[linux-2.6-block.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>
#include <linux/flex_proportions.h>
#include <linux/backing-dev-defs.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 */
#ifdef CONFIG_CGROUP_WRITEBACK
	struct bdi_writeback *wb;	/* wb this writeback is issued under */
	struct inode *inode;		/* inode being written out */

	/* foreign inode detection, see wbc_detach_inode() */
	int wb_id;			/* current wb id */
	int wb_lcand_id;		/* last foreign candidate wb id */
	int wb_tcand_id;		/* this foreign candidate wb id */
	size_t wb_bytes;		/* bytes written by current wb */
	size_t wb_lcand_bytes;		/* bytes written by last candidate */
	size_t wb_tcand_bytes;		/* bytes written by this candidate */
#endif
};

/*
 * A wb_domain represents a domain that wb's (bdi_writeback's) belong to
 * and are measured against each other in.  There always is one global
 * domain, global_wb_domain, that every wb in the system is a member of.
 * This allows measuring the relative bandwidth of each wb to distribute
 * dirtyable memory accordingly.
 */
struct wb_domain {
	spinlock_t lock;

	/*
	 * Scale the writeback cache size proportional to the relative
	 * writeout speed.
	 *
	 * We do this by keeping a floating proportion between BDIs, based
	 * on page writeback completions [end_page_writeback()]. Those
	 * devices that write out pages fastest will get the larger share,
	 * while the slower will get a smaller share.
	 *
	 * We use page writeout completions because we are interested in
	 * getting rid of dirty pages. Having them written out is the
	 * primary goal.
	 *
	 * We introduce a concept of time, a period over which we measure
	 * these events, because demand can/will vary over time. The length
	 * of this period itself is measured in page writeback completions.
	 */
	struct fprop_global completions;
	struct timer_list period_timer;	/* timer for aging of completions */
	unsigned long period_time;

	/*
	 * The dirtyable memory and dirty threshold could be suddenly
	 * knocked down by a large amount (eg. on the startup of KVM in a
	 * swapless system). This may throw the system into deep dirty
	 * exceeded state and throttle heavy/light dirtiers alike. To
	 * retain good responsiveness, maintain global_dirty_limit for
	 * tracking slowly down to the knocked down dirty threshold.
	 *
	 * Both fields are protected by ->lock.
	 */
	unsigned long dirty_limit_tstamp;
	unsigned long dirty_limit;
};

/**
 * wb_domain_size_changed - memory available to a wb_domain has changed
 * @dom: wb_domain of interest
 *
 * This function should be called when the amount of memory available to
 * @dom has changed.  It resets @dom's dirty limit parameters to prevent
 * the past values which don't match the current configuration from skewing
 * dirty throttling.  Without this, when memory size of a wb_domain is
 * greatly reduced, the dirty throttling logic may allow too many pages to
 * be dirtied leading to consecutive unnecessary OOMs and may get stuck in
 * that situation.
 */
static inline void wb_domain_size_changed(struct wb_domain *dom)
{
	spin_lock(&dom->lock);
	dom->dirty_limit_tstamp = jiffies;
	dom->dirty_limit = 0;
	spin_unlock(&dom->lock);
}

/*
 * fs/fs-writeback.c
 */	
struct bdi_writeback;
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);
bool try_to_writeback_inodes_sb(struct super_block *, enum wb_reason reason);
bool 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, TASK_UNINTERRUPTIBLE);
}

#ifdef CONFIG_CGROUP_WRITEBACK

#include <linux/cgroup.h>
#include <linux/bio.h>

void __inode_attach_wb(struct inode *inode, struct page *page);
void wbc_attach_and_unlock_inode(struct writeback_control *wbc,
				 struct inode *inode)
	__releases(&inode->i_lock);
void wbc_detach_inode(struct writeback_control *wbc);
void wbc_account_io(struct writeback_control *wbc, struct page *page,
		    size_t bytes);

