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cgroup: add subsys backlink pointer to cftype

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cgroup is transitioning to using css (cgroup_subsys_state) instead of
cgroup as the primary subsystem handle.  The cgroupfs file interface
will be converted to use css's which requires finding out the
subsystem from cftype so that the matching css can be determined from
the cgroup.

This patch adds cftype->ss which points to the subsystem the file
belongs to.  The field is initialized while a cftype is being
registered.  This makes it unnecessary to explicitly specify the
subsystem for other cftype handling functions.  @ss argument dropped
from various cftype handling functions.

This patch shouldn't introduce any behavior differences.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Tejun Heo 2013-08-08 20:11:23 -04:00
commit 2bb566cb68
3 changed files with 51 additions and 37 deletions
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8
include/linux/cgroup.h
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@ -429,6 +429,12 @@ struct cftype {
/* CFTYPE_* flags */
unsigned int flags;
/*
* The subsys this file belongs to. Initialized automatically
* during registration. NULL for cgroup core files.
*/
struct cgroup_subsys *ss;
int (*open)(struct inode *inode, struct file *file);
ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft,
struct file *file,
@ -542,7 +548,7 @@ static inline const char *cgroup_name(const struct cgroup *cgrp)
}
int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
int cgroup_rm_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
int cgroup_rm_cftypes(struct cftype *cfts);
bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor);