Re: [PATCH] xfs: test a race between dio reads and mapped writes

[Eryu Guan <eguan@redhat.com>]

On Tue, Jun 27, 2017 at 05:03:52PM +0800, Xiao Yang wrote:
> This regression test reproduces a race between a direct
> I/O read and a mapped write to a hole in a file.  If the
> race occurs, it will trigger a BUG_ON().  This XFS bug
> has been fixed by:
> 
> 04197b3 (xfs: don't BUG() on mixed direct and mapped I/O)
> 
> Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
> ---
>  tests/xfs/422     | 86 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  tests/xfs/422.out |  2 ++
>  tests/xfs/group   |  1 +
>  3 files changed, 89 insertions(+)
>  create mode 100755 tests/xfs/422
>  create mode 100644 tests/xfs/422.out
> 
> diff --git a/tests/xfs/422 b/tests/xfs/422
> new file mode 100755
> index 0000000..a57ffab
> --- /dev/null
> +++ b/tests/xfs/422
> @@ -0,0 +1,86 @@
> +#! /bin/bash
> +# FS QA Test No. 422
> +#
> +# Regression test for commit:
> +# 04197b3 ("xfs: don't BUG() on mixed direct and mapped I/O)
             ^^ missing ending " :)
> +#
> +# This case tests a race between a direct I/O read and a
> +# mapped write to a hole in a file.  If the race occurs,
> +# it will trigger a BUG_ON().
> +#
> +#-----------------------------------------------------------------------
> +# Copyright (c) 2017 Fujitsu.  All Rights Reserved.
> +# Author: Xiao Yang <yangx.jy@cn.fujitsu.com>
> +#
> +# 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()
> +{
> +	rm -rf $tmp.*
> +}
> +
> +# get standard environment and checks
> +. ./common/rc
> +
> +# real QA test starts here
> +_supported_os Linux
> +_supported_fs xfs

I see nothing xfs specific in this test, I think it can be made generic
easily.

> +_require_scratch
> +_disable_dmesg_check

Better to add comments on ignoring dmesg check result.

Thanks,
Eryu

> +_require_xfs_io_command "truncate"
> +_require_xfs_io_command "fpunch"
> +
> +rm -f $seqres.full
> +
> +# format and mount
> +_scratch_mkfs > $seqres.full 2>&1
> +_scratch_mount >> $seqres.full 2>&1
> +
> +filesz=$((65536 * 2))
> +
> +# create a test file with a hole
> +$XFS_IO_PROG -f -c "truncate $((filesz * 2))" $SCRATCH_MNT/file >> $seqres.full
> +
> +# run a background dio read to a hole in a loop
> +while true; do
> +	$XFS_IO_PROG -d -c "pread 0 $filesz" $SCRATCH_MNT/file > /dev/null 2>&1
> +done &
> +
> +dread_pid=$!
> +
> +# run mapped write to the same hole as dio read
> +for i in `seq 0 999`; do
> +	$XFS_IO_PROG -c "mmap 0 $filesz" -c "mwrite 0 $filesz" $SCRATCH_MNT/file \
> +		> /dev/null
> +	$XFS_IO_PROG -c "fpunch 0 $filesz" $SCRATCH_MNT/file > /dev/null
> +done
> +
> +kill -9 $dread_pid > /dev/null 2>&1
> +wait $dread_pid > /dev/null 2>&1
> +
> +echo "Silence is golden"
> +
> +# success, all done
> +status=0
> +exit
> diff --git a/tests/xfs/422.out b/tests/xfs/422.out
> new file mode 100644
> index 0000000..f70693f
> --- /dev/null
> +++ b/tests/xfs/422.out
> @@ -0,0 +1,2 @@
> +QA output created by 422
> +Silence is golden
> diff --git a/tests/xfs/group b/tests/xfs/group
> index 2a3b950..f43ffcf 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
> +422 auto quick dangerous
> -- 
> 1.8.3.1
> 
> 
> 
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