[PATCH v2] fstests: btrfs: Add test for corrupted childless qgroup numbers

[Qu Wenruo <wqu@suse.com>]

This bug is exposed by populating a high level qgroup, and then make it
childless with old qgroup numbers, and finally do rescan.

Normally rescan should zero out all qgroups' accounting number, but due
to a kernel bug which won't mark childless qgroups dirty, their on-disk
data is never updated, thus old numbers remain and cause qgroup
corruption.

Fixed by the following kernel patch:
"btrfs: qgroup: Dirty all qgroups before rescan"

Reported-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
changelog:
v2:
  Change the adjective for the offending group, from "orphan" to
  "childless"
---
 tests/btrfs/170     | 83 +++++++++++++++++++++++++++++++++++++++++++++
 tests/btrfs/170.out |  3 ++
 tests/btrfs/group   |  1 +
 3 files changed, 87 insertions(+)
 create mode 100755 tests/btrfs/170
 create mode 100644 tests/btrfs/170.out

diff --git a/tests/btrfs/170 b/tests/btrfs/170
new file mode 100755
index 000000000000..3a810e80562f
--- /dev/null
+++ b/tests/btrfs/170
@@ -0,0 +1,83 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2018 SUSE Linux Products GmbH.  All Rights Reserved.
+#
+# FS QA Test 170
+#
+# Test if btrfs can clear high level childless qgroup's accounting numbers
+# during rescan.
+#
+# Fixed by the following kernel patch:
+# "btrfs: qgroup: Dirty all qgroups before rescan"
+#
+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 $seqres.full
+
+# real QA test starts here
+
+# Modify as appropriate.
+_supported_fs btrfs
+_supported_os Linux
+_require_scratch
+
+_scratch_mkfs > /dev/null 2>&1
+_scratch_mount
+
+
+# Populate the fs
+_run_btrfs_util_prog subvolume create "$SCRATCH_MNT/subvol"
+_pwrite_byte 0xcdcd 0 1M "$SCRATCH_MNT/subvol/file1" | _filter_xfs_io > /dev/null
+
+# Ensure that file reach disk, so it will also appear in snapshot
+sync
+_run_btrfs_util_prog subvolume snapshot "$SCRATCH_MNT/subvol" "$SCRATCH_MNT/snapshot"
+
+
+_run_btrfs_util_prog quota enable "$SCRATCH_MNT"
+_run_btrfs_util_prog quota rescan -w "$SCRATCH_MNT"
+
+# Create high level qgroup
+_run_btrfs_util_prog qgroup create 1/0 "$SCRATCH_MNT"
+
+# Don't use _run_btrfs_util_prog here, as it can return 1 to info user
+# that qgroup is marked inconsistent, this is a bug in btrfs-progs, but
+# to ensure it will work, we just ignore the return value.
+$BTRFS_UTIL_PROG qgroup assign "$SCRATCH_MNT/snapshot" 1/0 "$SCRATCH_MNT"
+
+# Above assign will mark qgroup inconsistent due to the shared extents
+# between subvol/snapshot/high level qgroup, do rescan here
+_run_btrfs_util_prog quota rescan -w "$SCRATCH_MNT"
+
+# Now remove the qgroup relationship and make 1/0 childless
+# Due to the shared extent outside of 1/0, we will mark qgroup inconsistent
+# and keep the number of qgroup 1/0
+$BTRFS_UTIL_PROG qgroup remove "$SCRATCH_MNT/snapshot" 1/0 "$SCRATCH_MNT"
+
+# Above removal also marks qgroup inconsistent, rescan again
+_run_btrfs_util_prog quota rescan -w "$SCRATCH_MNT"
+
+# After the test, btrfs check will verify qgroup numbers to catch any
+# corruption.
+
+# success, all done
+status=0
+exit
diff --git a/tests/btrfs/170.out b/tests/btrfs/170.out
new file mode 100644
index 000000000000..9002199e48ed
--- /dev/null
+++ b/tests/btrfs/170.out
@@ -0,0 +1,3 @@
+QA output created by 170
+WARNING: quotas may be inconsistent, rescan needed
+WARNING: quotas may be inconsistent, rescan needed
diff --git a/tests/btrfs/group b/tests/btrfs/group
index b616c73d09bf..339c977135c0 100644
--- a/tests/btrfs/group
+++ b/tests/btrfs/group
@@ -172,3 +172,4 @@
 167 auto quick replace volume
 168 auto quick send
 169 auto quick send
+170 auto quick qgroup
-- 
2.18.0