/**
 * inode_attach_wb - associate an inode with its wb
 * @inode: inode of interest
 * @page: page being dirtied (may be NULL)
 *
 * If @inode doesn't have its wb, associate it with the wb matching the
 * memcg of @page or, if @page is NULL, %current.  May be called w/ or w/o
 * @inode->i_lock.
 */
static inline void inode_attach_wb(struct inode *inode, struct page *page)
{
	if (!inode->i_wb)
		__inode_attach_wb(inode, page);
}

/**
 * inode_detach_wb - disassociate an inode from its wb
 * @inode: inode of interest
 *
 * @inode is being freed.  Detach from its wb.
 */
static inline void inode_detach_wb(struct inode *inode)
{
	if (inode->i_wb) {
		wb_put(inode->i_wb);
		inode->i_wb = NULL;
	}
}

/**
 * wbc_attach_fdatawrite_inode - associate wbc and inode for fdatawrite
 * @wbc: writeback_control of interest
 * @inode: target inode
 *
 * This function is to be used by __filemap_fdatawrite_range(), which is an
 * alternative entry point into writeback code, and first ensures @inode is
 * associated with a bdi_writeback and attaches it to @wbc.
 */
static inline void wbc_attach_fdatawrite_inode(struct writeback_control *wbc,
					       struct inode *inode)
{
	spin_lock(&inode->i_lock);
	inode_attach_wb(inode, NULL);
	wbc_attach_and_unlock_inode(wbc, inode);
}

/**
 * wbc_init_bio - writeback specific initializtion of bio
 * @wbc: writeback_control for the writeback in progress
 * @bio: bio to be initialized
 *
 * @bio is a part of the writeback in progress controlled by @wbc.  Perform
 * writeback specific initialization.  This is used to apply the cgroup
 * writeback context.
 */
static inline void wbc_init_bio(struct writeback_control *wbc, struct bio *bio)
{
	/*
	 * pageout() path doesn't attach @wbc to the inode being written
	 * out.  This is intentional as we don't want the function to block
	 * behind a slow cgroup.  Ultimately, we want pageout() to kick off
	 * regular writeback instead of writing things out itself.
	 */
	if (wbc->wb)
		bio_associate_blkcg(bio, wbc->wb->blkcg_css);
}

#else	/* CONFIG_CGROUP_WRITEBACK */

static inline void inode_attach_wb(struct inode *inode, struct page *page)
{
}

static inline void inode_detach_wb(struct inode *inode)
{
}

static inline void wbc_attach_and_unlock_inode(struct writeback_control *wbc,
					       struct inode *inode)
	__releases(&inode->i_lock)
{
	spin_unlock(&inode->i_lock);
}

static inline void wbc_attach_fdatawrite_inode(struct writeback_control *wbc,
					       struct inode *inode)
{
}

static inline void wbc_detach_inode(struct writeback_control *wbc)
{
}

static inline void wbc_init_bio(struct writeback_control *wbc, struct bio *bio)
{
}

static inline void wbc_account_io(struct writeback_control *wbc,
				  struct page *page, size_t bytes)
{
}

#endif	/* CONFIG_CGROUP_WRITEBACK */

/*
 * 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);
int wb_domain_init(struct wb_domain *dom, gfp_t gfp);
#ifdef CONFIG_CGROUP_WRITEBACK
void wb_domain_exit(struct wb_domain *dom);
#endif

extern struct wb_domain global_wb_domain;

/* 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 unsigned int dirtytime_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);
int dirtytime_interval_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 wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh);

void wb_update_bandwidth(struct bdi_writeback *wb, unsigned long start_time);
void page_writeback_init(void);
void balance_dirty_pages_ratelimited(struct address_space *mapping);
bool wb_over_bg_thresh(struct bdi_writeback *wb);

