Re: [PATCH] fstests: generic: Check if cycle mount and sleep can affect fiemap result

Eryu Guan
2017-04-05T02:35:26Z

On Mon, Apr 03, 2017 at 03:09:23PM +0800, Qu Wenruo wrote:
> As long as we don't modify the on-disk data, fiemap result should always
> be constant.
>
> Operation like cycle mount and sleep should not affect fiemap result.
> While unfortunately, btrfs doesn't follow that behavior.
>
> Btrfs fiemap sometimes return merged result, while after cycle mount, it
> returns split result. Furthermore after a snap, btrfs returns merged
> result again.
>
> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>

Test fails with ext3/2 when driving with ext4 driver, fiemap changed
after umount/mount cycle, then changed back to original result after
sleeping some time. An ext4 bug? (cc'ed linux-ext4 list.)

=== Fiemap after dsync write and sleep ===
/vda6/file:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..127]: 12288..12415 128 0x1000
1: [128..255]: 12160..12287 128 0x1000
2: [256..511]: 16384..16639 256 0x1000
3: [512..2047]: 16896..18431 1536 0x1000
4: [2048..4095]: 19456..21503 2048 0x1001
=== Fiemap after cycle mount ===
/vda6/file:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..95]: 12288..12383 96 0x1000
1: [96..127]: 12384..12415 32 0x1000

[0-127] was split to two extents

2: [128..255]: 12160..12287 128 0x1000
3: [256..511]: 16384..16639 256 0x1000
4: [512..2047]: 16896..18431 1536 0x1000
5: [2048..4095]: 19456..21503 2048 0x1001
=== Fiemap after cycle mount and sleep ===
/vda6/file:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..127]: 12288..12415 128 0x1000
1: [128..255]: 12160..12287 128 0x1000
2: [256..511]: 16384..16639 256 0x1000
3: [512..2047]: 16896..18431 1536 0x1000
4: [2048..4095]: 19456..21503 2048 0x1001

> ---
> tests/generic/422 | 127 ++++++++++++++++++++++++++++++++++++++++++++++++++
> tests/generic/422.out | 2 +
> tests/generic/group | 1 +
> 3 files changed, 130 insertions(+)
> create mode 100755 tests/generic/422
> create mode 100644 tests/generic/422.out
>
> diff --git a/tests/generic/422 b/tests/generic/422
> new file mode 100755
> index 0000000..4ca4476
> --- /dev/null
> +++ b/tests/generic/422
> @@ -0,0 +1,127 @@
> +#! /bin/bash
> +# FS QA Test 422
> +#
> +# Test if a file system returns constant fiemap result after remount and
> +# fiemap.
> +# Unfortunately, btrfs doesn't follow this behavior.
> +#
> +#-----------------------------------------------------------------------
> +# Copyright (c) 2017 Fujitsu. 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.*
> +}
> +
> +# get standard environment, filters and checks
> +. ./common/rc
> +. ./common/filter
> +
> +# remove previous $seqres.full before test
> +rm -f $seqres.full
> +
> +# real QA test starts here
> +
> +# Modify as appropriate.
> +_supported_fs generic
> +_supported_os IRIX Linux
> +_require_scratch

Need _require_fiemap

> +
> +block_size=$((64 * 1024))
> +block_count=32
> +dst=$SCRATCH_MNT/file
> +sleeptime=3
> +
> +# It's almost 100% for btrfs to trigger inconstant fiemap result

Trailing whitespace in above line.

> +# just in case
> +runtime=$((2 * $LOAD_FACTOR))

I don't think this loop is necessary, as the comments state, it's almost
100% reproducible for btrfs (and for ext2/3 in my testing).

> +
> +# record fiemap as checkpoint, and output the hash of fiemap result
> +# to stdout
> +fiemap_checkpoint()
> +{
> + local number=$1
> + local message=$2
> +
> + echo "=== $message ===" >> $seqres.full
> + $XFS_IO_PROG -c "fiemap -v" $dst > ${tmp}.cp$number
> + cat ${tmp}.cp${number} >> $seqres.full
> +
> + md5sum ${tmp}.cp${number} | cut -d ' ' -f 1
> +}
> +
> +do_test()
> +{
> + local number=$1
> +
> + # Use 16 times of file size to ensure we have enough space
> + _scratch_mkfs_sized $((16 * $block_size * $block_count)) \

Use _require_fs_space for required space. Not all filesystems have
_scratch_mkfs_sized support so this could potentially reduce the
filesystem coverage.

> + > /dev/null 2>&1
> + _scratch_mount

Trailing whitespace issue.

Thanks,
Eryu

> +
> + echo "====== Loop $number ======" >> $seqres.full
> + touch $dst
> + # Xfsprogs 4.9.0 still has a bug that xfs_io "open" with O_SYNC command
> + # doesn't work well with "pwrite", although it gets fixed in v4.10.0,
> + # use dd here to avoid it won't hurt for non-xfs developers
> + dd if=/dev/zero of=$dst bs=$block_size count=$block_count oflag=dsync \
> + status=none 2>&1
> +
> + hash1=$(fiemap_checkpoint 1 "Fiemap just after dsync write")
> +
> + # Sleep should not modify fiemap result
> + sleep $sleeptime
> +
> + hash2=$(fiemap_checkpoint 2 "Fiemap after dsync write and sleep")
> +
> + # cycle mount should not modify fiemap result
> + _scratch_cycle_mount
> +
> + hash3=$(fiemap_checkpoint 3 "Fiemap after cycle mount")
> +
> + # Sleep should not modify fiemap result
> + sleep $sleeptime
> +
> + hash4=$(fiemap_checkpoint 4 "Fiemap after cycle mount and sleep")
> +
> + _scratch_unmount
> +
> + if [ $hash1 != $hash2 -o $hash2 != $hash3 -o $hash3 != $hash4 ]; then
> + echo "Inconstant fiemap result detected"
> + fi
> + echo >> $seqres.full
> +}
> +
> +for i in $(seq 1 $runtime); do
> + do_test $i
> +done
> +
> +echo "Silence is golden"
> +# success, all done
> +status=0
> +exit
> diff --git a/tests/generic/422.out b/tests/generic/422.out
> new file mode 100644
> index 0000000..f70693f
> --- /dev/null
> +++ b/tests/generic/422.out
> @@ -0,0 +1,2 @@
> +QA output created by 422
> +Silence is golden
> diff --git a/tests/generic/group b/tests/generic/group
> index 3c7c5e4..86d2325 100644
> --- a/tests/generic/group
> +++ b/tests/generic/group
> @@ -424,3 +424,4 @@
> 419 auto quick encrypt
> 420 auto quick punch
> 421 auto quick encrypt dangerous
> +422 auto
> --
> 2.9.3
>
>
>
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