2 * include/linux/writeback.h
7 #include <linux/sched.h>
10 DECLARE_PER_CPU(int, dirty_throttle_leaks);
13 * The 1/4 region under the global dirty thresh is for smooth dirty throttling:
15 * (thresh - thresh/DIRTY_FULL_SCOPE, thresh)
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.
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.
26 #define DIRTY_FULL_SCOPE (DIRTY_SCOPE / 2)
28 struct backing_dev_info;
33 enum writeback_sync_modes {
34 WB_SYNC_NONE, /* Don't wait on anything */
35 WB_SYNC_ALL, /* Wait on every mapping */
39 * why some writeback work was initiated
43 WB_REASON_TRY_TO_FREE_PAGES,
46 WB_REASON_LAPTOP_TIMER,
47 WB_REASON_FREE_MORE_MEM,
48 WB_REASON_FS_FREE_SPACE,
49 WB_REASON_FORKER_THREAD,
53 extern const char *wb_reason_name[];
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.
60 struct 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 */
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.
73 enum writeback_sync_modes sync_mode;
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 */
86 int inode_wait(void *);
87 void writeback_inodes_sb(struct super_block *, enum wb_reason reason);
88 void writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
89 enum wb_reason reason);
90 int writeback_inodes_sb_if_idle(struct super_block *, enum wb_reason reason);
91 int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr,
92 enum wb_reason reason);
93 void sync_inodes_sb(struct super_block *);
94 long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages,
95 enum wb_reason reason);
96 long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
97 void wakeup_flusher_threads(long nr_pages, enum wb_reason reason);
99 /* writeback.h requires fs.h; it, too, is not included from here. */
100 static inline void wait_on_inode(struct inode *inode)
103 wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
105 static inline void inode_sync_wait(struct inode *inode)
108 wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
109 TASK_UNINTERRUPTIBLE);
114 * mm/page-writeback.c
117 void laptop_io_completion(struct backing_dev_info *info);
118 void laptop_sync_completion(void);
119 void laptop_mode_sync(struct work_struct *work);
120 void laptop_mode_timer_fn(unsigned long data);
122 static inline void laptop_sync_completion(void) { }
124 void throttle_vm_writeout(gfp_t gfp_mask);
125 bool zone_dirty_ok(struct zone *zone);
127 extern unsigned long global_dirty_limit;
129 /* These are exported to sysctl. */
130 extern int dirty_background_ratio;
131 extern unsigned long dirty_background_bytes;
132 extern int vm_dirty_ratio;
133 extern unsigned long vm_dirty_bytes;
134 extern unsigned int dirty_writeback_interval;
135 extern unsigned int dirty_expire_interval;
136 extern int vm_highmem_is_dirtyable;
137 extern int block_dump;
138 extern int laptop_mode;
140 extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
141 void __user *buffer, size_t *lenp,
143 extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
144 void __user *buffer, size_t *lenp,
146 extern int dirty_ratio_handler(struct ctl_table *table, int write,
147 void __user *buffer, size_t *lenp,
149 extern int dirty_bytes_handler(struct ctl_table *table, int write,
150 void __user *buffer, size_t *lenp,
154 int dirty_writeback_centisecs_handler(struct ctl_table *, int,
155 void __user *, size_t *, loff_t *);
157 void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
158 unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
159 unsigned long dirty);
161 void __bdi_update_bandwidth(struct backing_dev_info *bdi,
162 unsigned long thresh,
163 unsigned long bg_thresh,
165 unsigned long bdi_thresh,
166 unsigned long bdi_dirty,
167 unsigned long start_time);
169 void page_writeback_init(void);
170 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
171 unsigned long nr_pages_dirtied);
174 balance_dirty_pages_ratelimited(struct address_space *mapping)
176 balance_dirty_pages_ratelimited_nr(mapping, 1);
179 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
182 int generic_writepages(struct address_space *mapping,
183 struct writeback_control *wbc);
184 void tag_pages_for_writeback(struct address_space *mapping,
185 pgoff_t start, pgoff_t end);
186 int write_cache_pages(struct address_space *mapping,
187 struct writeback_control *wbc, writepage_t writepage,
189 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
190 void set_page_dirty_balance(struct page *page, int page_mkwrite);
191 void writeback_set_ratelimit(void);
192 void tag_pages_for_writeback(struct address_space *mapping,
193 pgoff_t start, pgoff_t end);
195 void account_page_redirty(struct page *page);
198 extern int nr_pdflush_threads; /* Global so it can be exported to sysctl
202 #endif /* WRITEBACK_H */