[PATCH 2/2] blktests/033: add test to cover gendisk leak

[Ming Lei <ming.lei@redhat.com>]

So far only sync ublk removal is supported, and the device's
last reference is dropped in gendisk's ->free_disk(), so it
can be used to test gendisk leak issue.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 common/ublk         | 32 ++++++++++++++++++++++++++++++++
 tests/block/033     | 33 +++++++++++++++++++++++++++++++++
 tests/block/033.out |  2 ++
 3 files changed, 67 insertions(+)
 create mode 100644 common/ublk
 create mode 100755 tests/block/033
 create mode 100644 tests/block/033.out

diff --git a/common/ublk b/common/ublk
new file mode 100644
index 0000000..66b3a58
--- /dev/null
+++ b/common/ublk
@@ -0,0 +1,32 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-3.0+
+# Copyright (C) 2023 Ming Lei
+#
+# null_blk helper functions.
+
+. common/shellcheck
+
+_have_ublk() {
+	_have_driver ublk_drv
+	_have_src_program ublk/miniublk
+}
+
+_remove_ublk_devices() {
+	src/ublk/miniublk del -a
+}
+
+_init_ublk() {
+	if ! modprobe -r ublk_drv || ! modprobe ublk_drv "${args[@]}" ; then
+		SKIP_REASONS+=("requires modular ublk_drv")
+		return 1
+	fi
+
+	udevadm settle
+	return 0
+}
+
+_exit_ublk() {
+	_remove_ublk_devices
+	udevadm settle
+	modprobe -r -q ublk_drv
+}
diff --git a/tests/block/033 b/tests/block/033
new file mode 100755
index 0000000..342ccf3
--- /dev/null
+++ b/tests/block/033
@@ -0,0 +1,33 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-3.0+
+# Copyright (C) 2023 Ming Lei
+#
+# Test if gendisk is leaked, and regression in the following commit
+# c43332fe028c ("blk-cgroup: delay calling blkcg_exit_disk until disk_release")
+# can be covered
+
+. tests/block/rc
+. common/ublk
+
+DESCRIPTION="add & delete ublk device and test if gendisk is leaked"
+QUICK=1
+
+requires() {
+	_have_ublk
+}
+
+test() {
+	local ublk_prog="src/ublk/miniublk"
+	echo "Running ${TEST_NAME}"
+
+	if ! _init_ublk; then
+		return 1
+	fi
+
+	local ublk_dev=`$ublk_prog add -t null --quiet`
+	$ublk_prog del --disk=$ublk_dev > /dev/null 2>&1
+
+	_exit_ublk
+
+	echo "Test complete"
+}
diff --git a/tests/block/033.out b/tests/block/033.out
new file mode 100644
index 0000000..067846a
--- /dev/null
+++ b/tests/block/033.out
@@ -0,0 +1,2 @@
+Running block/033
+Test complete
-- 
2.31.1