[deliverable/linux.git] / include / linux / writeback.h

/*
 * include/linux/writeback.h
 */
#ifndef WRITEBACK_H
#define WRITEBACK_H

#include <linux/sched.h>
#include <linux/workqueue.h>
#include <linux/fs.h>

DECLARE_PER_CPU(int, dirty_throttle_leaks);

/*
 * The 1/4 region under the global dirty thresh is for smooth dirty throttling:
 *
 *	(thresh - thresh/DIRTY_FULL_SCOPE, thresh)
 *
 * Further beyond, all dirtier tasks will enter a loop waiting (possibly long
 * time) for the dirty pages to drop, unless written enough pages.
 *
 * The global dirty threshold is normally equal to the global dirty limit,
 * except when the system suddenly allocates a lot of anonymous memory and
 * knocks down the global dirty threshold quickly, in which case the global
 * dirty limit will follow down slowly to prevent livelocking all dirtier tasks.
 */
#define DIRTY_SCOPE		8
#define DIRTY_FULL_SCOPE	(DIRTY_SCOPE / 2)

struct backing_dev_info;

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

/*
 * why some writeback work was initiated
 */
enum wb_reason {
	WB_REASON_BACKGROUND,
	WB_REASON_TRY_TO_FREE_PAGES,
	WB_REASON_SYNC,
	WB_REASON_PERIODIC,
	WB_REASON_LAPTOP_TIMER,
	WB_REASON_FREE_MORE_MEM,
	WB_REASON_FS_FREE_SPACE,
	/*
	 * There is no bdi forker thread any more and works are done
	 * by emergency worker, however, this is TPs userland visible
	 * and we'll be exposing exactly the same information,
	 * so it has a mismatch name.
	 */
	WB_REASON_FORKER_THREAD,

	WB_REASON_MAX,
};

/*
 * 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 {
	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(): if 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;

	enum writeback_sync_modes sync_mode;

	unsigned for_kupdate:1;		/* A kupdate writeback */
	unsigned for_background:1;	/* A background writeback */
	unsigned tagged_writepages:1;	/* tag-and-write to avoid livelock */
	unsigned for_reclaim:1;		/* Invoked from the page allocator */
	unsigned range_cyclic:1;	/* range_start is cyclic */
	unsigned for_sync:1;		/* sync(2) WB_SYNC_ALL writeback */
};

/*
 * fs/fs-writeback.c
 */	
struct bdi_writeback;
int inode_wait(void *);
void writeback_inodes_sb(struct super_block *, enum wb_reason reason);
void writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
							enum wb_reason reason);
int try_to_writeback_inodes_sb(struct super_block *, enum wb_reason reason);
int try_to_writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
				  enum wb_reason reason);
void sync_inodes_sb(struct super_block *);
void wakeup_flusher_threads(long nr_pages, enum wb_reason reason);
void inode_wait_for_writeback(struct inode *inode);

/* 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);
}

/*
 * 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);
bool zone_dirty_ok(struct zone *zone);

extern unsigned long global_dirty_limit;

/* 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 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 __bdi_update_bandwidth(struct backing_dev_info *bdi,
			    unsigned long thresh,
			    unsigned long bg_thresh,
			    unsigned long dirty,
			    unsigned long bdi_thresh,
			    unsigned long bdi_dirty,
			    unsigned long start_time);

void page_writeback_init(void);
void balance_dirty_pages_ratelimited(struct address_space *mapping);

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

int generic_writepages(struct address_space *mapping,
		       struct writeback_control *wbc);
void tag_pages_for_writeback(struct address_space *mapping,
			     pgoff_t start, pgoff_t end);
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);
void writeback_set_ratelimit(void);
void tag_pages_for_writeback(struct address_space *mapping,
			     pgoff_t start, pgoff_t end);

void account_page_redirty(struct page *page);

