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

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

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

/*
 * The 1/4 region under the global dirty thresh is for smooth dirty throttling:
 *
 *	(thresh - thresh/DIRTY_FULL_SCOPE, thresh)
 *
 * The 1/16 region above the global dirty limit will be put to maximum pauses:
 *
 *	(limit, limit + limit/DIRTY_MAXPAUSE_AREA)
 *
 * The 1/16 region above the max-pause region, dirty exceeded bdi's will be put
 * to loops:
 *
 *	(limit + limit/DIRTY_MAXPAUSE_AREA, limit + limit/DIRTY_PASSGOOD_AREA)
 *
 * 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)
#define DIRTY_MAXPAUSE_AREA		16
#define DIRTY_PASSGOOD_AREA		8

/*
 * 4MB minimal write chunk size
 */
#define MIN_WRITEBACK_PAGES	(4096UL >> (PAGE_CACHE_SHIFT - 10))

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 */
};

/*
 * 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;
	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 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 */
};

/*
 * fs/fs-writeback.c
 */	
struct bdi_writeback;
int inode_wait(void *);
void writeback_inodes_sb(struct super_block *);
void writeback_inodes_sb_nr(struct super_block *, unsigned long nr);
int writeback_inodes_sb_if_idle(struct super_block *);
int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr);
void sync_inodes_sb(struct super_block *);
long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages);
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);

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 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 __bdi_update_bandwidth(struct backing_dev_info *bdi,
			    unsigned long 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_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);
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, int page_mkwrite);
void writeback_set_ratelimit(void);
void tag_pages_for_writeback(struct address_space *mapping,
			     pgoff_t start, pgoff_t end);

