[PATCH v2] btrfs: add test for enable/disable quota and create/destroy qgroup repeatedly

[Sidong Yang <realwakka@gmail.com>]

Test enable/disable quota and create/destroy qgroup repeatedly in
parallel and confirm it does not cause kernel hang. It only happens
in kernel staring with kernel 5.17-rc3. This is a regression test
for the problem reported to linux-btrfs list [1].

The hang was recreated using the test case and fixed by kernel patch
titled

  btrfs: qgroup: fix deadlock between rescan worker and remove qgroup

[1] https://lore.kernel.org/linux-btrfs/20220228014340.21309-1-realwakka@gmail.com/

Signed-off-by: Sidong Yang <realwakka@gmail.com>
---
v2 : fix changelog, comments, no wait pids argument
---
 tests/btrfs/262     | 40 ++++++++++++++++++++++++++++++++++++++++
 tests/btrfs/262.out |  2 ++
 2 files changed, 42 insertions(+)
 create mode 100755 tests/btrfs/262
 create mode 100644 tests/btrfs/262.out

diff --git a/tests/btrfs/262 b/tests/btrfs/262
new file mode 100755
index 00000000..8953a28e
--- /dev/null
+++ b/tests/btrfs/262
@@ -0,0 +1,40 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2022 Sidong Yang.  All Rights Reserved.
+#
+# FS QA Test 262
+#
+# Test that running qgroup enable, create, destroy, and disable commands in
+# parallel doesn't result in a deadlock, a crash or any filesystem
+# inconsistency.
+#
+. ./common/preamble
+_begin_fstest auto quick qgroup
+
+# Import common functions.
+. ./common/filter
+
+# real QA test starts here
+
+_supported_fs btrfs
+
+_require_scratch
+
+_scratch_mkfs > /dev/null 2>&1
+_scratch_mount
+
+for ((i = 0; i < 200; i++)); do
+	$BTRFS_UTIL_PROG quota enable $SCRATCH_MNT 2>> $seqres.full &
+	$BTRFS_UTIL_PROG qgroup create 1/0 $SCRATCH_MNT 2>> $seqres.full &
+	$BTRFS_UTIL_PROG qgroup destroy 1/0 $SCRATCH_MNT 2>> $seqres.full &
+	$BTRFS_UTIL_PROG quota disable $SCRATCH_MNT 2>> $seqres.full &
+done
+
+wait
+
+_scratch_unmount
+
+# success, all done
+echo "Silence is golden"
+status=0
+exit
diff --git a/tests/btrfs/262.out b/tests/btrfs/262.out
new file mode 100644
index 00000000..404badc3
--- /dev/null
+++ b/tests/btrfs/262.out
@@ -0,0 +1,2 @@
+QA output created by 262
+Silence is golden
-- 
2.25.1