xfs: Test root inode parent pointer repairing

Recently we found out xfs_repair were not repairing root inode
parent pointer when root inode is on short-form and parent points to
an invalid inode number (refer to: "xfs_repair: Fix root inode's
parent when it's bogus for sf directory" on xfs-devel list).

This test checks if xfs_repair successfully repair the filesystem in
the scenario mentioned before.

Signed-off-by: Marco Benatto <mbenatto@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

tests/xfs/451

@@ -0,0 +1,57 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2018 Red Hat Inc.  All Rights Reserved.
+#
+# FS QA Test 451
+#
+# Make sure xfs_repair can repair root inode parent's pointer
+# when it contains a bogus ino when it's using shot form directory
+
+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.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# remove previous $seqres.full before test
+rm -f $seqres.full
+
+echo "Silence is golden"
+
+# real QA test starts here
+
+# Modify as appropriate.
+_supported_fs xfs
+_supported_os Linux
+_require_scratch
+
+_scratch_mkfs >> /dev/null 2>&1
+
+rootino=$(_scratch_xfs_get_metadata_field 'rootino' 'sb 0')
+
+prefix=$(_scratch_get_sfdir_prefix ${rootino} || \
+			_fail "Cannot determine sfdir prefix")
+
+# Corrupt root inode parent pointer
+_scratch_xfs_set_metadata_field "${prefix}.hdr.parent.i4" 0 "inode ${rootino}"\
+						>> $seqres.full 2>&1
+
+_scratch_xfs_repair >> $seqres.full 2>&1
+
+# Post-test integrity check will detect any remaining corruption
+
+status=0
+exit

tests/xfs/451.out

@@ -0,0 +1,2 @@
+QA output created by 451
+Silence is golden

tests/xfs/group

@@ -448,3 +448,4 @@
 448 auto quick fuzzers
 449 auto quick
 450 auto quick rmap
+451 auto quick metadata repair