Return-Path: linux-nfs-owner@vger.kernel.org Received: from fn.samba.org ([216.83.154.106]:52047 "EHLO mail.samba.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755103Ab1LNT7e (ORCPT ); Wed, 14 Dec 2011 14:59:34 -0500 Date: Wed, 14 Dec 2011 11:59:31 -0800 From: Jeremy Allison To: Ric Wheeler Cc: "linux-scsi@vger.kernel.org" , linux-fsdevel , Hannes Reinecke , Andrew Morton , linux-nfs@vger.kernel.org, Joel Becker , James Bottomley Subject: Re: copy offload support in Linux - new system call needed? Message-ID: <20111214195931.GC10664@samba2> Reply-To: Jeremy Allison References: <4EE8F75F.6070800@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <4EE8F75F.6070800@gmail.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Wed, Dec 14, 2011 at 02:22:07PM -0500, Ric Wheeler wrote: > > Back at LinuxCon Prague, we talked about the new NFS and SCSI > commands that let us offload copy operations to a storage device > (like an NFS server or storage array). > > This got new life in the virtual machine world where you might want > to clone bulky guest files or ranges of blocks and was driven > through the standards bodies by vmware, microsoft and some of the > major storage vendors. Windows8 has this functionality fully coded > and integrated in the GUI, I assume vmware also uses it and there > are some vendors who announced support at the SNIA SDC conference. > > We had an active thread a couple of years back that came out of the > reflink work and, at the time, there seemed to be moderately > positive support for adding a new system call that would fit this > use case (Joel Becker's copyfile()). > > Can we resurrect this effort? Is copyfile() still a good way to go, > or should we look at other hooks? Windows uses a COPYCHUNK call, which specifies the following parameters: Definition of a copy "chunk": hyper source_off; hyper target_off; uint32 length; and an array of these chunks which is passed into their kernel. This is what we have to implement in Samba. Jeremy.