diff mbox

[V4] overlay: Test consistent d_ino feature for non-samefs setup

Message ID 20171012133432.20645-1-chandan@linux.vnet.ibm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Chandan Rajendra Oct. 12, 2017, 1:34 p.m. UTC 
This commit adds a test to verify consistent d_ino feature when
the overlayfs instance is composed of two different underlying
filesystem instances.

For example,
$ mount -t xfs /dev/loop0 /mnt/test
$ mount -t xfs /dev/loop1 /mnt/scratch
$ mkdir /mnt/scratch/upper
$ mkdir /mnt/scratch/work
$ mount -t overlay overlay -o lowerdir=/mnt/test \
        -o upperdir=/mnt/scratch/upper \
	-o workdir=/mnt/scratch/work /mnt/merge

The goal of this test is to verify that the inode numbers returned by
readdir(3) (i.e. dirent->d_ino) are consistent with inode numbers
returned by stat(2) (i.e. stat->st_ino) in all the below listed cases,
- Parent's (i.e. "..") d_ino must always be calculated because a
  pure dir can be residing inside a merged dir.
- d_ino for "." must always be calculated because the present
  directory can have a copy-up origin.
- Verify d_ino of '.' and '..' before and after dir becomes impure.
  While at it also verify if trusted.overlay.impure xattr is
  set/reset appropriately and invalidation of readdir cache.
- Verify copied up file's (inside a impure dir) d_ino.
- Verify invalidation of readdir cache.
- Verify d_ino values corresponding to "." and ".." entries of a
  pure lower dir.
- Verify d_ino of ".." entry of a merged dir.
- Verify pure lower residing in dir which has another lower layer

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
---
Eryu,
This test requires the following "yet to be upstreamed" overlayfs kernel
patches to be merged,
https://marc.info/?l=linux-unionfs&m=150728247029074&w=2
https://marc.info/?l=linux-unionfs&m=150728190228896&w=2
https://marc.info/?l=linux-unionfs&m=150728190428897&w=2

Changelog:
 v1->v2:
 Address the following review comments from Amir.
 1. overlay/041 now uses _overlay_scratch_mount_dirs() introduced by the patch
 "overlay: create helper _overlay_scratch_mount_dirs()" (unmerged patch from
 Amir Goldstein).
 2. Use _scratch_mkfs() instead of manually setting of the base filesystem.
 3. Use a directory in $OVL_BASE_TEST_DIR as the overlay instance's lowerdir.
 4. Remove redundant invocation of "chown" operation on a regular file to cause
 copy-up to occur.

 v2->v3:
 1. Remove debug code. Thanks to Amir for spotting this.
 2. Add a commit message describing non-samefs setup of an overlayfs instance
 and the scenarios being tested by this test.

 v3->v4:
 1. Replace _overlay_scratch_unmount invocation with _scratch_unmount.

tests/overlay/041     | 193 ++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/overlay/041.out |   2 +
 tests/overlay/group   |   1 +
 3 files changed, 196 insertions(+)
 create mode 100755 tests/overlay/041
 create mode 100644 tests/overlay/041.out

Comments

Amir Goldstein Oct. 12, 2017, 1:44 p.m. UTC | #1 
On Thu, Oct 12, 2017 at 4:34 PM, Chandan Rajendra
<chandan@linux.vnet.ibm.com> wrote:
> This commit adds a test to verify consistent d_ino feature when
> the overlayfs instance is composed of two different underlying
> filesystem instances.
>
> For example,
> $ mount -t xfs /dev/loop0 /mnt/test
> $ mount -t xfs /dev/loop1 /mnt/scratch
> $ mkdir /mnt/scratch/upper
> $ mkdir /mnt/scratch/work
> $ mount -t overlay overlay -o lowerdir=/mnt/test \
>         -o upperdir=/mnt/scratch/upper \
>         -o workdir=/mnt/scratch/work /mnt/merge
>
> The goal of this test is to verify that the inode numbers returned by
> readdir(3) (i.e. dirent->d_ino) are consistent with inode numbers
> returned by stat(2) (i.e. stat->st_ino) in all the below listed cases,
> - Parent's (i.e. "..") d_ino must always be calculated because a
>   pure dir can be residing inside a merged dir.
> - d_ino for "." must always be calculated because the present
>   directory can have a copy-up origin.
> - Verify d_ino of '.' and '..' before and after dir becomes impure.
>   While at it also verify if trusted.overlay.impure xattr is
>   set/reset appropriately and invalidation of readdir cache.
> - Verify copied up file's (inside a impure dir) d_ino.
> - Verify invalidation of readdir cache.
> - Verify d_ino values corresponding to "." and ".." entries of a
>   pure lower dir.
> - Verify d_ino of ".." entry of a merged dir.
> - Verify pure lower residing in dir which has another lower layer
>
> Reviewed-by: Amir Goldstein <amir73il@gmail.com>
> Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
> ---
> Eryu,
> This test requires the following "yet to be upstreamed" overlayfs kernel
> patches to be merged,

