Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
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;
93void writeback_inodes_sb(struct super_block *, enum wb_reason reason);
94void writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
95 enum wb_reason reason);
96int try_to_writeback_inodes_sb(struct super_block *, enum wb_reason reason);
97int try_to_writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
98 enum wb_reason reason);
99void sync_inodes_sb(struct super_block *);
100void wakeup_flusher_threads(long nr_pages, enum wb_reason reason);
101void inode_wait_for_writeback(struct inode *inode);
102
103/* writeback.h requires fs.h; it, too, is not included from here. */
104static inline void wait_on_inode(struct inode *inode)
105{
106 might_sleep();
107 wait_on_bit(&inode->i_state, __I_NEW, TASK_UNINTERRUPTIBLE);
108}
109
110/*
111 * mm/page-writeback.c
112 */
113#ifdef CONFIG_BLOCK
114void laptop_io_completion(struct backing_dev_info *info);
115void laptop_sync_completion(void);
116void laptop_mode_sync(struct work_struct *work);
117void laptop_mode_timer_fn(unsigned long data);
118#else
119static inline void laptop_sync_completion(void) { }
120#endif
121void throttle_vm_writeout(gfp_t gfp_mask);
122bool zone_dirty_ok(struct zone *zone);
123
124extern unsigned long global_dirty_limit;
125
126/* These are exported to sysctl. */
127extern int dirty_background_ratio;
128extern unsigned long dirty_background_bytes;
129extern int vm_dirty_ratio;
130extern unsigned long vm_dirty_bytes;
131extern unsigned int dirty_writeback_interval;
132extern unsigned int dirty_expire_interval;
133extern unsigned int dirtytime_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);
150int dirtytime_interval_handler(struct ctl_table *table, int write,
151 void __user *buffer, size_t *lenp, loff_t *ppos);
152
153struct ctl_table;
154int dirty_writeback_centisecs_handler(struct ctl_table *, int,
155 void __user *, size_t *, loff_t *);
156
157void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
158unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
159 unsigned long dirty);
160
161void __bdi_update_bandwidth(struct backing_dev_info *bdi,
162 unsigned long thresh,
163 unsigned long bg_thresh,
164 unsigned long dirty,
165 unsigned long bdi_thresh,
166 unsigned long bdi_dirty,
167 unsigned long start_time);
168
169void page_writeback_init(void);
170void balance_dirty_pages_ratelimited(struct address_space *mapping);
171
172typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
173 void *data);
174
175int generic_writepages(struct address_space *mapping,
176 struct writeback_control *wbc);
177void tag_pages_for_writeback(struct address_space *mapping,
178 pgoff_t start, pgoff_t end);
179int write_cache_pages(struct address_space *mapping,
180 struct writeback_control *wbc, writepage_t writepage,
181 void *data);
182int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
183void writeback_set_ratelimit(void);
184void tag_pages_for_writeback(struct address_space *mapping,
185 pgoff_t start, pgoff_t end);
186
187void account_page_redirty(struct page *page);
188
189#endif /* WRITEBACK_H */