From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Snitzer Subject: Re: [PATCH UPDATED 4/5] dm: implement REQ_FLUSH/FUA support for request-based dm Date: Mon, 30 Aug 2010 15:18:30 -0400 Message-ID: <20100830191829.GB8458@redhat.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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: jaxboe@fusionio.com, k-ueda@ct.jp.nec.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 To: Tejun Heo Return-path: Content-Disposition: inline In-Reply-To: <4C7BD202.4040700@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Mon, Aug 30 2010 at 11:45am -0400, Tejun Heo wrote: > This patch converts request-based dm to support the new REQ_FLUSH/FUA. > > The original request-based flush implementation depended on > request_queue blocking other requests while a barrier sequence is in > progress, which is no longer true for the new REQ_FLUSH/FUA. > > In general, request-based dm doesn't have infrastructure for cloning > one source request to multiple targets, but the original flush > implementation had a special mostly independent path which can issue > flushes to multiple targets and sequence them. However, the > capability isn't currently in use and adds a lot of complexity. > Moreoever, it's unlikely to be useful in its current form as it > doesn't make sense to be able to send out flushes to multiple targets > when write requests can't be. > > This patch rips out special flush code path and deals handles > REQ_FLUSH/FUA requests the same way as other requests. The only > special treatment is that REQ_FLUSH requests use the block address 0 > when finding target, which is enough for now. > > * added BUG_ON(!dm_target_is_valid(ti)) in dm_request_fn() as > suggested by Mike Snitzer > > Signed-off-by: Tejun Heo Looks good. Acked-by: Mike Snitzer Junichi and/or Kiyoshi, Could you please review this patch and add your Acked-by if it is OK? (Alasdair will want to see NEC's Ack to accept this patch). Thanks, Mike