Return-Path: linux-nfs-owner@vger.kernel.org Received: from zeniv.linux.org.uk ([195.92.253.2]:49752 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751300Ab1LPIAb (ORCPT ); Fri, 16 Dec 2011 03:00:31 -0500 Date: Fri, 16 Dec 2011 00:00:23 -0800 From: Joel Becker To: Ric Wheeler Cc: Al Viro , "linux-scsi@vger.kernel.org" , linux-fsdevel , Hannes Reinecke , Andrew Morton , linux-nfs@vger.kernel.org, James Bottomley Subject: Re: copy offload support in Linux - new system call needed? Message-ID: <20111216080022.GA5183@noexit.corp.google.com> References: <4EE8F75F.6070800@gmail.com> <20111214192739.GN2203@ZenIV.linux.org.uk> <4EE8FC2E.3010207@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <4EE8FC2E.3010207@gmail.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Wed, Dec 14, 2011 at 02:42:38PM -0500, Ric Wheeler wrote: > On 12/14/2011 02:27 PM, Al Viro wrote: > >On Wed, Dec 14, 2011 at 02:22:07PM -0500, Ric Wheeler wrote: > > > >>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? > >copyfile(2) is probably a good way to go, provided that we do _not_ > >go baroque as it had happened the last time syscall had been discussed. > > > >IOW, to hell with progress reports, etc. - just a fastpath kind of > >thing, in the same kind of relationship to cp(1) as rename(2) is to mv(1). > >If it works - fine, if not - caller has to be ready to deal with handling > >cross-device case anyway. > > I think that this approach makes a lot of sense. Most of the > devices/targets that support the copy offload, will do it in very > reasonable amounts of time. > > Let me see if I can dig up some of the presentations from the NetApp > guys who presented overviews or the specifications from the IETF and > T10.... Whee! I've been down the rabbit hole, but I've promised myself to get the updated patch out soon. I know that Trond et al are probably wondering what happened to the patch. more soon. Joel -- Life's Little Instruction Book #207 "Swing for the fence." http://www.jlbec.org/ jlbec@evilplan.org