Clarification. The test *requires* those patches to pass, but IMO
there is nothing to prevent merging the test now.
As several functional tests before it, the test fails on upstream kernel
because overlayfs doesn't behave as it should.

> https://marc.info/?l=linux-unionfs&m=150728247029074&w=2
> https://marc.info/?l=linux-unionfs&m=150728190228896&w=2
> https://marc.info/?l=linux-unionfs&m=150728190428897&w=2
>
> Changelog:
>  v1->v2:
>  Address the following review comments from Amir.
>  1. overlay/041 now uses _overlay_scratch_mount_dirs() introduced by the patch
>  "overlay: create helper _overlay_scratch_mount_dirs()" (unmerged patch from
>  Amir Goldstein).
>  2. Use _scratch_mkfs() instead of manually setting of the base filesystem.
>  3. Use a directory in $OVL_BASE_TEST_DIR as the overlay instance's lowerdir.
>  4. Remove redundant invocation of "chown" operation on a regular file to cause
>  copy-up to occur.
>
>  v2->v3:
>  1. Remove debug code. Thanks to Amir for spotting this.
>  2. Add a commit message describing non-samefs setup of an overlayfs instance
>  and the scenarios being tested by this test.
>
>  v3->v4:
>  1. Replace _overlay_scratch_unmount invocation with _scratch_unmount.
>
> tests/overlay/041     | 193 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  tests/overlay/041.out |   2 +
>  tests/overlay/group   |   1 +
>  3 files changed, 196 insertions(+)
>  create mode 100755 tests/overlay/041
>  create mode 100644 tests/overlay/041.out
>
> diff --git a/tests/overlay/041 b/tests/overlay/041
> new file mode 100755
> index 0000000..4d7feb8
> --- /dev/null
> +++ b/tests/overlay/041
> @@ -0,0 +1,193 @@
> +#! /bin/bash
> +# FSQA Test No. 041
> +#
> +# Test consistent d_ino numbers on non-samefs setup
> +# This is a variant of overlay/038 to test consistent d_ino numbers
> +# for non-samefs setup.
> +#
> +#-----------------------------------------------------------------------
> +#
> +# Copyright (C) 2017 IBM Corporation. All Rights Reserved.
> +# Author: Chandan Rajendra <chandan@linux.vnet.ibm.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()
> +{
> +       cd /
> +       rm -f $tmp.*
> +}
> +
> +# get standard environment, filters and checks
> +. ./common/rc
> +. ./common/filter
> +. ./common/attr
> +
> +# real QA test starts here
> +_supported_fs overlay
> +_supported_os Linux
> +_require_scratch
> +_require_test
> +_require_attrs
> +_require_test_program "t_dir_type"
> +
> +rm -f $seqres.full
> +
> +lowerdir=$OVL_BASE_TEST_DIR/$seq-ovl-lower
> +rm -rf $lowerdir
> +mkdir $lowerdir
> +
> +# Create our test files.
> +mkdir $lowerdir/test_dir/
> +mkdir $lowerdir/test_dir/pure_lower_dir
> +mkdir $lowerdir/test_dir/merged_dir
> +touch $lowerdir/test_file
> +
> +_scratch_mkfs
> +
> +upperdir=$OVL_BASE_SCRATCH_MNT/$OVL_UPPER
> +workdir=$OVL_BASE_SCRATCH_MNT/$OVL_WORK
> +
> +_overlay_scratch_mount_dirs $lowerdir $upperdir $workdir
> +
> +test_dir=$SCRATCH_MNT/test_dir/
> +merged_dir=$test_dir/merged_dir
> +pure_upper_dir=$merged_dir/pure_upper_dir
> +
> +mkdir -p $pure_upper_dir
> +
> +merged_dir_st_ino=$(stat -c '%i' $merged_dir)
> +
> +# Pure dir's parent d_ino must always be calculated because
> +# it can be residing inside a merged dir.
> +parent_d=$($here/src/t_dir_type $pure_upper_dir $merged_dir_st_ino)
> +[[ $parent_d == ".. d" ]] || \
> +       echo "Pure dir inside a merged dir: Invalid d_ino reported for .."
> +
> +# d_ino for "." must always be calculated because the present
