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 WB_REASON_FORKER_THREAD,
51
52 WB_REASON_MAX,
53};
54extern const char *wb_reason_name[];
55
56/*
57 * A control structure which tells the writeback code what to do. These are
58 * always on the stack, and hence need no locking. They are always initialised
59 * in a manner such that unspecified fields are set to zero.
60 */
61struct writeback_control {
62 long nr_to_write; /* Write this many pages, and decrement
63 this for each page written */
64 long pages_skipped; /* Pages which were not written */
65
66 /*
67 * For a_ops->writepages(): if start or end are non-zero then this is
68 * a hint that the filesystem need only write out the pages inside that
69 * byterange. The byte at `end' is included in the writeout request.
70 */
71 loff_t range_start;
72 loff_t range_end;
73
74 enum writeback_sync_modes sync_mode;
75
76 unsigned for_kupdate:1; /* A kupdate writeback */
77 unsigned for_background:1; /* A background writeback */
78 unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */
79 unsigned for_reclaim:1; /* Invoked from the page allocator */
80 unsigned range_cyclic:1; /* range_start is cyclic */
81};
82
83/*
84 * fs/fs-writeback.c
85 */
86struct bdi_writeback;
87int inode_wait(void *);
88void writeback_inodes_sb(struct super_block *, enum wb_reason reason);
89void writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
90 enum wb_reason reason);
91int try_to_writeback_inodes_sb(struct super_block *, enum wb_reason reason);
92int try_to_writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
93 enum wb_reason reason);
94void sync_inodes_sb(struct super_block *);
95long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages,
96 enum wb_reason reason);
97long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
98void wakeup_flusher_threads(long nr_pages, enum wb_reason reason);
99void inode_wait_for_writeback(struct inode *inode);
100
101/* writeback.h requires fs.h; it, too, is not included from here. */
102static inline void wait_on_inode(struct inode *inode)
103{
104 might_sleep();
105 wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
106}
107
108/*
109 * mm/page-writeback.c
110 */
111#ifdef CONFIG_BLOCK
112void laptop_io_completion(struct backing_dev_info *info);
113void laptop_sync_completion(void);
114void laptop_mode_sync(struct work_struct *work);
115void laptop_mode_timer_fn(unsigned long data);
116#else
117static inline void laptop_sync_completion(void) { }
118#endif
119void throttle_vm_writeout(gfp_t gfp_mask);
120bool zone_dirty_ok(struct zone *zone);
121
122extern unsigned long global_dirty_limit;
123
124/* These are exported to sysctl. */
125extern int dirty_background_ratio;
126extern unsigned long dirty_background_bytes;
127extern int vm_dirty_ratio;
128extern unsigned long vm_dirty_bytes;
129extern unsigned int dirty_writeback_interval;
130extern unsigned int dirty_expire_interval;
131extern int vm_highmem_is_dirtyable;
132extern int block_dump;
133extern int laptop_mode;
134
135extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
136 void __user *buffer, size_t *lenp,
137 loff_t *ppos);
138extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
139 void __user *buffer, size_t *lenp,
140 loff_t *ppos);
141extern int dirty_ratio_handler(struct ctl_table *table, int write,
142 void __user *buffer, size_t *lenp,
143 loff_t *ppos);
144extern int dirty_bytes_handler(struct ctl_table *table, int write,
145 void __user *buffer, size_t *lenp,
146 loff_t *ppos);
147
148struct ctl_table;
149int dirty_writeback_centisecs_handler(struct ctl_table *, int,
150 void __user *, size_t *, loff_t *);
151
152void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
153unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
154 unsigned long dirty);
155
156void __bdi_update_bandwidth(struct backing_dev_info *bdi,
157 unsigned long thresh,
158 unsigned long bg_thresh,
159 unsigned long dirty,
160 unsigned long bdi_thresh,
161 unsigned long bdi_dirty,
162 unsigned long start_time);
163
164void page_writeback_init(void);
165void balance_dirty_pages_ratelimited(struct address_space *mapping);
166
167typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
168 void *data);
169
170int generic_writepages(struct address_space *mapping,
171 struct writeback_control *wbc);
172void tag_pages_for_writeback(struct address_space *mapping,
173 pgoff_t start, pgoff_t end);
174int write_cache_pages(struct address_space *mapping,
175 struct writeback_control *wbc, writepage_t writepage,
176 void *data);
177int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
178void set_page_dirty_balance(struct page *page, int page_mkwrite);
179void writeback_set_ratelimit(void);
180void tag_pages_for_writeback(struct address_space *mapping,
181 pgoff_t start, pgoff_t end);
182
183void account_page_redirty(struct page *page);
184
185#endif /* WRITEBACK_H */