[mirror_ubuntu-artful-kernel.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>
#include <linux/blk_types.h>

struct bio;

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_VMSCAN,
	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
};

static inline int wbc_to_write_flags(struct writeback_control *wbc)
{
	if (wbc->sync_mode == WB_SYNC_ALL)
		return REQ_SYNC;
	else if (wbc->for_kupdate || wbc->for_background)
		return REQ_BACKGROUND;

	return 0;
}

/*
 * 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);
void cgroup_writeback_umount(void);

/**
 * 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) {
		WARN_ON_ONCE(!(inode->i_state & I_CLEAR));
		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)
{
}

static inline void cgroup_writeback_umount(void)
{
}

#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
bool node_dirty_ok(struct pglist_data *pgdat);
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 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);

void sb_mark_inode_writeback(struct inode *inode);
void sb_clear_inode_writeback(struct inode *inode);

#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>
7637241e	12	#include <linux/blk_types.h>
e8edc6e0	13
2f8b5444 CH	14	struct bio;
2f8b5444 CH	15
54848d73 WF	16	DECLARE_PER_CPU(int, dirty_throttle_leaks);
54848d73 WF	17
ffd1f609	18	/*
1a12d8bd WF	19	* The 1/4 region under the global dirty thresh is for smooth dirty throttling:
	20	*
	21	* (thresh - thresh/DIRTY_FULL_SCOPE, thresh)
	22	*
ffd1f609 WF	23	* Further beyond, all dirtier tasks will enter a loop waiting (possibly long
	24	* time) for the dirty pages to drop, unless written enough pages.
	25	*
	26	* The global dirty threshold is normally equal to the global dirty limit,
	27	* except when the system suddenly allocates a lot of anonymous memory and
	28	* knocks down the global dirty threshold quickly, in which case the global
	29	* dirty limit will follow down slowly to prevent livelocking all dirtier tasks.
	30	*/
1a12d8bd WF	31	#define DIRTY_SCOPE 8
1a12d8bd WF	32	#define DIRTY_FULL_SCOPE (DIRTY_SCOPE / 2)
ffd1f609	33
1da177e4 LT	34	struct backing_dev_info;
1da177e4 LT	35
1da177e4 LT	36	/*
	37	* fs/fs-writeback.c
	38	*/
	39	enum writeback_sync_modes {
	40	WB_SYNC_NONE, /* Don't wait on anything */
	41	WB_SYNC_ALL, /* Wait on every mapping */
1da177e4 LT	42	};
1da177e4 LT	43
0e175a18 CW	44	/*
	45	* why some writeback work was initiated
	46	*/
	47	enum wb_reason {
	48	WB_REASON_BACKGROUND,
726d061f	49	WB_REASON_VMSCAN,
0e175a18 CW	50	WB_REASON_SYNC,
	51	WB_REASON_PERIODIC,
	52	WB_REASON_LAPTOP_TIMER,
	53	WB_REASON_FREE_MORE_MEM,
	54	WB_REASON_FS_FREE_SPACE,
fc6df808 WL	55	/*
	56	* There is no bdi forker thread any more and works are done
	57	* by emergency worker, however, this is TPs userland visible
	58	* and we'll be exposing exactly the same information,
	59	* so it has a mismatch name.
	60	*/
0e175a18 CW	61	WB_REASON_FORKER_THREAD,
	62
	63	WB_REASON_MAX,
	64	};
0e175a18	65
1da177e4 LT	66	/*
	67	* A control structure which tells the writeback code what to do. These are
	68	* always on the stack, and hence need no locking. They are always initialised
	69	* in a manner such that unspecified fields are set to zero.
	70	*/
	71	struct writeback_control {
1da177e4 LT	72	long nr_to_write; /* Write this many pages, and decrement
	73	this for each page written */
	74	long pages_skipped; /* Pages which were not written */
	75
	76	/*
95468fd4	77	* For a_ops->writepages(): if start or end are non-zero then this is
1da177e4 LT	78	* a hint that the filesystem need only write out the pages inside that
	79	* byterange. The byte at `end' is included in the writeout request.
	80	*/
111ebb6e OH	81	loff_t range_start;
111ebb6e OH	82	loff_t range_end;
1da177e4	83
4cd9069a RK	84	enum writeback_sync_modes sync_mode;
4cd9069a RK	85
22905f77	86	unsigned for_kupdate:1; /* A kupdate writeback */
b17621fe	87	unsigned for_background:1; /* A background writeback */
6e6938b6	88	unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */
22905f77	89	unsigned for_reclaim:1; /* Invoked from the page allocator */
111ebb6e	90	unsigned range_cyclic:1; /* range_start is cyclic */
