1/*
2 * include/linux/writeback.h
3 */
4#ifndef WRITEBACK_H
5#define WRITEBACK_H
6
7#include <linux/sched.h>
8
9struct backing_dev_info;
10
11extern spinlock_t inode_lock;
12extern struct list_head inode_in_use;
13extern struct list_head inode_unused;
14
15/*
16 * Yes, writeback.h requires sched.h
17 * No, sched.h is not included from here.
18 */
19static inline int task_is_pdflush(struct task_struct *task)
20{
21	return task->flags & PF_FLUSHER;
22}
23
24#define current_is_pdflush()	task_is_pdflush(current)
25
26/*
27 * fs/fs-writeback.c
28 */
29enum writeback_sync_modes {
30	WB_SYNC_NONE,	/* Don't wait on anything */
31	WB_SYNC_ALL,	/* Wait on every mapping */
32	WB_SYNC_HOLD,	/* Hold the inode on sb_dirty for sys_sync() */
33};
34
35/*
36 * A control structure which tells the writeback code what to do.  These are
37 * always on the stack, and hence need no locking.  They are always initialised
38 * in a manner such that unspecified fields are set to zero.
39 */
40struct writeback_control {
41	struct backing_dev_info *bdi;	/* If !NULL, only write back this
42					   queue */
43	enum writeback_sync_modes sync_mode;
44	unsigned long *older_than_this;	/* If !NULL, only write back inodes
45					   older than this */
46	long nr_to_write;		/* Write this many pages, and decrement
47					   this for each page written */
48	long pages_skipped;		/* Pages which were not written */
49
50	/*
51	 * For a_ops->writepages(): is start or end are non-zero then this is
52	 * a hint that the filesystem need only write out the pages inside that
53	 * byterange.  The byte at `end' is included in the writeout request.
54	 */
55	loff_t range_start;
56	loff_t range_end;
57
58	unsigned nonblocking:1;		/* Don't get stuck on request queues */
59	unsigned encountered_congestion:1; /* An output: a queue is full */
60	unsigned for_kupdate:1;		/* A kupdate writeback */
61	unsigned for_reclaim:1;		/* Invoked from the page allocator */
62	unsigned for_writepages:1;	/* This is a writepages() call */
63	unsigned range_cyclic:1;	/* range_start is cyclic */
64
65	void *fs_private;		/* For use by ->writepages() */
66};
67
68/*
69 * fs/fs-writeback.c
70 */
71void writeback_inodes(struct writeback_control *wbc);
72void wake_up_inode(struct inode *inode);
73int inode_wait(void *);
74void sync_inodes_sb(struct super_block *, int wait);
75void sync_inodes(int wait);
76
77/* writeback.h requires fs.h; it, too, is not included from here. */
78static inline void wait_on_inode(struct inode *inode)
79{
80	might_sleep();
81	wait_on_bit(&inode->i_state, __I_LOCK, inode_wait,
82							TASK_UNINTERRUPTIBLE);
83}
84
85/*
86 * mm/page-writeback.c
87 */
88int wakeup_pdflush(long nr_pages);
89void laptop_io_completion(void);
90void laptop_sync_completion(void);
91void throttle_vm_writeout(gfp_t gfp_mask);
92
93/* These are exported to sysctl. */
94extern int dirty_background_ratio;
95extern int vm_dirty_ratio;
96extern int dirty_writeback_interval;
97extern int dirty_expire_interval;
98extern int block_dump;
99extern int laptop_mode;
100
101struct ctl_table;
102struct file;
103int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,
104				      void __user *, size_t *, loff_t *);
105
106void page_writeback_init(void);
107void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
108					unsigned long nr_pages_dirtied);
109
110static inline void
111balance_dirty_pages_ratelimited(struct address_space *mapping)
112{
113	balance_dirty_pages_ratelimited_nr(mapping, 1);
114}
115
116typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
117				void *data);
118
119int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
120int generic_writepages(struct address_space *mapping,
121		       struct writeback_control *wbc);
122int write_cache_pages(struct address_space *mapping,
123		      struct writeback_control *wbc, writepage_t writepage,
124		      void *data);
125int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
126int sync_page_range(struct inode *inode, struct address_space *mapping,
127			loff_t pos, loff_t count);
128int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
129			   loff_t pos, loff_t count);
130void set_page_dirty_balance(struct page *page);
131void writeback_set_ratelimit(void);
132
133/* pdflush.c */
134extern int nr_pdflush_threads;	/* Global so it can be exported to sysctl
135				   read-only. */
136
137
138#endif		/* WRITEBACK_H */
139