> +# directory can have a copy-up origin.
> +current_d=$($here/src/t_dir_type $merged_dir $merged_dir_st_ino)
> +[[ $current_d == ". d" ]] || echo "Merged dir: Invalid d_ino reported for ."
> +
> +# Verify d_ino of '.' and '..' before and after dir becomes impure.
> +impure_dir=$test_dir/impure_dir
> +mkdir -p $impure_dir
> +
> +impure_dir_st_ino=$(stat -c '%i' $impure_dir)
> +impure_dir_parent_st_ino=$(stat -c '%i' $test_dir)
> +
> +# Before $impure_dir becomes impure
> +parent_d=$($here/src/t_dir_type $impure_dir $impure_dir_parent_st_ino)
> +[[ $parent_d == ".. d" ]] || \
> +    echo "Before dir becomes impure: Invalid d_ino reported for .."
> +
> +current_d=$($here/src/t_dir_type $impure_dir $impure_dir_st_ino)
> +[[ $current_d == ". d" ]] || \
> +    echo "Before dir becomes impure: Invalid d_ino reported for ."
> +
> +
> +mv $SCRATCH_MNT/test_file $impure_dir
> +test_file_st_ino=$(stat -c '%i' $impure_dir/test_file)
> +
> +impure=$($GETFATTR_PROG --absolute-names --only-values -n 'trusted.overlay.impure' \
> +                       $upperdir/test_dir/impure_dir)
> +[[ $impure == "y" ]] || echo "Impure directory missing impure xattr"
> +
> +# After $impure_dir becomes impure
> +parent_d=$($here/src/t_dir_type $impure_dir $impure_dir_parent_st_ino)
> +[[ $parent_d == ".. d" ]] || \
> +    echo "After dir becomes impure: Invalid d_ino reported for .."
> +
> +current_d=$($here/src/t_dir_type $impure_dir $impure_dir_st_ino)
> +[[ $current_d == ". d" ]] || \
> +    echo "After dir becomes impure: Invalid d_ino reported for ."
> +
> +# Verify copy up file's d_ino
> +file_d=$($here/src/t_dir_type $impure_dir $test_file_st_ino)
> +[[ $file_d == "test_file f" ]] || \
> +       echo "Impure dir: Invalid d_ino reported for entry with copy-up origin"
> +
> +# Make $impure_dir pure
> +rm -rf $impure_dir/test_file
> +
> +# Verify invalidation of readdir cache
> +$here/src/t_dir_type $impure_dir $test_file_st_ino
> +[[ $? != 0 ]] || echo "Directory's readdir cache has stale entries"
> +
> +impure=$($GETFATTR_PROG --absolute-names --only-values -n 'trusted.overlay.impure' \
> +                       $upperdir/test_dir/impure_dir 2>/dev/null)
> +[[ -z $impure ]] || echo "Pure directory has impure xattr"
> +
> +# Verify d_ino values corresponding to "." and ".." entries of a
> +# pure lower dir.
> +parent_st_ino=$(stat -c '%i' $SCRATCH_MNT/test_dir)
> +pure_lower_dir=$SCRATCH_MNT/test_dir/pure_lower_dir
> +
> +parent_d=$($here/src/t_dir_type $pure_lower_dir $parent_st_ino)
> +[[ $parent_d == ".. d" ]] || echo "Pure lower dir: Invalid d_ino reported for .."
> +
> +pure_lower_dir_st_ino=$(stat -c '%i' $pure_lower_dir)
> +
> +current_d=$($here/src/t_dir_type $pure_lower_dir $pure_lower_dir_st_ino)
> +[[ $current_d == ". d" ]] || echo "Pure lower dir: Invalid d_ino reported for ."
> +
> +# Verify d_ino of ".." entry of a merged dir.
> +merged_dir=$SCRATCH_MNT/test_dir/merged_dir
> +
> +parent_d=$($here/src/t_dir_type $merged_dir $parent_st_ino)
> +[[ $parent_d == ".. d" ]] || echo "Merged dir: Invalid d_ino reported for .."
> +
> +_scratch_unmount
> +
> +# Verify pure lower residing in dir which has another lower layer
> +middir=$OVL_BASE_TEST_DIR/$seq-ovl-mid
> +lowerdir=$OVL_BASE_TEST_DIR/$seq-ovl-lower
> +rm -rf $middir
> +rm -rf $lowerdir
> +mkdir $middir
> +mkdir $lowerdir
> +
> +mkdir -p $middir/test_dir
> +mkdir -p $lowerdir/test_dir/pure_lower_dir
> +
> +_scratch_mkfs
