From patchwork Tue Oct 21 20:43:11 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Filipe Manana X-Patchwork-Id: 5127721 Return-Path: X-Original-To: patchwork-linux-btrfs@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id BEF799F374 for ; Tue, 21 Oct 2014 19:44:10 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 7898A201F2 for ; Tue, 21 Oct 2014 19:44:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9D5C520256 for ; Tue, 21 Oct 2014 19:44:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932831AbaJUTnz (ORCPT ); Tue, 21 Oct 2014 15:43:55 -0400 Received: from victor.provo.novell.com ([137.65.250.26]:33410 "EHLO prv3-mh.provo.novell.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755344AbaJUTnx (ORCPT ); Tue, 21 Oct 2014 15:43:53 -0400 Received: from debian-vm3.lan (prv-ext-foundry1int.gns.novell.com [137.65.251.240]) by prv3-mh.provo.novell.com with ESMTP (NOT encrypted); Tue, 21 Oct 2014 13:43:42 -0600 From: Filipe Manana To: fstests@vger.kernel.org Cc: linux-btrfs@vger.kernel.org, Filipe Manana Subject: [PATCH] fstests: btrfs, add regression test for clone ioctl Date: Tue, 21 Oct 2014 21:43:11 +0100 Message-Id: <1413924191-30467-1-git-send-email-fdmanana@suse.com> X-Mailer: git-send-email 1.9.1 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Spam-Status: No, score=-8.3 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Regression test for a btrfs clone ioctl issue where races between a clone operation and concurrent target file reads would result in leaving stale data in the page cache. After the clone operation finished, reading from the clone target file would return the old and no longer valid data. This affected only buffered reads (i.e. didn't affect direct IO reads). This issue was fixed by the following linux kernel patch: Btrfs: ensure readers see new data after a clone operation (commit c125b8bff1d9f6c8c91ce4eb8bd5616058c7d510) Signed-off-by: Filipe Manana --- tests/btrfs/081 | 131 ++++++++++++++++++++++++++++++++++++++++++++++++++++ tests/btrfs/081.out | 4 ++ tests/btrfs/group | 1 + 3 files changed, 136 insertions(+) create mode 100755 tests/btrfs/081 create mode 100644 tests/btrfs/081.out diff --git a/tests/btrfs/081 b/tests/btrfs/081 new file mode 100755 index 0000000..d2e3767 --- /dev/null +++ b/tests/btrfs/081 @@ -0,0 +1,131 @@ +#! /bin/bash +# FSQA Test No. 081 +# +# Regression test for a btrfs clone ioctl issue where races between +# a clone operation and concurrent target file reads would result in +# leaving stale data in the page cache. After the clone operation +# finished, reading from the clone target file would return the old +# and no longer valid data. This affected only buffered reads (i.e. +# didn't affect direct IO reads). +# +# This issue was fixed by the following linux kernel patch: +# +# Btrfs: ensure readers see new data after a clone operation +# (commit c125b8bff1d9f6c8c91ce4eb8bd5616058c7d510) +# +#----------------------------------------------------------------------- +# +# Copyright (C) 2014 SUSE Linux Products GmbH. All Rights Reserved. +# Author: Filipe Manana +# +# 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" +tmp=/tmp/$$ +status=1 # failure is the default! +trap "_cleanup; exit \$status" 0 1 2 3 15 + +_cleanup() +{ + rm -f $tmp.* +} + +# get standard environment, filters and checks +. ./common/rc +. ./common/filter + +# real QA test starts here +_need_to_be_root +_supported_fs btrfs +_supported_os Linux +_require_scratch +_require_btrfs_cloner + +rm -f $seqres.full + +num_extents=100 +extent_size=8192 + +create_source_file() +{ + name=$1 + + # Create a file with $num_extents extents, each with a size of + # $extent_size bytes. + touch $SCRATCH_MNT/$name + for ((i = 0; i < $num_extents; i++)); do + off=$((i * $extent_size)) + run_check $XFS_IO_PROG \ + -c "pwrite -S $i -b $extent_size $off $extent_size" \ + -c "fsync" $SCRATCH_MNT/$name + done +} + +create_target_file() +{ + name=$1 + file_size=$(($num_extents * $extent_size)) + + run_check $XFS_IO_PROG -f -c "pwrite -S 0xff 0 $file_size" \ + -c "fsync" $SCRATCH_MNT/$name +} + +reader_loop() +{ + name=$1 + + while true; do + cat $SCRATCH_MNT/$name > /dev/null + done +} + +_scratch_mkfs >>$seqres.full 2>&1 +_scratch_mount + +create_source_file "foo" +create_target_file "bar" + +reader_loop "bar" & +reader_pid=$! + +$CLONER_PROG -s 0 -d 0 -l $(($num_extents * $extent_size)) \ + $SCRATCH_MNT/foo $SCRATCH_MNT/bar + +kill $reader_pid > /dev/null 2>&1 + +# Now both foo and bar should have exactly the same content. +# This didn't use to be the case before the btrfs kernel fix mentioned +# above. The clone ioctl was racy, as it removed bar's pages from the +# page cache and only after it would update bar's metadata to point to +# the same extents that foo's metadata points to - and this was done in +# an unprotected way, so that a file read request done right after the +# clone ioctl removed the pages from the page cache and before it updated +# bar's metadata, would result in populating the page cache with stale +# data. Therefore a file read after the clone operation finished would +# not get the cloned data but it would get instead the old and no longer +# valid data. +md5sum $SCRATCH_MNT/foo | _filter_scratch +md5sum $SCRATCH_MNT/bar | _filter_scratch + +# Validate the content of bar still matches foo's content even after +# clearing all of bar's data from the page cache. +_scratch_remount +md5sum $SCRATCH_MNT/bar | _filter_scratch + +status=0 +exit diff --git a/tests/btrfs/081.out b/tests/btrfs/081.out new file mode 100644 index 0000000..3c7c3d2 --- /dev/null +++ b/tests/btrfs/081.out @@ -0,0 +1,4 @@ +QA output created by 081 +14968c092c68e32fa35e776392d14523 SCRATCH_MNT/foo +14968c092c68e32fa35e776392d14523 SCRATCH_MNT/bar +14968c092c68e32fa35e776392d14523 SCRATCH_MNT/bar diff --git a/tests/btrfs/group b/tests/btrfs/group index 801fc73..fc60c63 100644 --- a/tests/btrfs/group +++ b/tests/btrfs/group @@ -82,3 +82,4 @@ 077 auto quick 078 auto 080 auto +081 auto quick