[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)
 *
 * 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)

/*
 * 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 */
};

/*
 * 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,
	WB_REASON_FORKER_THREAD,

	WB_REASON_MAX,
};
extern const char *wb_reason_name[];

/*
 * 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 *, enum wb_reason reason);
void writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
							enum wb_reason reason);
int writeback_inodes_sb_if_idle(struct super_block *, enum wb_reason reason);
int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr,
							enum wb_reason reason);
void sync_inodes_sb(struct super_block *);
long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages,
				enum wb_reason reason);
long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
void wakeup_flusher_threads(long nr_pages, enum wb_reason reason);

/* 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 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_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	* Further beyond, all dirtier tasks will enter a loop waiting (possibly long
	16	* time) for the dirty pages to drop, unless written enough pages.
	17	*
	18	* The global dirty threshold is normally equal to the global dirty limit,
	19	* except when the system suddenly allocates a lot of anonymous memory and
	20	* knocks down the global dirty threshold quickly, in which case the global
	21	* dirty limit will follow down slowly to prevent livelocking all dirtier tasks.
	22	*/
1a12d8bd WF	23	#define DIRTY_SCOPE 8
1a12d8bd WF	24	#define DIRTY_FULL_SCOPE (DIRTY_SCOPE / 2)
ffd1f609	25
1a12d8bd WF	26	/*
	27	* 4MB minimal write chunk size
	28	*/
	29	#define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_CACHE_SHIFT - 10))
	30
1da177e4 LT	31	struct backing_dev_info;
1da177e4 LT	32
1da177e4 LT	33	/*
	34	* fs/fs-writeback.c
	35	*/
	36	enum writeback_sync_modes {
	37	WB_SYNC_NONE, /* Don't wait on anything */
	38	WB_SYNC_ALL, /* Wait on every mapping */
1da177e4 LT	39	};
1da177e4 LT	40
0e175a18 CW	41	/*
	42	* why some writeback work was initiated
	43	*/
	44	enum wb_reason {
	45	WB_REASON_BACKGROUND,
	46	WB_REASON_TRY_TO_FREE_PAGES,
	47	WB_REASON_SYNC,
	48	WB_REASON_PERIODIC,
	49	WB_REASON_LAPTOP_TIMER,
	50	WB_REASON_FREE_MORE_MEM,
	51	WB_REASON_FS_FREE_SPACE,
	52	WB_REASON_FORKER_THREAD,
	53
	54	WB_REASON_MAX,
	55	};
	56	extern const char *wb_reason_name[];
	57
1da177e4 LT	58	/*
	59	* A control structure which tells the writeback code what to do. These are
	60	* always on the stack, and hence need no locking. They are always initialised
	61	* in a manner such that unspecified fields are set to zero.
	62	*/
	63	struct writeback_control {
1da177e4	64	enum writeback_sync_modes sync_mode;
1da177e4 LT	65	long nr_to_write; /* Write this many pages, and decrement
	66	this for each page written */
	67	long pages_skipped; /* Pages which were not written */
	68
	69	/*
	70	* For a_ops->writepages(): is start or end are non-zero then this is
	71	* a hint that the filesystem need only write out the pages inside that
	72	* byterange. The byte at `end' is included in the writeout request.
	73	*/
111ebb6e OH	74	loff_t range_start;
111ebb6e OH	75	loff_t range_end;
1da177e4	76
22905f77	77	unsigned for_kupdate:1; /* A kupdate writeback */
b17621fe	78	unsigned for_background:1; /* A background writeback */
6e6938b6	79	unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */
22905f77	80	unsigned for_reclaim:1; /* Invoked from the page allocator */
111ebb6e	81	unsigned range_cyclic:1; /* range_start is cyclic */
1da177e4 LT	82	};
1da177e4 LT	83
1da177e4 LT	84	/*
	85	* fs/fs-writeback.c
	86	*/
03ba3782	87	struct bdi_writeback;
1da177e4	88	int inode_wait(void *);
0e175a18 CW	89	void writeback_inodes_sb(struct super_block *, enum wb_reason reason);
	90	void writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
	91	enum wb_reason reason);
	92	int writeback_inodes_sb_if_idle(struct super_block *, enum wb_reason reason);
	93	int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr,
	94	enum wb_reason reason);
b6e51316	95	void sync_inodes_sb(struct super_block *);
0e175a18 CW	96	long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages,
0e175a18 CW	97	enum wb_reason reason);