> +
> +upperdir=$OVL_BASE_SCRATCH_MNT/ovl-upper
> +workdir=$OVL_BASE_SCRATCH_MNT/ovl-work
> +
> +_overlay_scratch_mount_dirs $middir:$lowerdir $upperdir $workdir
> +
> +# Copy up test_dir
> +touch $SCRATCH_MNT/test_dir/test_file
> +
> +test_dir_st_ino=$(stat -c '%i' $SCRATCH_MNT/test_dir)
> +
> +parent_d=$($here/src/t_dir_type $SCRATCH_MNT/test_dir/pure_lower_dir $test_dir_st_ino)
> +[[ $parent_d == ".. d" ]] || \
> +       echo "Pure lower in dir which has another lower layer: Invalid d_ino reported for .."
> +
> +echo "Silence is golden"
> +status=0
> +exit
> diff --git a/tests/overlay/041.out b/tests/overlay/041.out
> new file mode 100644
> index 0000000..04f5bf1
> --- /dev/null
> +++ b/tests/overlay/041.out
> @@ -0,0 +1,2 @@
> +QA output created by 041
> +Silence is golden
> diff --git a/tests/overlay/group b/tests/overlay/group
> index 022f2ef..8629325 100644
> --- a/tests/overlay/group
> +++ b/tests/overlay/group
> @@ -43,3 +43,4 @@
>  038 auto quick copyup
>  039 auto quick atime
>  040 auto quick
> +041 auto quick copyup nonsamefs
> --
> 2.9.5
>
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Eryu Guan Oct. 12, 2017, 4:11 p.m. UTC | #2 
On Thu, Oct 12, 2017 at 04:44:53PM +0300, Amir Goldstein wrote:
> On Thu, Oct 12, 2017 at 4:34 PM, Chandan Rajendra
> <chandan@linux.vnet.ibm.com> wrote:
> > This commit adds a test to verify consistent d_ino feature when
> > the overlayfs instance is composed of two different underlying
> > filesystem instances.
> >
> > For example,
> > $ mount -t xfs /dev/loop0 /mnt/test
> > $ mount -t xfs /dev/loop1 /mnt/scratch
> > $ mkdir /mnt/scratch/upper
> > $ mkdir /mnt/scratch/work
> > $ mount -t overlay overlay -o lowerdir=/mnt/test \
> >         -o upperdir=/mnt/scratch/upper \
> >         -o workdir=/mnt/scratch/work /mnt/merge
> >
> > The goal of this test is to verify that the inode numbers returned by
> > readdir(3) (i.e. dirent->d_ino) are consistent with inode numbers
> > returned by stat(2) (i.e. stat->st_ino) in all the below listed cases,
> > - Parent's (i.e. "..") d_ino must always be calculated because a
> >   pure dir can be residing inside a merged dir.
> > - d_ino for "." must always be calculated because the present
> >   directory can have a copy-up origin.
> > - Verify d_ino of '.' and '..' before and after dir becomes impure.
> >   While at it also verify if trusted.overlay.impure xattr is
> >   set/reset appropriately and invalidation of readdir cache.
> > - Verify copied up file's (inside a impure dir) d_ino.
> > - Verify invalidation of readdir cache.
> > - Verify d_ino values corresponding to "." and ".." entries of a
> >   pure lower dir.
> > - Verify d_ino of ".." entry of a merged dir.
> > - Verify pure lower residing in dir which has another lower layer
> >
> > Reviewed-by: Amir Goldstein <amir73il@gmail.com>
> > Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
> > ---
> > Eryu,
> > This test requires the following "yet to be upstreamed" overlayfs kernel
> > patches to be merged,
> 
> Clarification. The test *requires* those patches to pass, but IMO
> there is nothing to prevent merging the test now.
> As several functional tests before it, the test fails on upstream kernel
> because overlayfs doesn't behave as it should.
> 
> > https://marc.info/?l=linux-unionfs&m=150728247029074&w=2
> > https://marc.info/?l=linux-unionfs&m=150728190228896&w=2
> > https://marc.info/?l=linux-unionfs&m=150728190428897&w=2