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 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
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>
a27bb332	8	#include <linux/workqueue.h>
f5ff8422	9	#include <linux/fs.h>
380c27ca	10	#include <linux/flex_proportions.h>
21c6321f	11	#include <linux/backing-dev-defs.h>
e8edc6e0	12
54848d73 WF	13	DECLARE_PER_CPU(int, dirty_throttle_leaks);
54848d73 WF	14
ffd1f609	15	/*
1a12d8bd WF	16	* The 1/4 region under the global dirty thresh is for smooth dirty throttling:
	17	*
	18	* (thresh - thresh/DIRTY_FULL_SCOPE, thresh)
	19	*
ffd1f609 WF	20	* Further beyond, all dirtier tasks will enter a loop waiting (possibly long
	21	* time) for the dirty pages to drop, unless written enough pages.
	22	*
	23	* The global dirty threshold is normally equal to the global dirty limit,
	24	* except when the system suddenly allocates a lot of anonymous memory and
	25	* knocks down the global dirty threshold quickly, in which case the global
	26	* dirty limit will follow down slowly to prevent livelocking all dirtier tasks.
	27	*/
1a12d8bd WF	28	#define DIRTY_SCOPE 8
1a12d8bd WF	29	#define DIRTY_FULL_SCOPE (DIRTY_SCOPE / 2)
ffd1f609	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,
fc6df808 WL	52	/*
	53	* There is no bdi forker thread any more and works are done
	54	* by emergency worker, however, this is TPs userland visible
	55	* and we'll be exposing exactly the same information,
	56	* so it has a mismatch name.
	57	*/
0e175a18 CW	58	WB_REASON_FORKER_THREAD,
	59
	60	WB_REASON_MAX,
	61	};
0e175a18	62
1da177e4 LT	63	/*
	64	* A control structure which tells the writeback code what to do. These are
	65	* always on the stack, and hence need no locking. They are always initialised
	66	* in a manner such that unspecified fields are set to zero.
	67	*/
	68	struct writeback_control {
1da177e4 LT	69	long nr_to_write; /* Write this many pages, and decrement
	70	this for each page written */
	71	long pages_skipped; /* Pages which were not written */
	72
	73	/*
95468fd4	74	* For a_ops->writepages(): if start or end are non-zero then this is
1da177e4 LT	75	* a hint that the filesystem need only write out the pages inside that
	76	* byterange. The byte at `end' is included in the writeout request.
	77	*/
111ebb6e OH	78	loff_t range_start;
111ebb6e OH	79	loff_t range_end;
1da177e4	80
4cd9069a RK	81	enum writeback_sync_modes sync_mode;
4cd9069a RK	82
22905f77	83	unsigned for_kupdate:1; /* A kupdate writeback */
b17621fe	84	unsigned for_background:1; /* A background writeback */
6e6938b6	85	unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */
22905f77	86	unsigned for_reclaim:1; /* Invoked from the page allocator */
111ebb6e	87	unsigned range_cyclic:1; /* range_start is cyclic */
7747bd4b	88	unsigned for_sync:1; /* sync(2) WB_SYNC_ALL writeback */
b16b1deb TH	89	#ifdef CONFIG_CGROUP_WRITEBACK
b16b1deb TH	90	struct bdi_writeback wb; / wb this writeback is issued under */
2a814908 TH	91	struct inode inode; / inode being written out */
	92
	93	/* foreign inode detection, see wbc_detach_inode() */
	94	int wb_id; /* current wb id */
	95	int wb_lcand_id; /* last foreign candidate wb id */
	96	int wb_tcand_id; /* this foreign candidate wb id */
	97	size_t wb_bytes; /* bytes written by current wb */
	98	size_t wb_lcand_bytes; /* bytes written by last candidate */
	99	size_t wb_tcand_bytes; /* bytes written by this candidate */
b16b1deb	100	#endif
1da177e4 LT	101	};
1da177e4 LT	102
380c27ca TH	103	/*
	104	* A wb_domain represents a domain that wb's (bdi_writeback's) belong to
	105	* and are measured against each other in. There always is one global
