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 try_to_writeback_inodes_sb(struct super_block *, enum wb_reason reason);
91int try_to_writeback_inodes_sb_nr(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 * mm/page-writeback.c
109 */
110#ifdef CONFIG_BLOCK
111void laptop_io_completion(struct backing_dev_info *info);
112void laptop_sync_completion(void);
113void laptop_mode_sync(struct work_struct *work);
114void laptop_mode_timer_fn(unsigned long data);
115#else
116static inline void laptop_sync_completion(void) { }
117#endif
118void throttle_vm_writeout(gfp_t gfp_mask);
119bool zone_dirty_ok(struct zone *zone);
120
121extern unsigned long global_dirty_limit;
122
123/* These are exported to sysctl. */
124extern int dirty_background_ratio;
125extern unsigned long dirty_background_bytes;
126extern int vm_dirty_ratio;
127extern unsigned long vm_dirty_bytes;
128extern unsigned int dirty_writeback_interval;
129extern unsigned int dirty_expire_interval;
130extern int vm_highmem_is_dirtyable;
131extern int block_dump;
132extern int laptop_mode;
133
134extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
135 void __user *buffer, size_t *lenp,
136 loff_t *ppos);
137extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
138 void __user *buffer, size_t *lenp,
139 loff_t *ppos);
140extern int dirty_ratio_handler(struct ctl_table *table, int write,
141 void __user *buffer, size_t *lenp,
142 loff_t *ppos);
143extern int dirty_bytes_handler(struct ctl_table *table, int write,
144 void __user *buffer, size_t *lenp,
145 loff_t *ppos);
146
147struct ctl_table;
148int dirty_writeback_centisecs_handler(struct ctl_table *, int,
149 void __user *, size_t *, loff_t *);
150
151void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
152unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
153 unsigned long dirty);
154
155void __bdi_update_bandwidth(struct backing_dev_info *bdi,
156 unsigned long thresh,
157 unsigned long bg_thresh,
158 unsigned long dirty,
159 unsigned long bdi_thresh,
160 unsigned long bdi_dirty,
161 unsigned long start_time);
162
163void page_writeback_init(void);
164void balance_dirty_pages_ratelimited(struct address_space *mapping);
165
166typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
167 void *data);
168
169int generic_writepages(struct address_space *mapping,
170 struct writeback_control *wbc);
171void tag_pages_for_writeback(struct address_space *mapping,
172 pgoff_t start, pgoff_t end);
173int write_cache_pages(struct address_space *mapping,
174 struct writeback_control *wbc, writepage_t writepage,
175 void *data);
176int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
177void set_page_dirty_balance(struct page *page, int page_mkwrite);
178void writeback_set_ratelimit(void);
179void tag_pages_for_writeback(struct address_space *mapping,
180 pgoff_t start, pgoff_t end);
181
182void account_page_redirty(struct page *page);
183
184#endif /* WRITEBACK_H */