Thanks all for updated test and review, and the upstream context!

Eryu
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diff mbox

Patch

diff --git a/tests/overlay/041 b/tests/overlay/041
new file mode 100755
index 0000000..4d7feb8
--- /dev/null
+++ b/tests/overlay/041
@@ -0,0 +1,193 @@ 
+#! /bin/bash
+# FSQA Test No. 041
+#
+# Test consistent d_ino numbers on non-samefs setup
+# This is a variant of overlay/038 to test consistent d_ino numbers
+# for non-samefs setup.
+#
+#-----------------------------------------------------------------------
+#
+# Copyright (C) 2017 IBM Corporation. All Rights Reserved.
+# Author: Chandan Rajendra <chandan@linux.vnet.ibm.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()
+{
+	cd /
+	rm -f $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+. ./common/attr
+
+# real QA test starts here
+_supported_fs overlay
+_supported_os Linux
+_require_scratch
+_require_test
+_require_attrs
+_require_test_program "t_dir_type"
+
+rm -f $seqres.full
+
+lowerdir=$OVL_BASE_TEST_DIR/$seq-ovl-lower
+rm -rf $lowerdir
+mkdir $lowerdir
+
+# Create our test files.
+mkdir $lowerdir/test_dir/
+mkdir $lowerdir/test_dir/pure_lower_dir
+mkdir $lowerdir/test_dir/merged_dir
+touch $lowerdir/test_file
+
+_scratch_mkfs
+
+upperdir=$OVL_BASE_SCRATCH_MNT/$OVL_UPPER
+workdir=$OVL_BASE_SCRATCH_MNT/$OVL_WORK
+
+_overlay_scratch_mount_dirs $lowerdir $upperdir $workdir
+
+test_dir=$SCRATCH_MNT/test_dir/
+merged_dir=$test_dir/merged_dir
+pure_upper_dir=$merged_dir/pure_upper_dir
+
+mkdir -p $pure_upper_dir
+
+merged_dir_st_ino=$(stat -c '%i' $merged_dir)
+
+# Pure dir's parent d_ino must always be calculated because
+# it can be residing inside a merged dir.
+parent_d=$($here/src/t_dir_type $pure_upper_dir $merged_dir_st_ino)
+[[ $parent_d == ".. d" ]] || \
+	echo "Pure dir inside a merged dir: Invalid d_ino reported for .."
+
+# d_ino for "." must always be calculated because the present
+# directory can have a copy-up origin.
+current_d=$($here/src/t_dir_type $merged_dir $merged_dir_st_ino)
+[[ $current_d == ". d" ]] || echo "Merged dir: Invalid d_ino reported for ."
+
+# Verify d_ino of '.' and '..' before and after dir becomes impure.
+impure_dir=$test_dir/impure_dir
+mkdir -p $impure_dir
+
+impure_dir_st_ino=$(stat -c '%i' $impure_dir)
+impure_dir_parent_st_ino=$(stat -c '%i' $test_dir)
+
+# Before $impure_dir becomes impure
+parent_d=$($here/src/t_dir_type $impure_dir $impure_dir_parent_st_ino)
+[[ $parent_d == ".. d" ]] || \
+    echo "Before dir becomes impure: Invalid d_ino reported for .."
+
+current_d=$($here/src/t_dir_type $impure_dir $impure_dir_st_ino)
+[[ $current_d == ". d" ]] || \
+    echo "Before dir becomes impure: Invalid d_ino reported for ."
+
+
+mv $SCRATCH_MNT/test_file $impure_dir
+test_file_st_ino=$(stat -c '%i' $impure_dir/test_file)
+
+impure=$($GETFATTR_PROG --absolute-names --only-values -n 'trusted.overlay.impure' \
+			$upperdir/test_dir/impure_dir)
+[[ $impure == "y" ]] || echo "Impure directory missing impure xattr"
+
+# After $impure_dir becomes impure
