From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH] dm: fix blk-mq request-based DM queue
	initialization
Date: Wed, 29 Apr 2015 15:00:37 +0200
Message-ID: <20150429130037.GA3017@lst.de>
References: <20150425092358.GA15550@infradead.org>
	<1430269153-647-1-git-send-email-snitzer@redhat.com>
Reply-To: device-mapper development <dm-devel@redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <dm-devel-bounces@redhat.com>
Content-Disposition: inline
In-Reply-To: <1430269153-647-1-git-send-email-snitzer@redhat.com>
List-Unsubscribe: <https://www.redhat.com/mailman/options/dm-devel>,
	<mailto:dm-devel-request@redhat.com?subject=unsubscribe>
List-Archive: <https://www.redhat.com/archives/dm-devel>
List-Post: <mailto:dm-devel@redhat.com>
List-Help: <mailto:dm-devel-request@redhat.com?subject=help>
List-Subscribe: <https://www.redhat.com/mailman/listinfo/dm-devel>,
	<mailto:dm-devel-request@redhat.com?subject=subscribe>
Sender: dm-devel-bounces@redhat.com
Errors-To: dm-devel-bounces@redhat.com
To: Mike Snitzer <snitzer@redhat.com>
Cc: dm-devel@redhat.com, Christoph Hellwig <hch@lst.de>
List-Id: dm-devel.ids

On Tue, Apr 28, 2015 at 08:59:13PM -0400, Mike Snitzer wrote:
> Commit bfebd1cdb4 ("dm: add full blk-mq support to request-based DM")
> didn't properly account for the need to short-circuit re-initializing
> DM's blk-mq request_queue if it was already initialized.
> 
> Fix dm_init_request_based_blk_mq_queue() to return early if the
> mapped_device's tag_set already has its driver_data set to the
> mapped_device pointer.

I'm not quite up to speed with this area of code, but shouldn't
we always tear the queue fully down before trying to reinitialize it?