[PATCH blktests] block: add test for io hang due to blk-iolatency

[Liu Bo <bo.liu@linux.alibaba.com>]

Add test for verifying io hang when enabling blk-iolatency after a few
IOs have been done.

This is a regression test for
"blk-iolatency: fix IO hang due to negative inflight counter".

Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
---
 tests/block/022     | 42 ++++++++++++++++++++++++++++++++++++++++++
 tests/block/022.out |  2 ++
 2 files changed, 44 insertions(+)
 create mode 100755 tests/block/022
 create mode 100644 tests/block/022.out

diff --git a/tests/block/022 b/tests/block/022
new file mode 100755
index 0000000..6e5ab42
--- /dev/null
+++ b/tests/block/022
@@ -0,0 +1,42 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-3.0+
+# Copyright (C) 2019 Bo Liu <bo.liu@linux.alibaba.com>
+#
+# This test is a regression test for io hang due to blk-iolatency, the patch is
+# "blk-iolatency: fix IO hang due to negative inflight counter"
+
+. tests/block/rc
+. common/cgroup
+. common/null_blk
+DESCRIPTION="This test will demonstrate io hang due to blk-iolatency"
+
+requires() {
+	_have_null_blk && _have_cgroup2_controller_file io io.latency
+}
+
+test() {
+	local CGROUP2_DIR
+	local dir
+	echo "Running ${TEST_NAME}"
+
+	if ! _init_null_blk queue_mode=2; then
+		return 1
+	fi
+
+	_init_cgroup2
+	dir=$(_cgroup2_base_dir)
+
+	echo $$ > ${CGROUP2_DIR}/cgroup.procs
+	xfs_io -f -d -c "pwrite 0 4k" /dev/nullb0
+
+	# target=1s
+	echo "`cat /sys/block/nullb0/dev` target=1000000" > ${CGROUP2_DIR}/io.latency
+
+	xfs_io -f -d -c "pwrite 0 4k" /dev/nullb0
+
+	echo $$ > ${dir}/cgroup.procs
+	_exit_cgroup2
+	_exit_null_blk
+
+	echo "Test complete"
+}
diff --git a/tests/block/022.out b/tests/block/022.out
new file mode 100644
index 0000000..14d43cb
--- /dev/null
+++ b/tests/block/022.out
@@ -0,0 +1,2 @@
+Running block/022
+Test complete
-- 
2.20.1.2.gb21ebb6