From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:42830 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751399AbdJXF2b (ORCPT ); Tue, 24 Oct 2017 01:28:31 -0400 Subject: Re: [PATCH] fstests: btrfs/143: make test case more reliable To: Liu Bo , fstests@vger.kernel.org Cc: linux-btrfs@vger.kernel.org References: <20171023205733.14896-1-bo.li.liu@oracle.com> From: Nikolay Borisov Message-ID: Date: Tue, 24 Oct 2017 08:28:28 +0300 MIME-Version: 1.0 In-Reply-To: <20171023205733.14896-1-bo.li.liu@oracle.com> Content-Type: text/plain; charset=utf-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 23.10.2017 23:57, Liu Bo wrote: > Currently drop_caches is used to invalidate file's page cache so that > buffered read can hit disk, but the problem is that it may also > invalidate metadata's page cache, so the test case may not get read > errors (and repair) if reading metadata has consumed the injected > faults. > > This changes it to do 'fadvise -d' to firstly access all metadata it > needs to locate the file and then only drops the test file's page > cache. Also this changes it to read the file only if pid%2 == 1. > > Reported-by: Nikolay Borisov > Signed-off-by: Liu Bo > --- > tests/btrfs/143 | 20 ++++++++++---------- > 1 file changed, 10 insertions(+), 10 deletions(-) > > diff --git a/tests/btrfs/143 b/tests/btrfs/143 > index da7bfd8..dabd03d 100755 > --- a/tests/btrfs/143 > +++ b/tests/btrfs/143 > @@ -127,16 +127,16 @@ echo "step 3......repair the bad copy" >>$seqres.full > # since raid1 consists of two copies, and the bad copy was put on stripe #1 > # while the good copy lies on stripe #0, the bad copy only gets access when the > # reader's pid % 2 == 1 is true > -while true; do > - # start_fail only fails the following buffered read so the repair is > - # supposed to work. > - echo 3 > /proc/sys/vm/drop_caches > - start_fail > - $XFS_IO_PROG -c "pread 0 4K" "$SCRATCH_MNT/foobar" > /dev/null & > - pid=$! > - wait > - stop_fail > - [ $((pid % 2)) == 1 ] && break > +while [[ -z ${result} ]]; do > + # invalidate the page cache. > + $XFS_IO_PROG -c "fadvise -d 0 128K" $SCRATCH_MNT/foobar I'm a bit worried about the expectations of the DONT_NEED: https://linux.die.net/man/2/posix_fadvise: The advice is not binding; it merely constitutes an expectation on behalf of the application. This might very well be a moot point but still > + > + start_fail > + result=$(bash -c " > + if [[ \$((\$\$ % 2)) -eq 1 ]]; then > + exec $XFS_IO_PROG -c \"pread 0 4K\" \"$SCRATCH_MNT/foobar\" > + fi"); > + stop_fail > done > > _scratch_unmount >