[PATCH] overlay: add test for rename of lower symlink with NOATIME attr

[Amir Goldstein <amir73il@gmail.com>]

A test for a regression from v5.15 reported by Ruiwen Zhao:
https://lore.kernel.org/linux-unionfs/CAKd=y5Hpg7J2gxrFT02F94o=FM9QvGp=kcH1Grctx8HzFYvpiA@mail.gmail.com/

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

Zorro,

This is a test for a regression in kernel v5.15.
The fix was merged for 6.6-rc2 and has been picked for
the upcoming LTS releases 5.15, 6.1, 6.5.

The reproducer only manifests the bug in fs that inherit noatime flag,
namely ext4, btrfs, ... but not xfs.

The test does _notrun on xfs for that reason.

Thanks,
Amir.

 tests/overlay/082     | 68 +++++++++++++++++++++++++++++++++++++++++++
 tests/overlay/082.out |  2 ++
 2 files changed, 70 insertions(+)
 create mode 100755 tests/overlay/082
 create mode 100644 tests/overlay/082.out

diff --git a/tests/overlay/082 b/tests/overlay/082
new file mode 100755
index 00000000..abea3c2b
--- /dev/null
+++ b/tests/overlay/082
@@ -0,0 +1,68 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2023 CTERA Networks. All Rights Reserved.
+#
+# FS QA Test 082
+#
+# kernel commit 72db82115d2b ("ovl: copy up sync/noatime fileattr flags")
+# from v5.15 introduced a regression.
+#
+. ./common/preamble
+_begin_fstest auto quick
+
+# Import common functions.
+. ./common/filter
+
+# real QA test starts here
+_supported_fs overlay
+_fixed_by_kernel_commit ab048302026d \
+	"ovl: fix failed copyup of fileattr on a symlink"
+
+_require_scratch
+_require_chattr A
+
+# remove all files from previous runs
+_scratch_mkfs
+
+# prepare lower test dir with NOATIME flag
+lowerdir=$OVL_BASE_SCRATCH_MNT/$OVL_LOWER
+mkdir -p $lowerdir/testdir
+$CHATTR_PROG +A $lowerdir/testdir >> $seqres.full 2>&1 ||
+	_notrun "base fs $OVL_BASE_FSTYP does not support No_Atime flag"
+
+# The NOATIME is inheritted to children symlink in ext4/fs2fs
+# (and on tmpfs on recent kernels).
+# The overlayfs test will not fail unless base fs is
+# one of those filesystems.
+#
+# The problem with this inheritence is that the NOATIME flag is inheritted
+# to a symlink and the flag does take effect, but there is no way to query
+# the flag (lsattr) or change it (chattr) on a symlink, so overlayfs will
+# fail when trying to copy up NOATIME flag from lower to upper symlink.
+#
+touch $lowerdir/testdir/foo
+ln -sf foo $lowerdir/testdir/lnk
+
+$LSATTR_PROG -l $lowerdir/testdir/foo >> $seqres.full 2>&1
+$LSATTR_PROG -l $lowerdir/testdir/foo | grep -q No_Atime || \
+	_notrun "base fs $OVL_BASE_FSTYP does not inherit No_Atime flag"
+
+before=$(stat -c %x $lowerdir/testdir/lnk)
+echo "symlink atime before readlink: $before" >> $seqres.full 2>&1
+cat $lowerdir/testdir/lnk
+after=$(stat -c %x $lowerdir/testdir/lnk)
+echo "symlink atime after readlink: $after" >> $seqres.full 2>&1
+
+[ "$before" == "$after" ] || \
+	_notrun "base fs $OVL_BASE_FSTYP does not inherit No_Atime flag on symlink"
+
+# mounting overlay
+_scratch_mount
+
+# moving symlink will try to copy up lower symlink flags
+mv $SCRATCH_MNT/testdir/lnk $SCRATCH_MNT/
+
+# success, all done
+echo "Silence is golden"
+status=0
+exit
diff --git a/tests/overlay/082.out b/tests/overlay/082.out
new file mode 100644
index 00000000..2977f141
--- /dev/null
+++ b/tests/overlay/082.out
@@ -0,0 +1,2 @@
+QA output created by 082
+Silence is golden
-- 
2.34.1