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=-18.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY autolearn=ham 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 C19E1C433DB for ; Sun, 7 Mar 2021 15:20:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 98036650FC for ; Sun, 7 Mar 2021 15:20:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232447AbhCGPUF (ORCPT ); Sun, 7 Mar 2021 10:20:05 -0500 Received: from out20-27.mail.aliyun.com ([115.124.20.27]:52472 "EHLO out20-27.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232306AbhCGPTh (ORCPT ); Sun, 7 Mar 2021 10:19:37 -0500 X-Alimail-AntiSpam: AC=CONTINUE;BC=0.07446809|-1;CH=green;DM=|CONTINUE|false|;DS=CONTINUE|ham_regular_dialog|0.293283-0.00204427-0.704673;FP=0|0|0|0|0|-1|-1|-1;HT=ay29a033018047206;MF=guan@eryu.me;NM=1;PH=DS;RN=4;RT=4;SR=0;TI=SMTPD_---.JhcltBe_1615130372; Received: from localhost(mailfrom:guan@eryu.me fp:SMTPD_---.JhcltBe_1615130372) by smtp.aliyun-inc.com(10.147.41.199); Sun, 07 Mar 2021 23:19:32 +0800 Date: Sun, 7 Mar 2021 23:19:32 +0800 From: Eryu Guan To: Filipe Manana Cc: fstests , linux-btrfs , Filipe Manana Subject: Re: [PATCH] btrfs: add test for cases when a dio write has to fallback to a buffered write Message-ID: References: <20210211170118.12551-1-fdmanana@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Sun, Mar 07, 2021 at 03:07:43PM +0000, Filipe Manana wrote: > On Sun, Mar 7, 2021 at 2:41 PM Eryu Guan wrote: > > > > On Thu, Feb 11, 2021 at 05:01:18PM +0000, fdmanana@kernel.org wrote: > > > From: Filipe Manana > > > > > > Test cases where a direct IO write, with O_DSYNC, can not be done and has > > > to fallback to a buffered write. > > > > > > This is motivated by a regression that was introduced in kernel 5.10 by > > > commit 0eb79294dbe328 ("btrfs: dio iomap DSYNC workaround")) and was > > > fixed in kernel 5.11 by commit ecfdc08b8cc65d ("btrfs: remove dio iomap > > > DSYNC workaround"). > > > > > > Signed-off-by: Filipe Manana > > > > Sorry for the late review.. > > > > So this is supposed to fail with v5.10 kernel, right? But I got it > > passed > > Because either you are testing with a patched 5.10.x kernel, or you > don't have CONFIG_BTRFS_ASSERT=y in your config. > The fix landed in 5.10.18: You're right, I don't have CONFIG_BTRFS_ASSERT=y. As the test dumps the od output of the file content, so I thought the failure would be a data corruption, and expected a od output diff failure. > > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v5.10.18&id=a6703c71153438d3ebdf58a75d53dd5e57b33095 > > > > > [root@fedoravm xfstests]# ./check -s btrfs btrfs/231 > > SECTION -- btrfs > > RECREATING -- btrfs on /dev/mapper/testvg-lv1 > > FSTYP -- btrfs > > PLATFORM -- Linux/x86_64 fedoravm 5.10.0 #6 SMP Sun Mar 7 22:25:35 CST 2021 > > MKFS_OPTIONS -- /dev/mapper/testvg-lv2 > > MOUNT_OPTIONS -- /dev/mapper/testvg-lv2 /mnt/scratch > > > > btrfs/231 13s ... 8s > > Ran: btrfs/231 > > Passed all 1 tests > > > > SECTION -- btrfs > > ========================= > > Ran: btrfs/231 > > Passed all 1 tests > > > > > --- > > > tests/btrfs/231 | 61 +++++++++++++++++++++++++++++++++++++++++++++ > > > tests/btrfs/231.out | 21 ++++++++++++++++ > > > tests/btrfs/group | 1 + > > > 3 files changed, 83 insertions(+) > > > create mode 100755 tests/btrfs/231 > > > create mode 100644 tests/btrfs/231.out > > > > > > diff --git a/tests/btrfs/231 b/tests/btrfs/231 > > > new file mode 100755 > > > index 00000000..9a404f57 > > > --- /dev/null > > > +++ b/tests/btrfs/231 > > > @@ -0,0 +1,61 @@ > > > +#! /bin/bash > > > +# SPDX-License-Identifier: GPL-2.0 > > > +# Copyright (C) 2021 SUSE Linux Products GmbH. All Rights Reserved. > > > +# > > > +# FS QA Test No. btrfs/231 > > > +# > > > +# Test cases where a direct IO write, with O_DSYNC, can not be done and has to > > > +# fallback to a buffered write. > > > +# > > > +seq=`basename $0` > > > +seqres=$RESULT_DIR/$seq > > > +echo "QA output created by $seq" > > > + > > > +tmp=/tmp/$$ > > > +status=1 # failure is the default! > > > +trap "_cleanup; exit \$status" 0 1 2 3 15 > > > + > > > +_cleanup() > > > +{ > > > + cd / > > > + rm -f $tmp.* > > > +} > > > + > > > +# get standard environment, filters and checks > > > +. ./common/rc > > > +. ./common/filter > > > +. ./common/attr > > > + > > > +# real QA test starts here > > > +_supported_fs btrfs > > > +_require_scratch > > > +_require_odirect > > > +_require_chattr c > > > + > > > +rm -f $seqres.full > > > + > > > +_scratch_mkfs >>$seqres.full 2>&1 > > > +_scratch_mount > > > + > > > +# First lets test with an attempt to write into a file range with compressed > > > +# extents. > > > +touch $SCRATCH_MNT/foo > > > +$CHATTR_PROG +c $SCRATCH_MNT/foo > > > > It's not so clear to me why writing into a compressed file is required, > > would you please add more comments? > > The test is meant to test cases where we can deterministically make a > direct IO write fallback to buffered IO. > There are 2 such cases: > > 1) Attempting to write to an unaligned offset - this was the bug in > 5.10 that resulted in a crash when CONFIG_BTRFS_ASSERT=y (default in > many distros, such as openSUSE). > > 2) Writing to a range that has compressed extents. This has nothing to > do with the 5.10 regression, I just added it since there's no existing > test that explicitly and deterministically triggers this. > So yes, I decided to add a test case for all possible cases of > direct IO falling back to buffered instead of adding one just to test > a regression (and help detecting any possible future regressions). Sounds good, thanks! Eryu