03ba3782	98	long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
0e175a18	99	void wakeup_flusher_threads(long nr_pages, enum wb_reason reason);
1da177e4 LT	100
	101	/* writeback.h requires fs.h; it, too, is not included from here. */
	102	static inline void wait_on_inode(struct inode *inode)
	103	{
	104	might_sleep();
eaff8079	105	wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
1da177e4	106	}
1c0eeaf5 JE	107	static inline void inode_sync_wait(struct inode *inode)
	108	{
	109	might_sleep();
	110	wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
	111	TASK_UNINTERRUPTIBLE);
	112	}
	113
1da177e4 LT	114
	115	/*
	116	* mm/page-writeback.c
	117	*/
c2c4986e	118	#ifdef CONFIG_BLOCK
31373d09	119	void laptop_io_completion(struct backing_dev_info *info);
1da177e4	120	void laptop_sync_completion(void);
31373d09 MG	121	void laptop_mode_sync(struct work_struct *work);
31373d09 MG	122	void laptop_mode_timer_fn(unsigned long data);
c2c4986e JA	123	#else
	124	static inline void laptop_sync_completion(void) { }
	125	#endif
232ea4d6	126	void throttle_vm_writeout(gfp_t gfp_mask);
1da177e4	127
c42843f2 WF	128	extern unsigned long global_dirty_limit;
c42843f2 WF	129
1da177e4 LT	130	/* These are exported to sysctl. */
1da177e4 LT	131	extern int dirty_background_ratio;
2da02997	132	extern unsigned long dirty_background_bytes;
1da177e4	133	extern int vm_dirty_ratio;
2da02997	134	extern unsigned long vm_dirty_bytes;
704503d8 AD	135	extern unsigned int dirty_writeback_interval;
704503d8 AD	136	extern unsigned int dirty_expire_interval;
195cf453	137	extern int vm_highmem_is_dirtyable;
1da177e4 LT	138	extern int block_dump;
	139	extern int laptop_mode;
	140
3eefae99 SR	141	extern unsigned long determine_dirtyable_memory(void);
3eefae99 SR	142
2da02997	143	extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
8d65af78	144	void __user buffer, size_t lenp,
2da02997 DR	145	loff_t *ppos);
2da02997 DR	146	extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
8d65af78	147	void __user buffer, size_t lenp,
2da02997	148	loff_t *ppos);
04fbfdc1	149	extern int dirty_ratio_handler(struct ctl_table *table, int write,
8d65af78	150	void __user buffer, size_t lenp,
04fbfdc1	151	loff_t *ppos);
2da02997	152	extern int dirty_bytes_handler(struct ctl_table *table, int write,
8d65af78	153	void __user buffer, size_t lenp,
2da02997	154	loff_t *ppos);
04fbfdc1	155
1da177e4	156	struct ctl_table;
8d65af78	157	int dirty_writeback_centisecs_handler(struct ctl_table *, int,
1da177e4 LT	158	void __user , size_t , loff_t *);
1da177e4 LT	159
16c4042f WF	160	void global_dirty_limits(unsigned long pbackground, unsigned long pdirty);
	161	unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
	162	unsigned long dirty);
cf0ca9fe	163
e98be2d5	164	void __bdi_update_bandwidth(struct backing_dev_info *bdi,
c42843f2	165	unsigned long thresh,
af6a3113	166	unsigned long bg_thresh,
c42843f2 WF	167	unsigned long dirty,
	168	unsigned long bdi_thresh,
	169	unsigned long bdi_dirty,
e98be2d5 WF	170	unsigned long start_time);
e98be2d5 WF	171
1da177e4	172	void page_writeback_init(void);
fa5a734e AM	173	void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
	174	unsigned long nr_pages_dirtied);
	175
	176	static inline void
	177	balance_dirty_pages_ratelimited(struct address_space *mapping)
	178	{
	179	balance_dirty_pages_ratelimited_nr(mapping, 1);
	180	}
	181
0ea97180 MS	182	typedef int (writepage_t)(struct page page, struct writeback_control *wbc,
	183	void *data);
	184
0ea97180 MS	185	int generic_writepages(struct address_space *mapping,
0ea97180 MS	186	struct writeback_control *wbc);
5b41d924 ES	187	void tag_pages_for_writeback(struct address_space *mapping,
5b41d924 ES	188	pgoff_t start, pgoff_t end);
0ea97180 MS	189	int write_cache_pages(struct address_space *mapping,
	190	struct writeback_control *wbc, writepage_t writepage,
	191	void *data);
1da177e4	192	int do_writepages(struct address_space mapping, struct writeback_control wbc);
a200ee18	193	void set_page_dirty_balance(struct page *page, int page_mkwrite);
2d1d43f6	194	void writeback_set_ratelimit(void);
92c09c04 NK	195	void tag_pages_for_writeback(struct address_space *mapping,
92c09c04 NK	196	pgoff_t start, pgoff_t end);
1da177e4 LT	197
	198	/* pdflush.c */
	199	extern int nr_pdflush_threads; /* Global so it can be exported to sysctl
	200	read-only. */
	201
	202
	203	#endif /* WRITEBACK_H */