From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:33474 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751614AbdF0OuW (ORCPT ); Tue, 27 Jun 2017 10:50:22 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1E471FEEF9 for ; Tue, 27 Jun 2017 14:50:17 +0000 (UTC) Received: from bfoster.bfoster (dhcp-41-20.bos.redhat.com [10.18.41.20]) by smtp.corp.redhat.com (Postfix) with ESMTP id E173885A51 for ; Tue, 27 Jun 2017 14:50:16 +0000 (UTC) From: Brian Foster Subject: [PATCH] tests/xfs: test for log recovery failure after tail overwrite Date: Tue, 27 Jun 2017 10:50:16 -0400 Message-Id: <1498575016-57959-1-git-send-email-bfoster@redhat.com> In-Reply-To: <1498574436-57561-1-git-send-email-bfoster@redhat.com> References: <1498574436-57561-1-git-send-email-bfoster@redhat.com> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: linux-xfs@vger.kernel.org XFS is susceptible to log recovery problems if the fs crashes under certain circumstances. If the tail has been pinned for long enough to the log to fill and the next batch of log buffer submissions happen to fail, the filesystem shutsdown having potentially overwritten part of the range between the last good tail->head range in the log. This causes log recovery to fail with crc mismatch or invalid log record errors. This problem is not yet fixed and thus known/expected to fail. At this time, this test serves as a reminder that the problem exists and a reproducer for future verification purposes. Note that this problem is currently only reproducible with larger (non-default) log buffer sizes (i.e., '-o logbsize=256k') or smaller block sizes (1k). Signed-off-by: Brian Foster --- Here's the latest variant of the test that can reproduce this problem. This version depends on the recent error injection sysfs knobs and the existence of the associated knobs for log item pinning and bad log record crc injection. I've left fstests off the cc list for now since much of that code is still outstanding. This is currently posted for reference. Brian tests/xfs/999 | 113 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ tests/xfs/999.out | 2 + tests/xfs/group | 1 + 3 files changed, 116 insertions(+) create mode 100755 tests/xfs/999 create mode 100644 tests/xfs/999.out diff --git a/tests/xfs/999 b/tests/xfs/999 new file mode 100755 index 0000000..e321d73 --- /dev/null +++ b/tests/xfs/999 @@ -0,0 +1,113 @@ +#! /bin/bash +# FS QA Test No. 999 +# +# Attempt to reproduce log recovery failure by writing corrupt log records over +# the last good tail in the log. The tail is force pinned while a workload runs +# the head as close as possible behind the tail. Once the head is pinned, +# corrupted log records are written to the log and the filesystem shuts down. +# +# While log recovery should handle the corrupted log records, it has historical +# problems dealing with the situation where the corrupted log records may have +# overwritten the tail of the previous good record in the log. If this occurs, +# log recovery may fail. +# +# This can be reproduced more reliably under non-default conditions such as with +# the smallest supported FSB sizes and/or largest supported log buffer sizes and +# counts (logbufs and logbsize mount options). +# +# Note that this test requires a DEBUG mode kernel. +# +#----------------------------------------------------------------------- +# Copyright (c) 2017 Red Hat, Inc. All Rights Reserved. +# +# This program is free software; you can redistribute it and/or +# modify it under the terms of the GNU General Public License as +# published by the Free Software Foundation. +# +# This program is distributed in the hope that it would be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program; if not, write the Free Software Foundation, +# Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA +#----------------------------------------------------------------------- +# + +seq=`basename $0` +seqres=$RESULT_DIR/$seq +echo "QA output created by $seq" + +here=`pwd` +tmp=/tmp/$$ +status=1 # failure is the default! +trap "_cleanup; exit \$status" 0 1 2 3 15 + +_cleanup() +{ + cd / + rm -f $tmp.* + $KILLALL_PROG -9 fsstress > /dev/null 2>&1 + [ -e /sys/fs/xfs/$sdev/errortag/log_item_pin ] && + echo 0 > /sys/fs/xfs/$sdev/errortag/log_item_pin + wait > /dev/null 2>&1 +} + +rm -f $seqres.full + +# get standard environment, filters and checks +. ./common/rc + +# real QA test starts here + +# Modify as appropriate. +_supported_fs xfs +_supported_os Linux +_require_xfs_sysfs $(_short_dev $TEST_DEV)/errortag/log_item_pin +_require_xfs_sysfs $(_short_dev $TEST_DEV)/errortag/log_bad_crc +_require_scratch +_require_command "$KILLALL_PROG" killall + +echo "Silence is golden." + +sdev=$(_short_dev $SCRATCH_DEV) + +_scratch_mkfs >> $seqres.full 2>&1 || _fail "mkfs failed" +_scratch_mount || _fail "mount failed" + +# populate the fs with some data and cycle the mount to reset the log head/tail +$FSSTRESS_PROG -d $SCRATCH_MNT -z -fcreat=1 -p 4 -n 100000 > /dev/null 2>&1 +_scratch_cycle_mount || _fail "mount failed" + +# Pin the tail and start a file removal workload. File removal tends to +# reproduce the corruption more reliably. +echo 1 > /sys/fs/xfs/$sdev/errortag/log_item_pin + +rm -rf $SCRATCH_MNT/* > /dev/null 2>&1 & +workpid=$! + +# wait for the head to stop pushing forward +prevhead=-1 +head=`cat /sys/fs/xfs/$sdev/log/log_head_lsn` +while [ "$head" != "$prevhead" ]; do + sleep 5 + prevhead=$head + head=`cat /sys/fs/xfs/$sdev/log/log_head_lsn` +done + +# Once the head is pinned behind the tail, enable log record corruption and +# unpin the tail. All subsequent log buffer writes end up corrupted on-disk and +# result in log I/O errors. +echo 1 > /sys/fs/xfs/$sdev/errortag/log_bad_crc +echo 0 > /sys/fs/xfs/$sdev/errortag/log_item_pin + +# wait for fs shutdown to kill the workload +wait $workpid + +# cycle mount to test log recovery +_scratch_cycle_mount + +# success, all done +status=0 +exit diff --git a/tests/xfs/999.out b/tests/xfs/999.out new file mode 100644 index 0000000..d254382 --- /dev/null +++ b/tests/xfs/999.out @@ -0,0 +1,2 @@ +QA output created by 999 +Silence is golden. diff --git a/tests/xfs/group b/tests/xfs/group index 2a3b950..a10fd6d 100644 --- a/tests/xfs/group +++ b/tests/xfs/group @@ -419,3 +419,4 @@ 419 auto quick 420 auto quick clone dedupe 421 auto quick clone dedupe +999 auto log -- 2.7.5