7747bd4b	91	unsigned for_sync:1; /* sync(2) WB_SYNC_ALL writeback */
b16b1deb TH	92	#ifdef CONFIG_CGROUP_WRITEBACK
b16b1deb TH	93	struct bdi_writeback wb; / wb this writeback is issued under */
2a814908 TH	94	struct inode inode; / inode being written out */
	95
	96	/* foreign inode detection, see wbc_detach_inode() */
	97	int wb_id; /* current wb id */
	98	int wb_lcand_id; /* last foreign candidate wb id */
	99	int wb_tcand_id; /* this foreign candidate wb id */
	100	size_t wb_bytes; /* bytes written by current wb */
	101	size_t wb_lcand_bytes; /* bytes written by last candidate */
	102	size_t wb_tcand_bytes; /* bytes written by this candidate */
b16b1deb	103	#endif
1da177e4 LT	104	};
1da177e4 LT	105
7637241e JA	106	static inline int wbc_to_write_flags(struct writeback_control *wbc)
	107	{
	108	if (wbc->sync_mode == WB_SYNC_ALL)
	109	return REQ_SYNC;
13edd5e7 JA	110	else if (wbc->for_kupdate \|\| wbc->for_background)
13edd5e7 JA	111	return REQ_BACKGROUND;
7637241e JA	112
	113	return 0;
	114	}
	115
380c27ca TH	116	/*
	117	* A wb_domain represents a domain that wb's (bdi_writeback's) belong to
	118	* and are measured against each other in. There always is one global
	119	* domain, global_wb_domain, that every wb in the system is a member of.
	120	* This allows measuring the relative bandwidth of each wb to distribute
	121	* dirtyable memory accordingly.
	122	*/
	123	struct wb_domain {
dcc25ae7 TH	124	spinlock_t lock;
dcc25ae7 TH	125
380c27ca TH	126	/*
	127	* Scale the writeback cache size proportional to the relative
	128	* writeout speed.
	129	*
	130	* We do this by keeping a floating proportion between BDIs, based
	131	* on page writeback completions [end_page_writeback()]. Those
	132	* devices that write out pages fastest will get the larger share,
	133	* while the slower will get a smaller share.
	134	*
	135	* We use page writeout completions because we are interested in
	136	* getting rid of dirty pages. Having them written out is the
	137	* primary goal.
	138	*
	139	* We introduce a concept of time, a period over which we measure
	140	* these events, because demand can/will vary over time. The length
	141	* of this period itself is measured in page writeback completions.
	142	*/
	143	struct fprop_global completions;
	144	struct timer_list period_timer; /* timer for aging of completions */
	145	unsigned long period_time;
dcc25ae7 TH	146
	147	/*
	148	* The dirtyable memory and dirty threshold could be suddenly
	149	* knocked down by a large amount (eg. on the startup of KVM in a
	150	* swapless system). This may throw the system into deep dirty
	151	* exceeded state and throttle heavy/light dirtiers alike. To
	152	* retain good responsiveness, maintain global_dirty_limit for
	153	* tracking slowly down to the knocked down dirty threshold.
	154	*
	155	* Both fields are protected by ->lock.
	156	*/
	157	unsigned long dirty_limit_tstamp;
	158	unsigned long dirty_limit;
380c27ca TH	159	};
380c27ca TH	160
2529bb3a TH	161	/**
	162	* wb_domain_size_changed - memory available to a wb_domain has changed
	163	* @dom: wb_domain of interest
	164	*
	165	* This function should be called when the amount of memory available to
	166	* @dom has changed. It resets @dom's dirty limit parameters to prevent
	167	* the past values which don't match the current configuration from skewing
	168	* dirty throttling. Without this, when memory size of a wb_domain is
	169	* greatly reduced, the dirty throttling logic may allow too many pages to
	170	* be dirtied leading to consecutive unnecessary OOMs and may get stuck in
	171	* that situation.
	172	*/
	173	static inline void wb_domain_size_changed(struct wb_domain *dom)
	174	{
	175	spin_lock(&dom->lock);
	176	dom->dirty_limit_tstamp = jiffies;
	177	dom->dirty_limit = 0;
	178	spin_unlock(&dom->lock);
	179	}
	180
1da177e4 LT	181	/*
	182	* fs/fs-writeback.c
	183	*/
03ba3782	184	struct bdi_writeback;
0e175a18 CW	185	void writeback_inodes_sb(struct super_block *, enum wb_reason reason);
	186	void writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
	187	enum wb_reason reason);
f30a7d0c TH	188	bool try_to_writeback_inodes_sb(struct super_block *, enum wb_reason reason);
