[PATCH] overlay: add a test for multiple redirects to the same lower dir

[Amir Goldstein <amir73il@gmail.com>]

Multiple redirects to the same lower dir will falsely return the
same st_ino/st_dev for two different upper dirs and will cause 'diff'
to falsely report that content of directories is the same when it is not.

This is a test for a regression introduced in kernel v4.12 by
commit 72b608f08528 ("ovl: constant st_ino/st_dev across copy up"),
but also the first xfstest to require the redirect_dir feature that
was introduced as an opt-in feature in kernel v4.10.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---

Eryu,

This test is for a "bug" that has not been acknoledges by Miklos
as a kernel bug yet. It may well fall within the jurisdiction of
fsck.overlayfs.

IMO, cp -a of upper files and dirs qualifies to the statement in
Documentation/filesystems/overlayfs.txt:
"Offline changes, when the overlay is not mounted, are allowed to either
the upper or the lower trees."

So unless Miklos objects to ever fixing this "bug"?
I suggest that we include the failing test until kernel is fixed.

Incidently, I already have patches for 'verify' feature [1], which
I intend to post after the merge window closes.
With 'verify' feature enabled this test passes.

Amir.

[1] https://github.com/amir73il/linux/commits/ovl-index-all

 tests/overlay/049     | 104 ++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/overlay/049.out |   2 +
 tests/overlay/group   |   1 +
 3 files changed, 107 insertions(+)
 create mode 100755 tests/overlay/049
 create mode 100644 tests/overlay/049.out

diff --git a/tests/overlay/049 b/tests/overlay/049
new file mode 100755
index 0000000..701a649
--- /dev/null
+++ b/tests/overlay/049
@@ -0,0 +1,104 @@
+#! /bin/bash
+# FS QA Test 049
+#
+# Test multiple redirects to the same lower dir.
+#
+# Multiple redirects to the same lower dir will falsely return
+# the same st_ino/st_dev for two different upper dirs and will
+# cause 'diff' to falsely report that content of directories
+# is the same when it is not.
+#
+#-----------------------------------------------------------------------
+# Copyright (C) 2017 CTERA Networks. All Rights Reserved.
+# Author: Amir Goldstein <amir73il@gmail.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.*
+}
+
+# Rename lower dir to create a redirected upper dir and
+# touch lower file to create copy up with origin xattr
+create_redirect()
+{
+	local redirect=$1
+
+	mkdir -p $lowerdir/origin
+	touch $lowerdir/origin/file
+
+	_scratch_mount -o redirect_dir=on
+	touch $SCRATCH_MNT/origin/file
+	mv $SCRATCH_MNT/origin $SCRATCH_MNT/$redirect
+
+	$UMOUNT_PROG $SCRATCH_MNT
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+rm -f $seqres.full
+
+# real QA test starts here
+_supported_fs overlay
+_supported_os Linux
+_require_scratch
+_require_scratch_feature redirect_dir
+
+# remove all files from previous runs
+_scratch_mkfs
+
+upperdir=$OVL_BASE_SCRATCH_MNT/$OVL_UPPER
+lowerdir=$OVL_BASE_SCRATCH_MNT/$OVL_LOWER
+
+# Create redirected dir with copied up file
+create_redirect redirect1
+# Duplicate the redirected dir and copied up file
+cp -a $upperdir/redirect1 $upperdir/redirect2
+
+# Diverge the content of the two copies of file
+# and the content of two copies of redirected dir
+echo right >> $upperdir/redirect1/file
+touch $upperdir/redirect1/right
+echo wrong >> $upperdir/redirect2/file
+touch $upperdir/redirect2/wrong
+
+_scratch_mount -o redirect_dir=on
+
+# If both copies of file/dir use the same st_dev/st_ino in overlay
+# diff won't detect that their content differs
+diff -q $SCRATCH_MNT/redirect1/file $SCRATCH_MNT/redirect2/file &>/dev/null && \
+	echo "diff on files inside duplicate redirect parent doesn't know right from wrong!"
+
+diff -q $SCRATCH_MNT/redirect1 $SCRATCH_MNT/redirect2 &> /dev/null && \
+	echo "diff on duplicate redirect dirs doesn't know right from wrong!"
+
+# success, all done
+echo "Silence is golden"
+status=0
+exit
diff --git a/tests/overlay/049.out b/tests/overlay/049.out
new file mode 100644
index 0000000..c69568a
--- /dev/null
+++ b/tests/overlay/049.out
@@ -0,0 +1,2 @@
+QA output created by 049
+Silence is golden
diff --git a/tests/overlay/group b/tests/overlay/group
index b32c6cd..cf21750 100644
--- a/tests/overlay/group
+++ b/tests/overlay/group
@@ -47,3 +47,4 @@
 042 auto quick copyup hardlink
 043 auto quick copyup nonsamefs
 044 auto quick copyup hardlink nonsamefs
+049 auto quick copyup redirect
-- 
2.7.4