From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f174.google.com ([209.85.192.174]:34805 "EHLO mail-pf0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S941174AbcJTPrf (ORCPT ); Thu, 20 Oct 2016 11:47:35 -0400 Received: by mail-pf0-f174.google.com with SMTP id r16so39402339pfg.1 for ; Thu, 20 Oct 2016 08:47:35 -0700 (PDT) Date: Thu, 20 Oct 2016 08:47:33 -0700 From: Omar Sandoval Subject: Re: About reflink len = 0 behavior Message-ID: <20161020154733.GA5436@vader> References: <94d643cc-fa49-4b20-b265-55d50af15e47@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <94d643cc-fa49-4b20-b265-55d50af15e47@cn.fujitsu.com> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Qu Wenruo Cc: "Darrick J. Wong" , fstests@vger.kernel.org, btrfs , linux-xfs@vger.kernel.org On Thu, Oct 20, 2016 at 03:50:46PM +0800, Qu Wenruo wrote: > Add cc to new xfs mail list. > > > At 10/20/2016 03:46 PM, Qu Wenruo wrote: > > Hi Darrick, xfs guys and btrfs guys. > > > > Although such question is quite late as reflink generic tests are in > > fstests for a long time, I'm still not sure what's the correct behavior > > for reflink len = 0. > > > > Test case generic/182 is causing different output between btrfs and xfs. > > > > For btrfs, dedupe will just return 0 and check nothing, while for xfs > > len == 0 means to check the whole file length. > > > > Both makes sense for me, for btrfs len = 0 behavior, it just follows > > read/write functions. > > And I assume xfs follows reflink behavior, when len is not specified, > > then reflink the length of src file. > > > > But since it's a generic test, we need to unify the behavior. > > > > So, which one is the standard and which document should we follow for > > such behavior definition? > > > > Thanks, > > Qu Hey, Qu, I brought this up a few months back here [1], and I think the conclusion was that consistency with clone (so the XFS behavior) was probably what we wanted. I just forgot to follow up and figure out if it would break any userspace programs in a way that mattered (I doubt it). 1: http://marc.info/?l=linux-btrfs&m=146828374631829&w=2 -- Omar