	189	bool try_to_writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
	190	enum wb_reason reason);
0dc83bd3	191	void sync_inodes_sb(struct super_block *);
0e175a18	192	void wakeup_flusher_threads(long nr_pages, enum wb_reason reason);
169ebd90	193	void inode_wait_for_writeback(struct inode *inode);
1da177e4 LT	194
	195	/* writeback.h requires fs.h; it, too, is not included from here. */
	196	static inline void wait_on_inode(struct inode *inode)
	197	{
	198	might_sleep();
74316201	199	wait_on_bit(&inode->i_state, __I_NEW, TASK_UNINTERRUPTIBLE);
1da177e4	200	}
1c0eeaf5	201
21c6321f TH	202	#ifdef CONFIG_CGROUP_WRITEBACK
21c6321f TH	203
b16b1deb TH	204	#include <linux/cgroup.h>
	205	#include <linux/bio.h>
	206
21c6321f	207	void __inode_attach_wb(struct inode inode, struct page page);
b16b1deb TH	208	void wbc_attach_and_unlock_inode(struct writeback_control *wbc,
	209	struct inode *inode)
	210	__releases(&inode->i_lock);
	211	void wbc_detach_inode(struct writeback_control *wbc);
2a814908 TH	212	void wbc_account_io(struct writeback_control wbc, struct page page,
2a814908 TH	213	size_t bytes);
a1a0e23e	214	void cgroup_writeback_umount(void);
21c6321f TH	215
	216	/**
	217	* inode_attach_wb - associate an inode with its wb
	218	* @inode: inode of interest
	219	* @page: page being dirtied (may be NULL)
	220	*
	221	* If @inode doesn't have its wb, associate it with the wb matching the
	222	* memcg of @page or, if @page is NULL, %current. May be called w/ or w/o
	223	* @inode->i_lock.
	224	*/
	225	static inline void inode_attach_wb(struct inode inode, struct page page)
	226	{
	227	if (!inode->i_wb)
	228	__inode_attach_wb(inode, page);
	229	}
	230
	231	/**
	232	* inode_detach_wb - disassociate an inode from its wb
	233	* @inode: inode of interest
	234	*
	235	* @inode is being freed. Detach from its wb.
	236	*/
	237	static inline void inode_detach_wb(struct inode *inode)
	238	{
	239	if (inode->i_wb) {
f759741d	240	WARN_ON_ONCE(!(inode->i_state & I_CLEAR));
21c6321f TH	241	wb_put(inode->i_wb);
	242	inode->i_wb = NULL;
	243	}
	244	}
	245
b16b1deb TH	246	/**
	247	* wbc_attach_fdatawrite_inode - associate wbc and inode for fdatawrite
	248	* @wbc: writeback_control of interest
	249	* @inode: target inode
	250	*
	251	* This function is to be used by __filemap_fdatawrite_range(), which is an
	252	* alternative entry point into writeback code, and first ensures @inode is
	253	* associated with a bdi_writeback and attaches it to @wbc.
	254	*/
	255	static inline void wbc_attach_fdatawrite_inode(struct writeback_control *wbc,
	256	struct inode *inode)
	257	{
	258	spin_lock(&inode->i_lock);
	259	inode_attach_wb(inode, NULL);
	260	wbc_attach_and_unlock_inode(wbc, inode);
	261	}
	262
	263	/**
	264	* wbc_init_bio - writeback specific initializtion of bio
	265	* @wbc: writeback_control for the writeback in progress
	266	* @bio: bio to be initialized
	267	*
	268	* @bio is a part of the writeback in progress controlled by @wbc. Perform
	269	* writeback specific initialization. This is used to apply the cgroup
	270	* writeback context.
	271	*/
	272	static inline void wbc_init_bio(struct writeback_control wbc, struct bio bio)
	273	{
	274	/*
	275	* pageout() path doesn't attach @wbc to the inode being written
	276	* out. This is intentional as we don't want the function to block
	277	* behind a slow cgroup. Ultimately, we want pageout() to kick off
	278	* regular writeback instead of writing things out itself.
	279	*/
	280	if (wbc->wb)
	281	bio_associate_blkcg(bio, wbc->wb->blkcg_css);
	282	}
	283
21c6321f TH	284	#else /* CONFIG_CGROUP_WRITEBACK */
	285
	286	static inline void inode_attach_wb(struct inode inode, struct page page)
	287	{
	288	}
	289
	290	static inline void inode_detach_wb(struct inode *inode)
	291	{
	292	}
	293
b16b1deb TH	294	static inline void wbc_attach_and_unlock_inode(struct writeback_control *wbc,
	295	struct inode *inode)
	296	__releases(&inode->i_lock)
	297	{
	298	spin_unlock(&inode->i_lock);
	299	}
	300
	301	static inline void wbc_attach_fdatawrite_inode(struct writeback_control *wbc,
	302	struct inode *inode)
	303	{
	304	}
	305