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


#endif		/* WRITEBACK_H */
Commit	Line	Data
1da177e4	1	/*
f30c2269	2	* include/linux/writeback.h
1da177e4 LT	3	*/
	4	#ifndef WRITEBACK_H
	5	#define WRITEBACK_H
	6
e8edc6e0	7	#include <linux/sched.h>
f5ff8422	8	#include <linux/fs.h>
e8edc6e0	9
ffd1f609	10	/*
1a12d8bd WF	11	* The 1/4 region under the global dirty thresh is for smooth dirty throttling:
	12	*
	13	* (thresh - thresh/DIRTY_FULL_SCOPE, thresh)
	14	*
ffd1f609 WF	15	* The 1/16 region above the global dirty limit will be put to maximum pauses:
	16	*
	17	* (limit, limit + limit/DIRTY_MAXPAUSE_AREA)
	18	*
	19	* The 1/16 region above the max-pause region, dirty exceeded bdi's will be put
	20	* to loops:
	21	*
	22	* (limit + limit/DIRTY_MAXPAUSE_AREA, limit + limit/DIRTY_PASSGOOD_AREA)
	23	*
	24	* Further beyond, all dirtier tasks will enter a loop waiting (possibly long
	25	* time) for the dirty pages to drop, unless written enough pages.
	26	*
	27	* The global dirty threshold is normally equal to the global dirty limit,
	28	* except when the system suddenly allocates a lot of anonymous memory and
	29	* knocks down the global dirty threshold quickly, in which case the global
	30	* dirty limit will follow down slowly to prevent livelocking all dirtier tasks.
	31	*/
1a12d8bd WF	32	#define DIRTY_SCOPE 8
1a12d8bd WF	33	#define DIRTY_FULL_SCOPE (DIRTY_SCOPE / 2)
ffd1f609 WF	34	#define DIRTY_MAXPAUSE_AREA 16
	35	#define DIRTY_PASSGOOD_AREA 8
	36
1a12d8bd WF	37	/*
	38	* 4MB minimal write chunk size
	39	*/
	40	#define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_CACHE_SHIFT - 10))
	41
1da177e4 LT	42	struct backing_dev_info;
1da177e4 LT	43
1da177e4 LT	44	/*
	45	* fs/fs-writeback.c
	46	*/
	47	enum writeback_sync_modes {
	48	WB_SYNC_NONE, /* Don't wait on anything */
	49	WB_SYNC_ALL, /* Wait on every mapping */
1da177e4 LT	50	};
	51
	52	/*
	53	* A control structure which tells the writeback code what to do. These are
	54	* always on the stack, and hence need no locking. They are always initialised
	55	* in a manner such that unspecified fields are set to zero.
	56	*/
	57	struct writeback_control {
1da177e4	58	enum writeback_sync_modes sync_mode;
1da177e4 LT	59	long nr_to_write; /* Write this many pages, and decrement
	60	this for each page written */
	61	long pages_skipped; /* Pages which were not written */
	62
	63	/*
	64	* For a_ops->writepages(): is start or end are non-zero then this is
	65	* a hint that the filesystem need only write out the pages inside that
	66	* byterange. The byte at `end' is included in the writeout request.
	67	*/
111ebb6e OH	68	loff_t range_start;
111ebb6e OH	69	loff_t range_end;
1da177e4	70
22905f77	71	unsigned for_kupdate:1; /* A kupdate writeback */
b17621fe	72	unsigned for_background:1; /* A background writeback */
6e6938b6	73	unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */
22905f77	74	unsigned for_reclaim:1; /* Invoked from the page allocator */
111ebb6e	75	unsigned range_cyclic:1; /* range_start is cyclic */
1da177e4 LT	76	};
1da177e4 LT	77
1da177e4 LT	78	/*
	79	* fs/fs-writeback.c
	80	*/
03ba3782	81	struct bdi_writeback;
1da177e4	82	int inode_wait(void *);
b6e51316	83	void writeback_inodes_sb(struct super_block *);
3259f8be	84	void writeback_inodes_sb_nr(struct super_block *, unsigned long nr);
17bd55d0	85	int writeback_inodes_sb_if_idle(struct super_block *);
3259f8be	86	int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr);
b6e51316	87	void sync_inodes_sb(struct super_block *);
d46db3d5	88	long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages);
03ba3782 JA	89	long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
03ba3782 JA	90	void wakeup_flusher_threads(long nr_pages);
1da177e4 LT	91
	92	/* writeback.h requires fs.h; it, too, is not included from here. */
	93	static inline void wait_on_inode(struct inode *inode)
	94	{
	95	might_sleep();
eaff8079	96	wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
1da177e4	97	}
1c0eeaf5 JE	98	static inline void inode_sync_wait(struct inode *inode)
	99	{
	100	might_sleep();
	101	wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
	102	TASK_UNINTERRUPTIBLE);
	103	}
	104
1da177e4 LT	105
	106	/*
	107	* mm/page-writeback.c
	108	*/
c2c4986e	109	#ifdef CONFIG_BLOCK
31373d09	110	void laptop_io_completion(struct backing_dev_info *info);
1da177e4	111	void laptop_sync_completion(void);
31373d09 MG	112	void laptop_mode_sync(struct work_struct *work);
31373d09 MG	113	void laptop_mode_timer_fn(unsigned long data);
c2c4986e JA	114	#else
	115	static inline void laptop_sync_completion(void) { }
	116	#endif
232ea4d6	117	void throttle_vm_writeout(gfp_t gfp_mask);
1da177e4	118
c42843f2 WF	119	extern unsigned long global_dirty_limit;
c42843f2 WF	120
1da177e4 LT	121	/* These are exported to sysctl. */
1da177e4 LT	122	extern int dirty_background_ratio;
2da02997	123	extern unsigned long dirty_background_bytes;
1da177e4	124	extern int vm_dirty_ratio;
2da02997	125	extern unsigned long vm_dirty_bytes;
704503d8 AD	126	extern unsigned int dirty_writeback_interval;
704503d8 AD	127	extern unsigned int dirty_expire_interval;
195cf453	128	extern int vm_highmem_is_dirtyable;
1da177e4 LT	129	extern int block_dump;
	130	extern int laptop_mode;
	131
3eefae99 SR	132	extern unsigned long determine_dirtyable_memory(void);
3eefae99 SR	133
2da02997	134	extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
8d65af78	135	void __user buffer, size_t lenp,
2da02997 DR	136	loff_t *ppos);
2da02997 DR	137	extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
8d65af78	138	void __user buffer, size_t lenp,
2da02997	139	loff_t *ppos);
04fbfdc1	140	extern int dirty_ratio_handler(struct ctl_table *table, int write,
8d65af78	141	void __user buffer, size_t lenp,
04fbfdc1	142	loff_t *ppos);
2da02997	143	extern int dirty_bytes_handler(struct ctl_table *table, int write,
8d65af78	144	void __user buffer, size_t lenp,
2da02997	145	loff_t *ppos);
04fbfdc1	146
1da177e4	147	struct ctl_table;
8d65af78	148	int dirty_writeback_centisecs_handler(struct ctl_table *, int,
1da177e4 LT	149	void __user , size_t , loff_t *);
1da177e4 LT	150
16c4042f WF	151	void global_dirty_limits(unsigned long pbackground, unsigned long pdirty);
	152	unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
	153	unsigned long dirty);
cf0ca9fe	154
e98be2d5	155	void __bdi_update_bandwidth(struct backing_dev_info *bdi,
c42843f2 WF	156	unsigned long thresh,
	157	unsigned long dirty,
	158	unsigned long bdi_thresh,
	159	unsigned long bdi_dirty,
e98be2d5 WF	160	unsigned long start_time);
e98be2d5 WF	161
1da177e4	162	void page_writeback_init(void);
fa5a734e AM	163	void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
	164	unsigned long nr_pages_dirtied);
	165
	166	static inline void
	167	balance_dirty_pages_ratelimited(struct address_space *mapping)
	168	{
	169	balance_dirty_pages_ratelimited_nr(mapping, 1);
	170	}
	171
0ea97180 MS	172	typedef int (writepage_t)(struct page page, struct writeback_control *wbc,
	173	void *data);
	174
0ea97180 MS	175	int generic_writepages(struct address_space *mapping,
0ea97180 MS	176	struct writeback_control *wbc);
5b41d924 ES	177	void tag_pages_for_writeback(struct address_space *mapping,
5b41d924 ES	178	pgoff_t start, pgoff_t end);
0ea97180 MS	179	int write_cache_pages(struct address_space *mapping,
	180	struct writeback_control *wbc, writepage_t writepage,
	181	void *data);
1da177e4	182	int do_writepages(struct address_space mapping, struct writeback_control wbc);
a200ee18	183	void set_page_dirty_balance(struct page *page, int page_mkwrite);
2d1d43f6	184	void writeback_set_ratelimit(void);
92c09c04 NK	185	void tag_pages_for_writeback(struct address_space *mapping,
92c09c04 NK	186	pgoff_t start, pgoff_t end);
1da177e4 LT	187
	188	/* pdflush.c */
	189	extern int nr_pdflush_threads; /* Global so it can be exported to sysctl
	190	read-only. */
	191
	192
	193	#endif /* WRITEBACK_H */