From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kiyoshi Ueda Subject: Re: [PATCH UPDATED 4/5] dm: implement REQ_FLUSH/FUA support for request-based dm Date: Fri, 03 Sep 2010 14:46:32 +0900 Message-ID: <4C808BB8.6040005@ct.jp.nec.com> References: <1283162296-13650-1-git-send-email-tj@kernel.org> <1283162296-13650-5-git-send-email-tj@kernel.org> <20100830132836.GB5283@redhat.com> <4C7BB932.1070405@kernel.org> <4C7BD202.4040700@kernel.org> <4C7DFD8F.6070200@ct.jp.nec.com> <4C7FA531.7060300@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4C7FA531.7060300@kernel.org> Sender: linux-raid-owner@vger.kernel.org To: Tejun Heo Cc: Mike Snitzer , jaxboe@fusionio.com, j-nomura@ce.jp.nec.com, jamie@shareable.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-raid@vger.kernel.org, hch@lst.de List-Id: linux-raid.ids Hi Tejun, On 09/02/2010 10:22 PM +0900, Tejun Heo wrote: > On 09/01/2010 09:15 AM, Kiyoshi Ueda wrote: >>> @@ -2619,9 +2458,8 @@ int dm_suspend(struct mapped_device *md, >>> up_write(&md->io_lock); >>> >>> /* >>> - * Request-based dm uses md->wq for barrier (dm_rq_barrier_work) which >>> - * can be kicked until md->queue is stopped. So stop md->queue before >>> - * flushing md->wq. >>> + * Stop md->queue before flushing md->wq in case request-based >>> + * dm defers requests to md->wq from md->queue. >>> */ >>> if (dm_request_based(md)) >>> stop_queue(md->queue); >> >> Request-based dm doesn't use md->wq now, so you can just remove >> the comment above. > > I sure can remove it but md->wq already has most stuff necessary to > process deferred requests and when someone starts using it, having the > comment there about the rather delicate ordering would definitely be > helpful, so I suggest keeping the comment. OK, makes sense. Thanks, Kiyoshi Ueda