+parent_d=$($here/src/t_dir_type $impure_dir $impure_dir_parent_st_ino)
+[[ $parent_d == ".. d" ]] || \
+    echo "After dir becomes impure: Invalid d_ino reported for .."
+
+current_d=$($here/src/t_dir_type $impure_dir $impure_dir_st_ino)
+[[ $current_d == ". d" ]] || \
+    echo "After dir becomes impure: Invalid d_ino reported for ."
+
+# Verify copy up file's d_ino
+file_d=$($here/src/t_dir_type $impure_dir $test_file_st_ino)
+[[ $file_d == "test_file f" ]] || \
+	echo "Impure dir: Invalid d_ino reported for entry with copy-up origin"
+
+# Make $impure_dir pure
+rm -rf $impure_dir/test_file
+
+# Verify invalidation of readdir cache
+$here/src/t_dir_type $impure_dir $test_file_st_ino
+[[ $? != 0 ]] || echo "Directory's readdir cache has stale entries"
+
+impure=$($GETFATTR_PROG --absolute-names --only-values -n 'trusted.overlay.impure' \
+			$upperdir/test_dir/impure_dir 2>/dev/null)
+[[ -z $impure ]] || echo "Pure directory has impure xattr"
+
+# Verify d_ino values corresponding to "." and ".." entries of a
+# pure lower dir.
+parent_st_ino=$(stat -c '%i' $SCRATCH_MNT/test_dir)
+pure_lower_dir=$SCRATCH_MNT/test_dir/pure_lower_dir
+
+parent_d=$($here/src/t_dir_type $pure_lower_dir $parent_st_ino)
+[[ $parent_d == ".. d" ]] || echo "Pure lower dir: Invalid d_ino reported for .."
+
+pure_lower_dir_st_ino=$(stat -c '%i' $pure_lower_dir)
+
+current_d=$($here/src/t_dir_type $pure_lower_dir $pure_lower_dir_st_ino)
+[[ $current_d == ". d" ]] || echo "Pure lower dir: Invalid d_ino reported for ."
+
+# Verify d_ino of ".." entry of a merged dir.
+merged_dir=$SCRATCH_MNT/test_dir/merged_dir
+
+parent_d=$($here/src/t_dir_type $merged_dir $parent_st_ino)
+[[ $parent_d == ".. d" ]] || echo "Merged dir: Invalid d_ino reported for .."
+
+_scratch_unmount
+
+# Verify pure lower residing in dir which has another lower layer
+middir=$OVL_BASE_TEST_DIR/$seq-ovl-mid
+lowerdir=$OVL_BASE_TEST_DIR/$seq-ovl-lower
+rm -rf $middir
+rm -rf $lowerdir
+mkdir $middir
+mkdir $lowerdir
+
+mkdir -p $middir/test_dir
+mkdir -p $lowerdir/test_dir/pure_lower_dir
+
+_scratch_mkfs
+
+upperdir=$OVL_BASE_SCRATCH_MNT/ovl-upper
+workdir=$OVL_BASE_SCRATCH_MNT/ovl-work
+
+_overlay_scratch_mount_dirs $middir:$lowerdir $upperdir $workdir
+
+# Copy up test_dir
+touch $SCRATCH_MNT/test_dir/test_file
+
+test_dir_st_ino=$(stat -c '%i' $SCRATCH_MNT/test_dir)
+
+parent_d=$($here/src/t_dir_type $SCRATCH_MNT/test_dir/pure_lower_dir $test_dir_st_ino)
+[[ $parent_d == ".. d" ]] || \
+	echo "Pure lower in dir which has another lower layer: Invalid d_ino reported for .."
+
+echo "Silence is golden"
+status=0
+exit
diff --git a/tests/overlay/041.out b/tests/overlay/041.out
new file mode 100644
index 0000000..04f5bf1
--- /dev/null
+++ b/tests/overlay/041.out
@@ -0,0 +1,2 @@ 
+QA output created by 041
+Silence is golden
diff --git a/tests/overlay/group b/tests/overlay/group
index 022f2ef..8629325 100644
--- a/tests/overlay/group
+++ b/tests/overlay/group
@@ -43,3 +43,4 @@ 
 038 auto quick copyup
 039 auto quick atime
 040 auto quick
+041 auto quick copyup nonsamefs