	106	* domain, global_wb_domain, that every wb in the system is a member of.
	107	* This allows measuring the relative bandwidth of each wb to distribute
	108	* dirtyable memory accordingly.
	109	*/
	110	struct wb_domain {
dcc25ae7 TH	111	spinlock_t lock;
dcc25ae7 TH	112
380c27ca TH	113	/*
	114	* Scale the writeback cache size proportional to the relative
	115	* writeout speed.
	116	*
	117	* We do this by keeping a floating proportion between BDIs, based
	118	* on page writeback completions [end_page_writeback()]. Those
	119	* devices that write out pages fastest will get the larger share,
	120	* while the slower will get a smaller share.
	121	*
	122	* We use page writeout completions because we are interested in
	123	* getting rid of dirty pages. Having them written out is the
	124	* primary goal.
	125	*
	126	* We introduce a concept of time, a period over which we measure
	127	* these events, because demand can/will vary over time. The length
	128	* of this period itself is measured in page writeback completions.
	129	*/
	130	struct fprop_global completions;
	131	struct timer_list period_timer; /* timer for aging of completions */
	132	unsigned long period_time;
dcc25ae7 TH	133
	134	/*
	135	* The dirtyable memory and dirty threshold could be suddenly
	136	* knocked down by a large amount (eg. on the startup of KVM in a
	137	* swapless system). This may throw the system into deep dirty
	138	* exceeded state and throttle heavy/light dirtiers alike. To
	139	* retain good responsiveness, maintain global_dirty_limit for
	140	* tracking slowly down to the knocked down dirty threshold.
	141	*
	142	* Both fields are protected by ->lock.
	143	*/
	144	unsigned long dirty_limit_tstamp;
	145	unsigned long dirty_limit;
380c27ca TH	146	};
380c27ca TH	147
2529bb3a TH	148	/**
	149	* wb_domain_size_changed - memory available to a wb_domain has changed
	150	* @dom: wb_domain of interest
	151	*
	152	* This function should be called when the amount of memory available to
	153	* @dom has changed. It resets @dom's dirty limit parameters to prevent
	154	* the past values which don't match the current configuration from skewing
	155	* dirty throttling. Without this, when memory size of a wb_domain is
	156	* greatly reduced, the dirty throttling logic may allow too many pages to
	157	* be dirtied leading to consecutive unnecessary OOMs and may get stuck in
	158	* that situation.
	159	*/
	160	static inline void wb_domain_size_changed(struct wb_domain *dom)
	161	{
	162	spin_lock(&dom->lock);
	163	dom->dirty_limit_tstamp = jiffies;
	164	dom->dirty_limit = 0;
	165	spin_unlock(&dom->lock);
	166	}
	167
1da177e4 LT	168	/*
	169	* fs/fs-writeback.c
	170	*/
03ba3782	171	struct bdi_writeback;
0e175a18 CW	172	void writeback_inodes_sb(struct super_block *, enum wb_reason reason);
	173	void writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
	174	enum wb_reason reason);
f30a7d0c TH	175	bool try_to_writeback_inodes_sb(struct super_block *, enum wb_reason reason);
	176	bool try_to_writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
	177	enum wb_reason reason);
0dc83bd3	178	void sync_inodes_sb(struct super_block *);
0e175a18	179	void wakeup_flusher_threads(long nr_pages, enum wb_reason reason);
169ebd90	180	void inode_wait_for_writeback(struct inode *inode);
1da177e4 LT	181
	182	/* writeback.h requires fs.h; it, too, is not included from here. */
	183	static inline void wait_on_inode(struct inode *inode)
	184	{
	185	might_sleep();
74316201	186	wait_on_bit(&inode->i_state, __I_NEW, TASK_UNINTERRUPTIBLE);
1da177e4	187	}
1c0eeaf5	188
21c6321f TH	189	#ifdef CONFIG_CGROUP_WRITEBACK
21c6321f TH	190
b16b1deb TH	191	#include <linux/cgroup.h>
