[PATCH blktests 1/2] blktests: split out cgroup2 controller and file check

[Dennis Zhou <dennis@kernel.org>]

This is a prep patch for a new test that will race blkg association and
request_queue cleanup. As blkg association is a underlying cgroup io
controller feature, we need the ability to check if the controller is
available.

Signed-off-by: Dennis Zhou <dennis@kernel.org>
---
v2:
- fixed minor typo.

 common/cgroup | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/common/cgroup b/common/cgroup
index d445093..48e546f 100644
--- a/common/cgroup
+++ b/common/cgroup
@@ -37,19 +37,27 @@ _have_cgroup2()
 	return 0
 }
 
-_have_cgroup2_controller_file()
+_have_cgroup2_controller()
 {
-	_have_cgroup2 || return 1
-
 	local controller="$1"
-	local file="$2"
-	local dir
+
+	_have_cgroup2 || return 1
 
 	dir="$(_cgroup2_base_dir)"
+
 	if ! grep -q "$controller" "$dir/cgroup.controllers"; then
 		SKIP_REASON="no support for $controller cgroup controller; if it is enabled, you may need to boot with cgroup_no_v1=$controller"
 		return 1
 	fi
+}
+
+_have_cgroup2_controller_file()
+{
+	local controller="$1"
+	local file="$2"
+	local dir
+
+	_have_cgroup2_controller "$controller" || return 1
 
 	mkdir "$dir/blktests"
 	echo "+$controller" > "$dir/cgroup.subtree_control"
-- 
2.17.1