xfs: fuzz every field of every structure and test kernel crashes

Fuzz every field of every structure and then try to write the
filesystem, to see how many of these writes can crash the kernel.

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

tests/xfs/468

@@ -0,0 +1,53 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2018 Oracle, Inc.  All rights reserved.
+#
+# FS QA Test No. 468
+#
+# Populate a XFS filesystem and fuzz every bmbt block field.
+# Do not fix the filesystem, to test metadata verifiers.
+
+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 7 15
+
+_cleanup()
+{
+	cd /
+	rm -rf $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+. ./common/populate
+. ./common/fuzzy
+
+# real QA test starts here
+_supported_os Linux
+_supported_fs xfs
+_require_scratch_xfs_fuzz_fields
+_disable_dmesg_check
+
+echo "Format and populate"
+_scratch_populate_cached nofill > $seqres.full 2>&1
+
+echo "Find bmbt block"
+_scratch_mount
+inum=$(stat -c '%i' $SCRATCH_MNT/S_IFREG.FMT_BTREE)
+_scratch_unmount
+
+inode_ver=$(_scratch_xfs_get_metadata_field "core.version" "inode ${inum}")
+
+echo "Fuzz bmbt"
+_scratch_xfs_fuzz_metadata '' 'none'  "inode ${inum}" "addr u${inode_ver}.bmbt.ptrs[1]" >> $seqres.full
+echo "Done fuzzing bmbt"
+
+# success, all done
+status=0
+exit