Return-Path: Received: from bombadil.infradead.org ([198.137.202.9]:44510 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932869AbbDNQxq (ORCPT ); Tue, 14 Apr 2015 12:53:46 -0400 Date: Tue, 14 Apr 2015 09:53:44 -0700 From: Christoph Hellwig To: Jeff Layton Cc: Trond Myklebust , Zach Brown , Linux Kernel Mailing List , Linux FS-devel Mailing List , linux-btrfs@vger.kernel.org, Linux NFS Mailing List , linux-scsi@vger.kernel.org Subject: Re: [PATCH RFC 1/3] vfs: add copy_file_range syscall and vfs helper Message-ID: <20150414165344.GA21421@infradead.org> References: <1428703236-24735-1-git-send-email-zab@redhat.com> <1428703236-24735-2-git-send-email-zab@redhat.com> <20150411000208.GA20949@lenny.home.zabbo.net> <20150411090402.67d22d02@tlielax.poochiereds.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20150411090402.67d22d02@tlielax.poochiereds.net> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Sat, Apr 11, 2015 at 09:04:02AM -0400, Jeff Layton wrote: > Yuck! How the heck do you clean up the mess if that happens? I guess > you're just stuck redoing the copy with normal READ/WRITE? > > Maybe we need to have the interface return a hard error in that > case and not try to give back any sort of offset? The NFSv4.2 COPY interface is a train wreck. At least for Linux I'd expect us to simply ignore it and only implement my new CLONE operation with sane semantics. That is unless someone can show some real life use case for the inter server copy, in which case we'll have to deal with that mess. But getting that one right at the VFS level will be a nightmare anyway. Make this a vote from me to not support partial copies and just return and error in that case.