Linux kernel mirror (for testing)
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linux
1/*
2 * include/linux/writeback.h
3 */
4#ifndef WRITEBACK_H
5#define WRITEBACK_H
6
7#include <linux/sched.h>
8#include <linux/workqueue.h>
9#include <linux/fs.h>
10
11DECLARE_PER_CPU(int, dirty_throttle_leaks);
12
13/*
14 * The 1/4 region under the global dirty thresh is for smooth dirty throttling:
15 *
16 * (thresh - thresh/DIRTY_FULL_SCOPE, thresh)
17 *
18 * Further beyond, all dirtier tasks will enter a loop waiting (possibly long
19 * time) for the dirty pages to drop, unless written enough pages.
20 *
21 * The global dirty threshold is normally equal to the global dirty limit,
22 * except when the system suddenly allocates a lot of anonymous memory and
23 * knocks down the global dirty threshold quickly, in which case the global
24 * dirty limit will follow down slowly to prevent livelocking all dirtier tasks.
25 */
26#define DIRTY_SCOPE 8
27#define DIRTY_FULL_SCOPE (DIRTY_SCOPE / 2)
28
29struct backing_dev_info;
30
31/*
32 * fs/fs-writeback.c
33 */
34enum writeback_sync_modes {
35 WB_SYNC_NONE, /* Don't wait on anything */
36 WB_SYNC_ALL, /* Wait on every mapping */
37};
38
39/*
40 * why some writeback work was initiated
41 */
42enum wb_reason {
43 WB_REASON_BACKGROUND,
44 WB_REASON_TRY_TO_FREE_PAGES,
45 WB_REASON_SYNC,
46 WB_REASON_PERIODIC,
47 WB_REASON_LAPTOP_TIMER,
48 WB_REASON_FREE_MORE_MEM,
49 WB_REASON_FS_FREE_SPACE,
50 /*
51 * There is no bdi forker thread any more and works are done
52 * by emergency worker, however, this is TPs userland visible
53 * and we'll be exposing exactly the same information,
54 * so it has a mismatch name.
55 */
56 WB_REASON_FORKER_THREAD,
57
58 WB_REASON_MAX,
59};
60
61/*
62 * A control structure which tells the writeback code what to do. These are
63 * always on the stack, and hence need no locking. They are always initialised
64 * in a manner such that unspecified fields are set to zero.
65 */
66struct writeback_control {
67 long nr_to_write; /* Write this many pages, and decrement
68 this for each page written */
69 long pages_skipped; /* Pages which were not written */
70
71 /*
72 * For a_ops->writepages(): if start or end are non-zero then this is
73 * a hint that the filesystem need only write out the pages inside that
74 * byterange. The byte at `end' is included in the writeout request.
75 */
76 loff_t range_start;
77 loff_t range_end;
78
79 enum writeback_sync_modes sync_mode;
80
81 unsigned for_kupdate:1; /* A kupdate writeback */
82 unsigned for_background:1; /* A background writeback */
83 unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */
84 unsigned for_reclaim:1; /* Invoked from the page allocator */
85 unsigned range_cyclic:1; /* range_start is cyclic */
86 unsigned for_sync:1; /* sync(2) WB_SYNC_ALL writeback */
87};
88
89/*
90 * fs/fs-writeback.c
91 */
92struct bdi_writeback;
93int inode_wait(void *);
94void writeback_inodes_sb(struct super_block *, enum wb_reason reason);
95void writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
96 enum wb_reason reason);
97int try_to_writeback_inodes_sb(struct super_block *, enum wb_reason reason);
98int try_to_writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
99 enum wb_reason reason);
100void sync_inodes_sb(struct super_block *);
101void wakeup_flusher_threads(long nr_pages, enum wb_reason reason);
102void inode_wait_for_writeback(struct inode *inode);
103
104/* writeback.h requires fs.h; it, too, is not included from here. */
105static inline void wait_on_inode(struct inode *inode)
106{
107 might_sleep();
108 wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
109}
110
111/*
112 * mm/page-writeback.c
113 */
114#ifdef CONFIG_BLOCK
115void laptop_io_completion(struct backing_dev_info *info);
116void laptop_sync_completion(void);
117void laptop_mode_sync(struct work_struct *work);
118void laptop_mode_timer_fn(unsigned long data);
119#else
120static inline void laptop_sync_completion(void) { }
121#endif
122void throttle_vm_writeout(gfp_t gfp_mask);
123bool zone_dirty_ok(struct zone *zone);
124
125extern unsigned long global_dirty_limit;
126
127/* These are exported to sysctl. */
128extern int dirty_background_ratio;
129extern unsigned long dirty_background_bytes;
130extern int vm_dirty_ratio;
131extern unsigned long vm_dirty_bytes;
132extern unsigned int dirty_writeback_interval;
133extern unsigned int dirty_expire_interval;
134extern int vm_highmem_is_dirtyable;
135extern int block_dump;
136extern int laptop_mode;
137
138extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
139 void __user *buffer, size_t *lenp,
140 loff_t *ppos);
141extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
142 void __user *buffer, size_t *lenp,
143 loff_t *ppos);
144extern int dirty_ratio_handler(struct ctl_table *table, int write,
145 void __user *buffer, size_t *lenp,
146 loff_t *ppos);
147extern int dirty_bytes_handler(struct ctl_table *table, int write,
148 void __user *buffer, size_t *lenp,
149 loff_t *ppos);
150
151struct ctl_table;
152int dirty_writeback_centisecs_handler(struct ctl_table *, int,
153 void __user *, size_t *, loff_t *);
154
155void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
156unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
157 unsigned long dirty);
158
159void __bdi_update_bandwidth(struct backing_dev_info *bdi,
160 unsigned long thresh,
161 unsigned long bg_thresh,
162 unsigned long dirty,
163 unsigned long bdi_thresh,
164 unsigned long bdi_dirty,
165 unsigned long start_time);
166
167void page_writeback_init(void);
168void balance_dirty_pages_ratelimited(struct address_space *mapping);
169
170typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
171 void *data);
172
173int generic_writepages(struct address_space *mapping,
174 struct writeback_control *wbc);
175void tag_pages_for_writeback(struct address_space *mapping,
176 pgoff_t start, pgoff_t end);
177int write_cache_pages(struct address_space *mapping,
178 struct writeback_control *wbc, writepage_t writepage,
179 void *data);
180int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
181void set_page_dirty_balance(struct page *page);
182void writeback_set_ratelimit(void);
183void tag_pages_for_writeback(struct address_space *mapping,
184 pgoff_t start, pgoff_t end);
185
186void account_page_redirty(struct page *page);
187
188#endif /* WRITEBACK_H */