#endif		/* WRITEBACK_H */
Commit	Line	Data
	1	/*
	2	* include/linux/writeback.h
	3	*/
	4	#ifndef WRITEBACK_H
	5	#define WRITEBACK_H
	6
	7	#include <linux/sched.h>
	8	#include <linux/workqueue.h>
	9	#include <linux/fs.h>
	10
	11	DECLARE_PER_CPU(int, dirty_throttle_leaks);
	12
	13	/*
	14	* The 1/4 region under the global dirty thresh is for smooth dirty throttling:
	15	*
	16	* (thresh - thresh/DIRTY_FULL_SCOPE, thresh)
	17	*
	18	* Further beyond, all dirtier tasks will enter a loop waiting (possibly long
	19	* time) for the dirty pages to drop, unless written enough pages.
	20	*
	21	* The global dirty threshold is normally equal to the global dirty limit,
	22	* except when the system suddenly allocates a lot of anonymous memory and
	23	* knocks down the global dirty threshold quickly, in which case the global
	24	* dirty limit will follow down slowly to prevent livelocking all dirtier tasks.
	25	*/
	26	#define DIRTY_SCOPE 8
	27	#define DIRTY_FULL_SCOPE (DIRTY_SCOPE / 2)
	28
	29	struct backing_dev_info;
	30
	31	/*
	32	* fs/fs-writeback.c
	33	*/
	34	enum writeback_sync_modes {
	35	WB_SYNC_NONE, /* Don't wait on anything */
	36	WB_SYNC_ALL, /* Wait on every mapping */
	37	};
	38
	39	/*
	40	* why some writeback work was initiated
	41	*/
	42	enum wb_reason {
	43	WB_REASON_BACKGROUND,
	44	WB_REASON_TRY_TO_FREE_PAGES,
	45	WB_REASON_SYNC,
	46	WB_REASON_PERIODIC,
	47	WB_REASON_LAPTOP_TIMER,
	48	WB_REASON_FREE_MORE_MEM,
	49	WB_REASON_FS_FREE_SPACE,
	50	/*
	51	* There is no bdi forker thread any more and works are done
	52	* by emergency worker, however, this is TPs userland visible
	53	* and we'll be exposing exactly the same information,
	54	* so it has a mismatch name.
	55	*/
	56	WB_REASON_FORKER_THREAD,
	57
	58	WB_REASON_MAX,
	59	};
	60
	61	/*
	62	* A control structure which tells the writeback code what to do. These are
	63	* always on the stack, and hence need no locking. They are always initialised
	64	* in a manner such that unspecified fields are set to zero.
	65	*/
	66	struct writeback_control {
	67	long nr_to_write; /* Write this many pages, and decrement
	68	this for each page written */
	69	long pages_skipped; /* Pages which were not written */
	70
	71	/*
	72	* For a_ops->writepages(): if start or end are non-zero then this is
	73	* a hint that the filesystem need only write out the pages inside that
	74	* byterange. The byte at `end' is included in the writeout request.
	75	*/
	76	loff_t range_start;
	77	loff_t range_end;
	78
	79	enum writeback_sync_modes sync_mode;
	80
	81	unsigned for_kupdate:1; /* A kupdate writeback */
	82	unsigned for_background:1; /* A background writeback */
	83	unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */
	84	unsigned for_reclaim:1; /* Invoked from the page allocator */
	85	unsigned range_cyclic:1; /* range_start is cyclic */
	86	unsigned for_sync:1; /* sync(2) WB_SYNC_ALL writeback */
	87	};
	88
	89	/*
	90	* fs/fs-writeback.c
	91	*/
	92	struct bdi_writeback;
	93	int inode_wait(void *);
	94	void writeback_inodes_sb(struct super_block *, enum wb_reason reason);
	95	void writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
	96	enum wb_reason reason);
	97	int try_to_writeback_inodes_sb(struct super_block *, enum wb_reason reason);
	98	int try_to_writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
	99	enum wb_reason reason);
	100	void sync_inodes_sb(struct super_block *);
	101	void wakeup_flusher_threads(long nr_pages, enum wb_reason reason);
	102	void inode_wait_for_writeback(struct inode *inode);
	103
	104	/* writeback.h requires fs.h; it, too, is not included from here. */
	105	static inline void wait_on_inode(struct inode *inode)
	106	{
	107	might_sleep();
	108	wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
	109	}
	110
	111	/*
	112	* mm/page-writeback.c
	113	*/
	114	#ifdef CONFIG_BLOCK
	115	void laptop_io_completion(struct backing_dev_info *info);
	116	void laptop_sync_completion(void);
	117	void laptop_mode_sync(struct work_struct *work);
	118	void laptop_mode_timer_fn(unsigned long data);
	119	#else
	120	static inline void laptop_sync_completion(void) { }
	121	#endif
	122	void throttle_vm_writeout(gfp_t gfp_mask);
	123	bool zone_dirty_ok(struct zone *zone);
	124
	125	extern unsigned long global_dirty_limit;
	126
	127	/* These are exported to sysctl. */
	128	extern int dirty_background_ratio;
	129	extern unsigned long dirty_background_bytes;
	130	extern int vm_dirty_ratio;
	131	extern unsigned long vm_dirty_bytes;
	132	extern unsigned int dirty_writeback_interval;
	133	extern unsigned int dirty_expire_interval;
	134	extern int vm_highmem_is_dirtyable;
	135	extern int block_dump;
	136	extern int laptop_mode;
	137
	138	extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
	139	void __user buffer, size_t lenp,
	140	loff_t *ppos);
	141	extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
	142	void __user buffer, size_t lenp,
	143	loff_t *ppos);
	144	extern int dirty_ratio_handler(struct ctl_table *table, int write,
	145	void __user buffer, size_t lenp,
	146	loff_t *ppos);
	147	extern int dirty_bytes_handler(struct ctl_table *table, int write,
	148	void __user buffer, size_t lenp,
	149	loff_t *ppos);
	150
	151	struct ctl_table;
	152	int dirty_writeback_centisecs_handler(struct ctl_table *, int,
	153	void __user , size_t , loff_t *);
	154
	155	void global_dirty_limits(unsigned long pbackground, unsigned long pdirty);
	156	unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
	157	unsigned long dirty);
	158
	159	void __bdi_update_bandwidth(struct backing_dev_info *bdi,
	160	unsigned long thresh,
	161	unsigned long bg_thresh,
	162	unsigned long dirty,
	163	unsigned long bdi_thresh,
	164	unsigned long bdi_dirty,
	165	unsigned long start_time);
	166
	167	void page_writeback_init(void);
	168	void balance_dirty_pages_ratelimited(struct address_space *mapping);
	169
	170	typedef int (writepage_t)(struct page page, struct writeback_control *wbc,
	171	void *data);
	172
	173	int generic_writepages(struct address_space *mapping,
	174	struct writeback_control *wbc);
	175	void tag_pages_for_writeback(struct address_space *mapping,
	176	pgoff_t start, pgoff_t end);
	177	int write_cache_pages(struct address_space *mapping,
	178	struct writeback_control *wbc, writepage_t writepage,
	179	void *data);
	180	int do_writepages(struct address_space mapping, struct writeback_control wbc);
	181	void set_page_dirty_balance(struct page *page);
	182	void writeback_set_ratelimit(void);
	183	void tag_pages_for_writeback(struct address_space *mapping,
	184	pgoff_t start, pgoff_t end);
	185
	186	void account_page_redirty(struct page *page);
	187
	188	#endif /* WRITEBACK_H */