From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Christie Subject: Re: [PATCH 01/18] libceph: add scatterlist messenger data type Date: Wed, 29 Jul 2015 17:59:24 -0500 Message-ID: <55B95ACC.2030306@redhat.com> References: <1438161835-27960-1-git-send-email-mchristi@redhat.com> <20150729175515.GA16804@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150729175515.GA16804@infradead.org> Sender: target-devel-owner@vger.kernel.org To: Christoph Hellwig Cc: ceph-devel@vger.kernel.org, target-devel@vger.kernel.org List-Id: ceph-devel.vger.kernel.org On 07/29/2015 12:55 PM, Christoph Hellwig wrote: > On Wed, Jul 29, 2015 at 04:23:38AM -0500, mchristi@redhat.com wrote: >> From: Mike Christie >> >> LIO uses scatterlist for its page/data management. This patch >> adds a scatterlist messenger data type, so LIO can pass its sg >> down directly to rbd. > > Just as I mentioned for David's patches this is the wrong way to attack > your problem. The block layer already supports WRITE SAME, and COMPARE > and WRITE nees to be supported at that level too insted of creating > artifical bypasses. Why do I have to use the block layer? I just want to map the se_cmd to a ceph request and then put it back on the wire. I don't think I need any of the block layer services. We will do things like io scheduling on the OSD side. We just want to use LIO as more of a passthrough.