linux/block/blk-cgroup.h

#ifndef _BLK_CGROUP_H
#define _BLK_CGROUP_H
/*
 * Common Block IO controller cgroup interface
 *
 * Based on ideas and code from CFQ, CFS and BFQ:
 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
 *
 * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
 *		      Paolo Valente <paolo.valente@unimore.it>
 *
 * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
 * 	              Nauman Rafique <nauman@google.com>
 */

#include <linux/cgroup.h>

struct blkio_cgroup {
	struct cgroup_subsys_state css;
	unsigned int weight;
	spinlock_t lock;
	struct hlist_head blkg_list;
};

struct blkio_group {
	/* An rcu protected unique identifier for the group */
	void *key;
	struct hlist_node blkcg_node;
	unsigned short blkcg_id;
};

#define BLKIO_WEIGHT_MIN	100
#define BLKIO_WEIGHT_MAX	1000
#define BLKIO_WEIGHT_DEFAULT	500

#ifdef CONFIG_BLK_CGROUP
extern struct blkio_cgroup blkio_root_cgroup;
extern struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup);
extern void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
				struct blkio_group *blkg, void *key);
extern int blkiocg_del_blkio_group(struct blkio_group *blkg);
extern struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg,
						void *key);
#else
static inline struct blkio_cgroup *
cgroup_to_blkio_cgroup(struct cgroup *cgroup) { return NULL; }

static inline void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
			struct blkio_group *blkg, void *key)
{
}

static inline int
blkiocg_del_blkio_group(struct blkio_group *blkg) { return 0; }

static inline struct blkio_group *
blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key) { return NULL; }
#endif
#endif /* _BLK_CGROUP_H */