[PATCH v5 02/11] cgroup: implement CFTYPE_NO_PREFIX

From: Glauber Costa
Date: Wed Jan 09 2013 - 06:45:11 EST


From: Tejun Heo <tj@xxxxxxxxxx>

When cgroup files are created, cgroup core automatically prepends the
name of the subsystem as prefix. This patch adds CFTYPE_NO_PREFIX
which disables the automatic prefix.

This will be used to deprecate cpuacct which will make cpu create and
serve the cpuacct files.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Glauber Costa <glommer@xxxxxxxxxxxxx>
---
include/linux/cgroup.h | 1 +
kernel/cgroup.c | 3 ++-
2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 7d73905..7d193f9 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -277,6 +277,7 @@ struct cgroup_map_cb {
/* cftype->flags */
#define CFTYPE_ONLY_ON_ROOT (1U << 0) /* only create on root cg */
#define CFTYPE_NOT_ON_ROOT (1U << 1) /* don't create on root cg */
+#define CFTYPE_NO_PREFIX (1U << 2) /* skip subsys prefix */

#define MAX_CFTYPE_NAME 64

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 4855892..2f98398 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2723,7 +2723,8 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,

simple_xattrs_init(&cft->xattrs);

- if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) {
+ if (subsys && !(cft->flags & CFTYPE_NO_PREFIX) &&
+ !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) {
strcpy(name, subsys->name);
strcat(name, ".");
}
--
1.7.11.7

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