	306	static inline void wbc_detach_inode(struct writeback_control *wbc)
	307	{
	308	}
	309
	310	static inline void wbc_init_bio(struct writeback_control wbc, struct bio bio)
	311	{
	312	}
	313
2a814908 TH	314	static inline void wbc_account_io(struct writeback_control *wbc,
	315	struct page *page, size_t bytes)
	316	{
	317	}
	318
a1a0e23e TH	319	static inline void cgroup_writeback_umount(void)
	320	{
	321	}
	322
21c6321f TH	323	#endif /* CONFIG_CGROUP_WRITEBACK */
21c6321f TH	324
1da177e4 LT	325	/*
	326	* mm/page-writeback.c
	327	*/
c2c4986e	328	#ifdef CONFIG_BLOCK
31373d09	329	void laptop_io_completion(struct backing_dev_info *info);
1da177e4	330	void laptop_sync_completion(void);
31373d09 MG	331	void laptop_mode_sync(struct work_struct *work);
31373d09 MG	332	void laptop_mode_timer_fn(unsigned long data);
c2c4986e JA	333	#else
	334	static inline void laptop_sync_completion(void) { }
	335	#endif
281e3726	336	bool node_dirty_ok(struct pglist_data *pgdat);
380c27ca	337	int wb_domain_init(struct wb_domain *dom, gfp_t gfp);
841710aa TH	338	#ifdef CONFIG_CGROUP_WRITEBACK
	339	void wb_domain_exit(struct wb_domain *dom);
	340	#endif
1da177e4	341
dcc25ae7	342	extern struct wb_domain global_wb_domain;
c42843f2	343
1da177e4 LT	344	/* These are exported to sysctl. */
1da177e4 LT	345	extern int dirty_background_ratio;
2da02997	346	extern unsigned long dirty_background_bytes;
1da177e4	347	extern int vm_dirty_ratio;
2da02997	348	extern unsigned long vm_dirty_bytes;
704503d8 AD	349	extern unsigned int dirty_writeback_interval;
704503d8 AD	350	extern unsigned int dirty_expire_interval;
1efff914	351	extern unsigned int dirtytime_expire_interval;
195cf453	352	extern int vm_highmem_is_dirtyable;
1da177e4 LT	353	extern int block_dump;
	354	extern int laptop_mode;
	355
2da02997	356	extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
8d65af78	357	void __user buffer, size_t lenp,
2da02997 DR	358	loff_t *ppos);
2da02997 DR	359	extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
8d65af78	360	void __user buffer, size_t lenp,
2da02997	361	loff_t *ppos);
04fbfdc1	362	extern int dirty_ratio_handler(struct ctl_table *table, int write,
8d65af78	363	void __user buffer, size_t lenp,
04fbfdc1	364	loff_t *ppos);
2da02997	365	extern int dirty_bytes_handler(struct ctl_table *table, int write,
8d65af78	366	void __user buffer, size_t lenp,
2da02997	367	loff_t *ppos);
1efff914 TT	368	int dirtytime_interval_handler(struct ctl_table *table, int write,
1efff914 TT	369	void __user buffer, size_t lenp, loff_t *ppos);
04fbfdc1	370
1da177e4	371	struct ctl_table;
8d65af78	372	int dirty_writeback_centisecs_handler(struct ctl_table *, int,
1da177e4 LT	373	void __user , size_t , loff_t *);
1da177e4 LT	374
16c4042f	375	void global_dirty_limits(unsigned long pbackground, unsigned long pdirty);
0d960a38	376	unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh);
a88a341a	377
8a731799	378	void wb_update_bandwidth(struct bdi_writeback *wb, unsigned long start_time);
d0e1d66b	379	void balance_dirty_pages_ratelimited(struct address_space *mapping);
aa661bbe	380	bool wb_over_bg_thresh(struct bdi_writeback *wb);
fa5a734e	381
0ea97180 MS	382	typedef int (writepage_t)(struct page page, struct writeback_control *wbc,
	383	void *data);
	384
0ea97180 MS	385	int generic_writepages(struct address_space *mapping,
0ea97180 MS	386	struct writeback_control *wbc);
5b41d924 ES	387	void tag_pages_for_writeback(struct address_space *mapping,
5b41d924 ES	388	pgoff_t start, pgoff_t end);
0ea97180 MS	389	int write_cache_pages(struct address_space *mapping,
	390	struct writeback_control *wbc, writepage_t writepage,
	391	void *data);
1da177e4	392	int do_writepages(struct address_space mapping, struct writeback_control wbc);
2d1d43f6	393	void writeback_set_ratelimit(void);
92c09c04 NK	394	void tag_pages_for_writeback(struct address_space *mapping,
92c09c04 NK	395	pgoff_t start, pgoff_t end);
1da177e4	396
2f800fbd WF	397	void account_page_redirty(struct page *page);
2f800fbd WF	398
6c60d2b5 DC	399	void sb_mark_inode_writeback(struct inode *inode);
	400	void sb_clear_inode_writeback(struct inode *inode);
	401
1da177e4	402	#endif /* WRITEBACK_H */