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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable 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 AAFCAC33CB3 for ; Tue, 14 Jan 2020 19:00:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 91B4E24655 for ; Tue, 14 Jan 2020 19:00:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728844AbgANTA6 (ORCPT ); Tue, 14 Jan 2020 14:00:58 -0500 Received: from mga06.intel.com ([134.134.136.31]:52152 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726450AbgANTA6 (ORCPT ); Tue, 14 Jan 2020 14:00:58 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 14 Jan 2020 11:00:57 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,319,1574150400"; d="scan'208";a="219689462" Received: from iweiny-desk2.sc.intel.com ([10.3.52.157]) by fmsmga008.fm.intel.com with ESMTP; 14 Jan 2020 11:00:57 -0800 Date: Tue, 14 Jan 2020 11:00:57 -0800 From: Ira Weiny To: "Darrick J. Wong" Cc: linux-kernel@vger.kernel.org, Alexander Viro , Dan Williams , Dave Chinner , Christoph Hellwig , "Theodore Y. Ts'o" , Jan Kara , linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [RFC PATCH V2 10/12] fs/xfs: Fix truncate up Message-ID: <20200114190057.GB7871@iweiny-DESK2.sc.intel.com> References: <20200110192942.25021-1-ira.weiny@intel.com> <20200110192942.25021-11-ira.weiny@intel.com> <20200113222755.GP8247@magnolia> <20200114004047.GC29860@iweiny-DESK2.sc.intel.com> <20200114011407.GT8247@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200114011407.GT8247@magnolia> User-Agent: Mutt/1.11.1 (2018-12-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 13, 2020 at 05:14:07PM -0800, Darrick J. Wong wrote: > On Mon, Jan 13, 2020 at 04:40:47PM -0800, Ira Weiny wrote: > > On Mon, Jan 13, 2020 at 02:27:55PM -0800, Darrick J. Wong wrote: > > > On Fri, Jan 10, 2020 at 11:29:40AM -0800, ira.weiny@intel.com wrote: > > > > From: Ira Weiny > > > > > > > > When zeroing the end of a file we must account for bytes contained in > > > > the final page which are past EOF. > > > > > > > > Extend the range passed to iomap_zero_range() to reach LLONG_MAX which > > > > will include all bytes of the final page. > > > > > > > > Signed-off-by: Ira Weiny > > > > --- > > > > fs/xfs/xfs_iops.c | 2 +- > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c > > > > index a2f2604c3187..a34b04e8ac9c 100644 > > > > --- a/fs/xfs/xfs_iops.c > > > > +++ b/fs/xfs/xfs_iops.c > > > > @@ -910,7 +910,7 @@ xfs_setattr_size( > > > > */ > > > > if (newsize > oldsize) { > > > > trace_xfs_zero_eof(ip, oldsize, newsize - oldsize); > > > > - error = iomap_zero_range(inode, oldsize, newsize - oldsize, > > > > + error = iomap_zero_range(inode, oldsize, LLONG_MAX - oldsize, > > > > > > Huh? Won't this cause the file size to be set to LLONG_MAX? > > > > Not as I understand the code. > > iomap_zero_range uses the standard iomap_write_{begin,end} functions, > which means that if you pass it an (offset, length) that extend beyond > EOF it will change isize to offset+length. I don't see that but I'll take your word for it... That is unfortunate because I would have thought that the full page would have been zero'ed by something already. I found code in xfs_free_file_space() with this comment: /* * If we zeroed right up to EOF and EOF straddles a page boundary we * must make sure that the post-EOF area is also zeroed because the * page could be mmap'd and iomap_zero_range doesn't do that for us. * Writeback of the eof page will do this, albeit clumsily. */ But that just calls filemap_write_and_wait_range()... :-/ > > > But as I said in the cover I am not 100% sure of > > this fix. > > > From what I can tell xfs_ioctl_setattr_dax_invalidate() should invalidate the > > mappings and the page cache and the traces I have indicate that the DAX mode > > is not changing or was properly held off. > > Hmm, that implies the invalidation didn't work. Can you find a way to > report the contents of the page cache after the dax mode change > invalidation fails? I wonder if this is something dorky like rounding > down such that the EOF page doesn't actually get invalidated? > > Hmm, no, xfs_ioctl_setattr_dax_invalidate should be nuking all the > pages... do you have a quick reproducer? I thought I did... What I have done is take this patch: https://www.spinics.net/lists/fstests/msg13313.html and put [run_fsx ""] in a loop... (diff below) And without this truncate fix patch it was failing in about 5 - 10 iterations. But I'm running it right now and it has gone for 30+... :-( I am 90% confident that this series works for 100% of the use cases we have. I think this is an existing bug which I've just managed to find. And again I'm not comfortable with this patch either. So I'm not trying to argue for it but I just don't know what could be wrong... Ira diff --git a/tests/generic/999 b/tests/generic/999 index 6dd5529dbc65..929c20c6db04 100755 --- a/tests/generic/999 +++ b/tests/generic/999 @@ -274,7 +274,9 @@ function run_fsx { pid="" } -run_fsx "" +while [ 1 ]; do + run_fsx "" +done run_fsx "-A" run_fsx "-Z -r 4096 -w 4096"