From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756321Ab3BUWGg (ORCPT ); Thu, 21 Feb 2013 17:06:36 -0500 Received: from mx1.redhat.com ([209.132.183.28]:36020 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756037Ab3BUWGd (ORCPT ); Thu, 21 Feb 2013 17:06:33 -0500 Message-ID: <51269A2B.7070000@redhat.com> Date: Thu, 21 Feb 2013 23:05:31 +0100 From: Ric Wheeler User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 MIME-Version: 1.0 To: Paolo Bonzini CC: "Myklebust, Trond" , Linux FS Devel , "linux-kernel@vger.kernel.org" , "Chris L. Mason" , Christoph Hellwig , Alexander Viro , "Martin K. Petersen" , Hannes Reinecke , Joel Becker Subject: Re: New copyfile system call - discuss before LSF? References: <512606DF.5050706@redhat.com> <4FA345DA4F4AE44899BD2B03EEEC2FA9235D998C@SACEXCMBX04-PRD.hq.netapp.com> <512635D2.4090207@redhat.com> <51267CEB.8070805@redhat.com> In-Reply-To: <51267CEB.8070805@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/21/2013 09:00 PM, Paolo Bonzini wrote: > Il 21/02/2013 15:57, Ric Wheeler ha scritto: >>> sendfile64() pretty much already has the right arguments for a >>> "copyfile", however it would be nice to add a 'flags' parameter: the >>> NFSv4.2 version would use that to specify whether or not to copy file >>> metadata. >> That would seem to be enough to me and has the advantage that it is an >> relatively obvious extension to something that is at least not totally >> unknown to developers. >> >> Do we need more than that for non-NFS paths I wonder? What does reflink >> need or the SCSI mechanism? > For virt we would like to be able to specify arbitrary block ranges. > Copying an entire file helps some copy operations like storage > migration. However, it is not enough to convert the guest's offloaded > copies to host-side offloaded copies. > > Paolo I don't think that the NFS protocol allows arbitrary ranges, but the SCSI commands are ranged based. If I remember what the windows people said at a SNIA event a few years back, they have a requirement that the target file be pre-allocated (at least for the SCSI based copy). Not clear to me where they iterate over that target file to do the block range copies, but I suspect it is in their kernel. Ric