From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D0ECFECE599 for ; Wed, 16 Oct 2019 20:31:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A1B0B21835 for ; Wed, 16 Oct 2019 20:31:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2437166AbfJPUbv (ORCPT ); Wed, 16 Oct 2019 16:31:51 -0400 Received: from fieldses.org ([173.255.197.46]:36544 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728881AbfJPUbv (ORCPT ); Wed, 16 Oct 2019 16:31:51 -0400 Received: by fieldses.org (Postfix, from userid 2815) id B2BCEBDB; Wed, 16 Oct 2019 16:31:50 -0400 (EDT) Date: Wed, 16 Oct 2019 16:31:50 -0400 From: "J. Bruce Fields" To: "Kornievskaia, Olga" Cc: Rick Macklem , "linux-nfs@vger.kernel.org" Subject: Re: NFSv4.2 server replies to Copy with length == 0 Message-ID: <20191016203150.GC17543@fieldses.org> References: <20191016155838.GA17543@fieldses.org> <31E6043B-090D-4E37-B66F-A45AC0CFC970@netapp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <31E6043B-090D-4E37-B66F-A45AC0CFC970@netapp.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Wed, Oct 16, 2019 at 07:53:45PM +0000, Kornievskaia, Olga wrote: > On 10/16/19, 11:58 AM, "J. Bruce Fields" wrote: > On Wed, Oct 16, 2019 at 06:22:42AM +0000, Rick Macklem wrote: > > It seems that the Copy reply with wr_count == 0 occurs when the > > client sends a Copy request with ca_src_offset beyond EOF in the > > input file. (It happened because I was testing an old/broken > > version of my client, but I can reproduce it, if you need a > > bugfix to be tested. I don't know if the case of > > ca_src_offset+ca_count beyond EOF behaves the same?) --> The RFC > > seems to require a reply of NFS4ERR_INVAL for this case. > > I've never understood that INVAL requirement. But I know it's > been discussed before, maybe there was some justification for it > that I've forgotten. > > Sigh, well, I don’t know if we should consider adding the check to the > NFS server to be NFS spec compliant. VFS layer didn't want the check > and instead the preference has been to keep read() semantics of > returning a short read (when the len was beyond the end of the file or > if the source) to something beyond the end of the file. I'm inclined to think the spec's just wrong. And how else could a client possibly interpret a 0 return? > On the client if VFS did read of len=0 then VFS itself we return 0, > thus this doesn't protect against other clients sending an NFS copy > with len=0. And in NFS, receiving copy with len=0 means copy to the > end of the file. It's not implemented for any "intra" or "inter" code. A call with len=0 sounds like a different case. --b.