/*

   * include/linux/writeback.h

   */
  #ifndef WRITEBACK_H
  #define WRITEBACK_H

  #include <linux/sched.h>

  #include <linux/fs.h>

  struct backing_dev_info;
  
  extern spinlock_t inode_lock;
  extern struct list_head inode_in_use;
  extern struct list_head inode_unused;
  
  /*

   * fs/fs-writeback.c
   */
  enum writeback_sync_modes {
  	WB_SYNC_NONE,	/* Don't wait on anything */
  	WB_SYNC_ALL,	/* Wait on every mapping */

  };
  
  /*
   * A control structure which tells the writeback code what to do.  These are
   * always on the stack, and hence need no locking.  They are always initialised
   * in a manner such that unspecified fields are set to zero.
   */
  struct writeback_control {

  	enum writeback_sync_modes sync_mode;
  	unsigned long *older_than_this;	/* If !NULL, only write back inodes
  					   older than this */

  	unsigned long wb_start;         /* Time writeback_inodes_wb was
  					   called. This is needed to avoid
  					   extra jobs and livelock */

  	long nr_to_write;		/* Write this many pages, and decrement
  					   this for each page written */
  	long pages_skipped;		/* Pages which were not written */
  
  	/*
  	 * For a_ops->writepages(): is start or end are non-zero then this is
  	 * a hint that the filesystem need only write out the pages inside that
  	 * byterange.  The byte at `end' is included in the writeout request.
  	 */

  	loff_t range_start;
  	loff_t range_end;

  	unsigned nonblocking:1;		/* Don't get stuck on request queues */
  	unsigned encountered_congestion:1; /* An output: a queue is full */
  	unsigned for_kupdate:1;		/* A kupdate writeback */

  	unsigned for_background:1;	/* A background writeback */

  	unsigned for_reclaim:1;		/* Invoked from the page allocator */

  	unsigned range_cyclic:1;	/* range_start is cyclic */

  	unsigned more_io:1;		/* more io to be dispatched */

  };
  
  /*

   * fs/fs-writeback.c
   */	

  struct bdi_writeback;

  int inode_wait(void *);

  void writeback_inodes_sb(struct super_block *);

  int writeback_inodes_sb_if_idle(struct super_block *);

  void sync_inodes_sb(struct super_block *);

  void writeback_inodes_wb(struct bdi_writeback *wb,
  		struct writeback_control *wbc);

  long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
  void wakeup_flusher_threads(long nr_pages);

  
  /* writeback.h requires fs.h; it, too, is not included from here. */
  static inline void wait_on_inode(struct inode *inode)
  {
  	might_sleep();

  	wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);

  }

  static inline void inode_sync_wait(struct inode *inode)
  {
  	might_sleep();
  	wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
  							TASK_UNINTERRUPTIBLE);
  }

  
  /*
   * mm/page-writeback.c
   */

  #ifdef CONFIG_BLOCK

  void laptop_io_completion(struct backing_dev_info *info);

  void laptop_sync_completion(void);

  void laptop_mode_sync(struct work_struct *work);
  void laptop_mode_timer_fn(unsigned long data);

  #else
  static inline void laptop_sync_completion(void) { }
  #endif

  void throttle_vm_writeout(gfp_t gfp_mask);

  
  /* These are exported to sysctl. */
  extern int dirty_background_ratio;

  extern unsigned long dirty_background_bytes;

  extern int vm_dirty_ratio;

  extern unsigned long vm_dirty_bytes;

  extern unsigned int dirty_writeback_interval;
  extern unsigned int dirty_expire_interval;

  extern int vm_highmem_is_dirtyable;

  extern int block_dump;
  extern int laptop_mode;

  extern unsigned long determine_dirtyable_memory(void);

  extern int dirty_background_ratio_handler(struct ctl_table *table, int write,

  		void __user *buffer, size_t *lenp,

  		loff_t *ppos);
  extern int dirty_background_bytes_handler(struct ctl_table *table, int write,

  		void __user *buffer, size_t *lenp,

  		loff_t *ppos);

  extern int dirty_ratio_handler(struct ctl_table *table, int write,

  		void __user *buffer, size_t *lenp,

  		loff_t *ppos);

  extern int dirty_bytes_handler(struct ctl_table *table, int write,

  		void __user *buffer, size_t *lenp,

  		loff_t *ppos);

  struct ctl_table;

  int dirty_writeback_centisecs_handler(struct ctl_table *, int,

  				      void __user *, size_t *, loff_t *);

  void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
  unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
  			       unsigned long dirty);

  void page_writeback_init(void);

  void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
  					unsigned long nr_pages_dirtied);
  
  static inline void
  balance_dirty_pages_ratelimited(struct address_space *mapping)
  {
  	balance_dirty_pages_ratelimited_nr(mapping, 1);
  }

  typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
  				void *data);

  int generic_writepages(struct address_space *mapping,
  		       struct writeback_control *wbc);
  int write_cache_pages(struct address_space *mapping,
  		      struct writeback_control *wbc, writepage_t writepage,
  		      void *data);

  int do_writepages(struct address_space *mapping, struct writeback_control *wbc);

  void set_page_dirty_balance(struct page *page, int page_mkwrite);

  void writeback_set_ratelimit(void);

  
  /* pdflush.c */
  extern int nr_pdflush_threads;	/* Global so it can be exported to sysctl
  				   read-only. */
  
  
  #endif		/* WRITEBACK_H */