From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Martin K. Petersen" Subject: Re: [PATCH 22/23] drbd: implement REQ_OP_WRITE_ZEROES Date: Thu, 30 Mar 2017 11:20:09 -0400 Message-ID: References: <20170323143341.31549-1-hch@lst.de> <20170323143341.31549-23-hch@lst.de> <20170330100641.GI5939@soda.linbit> <20170330114408.GA15777@lst.de> <20170330134957.GA508@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170330134957.GA508-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> (Mike Snitzer's message of "Thu, 30 Mar 2017 09:49:57 -0400") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: drbd-dev-bounces-cunTk1MwBs8qoQakbn7OcQ@public.gmane.org Errors-To: drbd-dev-bounces-cunTk1MwBs8qoQakbn7OcQ@public.gmane.org To: Mike Snitzer Cc: axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org, linux-raid-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, martin.petersen-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, philipp.reisner-63ez5xqkn6DQT0dZR+AlfA@public.gmane.org, linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, shli-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, Christoph Hellwig , agk-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, drbd-dev-cunTk1MwBs8qoQakbn7OcQ@public.gmane.org List-Id: linux-raid.ids Mike Snitzer writes: > I can work on this now. Only question I have is: should DM thinp take > care to zero any misaligned head and tail? (I assume so but with all > the back and forth between Bart, Paolo and Martin I figured I'd ask > explicitly). Yep, let's make sure our semantics match the hardware ditto. - So write zeroes should behave deterministically and explicitly handle any blocks that can't be cleared via deprovisioning. - And discard can work at the discard granularity in a non-deterministic fashion. -- Martin K. Petersen Oracle Linux Engineering From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: To: Mike Snitzer Cc: Christoph Hellwig , axboe@kernel.dk, martin.petersen@oracle.com, agk@redhat.com, shli@kernel.org, philipp.reisner@linbit.com, linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, drbd-dev@lists.linbit.com, dm-devel@redhat.com, linux-raid@vger.kernel.org Subject: Re: [PATCH 22/23] drbd: implement REQ_OP_WRITE_ZEROES From: "Martin K. Petersen" References: <20170323143341.31549-1-hch@lst.de> <20170323143341.31549-23-hch@lst.de> <20170330100641.GI5939@soda.linbit> <20170330114408.GA15777@lst.de> <20170330134957.GA508@redhat.com> Date: Thu, 30 Mar 2017 11:20:09 -0400 In-Reply-To: <20170330134957.GA508@redhat.com> (Mike Snitzer's message of "Thu, 30 Mar 2017 09:49:57 -0400") Message-ID: MIME-Version: 1.0 Content-Type: text/plain List-ID: Mike Snitzer writes: > I can work on this now. Only question I have is: should DM thinp take > care to zero any misaligned head and tail? (I assume so but with all > the back and forth between Bart, Paolo and Martin I figured I'd ask > explicitly). Yep, let's make sure our semantics match the hardware ditto. - So write zeroes should behave deterministically and explicitly handle any blocks that can't be cleared via deprovisioning. - And discard can work at the discard granularity in a non-deterministic fashion. -- Martin K. Petersen Oracle Linux Engineering