#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>

  #if defined(CONFIG_BLK_CGROUP) || defined(CONFIG_BLK_CGROUP_MODULE)
  
  #ifndef CONFIG_BLK_CGROUP
  /* When blk-cgroup is a module, its subsys_id isn't a compile-time constant */
  extern struct cgroup_subsys blkio_subsys;
  #define blkio_subsys_id blkio_subsys.subsys_id
  #endif

  enum stat_type {
  	/* Total time spent (in ns) between request dispatch to the driver and
  	 * request completion for IOs doen by this cgroup. This may not be
  	 * accurate when NCQ is turned on. */
  	BLKIO_STAT_SERVICE_TIME = 0,
  	/* Total bytes transferred */
  	BLKIO_STAT_SERVICE_BYTES,
  	/* Total IOs serviced, post merge */
  	BLKIO_STAT_SERVICED,
  	/* Total time spent waiting in scheduler queue in ns */
  	BLKIO_STAT_WAIT_TIME,

  	/* Number of IOs merged */
  	BLKIO_STAT_MERGED,

  	/* Number of IOs queued up */
  	BLKIO_STAT_QUEUED,

  	/* All the single valued stats go below this */
  	BLKIO_STAT_TIME,
  	BLKIO_STAT_SECTORS,
  #ifdef CONFIG_DEBUG_BLK_CGROUP

  	BLKIO_STAT_AVG_QUEUE_SIZE,

  	BLKIO_STAT_IDLE_TIME,
  	BLKIO_STAT_EMPTY_TIME,
  	BLKIO_STAT_GROUP_WAIT_TIME,

  	BLKIO_STAT_DEQUEUE
  #endif
  };
  
  enum stat_sub_type {
  	BLKIO_STAT_READ = 0,
  	BLKIO_STAT_WRITE,
  	BLKIO_STAT_SYNC,
  	BLKIO_STAT_ASYNC,
  	BLKIO_STAT_TOTAL

  };

  /* blkg state flags */
  enum blkg_state_flags {
  	BLKG_waiting = 0,
  	BLKG_idling,
  	BLKG_empty,
  };

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

  	struct list_head policy_list; /* list of blkio_policy_node */

  };

  struct blkio_group_stats {
  	/* total disk time and nr sectors dispatched by this group */
  	uint64_t time;
  	uint64_t sectors;

  	uint64_t stat_arr[BLKIO_STAT_QUEUED + 1][BLKIO_STAT_TOTAL];

  #ifdef CONFIG_DEBUG_BLK_CGROUP

  	/* Sum of number of IOs queued across all samples */
  	uint64_t avg_queue_size_sum;
  	/* Count of samples taken for average */
  	uint64_t avg_queue_size_samples;

  	/* How many times this group has been removed from service tree */
  	unsigned long dequeue;

  
  	/* Total time spent waiting for it to be assigned a timeslice. */
  	uint64_t group_wait_time;
  	uint64_t start_group_wait_time;
  
  	/* Time spent idling for this blkio_group */
  	uint64_t idle_time;
  	uint64_t start_idle_time;
  	/*
  	 * Total time when we have requests queued and do not contain the
  	 * current active queue.
  	 */
  	uint64_t empty_time;
  	uint64_t start_empty_time;
  	uint16_t flags;

  #endif
  };

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

  	unsigned short blkcg_id;

  	/* Store cgroup path */
  	char path[128];

  	/* The device MKDEV(major, minor), this group has been created for */

  	dev_t dev;

  	/* Need to serialize the stats in the case of reset/update */
  	spinlock_t stats_lock;
  	struct blkio_group_stats stats;

  };

  struct blkio_policy_node {
  	struct list_head node;
  	dev_t dev;
  	unsigned int weight;
  };
  
  extern unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg,
  				     dev_t dev);

  typedef void (blkio_unlink_group_fn) (void *key, struct blkio_group *blkg);
  typedef void (blkio_update_group_weight_fn) (struct blkio_group *blkg,
  						unsigned int weight);
  
  struct blkio_policy_ops {
  	blkio_unlink_group_fn *blkio_unlink_group_fn;
  	blkio_update_group_weight_fn *blkio_update_group_weight_fn;
  };
  
  struct blkio_policy_type {
  	struct list_head list;
  	struct blkio_policy_ops ops;
  };
  
