->rq) == REQ_OP_DISCARD))
-		cmd->use_aio = true;
-	else
+	switch (req_op(cmd->rq)) {
+	case REQ_OP_FLUSH:
+	case REQ_OP_DISCARD:
 		cmd->use_aio = false;
+		break;
+	default:
+		cmd->use_aio = lo->use_dio;
+		break;
+	}
 
 	queue_kthread_work(&lo->worker, &cmd->work);
 