	192	#include <linux/bio.h>
	193
21c6321f	194	void __inode_attach_wb(struct inode inode, struct page page);
b16b1deb TH	195	void wbc_attach_and_unlock_inode(struct writeback_control *wbc,
	196	struct inode *inode)
	197	__releases(&inode->i_lock);
	198	void wbc_detach_inode(struct writeback_control *wbc);
2a814908 TH	199	void wbc_account_io(struct writeback_control wbc, struct page page,
2a814908 TH	200	size_t bytes);
21c6321f TH	201
	202	/**
	203	* inode_attach_wb - associate an inode with its wb
	204	* @inode: inode of interest
	205	* @page: page being dirtied (may be NULL)
	206	*
	207	* If @inode doesn't have its wb, associate it with the wb matching the
	208	* memcg of @page or, if @page is NULL, %current. May be called w/ or w/o
	209	* @inode->i_lock.
	210	*/
	211	static inline void inode_attach_wb(struct inode inode, struct page page)
	212	{
	213	if (!inode->i_wb)
	214	__inode_attach_wb(inode, page);
	215	}
	216
	217	/**
	218	* inode_detach_wb - disassociate an inode from its wb
	219	* @inode: inode of interest
	220	*
	221	* @inode is being freed. Detach from its wb.
	222	*/
	223	static inline void inode_detach_wb(struct inode *inode)
	224	{
	225	if (inode->i_wb) {
	226	wb_put(inode->i_wb);
	227	inode->i_wb = NULL;
	228	}
	229	}
	230
b16b1deb TH	231	/**
	232	* wbc_attach_fdatawrite_inode - associate wbc and inode for fdatawrite
	233	* @wbc: writeback_control of interest
	234	* @inode: target inode
	235	*
	236	* This function is to be used by __filemap_fdatawrite_range(), which is an
	237	* alternative entry point into writeback code, and first ensures @inode is
	238	* associated with a bdi_writeback and attaches it to @wbc.
	239	*/
	240	static inline void wbc_attach_fdatawrite_inode(struct writeback_control *wbc,
	241	struct inode *inode)
	242	{
	243	spin_lock(&inode->i_lock);
	244	inode_attach_wb(inode, NULL);
	245	wbc_attach_and_unlock_inode(wbc, inode);
	246	}
	247
	248	/**
	249	* wbc_init_bio - writeback specific initializtion of bio
	250	* @wbc: writeback_control for the writeback in progress
	251	* @bio: bio to be initialized
	252	*
	253	* @bio is a part of the writeback in progress controlled by @wbc. Perform
	254	* writeback specific initialization. This is used to apply the cgroup
	255	* writeback context.
	256	*/
	257	static inline void wbc_init_bio(struct writeback_control wbc, struct bio bio)
	258	{
	259	/*
	260	* pageout() path doesn't attach @wbc to the inode being written
	261	* out. This is intentional as we don't want the function to block
	262	* behind a slow cgroup. Ultimately, we want pageout() to kick off
	263	* regular writeback instead of writing things out itself.
	264	*/
	265	if (wbc->wb)
	266	bio_associate_blkcg(bio, wbc->wb->blkcg_css);
	267	}
	268
21c6321f TH	269	#else /* CONFIG_CGROUP_WRITEBACK */
	270
	271	static inline void inode_attach_wb(struct inode inode, struct page page)
	272	{
	273	}
	274
	275	static inline void inode_detach_wb(struct inode *inode)
	276	{
	277	}
	278
b16b1deb TH	279	static inline void wbc_attach_and_unlock_inode(struct writeback_control *wbc,
	280	struct inode *inode)
	281	__releases(&inode->i_lock)
	282	{
	283	spin_unlock(&inode->i_lock);
	284	}
	285
	286	static inline void wbc_attach_fdatawrite_inode(struct writeback_control *wbc,
	287	struct inode *inode)
	288	{
	289	}
	290
	291	static inline void wbc_detach_inode(struct writeback_control *wbc)
	292	{
	293	}
	294
	295	static inline void wbc_init_bio(struct writeback_control wbc, struct bio bio)
	296	{
	297	}
	298
2a814908 TH	299	static inline void wbc_account_io(struct writeback_control *wbc,
	300	struct page *page, size_t bytes)
	301	{
	302	}
	303
21c6321f TH	304	#endif /* CONFIG_CGROUP_WRITEBACK */
