btrfs: add a test case to check btrfs won't crash on certain corruption

The test case would reproduce the situation by creating an empty fs,
with SINGLE metadata profile, then corrupt the tree root manually.
Finally try mounting the corrupted fs, the mount should fail while our
kernel should not fail.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
[ Update commit log. Fix a line gt 80 chars. Use append to $seqres.full.
  Fix comment ]
Signed-off-by: Anand Jain <anand.jain@oracle.com>

diff --git a/tests/btrfs/295 b/tests/btrfs/295
new file mode 100755 (executable)
index 0000000..a9a8e55
--- /dev/null
+++ b/tests/btrfs/295
@@ -0,0 +1,38 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2023 SUSE Linux Products GmbH. All Rights Reserved.
+#
+# FS QA Test No. 295
+#
+# Make sure btrfs handles critical errors gracefully during mount.
+#
+. ./common/preamble
+_begin_fstest auto quick dangerous
+
+. ./common/filter
+_supported_fs btrfs
+_require_scratch
+
+# Use single metadata profile so we only need to corrupt one copy of tree block
+_scratch_mkfs -m single > $seqres.full
+
+logical_root=$($BTRFS_UTIL_PROG inspect dump-tree -t root "$SCRATCH_DEV" | \
+              grep leaf | head -n1 | cut -f2 -d\ )
+physical_root=$(_btrfs_get_physical $logical_root 1)
+
+echo "tree root logical=$logical_root" >> $seqres.full
+echo "tree root physical=$physical_root" >> $seqres.full
+
+_pwrite_byte 0x00 "$physical_root" 4 $SCRATCH_DEV >> $seqres.full
+
+# mount may lead to crash
+_try_scratch_mount >> $seqres.full 2>&1
+
+echo "Silence is golden"
+
+# Re-create the fs to avoid false alert from the corrupted fs.
+_scratch_mkfs -m single >> $seqres.full
+
+# success, all done
+status=0
+exit

diff --git a/tests/btrfs/295.out b/tests/btrfs/295.out
new file mode 100644 (file)
index 0000000..cbebcba
--- /dev/null
+++ b/tests/btrfs/295.out
@@ -0,0 +1,2 @@
+QA output created by 295
+Silence is golden