cgroup: implement CFTYPE_ONLY_ON_DFL
This cftype flag makes the file only appear on the default hierarchy.
This will later be used for cgroup.controllers file.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 7e9fa50..43d1ed3 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -384,6 +384,7 @@
CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */
CFTYPE_INSANE = (1 << 2), /* don't create if sane_behavior */
CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */
+ CFTYPE_ONLY_ON_DFL = (1 << 4), /* only on default hierarchy */
};
#define MAX_CFTYPE_NAME 64
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 69b4939..37b6d53 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2356,6 +2356,8 @@
for (cft = cfts; cft->name[0] != '\0'; cft++) {
/* does cft->flags tell us to skip this file on @cgrp? */
+ if ((cft->flags & CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp))
+ continue;
if ((cft->flags & CFTYPE_INSANE) && cgroup_sane_behavior(cgrp))
continue;
if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent)