Re: [PATCH] btrfs: Add test that checks rmdir(2) can delete a subvolume

[Eryu Guan <guaneryu@gmail.com>]

On Thu, Apr 19, 2018 at 04:23:35PM +0900, Misono Tomohiro wrote:
> Add btrfs test that checks "rmdir" or "rm -r" command can delete a
> subvolume like an ordinary drectory.
> 
> This behavior has been restricted long time but becomes allowed by
> following patch in the kernel:
>   btrfs: Allow rmdir(2) to delete an empty subvolume
> 
> Signed-off-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>

Looks fine to me overall from fstests' perspective of view, some minor
issues inline.

But I'd like a Reviewed-by tag from btrfs developers too.

> ---
>  tests/btrfs/159     | 140 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  tests/btrfs/159.out |   2 +
>  tests/btrfs/group   |   1 +
>  3 files changed, 143 insertions(+)
>  create mode 100755 tests/btrfs/159
>  create mode 100644 tests/btrfs/159.out
> 
> diff --git a/tests/btrfs/159 b/tests/btrfs/159
> new file mode 100755
> index 00000000..2d830502
> --- /dev/null
> +++ b/tests/btrfs/159
> @@ -0,0 +1,140 @@
> +#! /bin/bash
> +# FS QA Test btrfs/159
> +#
> +# QA test that checks rmdir(2) works for subvolumes like ordinary directories.
> +#
> +# This behavior has been restricted long time but becomes allowed by following
> +# patch in the kernel:
> +#   btrfs: Allow rmdir(2) to delete an empty subvolume
> +#
> +#-----------------------------------------------------------------------
> +# Copyright (c) 2018 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.*
> +}
> +
> +_create_subvol()

There's no need to name these local helper functions with the leading
underscore.

> +{
> +	$BTRFS_UTIL_PROG subvolume create $1 2>&1 | \
> +		_filter_scratch >> $seqres.full

No need to do _filter_scratch if the output won't go to stdout/stderr,
it's fine or even recommended to not filter the output when dumping them
to $seqres.full for debug purpose.

There're a few other places that _filter_scratch can be dropped.

> +}
> +
> +_create_snapshot()
> +{
> +	$BTRFS_UTIL_PROG subvolume snapshot $@ 2>&1 | \
> +		_filter_scratch >> $seqres.full
> +}
> +
> +_rmdir_subvol()
> +{
> +	rmdir $1 2>&1 | _filter_scratch

I notice that we don't expect any output from the test script ("Silence
is golden" in .out file), so I don't think it's necessary to do
redirection and filter here, just do "rmdir $1" and any error message
would break golden image and fail the test.

> +	return ${PIPESTATUS[0]}

If you only care about the return value, just dump the rmdir output to
$seqres.full or /dev/null.

> +}
> +
> +_rm_r_subvol() {
> +	rm -r $1 2>&1 | _filter_scratch
> +	return ${PIPESTATUS[0]}

Same here.

> +}
> +
> +# get standard environment, filters and checks
> +. ./common/rc
> +. ./common/filter
> +. ./common/btrfs

No need to source common/btrfs, it's already sourced by common/rc based
on current $FSTYP.

> +
> +# remove previous $seqres.full before test
> +rm -f $seqres.full
> +
> +# real QA test starts here
> +
> +# Modify as appropriate.
> +_supported_fs btrfs
> +_supported_os Linux
> +_require_scratch
> +
> +_scratch_mkfs > /dev/null 2>&1 || _fail "mkfs failed"
> +_scratch_mount
> +
> +# Check that an empty subvolume can be deleted by rmdir
> +_create_subvol $SCRATCH_MNT/sub1
> +_rmdir_subvol $SCRATCH_MNT/sub1
> +
> +# Check that non-empty subvolume cannot be deleted by rmdir
> +_create_subvol $SCRATCH_MNT/sub2
> +touch $SCRATCH_MNT/sub2/file
> +_rmdir_subvol $SCRATCH_MNT/sub2 >> $seqres.full && \
> +	_fail "rmdir should fail for non-empty subvolume"

Just echo the error message, instead of exiting the test, test could
continue. Or even simpler, don't rely on the return status of
_rmdir_subvol, just put any expected output from _rmdir_subvol to .out
file, e.g.

_rmdir_subvol $SCRATCH_MNT/sub2 | _filter_scratch

So that, again, any failure message could break the golden image and
fail the test.

> +rm $SCRATCH_MNT/sub2/file
> +_rmdir_subvol $SCRATCH_MNT/sub2
> +
> +# Check that read-only empty subvolume can be deleted by rmdir
> +_create_subvol $SCRATCH_MNT/sub3
> +_create_snapshot -r $SCRATCH_MNT/sub3 $SCRATCH_MNT/snap
> +$BTRFS_UTIL_PROG property set $SCRATCH_MNT/sub3 ro true 2>&1 | \
> +	_filter_scratch >> $seqres.full
> +_rmdir_subvol $SCRATCH_MNT/sub3
> +_rmdir_subvol $SCRATCH_MNT/snap
> +
> +# Check that the default subvolume cannot be deleted by rmdir
> +_create_subvol $SCRATCH_MNT/sub4
> +subvolid=$(_btrfs_get_subvolid $SCRATCH_MNT sub4)
> +$BTRFS_UTIL_PROG subvolume set-default $subvolid $SCRATCH_MNT 2>&1 | \
> +	_filter_scratch >> $seqres.full
> +_rmdir_subvol $SCRATCH_MNT/sub4 >> $seqres.full && \
> +	_fail "rmdir should fail for the default subvolume"

Same here.

> +
> +# Check that subvolume stub (created by snapshot) can be deleted by rmdir
> +# (Note: this has been always allowed)
> +_create_subvol $SCRATCH_MNT/sub5
> +_create_subvol $SCRATCH_MNT/sub5/sub6
> +_create_snapshot $SCRATCH_MNT/sub5 $SCRATCH_MNT/snap2
> +rmdir $SCRATCH_MNT/snap2/sub6
> +
> +# Check that rm -r works for both non-snapshot subvolume and snapshot
> +_create_subvol $SCRATCH_MNT/sub7
> +mkdir $SCRATCH_MNT/sub7/dir
> +_create_subvol $SCRATCH_MNT/sub7/dir/sub8
> +touch $SCRATCH_MNT/sub7/dir/sub8/file
> +
> +_create_snapshot $SCRATCH_MNT/sub7 $SCRATCH_MNT/snap3
> +_create_snapshot -r $SCRATCH_MNT/sub7 $SCRATCH_MNT/snap4
> +
> +_rm_r_subvol $SCRATCH_MNT/sub7
> +_rm_r_subvol $SCRATCH_MNT/snap3
> +_rm_r_subvol $SCRATCH_MNT/snap4 >> $seqres.full && \
> +	_fail "rm -r should fail for non-empty readonly subvolume"

Same here.

Thanks,
Eryu

> +
> +$BTRFS_UTIL_PROG property set $SCRATCH_MNT/snap4 ro false 2>&1 | \
> +	_filter_scratch >> $seqres.full
> +_rm_r_subvol $SCRATCH_MNT/snap4
> +
> +# success, all done
> +echo "Silence is golden"
> +status=0
> +exit
> diff --git a/tests/btrfs/159.out b/tests/btrfs/159.out
> new file mode 100644
> index 00000000..e569e60c
> --- /dev/null
> +++ b/tests/btrfs/159.out
> @@ -0,0 +1,2 @@
> +QA output created by 159
> +Silence is golden
> diff --git a/tests/btrfs/group b/tests/btrfs/group
> index 8007e07e..6a288285 100644
> --- a/tests/btrfs/group
> +++ b/tests/btrfs/group
> @@ -161,3 +161,4 @@
>  156 auto quick trim
>  157 auto quick raid
>  158 auto quick raid scrub
> +159 auto quick subvol
> -- 
> 2.14.3
> 
> 
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