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1/*
2 * include/linux/writeback.h
3 */
4#ifndef WRITEBACK_H
5#define WRITEBACK_H
6
7#include <linux/sched.h>
8#include <linux/fs.h>
9
10struct backing_dev_info;
11
12extern spinlock_t inode_lock;
13extern struct list_head inode_in_use;
14extern struct list_head inode_unused;
15
16/*
17 * Yes, writeback.h requires sched.h
18 * No, sched.h is not included from here.
19 */
20static inline int task_is_pdflush(struct task_struct *task)
21{
22 return task->flags & PF_FLUSHER;
23}
24
25#define current_is_pdflush() task_is_pdflush(current)
26
27/*
28 * fs/fs-writeback.c
29 */
30enum writeback_sync_modes {
31 WB_SYNC_NONE, /* Don't wait on anything */
32 WB_SYNC_ALL, /* Wait on every mapping */
33 WB_SYNC_HOLD, /* Hold the inode on sb_dirty for sys_sync() */
34};
35
36/*
37 * A control structure which tells the writeback code what to do. These are
38 * always on the stack, and hence need no locking. They are always initialised
39 * in a manner such that unspecified fields are set to zero.
40 */
41struct writeback_control {
42 struct backing_dev_info *bdi; /* If !NULL, only write back this
43 queue */
44 enum writeback_sync_modes sync_mode;
45 unsigned long *older_than_this; /* If !NULL, only write back inodes
46 older than this */
47 long nr_to_write; /* Write this many pages, and decrement
48 this for each page written */
49 long pages_skipped; /* Pages which were not written */
50
51 /*
52 * For a_ops->writepages(): is start or end are non-zero then this is
53 * a hint that the filesystem need only write out the pages inside that
54 * byterange. The byte at `end' is included in the writeout request.
55 */
56 loff_t range_start;
57 loff_t range_end;
58
59 unsigned nonblocking:1; /* Don't get stuck on request queues */
60 unsigned encountered_congestion:1; /* An output: a queue is full */
61 unsigned for_kupdate:1; /* A kupdate writeback */
62 unsigned for_reclaim:1; /* Invoked from the page allocator */
63 unsigned for_writepages:1; /* This is a writepages() call */
64 unsigned range_cyclic:1; /* range_start is cyclic */
65 unsigned more_io:1; /* more io to be dispatched */
66 /*
67 * write_cache_pages() won't update wbc->nr_to_write and
68 * mapping->writeback_index if no_nrwrite_index_update
69 * is set. write_cache_pages() may write more than we
70 * requested and we want to make sure nr_to_write and
71 * writeback_index are updated in a consistent manner
72 * so we use a single control to update them
73 */
74 unsigned no_nrwrite_index_update:1;
75};
76
77/*
78 * fs/fs-writeback.c
79 */
80void writeback_inodes(struct writeback_control *wbc);
81int inode_wait(void *);
82void sync_inodes_sb(struct super_block *, int wait);
83void sync_inodes(int wait);
84
85/* writeback.h requires fs.h; it, too, is not included from here. */
86static inline void wait_on_inode(struct inode *inode)
87{
88 might_sleep();
89 wait_on_bit(&inode->i_state, __I_LOCK, inode_wait,
90 TASK_UNINTERRUPTIBLE);
91}
92static inline void inode_sync_wait(struct inode *inode)
93{
94 might_sleep();
95 wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
96 TASK_UNINTERRUPTIBLE);
97}
98
99
100/*
101 * mm/page-writeback.c
102 */
103int wakeup_pdflush(long nr_pages);
104void laptop_io_completion(void);
105void laptop_sync_completion(void);
106void throttle_vm_writeout(gfp_t gfp_mask);
107
108/* These are exported to sysctl. */
109extern int dirty_background_ratio;
110extern int vm_dirty_ratio;
111extern int dirty_writeback_interval;
112extern int dirty_expire_interval;
113extern int vm_highmem_is_dirtyable;
114extern int block_dump;
115extern int laptop_mode;
116
117extern unsigned long determine_dirtyable_memory(void);
118
119extern int dirty_ratio_handler(struct ctl_table *table, int write,
120 struct file *filp, void __user *buffer, size_t *lenp,
121 loff_t *ppos);
122
123struct ctl_table;
124struct file;
125int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,
126 void __user *, size_t *, loff_t *);
127
128void get_dirty_limits(long *pbackground, long *pdirty, long *pbdi_dirty,
129 struct backing_dev_info *bdi);
130
131void page_writeback_init(void);
132void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
133 unsigned long nr_pages_dirtied);
134
135static inline void
136balance_dirty_pages_ratelimited(struct address_space *mapping)
137{
138 balance_dirty_pages_ratelimited_nr(mapping, 1);
139}
140
141typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
142 void *data);
143
144int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
145int generic_writepages(struct address_space *mapping,
146 struct writeback_control *wbc);
147int write_cache_pages(struct address_space *mapping,
148 struct writeback_control *wbc, writepage_t writepage,
149 void *data);
150int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
151int sync_page_range(struct inode *inode, struct address_space *mapping,
152 loff_t pos, loff_t count);
153int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
154 loff_t pos, loff_t count);
155void set_page_dirty_balance(struct page *page, int page_mkwrite);
156void writeback_set_ratelimit(void);
157
158/* pdflush.c */
159extern int nr_pdflush_threads; /* Global so it can be exported to sysctl
160 read-only. */
161
162
163#endif /* WRITEBACK_H */