21c6321f TH	305
1da177e4 LT	306	/*
	307	* mm/page-writeback.c
	308	*/
c2c4986e	309	#ifdef CONFIG_BLOCK
31373d09	310	void laptop_io_completion(struct backing_dev_info *info);
1da177e4	311	void laptop_sync_completion(void);
31373d09 MG	312	void laptop_mode_sync(struct work_struct *work);
31373d09 MG	313	void laptop_mode_timer_fn(unsigned long data);
c2c4986e JA	314	#else
	315	static inline void laptop_sync_completion(void) { }
	316	#endif
232ea4d6	317	void throttle_vm_writeout(gfp_t gfp_mask);
a756cf59	318	bool zone_dirty_ok(struct zone *zone);
380c27ca	319	int wb_domain_init(struct wb_domain *dom, gfp_t gfp);
841710aa TH	320	#ifdef CONFIG_CGROUP_WRITEBACK
	321	void wb_domain_exit(struct wb_domain *dom);
	322	#endif
1da177e4	323
dcc25ae7	324	extern struct wb_domain global_wb_domain;
c42843f2	325
1da177e4 LT	326	/* These are exported to sysctl. */
1da177e4 LT	327	extern int dirty_background_ratio;
2da02997	328	extern unsigned long dirty_background_bytes;
1da177e4	329	extern int vm_dirty_ratio;
2da02997	330	extern unsigned long vm_dirty_bytes;
704503d8 AD	331	extern unsigned int dirty_writeback_interval;
704503d8 AD	332	extern unsigned int dirty_expire_interval;
1efff914	333	extern unsigned int dirtytime_expire_interval;
195cf453	334	extern int vm_highmem_is_dirtyable;
1da177e4 LT	335	extern int block_dump;
	336	extern int laptop_mode;
	337
2da02997	338	extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
8d65af78	339	void __user buffer, size_t lenp,
2da02997 DR	340	loff_t *ppos);
2da02997 DR	341	extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
8d65af78	342	void __user buffer, size_t lenp,
2da02997	343	loff_t *ppos);
04fbfdc1	344	extern int dirty_ratio_handler(struct ctl_table *table, int write,
8d65af78	345	void __user buffer, size_t lenp,
04fbfdc1	346	loff_t *ppos);
2da02997	347	extern int dirty_bytes_handler(struct ctl_table *table, int write,
8d65af78	348	void __user buffer, size_t lenp,
2da02997	349	loff_t *ppos);
1efff914 TT	350	int dirtytime_interval_handler(struct ctl_table *table, int write,
1efff914 TT	351	void __user buffer, size_t lenp, loff_t *ppos);
04fbfdc1	352
1da177e4	353	struct ctl_table;
8d65af78	354	int dirty_writeback_centisecs_handler(struct ctl_table *, int,
1da177e4 LT	355	void __user , size_t , loff_t *);
1da177e4 LT	356
16c4042f	357	void global_dirty_limits(unsigned long pbackground, unsigned long pdirty);
0d960a38	358	unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh);
a88a341a	359
8a731799	360	void wb_update_bandwidth(struct bdi_writeback *wb, unsigned long start_time);
1da177e4	361	void page_writeback_init(void);
d0e1d66b	362	void balance_dirty_pages_ratelimited(struct address_space *mapping);
aa661bbe	363	bool wb_over_bg_thresh(struct bdi_writeback *wb);
fa5a734e	364
0ea97180 MS	365	typedef int (writepage_t)(struct page page, struct writeback_control *wbc,
	366	void *data);
	367
0ea97180 MS	368	int generic_writepages(struct address_space *mapping,
0ea97180 MS	369	struct writeback_control *wbc);
5b41d924 ES	370	void tag_pages_for_writeback(struct address_space *mapping,
5b41d924 ES	371	pgoff_t start, pgoff_t end);
0ea97180 MS	372	int write_cache_pages(struct address_space *mapping,
	373	struct writeback_control *wbc, writepage_t writepage,
	374	void *data);
1da177e4	375	int do_writepages(struct address_space mapping, struct writeback_control wbc);
2d1d43f6	376	void writeback_set_ratelimit(void);
92c09c04 NK	377	void tag_pages_for_writeback(struct address_space *mapping,
92c09c04 NK	378	pgoff_t start, pgoff_t end);
1da177e4	379
2f800fbd WF	380	void account_page_redirty(struct page *page);
2f800fbd WF	381
1da177e4	382	#endif /* WRITEBACK_H */