[RFC PATCH xfstests] cifs: new test to check directory rename with an nonposix open child

From: ChenXiaoSong <[email protected]>

Add a test to verify that renaming a directory fails with EACCES
while a file in it is held open without a POSIX create context.

Link: https://lore.kernel.org/linux-cifs/[email protected]/
Signed-off-by: ChenXiaoSong <[email protected]>
---
 tests/cifs/002     | 76 ++++++++++++++++++++++++++++++++++++++++++++++
 tests/cifs/002.out |  2 ++
 2 files changed, 78 insertions(+)
 create mode 100755 tests/cifs/002
 create mode 100644 tests/cifs/002.out

diff --git a/tests/cifs/002 b/tests/cifs/002
new file mode 100755
index 00000000..aa011fdf
--- /dev/null
+++ b/tests/cifs/002
@@ -0,0 +1,76 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2026 KylinSoft Co., Ltd. All rights reserved.
+# Author(s): ChenXiaoSong <[email protected]>
+#
+# FS QA Test No. 002
+#
+# Regression test for a ksmbd bug where a directory could be renamed while a
+# file in it was held open without a POSIX create context.
+#
+. ./common/preamble
+_begin_fstest auto quick rename
+
+_require_scratch
+_require_test_program "rename"
+
+# TODO: This patch has not been merged into mainline yet.
+# https://lore.kernel.org/linux-cifs/[email protected]/
+# _fixed_by_kernel_commit xxxxxxxx \
+# 	"smb/server: fix posix state check for directory rename"
+
+testdir=$SCRATCH_MNT/test-$seq
+srcdir=$testdir/dir1
+dstdir=$testdir/dir2
+
+_cleanup()
+{
+	exec 73<&-
+	rm -rf "$testdir"
+	rm -f $tmp.*
+}
+
+# SMB3.1.1 is needed to negotiate POSIX extensions with the server.  Disable
+# POSIX create contexts explicitly so that the opens below use normal SMB
+# handles, regardless of the mount options in the test configuration.
+_try_scratch_mount -o vers=3.1.1,noposix >> $seqres.full 2>&1 || \
+	_notrun "mounting the scratch share with vers=3.1.1,noposix failed"
+
+# Make sure a conflicting option from the test configuration did not win.  The
+# CIFS client reports the noposix alias as nounix in /proc/mounts.
+_fs_options "$SCRATCH_DEV" | grep -Eq '(^|,)nounix(,|$)' || \
+	_notrun "the scratch share was not mounted with POSIX extensions disabled"
+
+rm -rf "$testdir"
+mkdir -p "$testdir/control" "$srcdir" || \
+	_fail "failed to create test directories"
+
+# Verify that ordinary directory renames are permitted on this share, so an
+# EACCES result below cannot be caused by a read-only share or its permissions.
+$here/src/rename "$testdir/control" "$testdir/control-renamed" \
+	>> $seqres.full 2>&1 || _fail "ordinary directory rename failed"
+
+touch "$srcdir/file" || _fail "failed to create child file"
+
+# Keep a normal SMB handle open for a child of the directory.  Renaming the
+# directory must be rejected with EACCES until that handle is closed.
+exec 73< "$srcdir/file" || _fail "failed to open child file"
+
+$here/src/rename "$srcdir" "$dstdir" > $tmp.rename 2>&1
+ret=$?
+cat $tmp.rename >> $seqres.full
+if [ $ret -eq 0 ]; then
+	_fail "directory rename with an open child unexpectedly succeeded"
+fi
+
+if ! grep -qx 'rename: Permission denied' $tmp.rename; then
+	cat $tmp.rename >> $seqres.full
+	_fail "directory rename failed with an unexpected error"
+fi
+
+exec 73<&-
+
+echo "Silence is golden"
+
+status=0
+exit
diff --git a/tests/cifs/002.out b/tests/cifs/002.out
new file mode 100644
index 00000000..61705c7c
--- /dev/null
+++ b/tests/cifs/002.out
@@ -0,0 +1,2 @@
+QA output created by 002
+Silence is golden
-- 
2.53.0