From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1754885AbcG0LAB (ORCPT <rfc822;w@1wt.eu>);
	Wed, 27 Jul 2016 07:00:01 -0400
Received: from smtp02.citrix.com ([66.165.176.63]:12354 "EHLO
	SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1752142AbcG0K74 (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Wed, 27 Jul 2016 06:59:56 -0400
X-IronPort-AV: E=Sophos;i="5.28,429,1464652800"; 
   d="scan'208";a="375699083"
Date: Wed, 27 Jul 2016 12:59:49 +0200
From: Roger Pau =?iso-8859-1?Q?Monn=E9?= <roger.pau@citrix.com>
To: Bob Liu <bob.liu@oracle.com>
CC: <linux-kernel@vger.kernel.org>, <xen-devel@lists.xenproject.org>,
        <konrad.wilk@oracle.com>
Subject: Re: [PATCH v3] xen-blkfront: dynamic configuration of per-vbd
 resources
Message-ID: <20160727105949.3rtlnl2zr4lpsvbc@mac>
References: <1469589685-31630-1-git-send-email-bob.liu@oracle.com>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Disposition: inline
In-Reply-To: <1469589685-31630-1-git-send-email-bob.liu@oracle.com>
User-Agent: Mutt/1.6.2-neo (2016-06-11)
X-DLP: MIA2
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wed, Jul 27, 2016 at 11:21:25AM +0800, Bob Liu wrote:
[...]
> +static ssize_t dynamic_reconfig_device(struct blkfront_info *info, ssize_t count)
> +{
> +	/*
> +	 * Prevent new requests even to software request queue.
> +	 */
> +	blk_mq_freeze_queue(info->rq);
> +
> +	/*
> +	 * Guarantee no uncompleted reqs.
> +	 */

I'm also wondering, why do you need to guarantee that there are no 
uncompleted requests? The resume procedure is going to call blkif_recover 
that will take care of requeuing any unfinished requests that are on the 
ring.

> +	if (part_in_flight(&info->gd->part0) || info->reconfiguring) {
> +		blk_mq_unfreeze_queue(info->rq);
> +		pr_err("Dev:%s busy, please retry later.\n", dev_name(&info->xbdev->dev));
> +		return -EBUSY;
> +	}

Roger.