f2fs: do sanity check on i_xattr_nid

This is a regression test:
1. create directory
2. add a new xattr entry to create xattr node
3. use inject.f2fs to inject nid of xattr node w/ ino in a file
4. check whether f2fs kernel module will detect and report such
   corruption in the file

Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Chao Yu <chao@kernel.org>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>

tests/f2fs/020

diff --git a/tests/f2fs/020 b/tests/f2fs/020
new file mode 100755
index 0000000..38bc658
--- /dev/null
+++ b/tests/f2fs/020
@@ -0,0 +1,51 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2025 Chao Yu.  All Rights Reserved.
+#
+# FS QA Test No. f2fs/020
+#
+# This is a regression test:
+# 1. create directory
+# 2. add a new xattr entry to create xattr node
+# 3. use inject.f2fs to inject nid of xattr node w/ ino in a file
+# 4. check whether f2fs kernel module will detect and report such
+#    corruption in the file
+#
+. ./common/preamble
+_begin_fstest auto quick rw
+
+. ./common/attr
+
+_fixed_by_kernel_commit 061cf3a84bde \
+	"f2fs: fix to do sanity check on ino and xnid"
+
+_require_scratch_nocheck
+_require_command "$F2FS_INJECT_PROG" inject.f2fs
+_require_attrs user
+
+# remove all mkfs options to avoid layout change of on-disk inode
+export MKFS_OPTIONS=""
+
+testdir=$SCRATCH_MNT/testdir
+
+_scratch_mkfs >> $seqres.full
+_scratch_mount "-o user_xattr,noinline_xattr"
+
+mkdir $testdir
+# add a new xattr entry to create xattr node
+$SETFATTR_PROG -n user.abc -v 123 $testdir
+
+_scratch_unmount
+
+# inject i_xattr_nid w/ nid of inode node
+$F2FS_INJECT_PROG --node --mb i_xattr_nid --nid 4 --val 4 $SCRATCH_DEV >> $seqres.full || _fail "failed to inject"
+
+_scratch_mount "-o acl,user_xattr"
+# may potentially trigger a deadlock w/ double inode_lock on parent's inode
+mkdir $testdir/dir >> $seqres.full 2>&1
+_scratch_unmount
+
+echo "Silence is golden"
+
+status=0
+exit

tests/f2fs/020.out

diff --git a/tests/f2fs/020.out b/tests/f2fs/020.out
new file mode 100644
index 0000000..20d7944
--- /dev/null
+++ b/tests/f2fs/020.out
@@ -0,0 +1,2 @@
+QA output created by 020
+Silence is golden