[PATCH 08/49] blkcg: implement task_get_blkcg_css()

Tejun Heo
2015-04-06T19:59:45Z

Implement a wrapper around task_get_css() to acquire the blkcg css for
a given task. The wrapper is necessary for cgroup writeback support
as there will be places outside blkcg proper trying to acquire
blkcg_css and blkio_cgrp_id will be undefined when !CONFIG_BLK_CGROUP.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
include/linux/blk-cgroup.h | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index 65f0c17..4dc643f 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -195,6 +195,12 @@ static inline struct blkcg *bio_blkcg(struct bio *bio)
return task_blkcg(current);
}

+static inline struct cgroup_subsys_state *
+task_get_blkcg_css(struct task_struct *task)
+{
+ return task_get_css(task, blkio_cgrp_id);
+}
+
/**
* blkcg_parent - get the parent of a blkcg
* @blkcg: blkcg of interest
@@ -573,6 +579,12 @@ struct blkcg_policy {

#define blkcg_root_css ((struct cgroup_subsys_state *)ERR_PTR(-EINVAL))

+static inline struct cgroup_subsys_state *
+task_get_blkcg_css(struct task_struct *task)
+{
+ return NULL;
+}
+
#ifdef CONFIG_BLOCK

static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
--
2.1.0