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/fs.h>
9
10DECLARE_PER_CPU(int, dirty_throttle_leaks);
11
12/*
13 * The 1/4 region under the global dirty thresh is for smooth dirty throttling:
14 *
15 * (thresh - thresh/DIRTY_FULL_SCOPE, thresh)
16 *
17 * Further beyond, all dirtier tasks will enter a loop waiting (possibly long
18 * time) for the dirty pages to drop, unless written enough pages.
19 *
20 * The global dirty threshold is normally equal to the global dirty limit,
21 * except when the system suddenly allocates a lot of anonymous memory and
22 * knocks down the global dirty threshold quickly, in which case the global
23 * dirty limit will follow down slowly to prevent livelocking all dirtier tasks.
24 */
25#define DIRTY_SCOPE 8
26#define DIRTY_FULL_SCOPE (DIRTY_SCOPE / 2)
27
28struct backing_dev_info;
29
30/*
31 * fs/fs-writeback.c
32 */
33enum writeback_sync_modes {
34 WB_SYNC_NONE, /* Don't wait on anything */
35 WB_SYNC_ALL, /* Wait on every mapping */
36};
37
38/*
39 * why some writeback work was initiated
40 */
41enum wb_reason {
42 WB_REASON_BACKGROUND,
43 WB_REASON_TRY_TO_FREE_PAGES,
44 WB_REASON_SYNC,
45 WB_REASON_PERIODIC,
46 WB_REASON_LAPTOP_TIMER,
47 WB_REASON_FREE_MORE_MEM,
48 WB_REASON_FS_FREE_SPACE,
49 WB_REASON_FORKER_THREAD,
50
51 WB_REASON_MAX,
52};
53extern const char *wb_reason_name[];
54
55/*
56 * A control structure which tells the writeback code what to do. These are
57 * always on the stack, and hence need no locking. They are always initialised
58 * in a manner such that unspecified fields are set to zero.
59 */
60struct writeback_control {
61 long nr_to_write; /* Write this many pages, and decrement
62 this for each page written */
63 long pages_skipped; /* Pages which were not written */
64
65 /*
66 * For a_ops->writepages(): if start or end are non-zero then this is
67 * a hint that the filesystem need only write out the pages inside that
68 * byterange. The byte at `end' is included in the writeout request.
69 */
70 loff_t range_start;
71 loff_t range_end;
72
73 enum writeback_sync_modes sync_mode;
74
75 unsigned for_kupdate:1; /* A kupdate writeback */
76 unsigned for_background:1; /* A background writeback */
77 unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */
78 unsigned for_reclaim:1; /* Invoked from the page allocator */
79 unsigned range_cyclic:1; /* range_start is cyclic */
80};
81
82/*
83 * fs/fs-writeback.c
84 */
85struct bdi_writeback;
86int inode_wait(void *);
87void writeback_inodes_sb(struct super_block *, enum wb_reason reason);
88void writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
89 enum wb_reason reason);
90int writeback_inodes_sb_if_idle(struct super_block *, enum wb_reason reason);
91int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr,
92 enum wb_reason reason);
93void sync_inodes_sb(struct super_block *);
94long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages,
95 enum wb_reason reason);
96long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
97void wakeup_flusher_threads(long nr_pages, enum wb_reason reason);
98void inode_wait_for_writeback(struct inode *inode);
99
100/* writeback.h requires fs.h; it, too, is not included from here. */
101static inline void wait_on_inode(struct inode *inode)
102{
103 might_sleep();
104 wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
105}
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_nr(struct address_space *mapping,
166 unsigned long nr_pages_dirtied);
167
168static inline void
169balance_dirty_pages_ratelimited(struct address_space *mapping)
170{
171 balance_dirty_pages_ratelimited_nr(mapping, 1);
172}
173
174typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
175 void *data);
176
177int generic_writepages(struct address_space *mapping,
178 struct writeback_control *wbc);
179void tag_pages_for_writeback(struct address_space *mapping,
180 pgoff_t start, pgoff_t end);
181int write_cache_pages(struct address_space *mapping,
182 struct writeback_control *wbc, writepage_t writepage,
183 void *data);
184int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
185void set_page_dirty_balance(struct page *page, int page_mkwrite);
186void writeback_set_ratelimit(void);
187void tag_pages_for_writeback(struct address_space *mapping,
188 pgoff_t start, pgoff_t end);
189
190void account_page_redirty(struct page *page);
191
192/* pdflush.c */
193extern int nr_pdflush_threads; /* Global so it can be exported to sysctl
194 read-only. */
195
196
197#endif /* WRITEBACK_H */