From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: dm: fix blk-mq request-based DM queue initialization Date: Thu, 30 Apr 2015 09:22:00 +0200 Message-ID: <20150430072200.GB15819@lst.de> References: <20150425092358.GA15550@infradead.org> <1430269153-647-1-git-send-email-snitzer@redhat.com> <20150429130037.GA3017@lst.de> <20150430014152.GA26430@redhat.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20150430014152.GA26430@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Mike Snitzer Cc: dm-devel@redhat.com, Christoph Hellwig List-Id: dm-devel.ids On Wed, Apr 29, 2015 at 09:41:52PM -0400, Mike Snitzer wrote: > > 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? > > No, the same request_queue should be used for the lifetime of a DM > device. > > I'm not interested in reinitializing the queue. A DM table reload has > no need to destroy and recreate the request_queue associated with > the DM device. It would be bad to do so too because we actually use the > queue across table reloads in the case of dm-multipath with no paths > (see: map_request's handling of DM_MAPIO_REQUEUE which triggers > dm_requeue_request). Well - we're obviously trying to reinitialize it here and only error out very low level with your patch. What I mean is that we shouldn't even try to reinitialize it at a much higher level, so we don't need this blk-mq specific hack down here.