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
11 DECLARE_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
29 struct backing_dev_info;
30
31 /*
32 * fs/fs-writeback.c
33 */
34 enum 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 */
42 enum 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 };
54 extern 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 */
61 struct 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 unsigned for_sync:1; /* sync(2) WB_SYNC_ALL writeback */
82 };
83
84 /*
85 * fs/fs-writeback.c
86 */
87 struct bdi_writeback;
88 int inode_wait(void *);
89 void writeback_inodes_sb(struct super_block *, enum wb_reason reason);
90 void writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
91 enum wb_reason reason);
92 int try_to_writeback_inodes_sb(struct super_block *, enum wb_reason reason);
93 int try_to_writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
94 enum wb_reason reason);
95 void sync_inodes_sb(struct super_block *);
96 long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages,
97 enum wb_reason reason);
98 long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
99 void wakeup_flusher_threads(long nr_pages, enum wb_reason reason);
100 void inode_wait_for_writeback(struct inode *inode);
101
102 /* writeback.h requires fs.h; it, too, is not included from here. */
wait_on_inode(struct inode * inode)103 static inline void wait_on_inode(struct inode *inode)
104 {
105 might_sleep();
106 wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
107 }
108
109 /*
110 * mm/page-writeback.c
111 */
112 #ifdef CONFIG_BLOCK
113 void laptop_io_completion(struct backing_dev_info *info);
114 void laptop_sync_completion(void);
115 void laptop_mode_sync(struct work_struct *work);
116 void laptop_mode_timer_fn(unsigned long data);
117 #else
laptop_sync_completion(void)118 static inline void laptop_sync_completion(void) { }
119 #endif
120 void throttle_vm_writeout(gfp_t gfp_mask);
121 bool zone_dirty_ok(struct zone *zone);
122
123 extern unsigned long global_dirty_limit;
124
125 /* These are exported to sysctl. */
126 extern int dirty_background_ratio;
127 extern unsigned long dirty_background_bytes;
128 extern int vm_dirty_ratio;
129 extern unsigned long vm_dirty_bytes;
130 extern unsigned int dirty_writeback_interval;
131 extern unsigned int dirty_expire_interval;
132 extern int vm_highmem_is_dirtyable;
133 extern int block_dump;
134 extern int laptop_mode;
135
136 extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
137 void __user *buffer, size_t *lenp,
138 loff_t *ppos);
139 extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
140 void __user *buffer, size_t *lenp,
141 loff_t *ppos);
142 extern int dirty_ratio_handler(struct ctl_table *table, int write,
143 void __user *buffer, size_t *lenp,
144 loff_t *ppos);
145 extern int dirty_bytes_handler(struct ctl_table *table, int write,
146 void __user *buffer, size_t *lenp,
147 loff_t *ppos);
148
149 struct ctl_table;
150 int dirty_writeback_centisecs_handler(struct ctl_table *, int,
151 void __user *, size_t *, loff_t *);
152
153 void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
154 unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
155 unsigned long dirty);
156
157 void __bdi_update_bandwidth(struct backing_dev_info *bdi,
158 unsigned long thresh,
159 unsigned long bg_thresh,
160 unsigned long dirty,
161 unsigned long bdi_thresh,
162 unsigned long bdi_dirty,
163 unsigned long start_time);
164
165 void page_writeback_init(void);
166 void balance_dirty_pages_ratelimited(struct address_space *mapping);
167
168 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
169 void *data);
170
171 int generic_writepages(struct address_space *mapping,
172 struct writeback_control *wbc);
173 void tag_pages_for_writeback(struct address_space *mapping,
174 pgoff_t start, pgoff_t end);
175 int write_cache_pages(struct address_space *mapping,
176 struct writeback_control *wbc, writepage_t writepage,
177 void *data);
178 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
179 void set_page_dirty_balance(struct page *page, int page_mkwrite);
180 void writeback_set_ratelimit(void);
181 void tag_pages_for_writeback(struct address_space *mapping,
182 pgoff_t start, pgoff_t end);
183
184 void account_page_redirty(struct page *page);
185
186 #endif /* WRITEBACK_H */
187