  /* Blkio controller policy registration */
  extern void blkio_policy_register(struct blkio_policy_type *);
  extern void blkio_policy_unregister(struct blkio_policy_type *);

  static inline char *blkg_path(struct blkio_group *blkg)
  {
  	return blkg->path;
  }

  #else
  
  struct blkio_group {
  };

  struct blkio_policy_type {
  };
  
  static inline void blkio_policy_register(struct blkio_policy_type *blkiop) { }
  static inline void blkio_policy_unregister(struct blkio_policy_type *blkiop) { }

  static inline char *blkg_path(struct blkio_group *blkg) { return NULL; }

  #endif

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

  #ifdef CONFIG_DEBUG_BLK_CGROUP

  void blkiocg_update_avg_queue_size_stats(struct blkio_group *blkg);

  void blkiocg_update_dequeue_stats(struct blkio_group *blkg,

  				unsigned long dequeue);

  void blkiocg_update_set_idle_time_stats(struct blkio_group *blkg);
  void blkiocg_update_idle_time_stats(struct blkio_group *blkg);

  void blkiocg_set_start_empty_time(struct blkio_group *blkg);

  
  #define BLKG_FLAG_FNS(name)						\
  static inline void blkio_mark_blkg_##name(				\
  		struct blkio_group_stats *stats)			\
  {									\
  	stats->flags |= (1 << BLKG_##name);				\
  }									\
  static inline void blkio_clear_blkg_##name(				\
  		struct blkio_group_stats *stats)			\
  {									\
  	stats->flags &= ~(1 << BLKG_##name);				\
  }									\
  static inline int blkio_blkg_##name(struct blkio_group_stats *stats)	\
  {									\
  	return (stats->flags & (1 << BLKG_##name)) != 0;		\
  }									\
  
  BLKG_FLAG_FNS(waiting)
  BLKG_FLAG_FNS(idling)
  BLKG_FLAG_FNS(empty)
  #undef BLKG_FLAG_FNS

  #else

  static inline void blkiocg_update_avg_queue_size_stats(

  						struct blkio_group *blkg) {}

  static inline void blkiocg_update_dequeue_stats(struct blkio_group *blkg,
  						unsigned long dequeue) {}

  static inline void blkiocg_update_set_idle_time_stats(struct blkio_group *blkg)
  {}
  static inline void blkiocg_update_idle_time_stats(struct blkio_group *blkg) {}

  static inline void blkiocg_set_start_empty_time(struct blkio_group *blkg) {}

  #endif

  #if defined(CONFIG_BLK_CGROUP) || defined(CONFIG_BLK_CGROUP_MODULE)

  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, dev_t dev);

  extern int blkiocg_del_blkio_group(struct blkio_group *blkg);
  extern struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg,
  						void *key);

  void blkiocg_update_timeslice_used(struct blkio_group *blkg,
  					unsigned long time);

  void blkiocg_update_dispatch_stats(struct blkio_group *blkg, uint64_t bytes,
  						bool direction, bool sync);
  void blkiocg_update_completion_stats(struct blkio_group *blkg,
  	uint64_t start_time, uint64_t io_start_time, bool direction, bool sync);

  void blkiocg_update_io_merged_stats(struct blkio_group *blkg, bool direction,
  					bool sync);

  void blkiocg_update_io_add_stats(struct blkio_group *blkg,

  		struct blkio_group *curr_blkg, bool direction, bool sync);

  void blkiocg_update_io_remove_stats(struct blkio_group *blkg,

  					bool direction, bool sync);

  #else

  struct cgroup;

  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, dev_t dev) {}

  
  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; }

  static inline void blkiocg_update_timeslice_used(struct blkio_group *blkg,

  						unsigned long time) {}

  static inline void blkiocg_update_dispatch_stats(struct blkio_group *blkg,
  				uint64_t bytes, bool direction, bool sync) {}
  static inline void blkiocg_update_completion_stats(struct blkio_group *blkg,
  		uint64_t start_time, uint64_t io_start_time, bool direction,
  		bool sync) {}

  static inline void blkiocg_update_io_merged_stats(struct blkio_group *blkg,
  						bool direction, bool sync) {}

  static inline void blkiocg_update_io_add_stats(struct blkio_group *blkg,

  		struct blkio_group *curr_blkg, bool direction, bool sync) {}

  static inline void blkiocg_update_io_remove_stats(struct blkio_group *blkg,

  						bool direction, bool sync) {}

  #endif
  #endif /* _BLK_CGROUP_H */