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 enum writeback_sync_modes sync_mode;
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 unsigned for_kupdate:1; /* A kupdate writeback */
75 unsigned for_background:1; /* A background writeback */
76 unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */
77 unsigned for_reclaim:1; /* Invoked from the page allocator */
78 unsigned range_cyclic:1; /* range_start is cyclic */
79};
80
81/*
82 * fs/fs-writeback.c
83 */
84struct bdi_writeback;
85int inode_wait(void *);
86void writeback_inodes_sb(struct super_block *, enum wb_reason reason);
87void writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
88 enum wb_reason reason);
89int writeback_inodes_sb_if_idle(struct super_block *, enum wb_reason reason);
90int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr,
91 enum wb_reason reason);
92void sync_inodes_sb(struct super_block *);
93long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages,
94 enum wb_reason reason);
95long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
96void wakeup_flusher_threads(long nr_pages, enum wb_reason reason);
97
98/* writeback.h requires fs.h; it, too, is not included from here. */
99static inline void wait_on_inode(struct inode *inode)
100{
101 might_sleep();
102 wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
103}
104static inline void inode_sync_wait(struct inode *inode)
105{
106 might_sleep();
107 wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
108 TASK_UNINTERRUPTIBLE);
109}
110
111
112/*
113 * mm/page-writeback.c
114 */
115#ifdef CONFIG_BLOCK
116void laptop_io_completion(struct backing_dev_info *info);
117void laptop_sync_completion(void);
118void laptop_mode_sync(struct work_struct *work);
119void laptop_mode_timer_fn(unsigned long data);
120#else
121static inline void laptop_sync_completion(void) { }
122#endif
123void throttle_vm_writeout(gfp_t gfp_mask);
124bool zone_dirty_ok(struct zone *zone);
125
126extern unsigned long global_dirty_limit;
127
128/* These are exported to sysctl. */
129extern int dirty_background_ratio;
130extern unsigned long dirty_background_bytes;
131extern int vm_dirty_ratio;
132extern unsigned long vm_dirty_bytes;
133extern unsigned int dirty_writeback_interval;
134extern unsigned int dirty_expire_interval;
135extern int vm_highmem_is_dirtyable;
136extern int block_dump;
137extern int laptop_mode;
138
139extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
140 void __user *buffer, size_t *lenp,
141 loff_t *ppos);
142extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
143 void __user *buffer, size_t *lenp,
144 loff_t *ppos);
145extern int dirty_ratio_handler(struct ctl_table *table, int write,
146 void __user *buffer, size_t *lenp,
147 loff_t *ppos);
148extern int dirty_bytes_handler(struct ctl_table *table, int write,
149 void __user *buffer, size_t *lenp,
150 loff_t *ppos);
151
152struct ctl_table;
153int dirty_writeback_centisecs_handler(struct ctl_table *, int,
154 void __user *, size_t *, loff_t *);
155
156void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
157unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
158 unsigned long dirty);
159
160void __bdi_update_bandwidth(struct backing_dev_info *bdi,
161 unsigned long thresh,
162 unsigned long bg_thresh,
163 unsigned long dirty,
164 unsigned long bdi_thresh,
165 unsigned long bdi_dirty,
166 unsigned long start_time);
167
168void page_writeback_init(void);
169void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
170 unsigned long nr_pages_dirtied);
171
172static inline void
173balance_dirty_pages_ratelimited(struct address_space *mapping)
174{
175 balance_dirty_pages_ratelimited_nr(mapping, 1);
176}
177
178typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
179 void *data);
180
181int generic_writepages(struct address_space *mapping,
182 struct writeback_control *wbc);
183void tag_pages_for_writeback(struct address_space *mapping,
184 pgoff_t start, pgoff_t end);
185int write_cache_pages(struct address_space *mapping,
186 struct writeback_control *wbc, writepage_t writepage,
187 void *data);
188int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
189void set_page_dirty_balance(struct page *page, int page_mkwrite);
190void writeback_set_ratelimit(void);
191void tag_pages_for_writeback(struct address_space *mapping,
192 pgoff_t start, pgoff_t end);
193
194void account_page_redirty(struct page *page);
195
196/* pdflush.c */
197extern int nr_pdflush_threads; /* Global so it can be exported to sysctl
198 read-only. */
199
200
201#endif /* WRITEBACK_H */