[PATCH] generic: test creating and removing symlink xattrs

["Darrick J. Wong" <djwong@kernel.org>]

From: Darrick J. Wong <djwong@kernel.org>

This began as a regression test for the issues identified in "xfs: allow
symlinks with short remote targets".  To summarize, the kernel XFS code
does not convert a remote symlink back to a shortform symlink after
deleting the attr fork.  Recent attempts to tighten validation have
flagged this incorrectly, so we need a regression test to focus on this
dusty corner of the codebase.

However, there's nothing in here that's xfs-specific so it's a generic
test.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 tests/generic/1836     |   53 ++++++++++++++++++++++++++++++++++++++++++++++++
 tests/generic/1836.out |    2 ++
 2 files changed, 55 insertions(+)
 create mode 100755 tests/generic/1836
 create mode 100644 tests/generic/1836.out

diff --git a/tests/generic/1836 b/tests/generic/1836
new file mode 100755
index 0000000000..d5e45bb47a
--- /dev/null
+++ b/tests/generic/1836
@@ -0,0 +1,53 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2024 Oracle.  All Rights Reserved.
+#
+# FS QA Test 1836
+#
+# Test that we can add xattrs to a symbolic link, remove all the xattrs, and
+# that the symbolic link doesn't get corrupted.
+#
+. ./common/preamble
+_begin_fstest auto
+
+_supported_fs generic
+_require_scratch
+
+_scratch_mkfs >> $seqres.full
+_scratch_mount >> $seqres.full
+
+SYMLINK_ADD="0123456789ABCDEF01234567890ABCDEF"
+
+# test from 32 to MAXPATHLEN sized symlink. This should make sure that
+# 256-1024 byte version 2 and 3 inodes are covered.
+SYMLINK=""
+for ((SIZE = 32; SIZE < 1024; SIZE += 32)); do
+	SYMLINK_FILE="$SCRATCH_MNT/symlink.$SIZE"
+	SYMLINK="${SYMLINK}${SYMLINK_ADD}"
+	ln -s $SYMLINK $SYMLINK_FILE > /dev/null 2>&1
+
+# add the extended attributes
+	attr  -Rs 1234567890ab $SYMLINK_FILE < /dev/null > /dev/null 2>&1
+	attr  -Rs 1234567890ac $SYMLINK_FILE < /dev/null > /dev/null 2>&1
+	attr  -Rs 1234567890ad $SYMLINK_FILE < /dev/null > /dev/null 2>&1
+# remove the extended attributes
+	attr  -Rr 1234567890ab $SYMLINK_FILE > /dev/null 2>&1
+	attr  -Rr 1234567890ac $SYMLINK_FILE > /dev/null 2>&1
+	attr  -Rr 1234567890ad $SYMLINK_FILE > /dev/null 2>&1
+done
+
+_scratch_cycle_mount
+
+# Now check the symlink target contents
+SYMLINK=""
+for ((SIZE = 32; SIZE < 1024; SIZE += 32)); do
+	SYMLINK_FILE="$SCRATCH_MNT/symlink.$SIZE"
+	SYMLINK="${SYMLINK}${SYMLINK_ADD}"
+
+	target="$(readlink $SYMLINK_FILE)"
+	test "$target" = "$SYMLINK" || echo "$SYMLINK_FILE: target is corrupt"
+done
+
+echo Silence is golden
+status=0
+exit
diff --git a/tests/generic/1836.out b/tests/generic/1836.out
new file mode 100644
index 0000000000..cf78922dea
--- /dev/null
+++ b/tests/generic/1836.out
@@ -0,0 +1,2 @@
+QA output created by 1836
+Silence is golden