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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
10struct backing_dev_info;
11
12extern spinlock_t inode_lock;
13extern struct list_head inode_in_use;
14extern struct list_head inode_unused;
15
16/*
17 * fs/fs-writeback.c
18 */
19enum writeback_sync_modes {
20 WB_SYNC_NONE, /* Don't wait on anything */
21 WB_SYNC_ALL, /* Wait on every mapping */
22};
23
24/*
25 * A control structure which tells the writeback code what to do. These are
26 * always on the stack, and hence need no locking. They are always initialised
27 * in a manner such that unspecified fields are set to zero.
28 */
29struct writeback_control {
30 struct backing_dev_info *bdi; /* If !NULL, only write back this
31 queue */
32 struct super_block *sb; /* if !NULL, only write inodes from
33 this super_block */
34 enum writeback_sync_modes sync_mode;
35 unsigned long *older_than_this; /* If !NULL, only write back inodes
36 older than this */
37 unsigned long wb_start; /* Time writeback_inodes_wb was
38 called. This is needed to avoid
39 extra jobs and livelock */
40 long nr_to_write; /* Write this many pages, and decrement
41 this for each page written */
42 long pages_skipped; /* Pages which were not written */
43
44 /*
45 * For a_ops->writepages(): is start or end are non-zero then this is
46 * a hint that the filesystem need only write out the pages inside that
47 * byterange. The byte at `end' is included in the writeout request.
48 */
49 loff_t range_start;
50 loff_t range_end;
51
52 unsigned nonblocking:1; /* Don't get stuck on request queues */
53 unsigned encountered_congestion:1; /* An output: a queue is full */
54 unsigned for_kupdate:1; /* A kupdate writeback */
55 unsigned for_background:1; /* A background writeback */
56 unsigned for_reclaim:1; /* Invoked from the page allocator */
57 unsigned range_cyclic:1; /* range_start is cyclic */
58 unsigned more_io:1; /* more io to be dispatched */
59 /*
60 * write_cache_pages() won't update wbc->nr_to_write and
61 * mapping->writeback_index if no_nrwrite_index_update
62 * is set. write_cache_pages() may write more than we
63 * requested and we want to make sure nr_to_write and
64 * writeback_index are updated in a consistent manner
65 * so we use a single control to update them
66 */
67 unsigned no_nrwrite_index_update:1;
68
69 /*
70 * For WB_SYNC_ALL, the sb must always be pinned. For WB_SYNC_NONE,
71 * the writeback code will pin the sb for the caller. However,
72 * for eg umount, the caller does WB_SYNC_NONE but already has
73 * the sb pinned. If the below is set, caller already has the
74 * sb pinned.
75 */
76 unsigned sb_pinned:1;
77};
78
79/*
80 * fs/fs-writeback.c
81 */
82struct bdi_writeback;
83int inode_wait(void *);
84void writeback_inodes_sb(struct super_block *);
85void writeback_inodes_sb_locked(struct super_block *);
86int writeback_inodes_sb_if_idle(struct super_block *);
87void sync_inodes_sb(struct super_block *);
88void writeback_inodes_wbc(struct writeback_control *wbc);
89long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
90void wakeup_flusher_threads(long nr_pages);
91
92/* writeback.h requires fs.h; it, too, is not included from here. */
93static inline void wait_on_inode(struct inode *inode)
94{
95 might_sleep();
96 wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
97}
98static inline void inode_sync_wait(struct inode *inode)
99{
100 might_sleep();
101 wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
102 TASK_UNINTERRUPTIBLE);
103}
104
105
106/*
107 * mm/page-writeback.c
108 */
109#ifdef CONFIG_BLOCK
110void laptop_io_completion(struct backing_dev_info *info);
111void laptop_sync_completion(void);
112void laptop_mode_sync(struct work_struct *work);
113void laptop_mode_timer_fn(unsigned long data);
114#else
115static inline void laptop_sync_completion(void) { }
116#endif
117void throttle_vm_writeout(gfp_t gfp_mask);
118
119/* These are exported to sysctl. */
120extern int dirty_background_ratio;
121extern unsigned long dirty_background_bytes;
122extern int vm_dirty_ratio;
123extern unsigned long vm_dirty_bytes;
124extern unsigned int dirty_writeback_interval;
125extern unsigned int dirty_expire_interval;
126extern int vm_highmem_is_dirtyable;
127extern int block_dump;
128extern int laptop_mode;
129
130extern unsigned long determine_dirtyable_memory(void);
131
132extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
133 void __user *buffer, size_t *lenp,
134 loff_t *ppos);
135extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
136 void __user *buffer, size_t *lenp,
137 loff_t *ppos);
138extern int dirty_ratio_handler(struct ctl_table *table, int write,
139 void __user *buffer, size_t *lenp,
140 loff_t *ppos);
141extern int dirty_bytes_handler(struct ctl_table *table, int write,
142 void __user *buffer, size_t *lenp,
143 loff_t *ppos);
144
145struct ctl_table;
146int dirty_writeback_centisecs_handler(struct ctl_table *, int,
147 void __user *, size_t *, loff_t *);
148
149void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
150 unsigned long *pbdi_dirty, struct backing_dev_info *bdi);
151
152void page_writeback_init(void);
153void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
154 unsigned long nr_pages_dirtied);
155
156static inline void
157balance_dirty_pages_ratelimited(struct address_space *mapping)
158{
159 balance_dirty_pages_ratelimited_nr(mapping, 1);
160}
161
162typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
163 void *data);
164
165int generic_writepages(struct address_space *mapping,
166 struct writeback_control *wbc);
167int write_cache_pages(struct address_space *mapping,
168 struct writeback_control *wbc, writepage_t writepage,
169 void *data);
170int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
171void set_page_dirty_balance(struct page *page, int page_mkwrite);
172void writeback_set_ratelimit(void);
173
174/* pdflush.c */
175extern int nr_pdflush_threads; /* Global so it can be exported to sysctl
176 read-only. */
177
178
179#endif /* WRITEBACK_H */