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
10 struct backing_dev_info;
11
12 extern spinlock_t inode_lock;
13 extern struct list_head inode_in_use;
14 extern struct list_head inode_unused;
15
16 /*
17 * Yes, writeback.h requires sched.h
18 * No, sched.h is not included from here.
19 */
20 static inline int task_is_pdflush(struct task_struct *task)
21 {
22 return task->flags & PF_FLUSHER;
23 }
24
25 #define current_is_pdflush() task_is_pdflush(current)
26
27 /*
28 * fs/fs-writeback.c
29 */
30 enum writeback_sync_modes {
31 WB_SYNC_NONE, /* Don't wait on anything */
32 WB_SYNC_ALL, /* Wait on every mapping */
33 WB_SYNC_HOLD, /* Hold the inode on sb_dirty for sys_sync() */
34 };
35
36 /*
37 * A control structure which tells the writeback code what to do. These are
38 * always on the stack, and hence need no locking. They are always initialised
39 * in a manner such that unspecified fields are set to zero.
40 */
41 struct writeback_control {
42 struct backing_dev_info *bdi; /* If !NULL, only write back this
43 queue */
44 enum writeback_sync_modes sync_mode;
45 unsigned long *older_than_this; /* If !NULL, only write back inodes
46 older than this */
47 long nr_to_write; /* Write this many pages, and decrement
48 this for each page written */
49 long pages_skipped; /* Pages which were not written */
50
51 /*
52 * For a_ops->writepages(): is start or end are non-zero then this is
53 * a hint that the filesystem need only write out the pages inside that
54 * byterange. The byte at `end' is included in the writeout request.
55 */
56 loff_t range_start;
57 loff_t range_end;
58
59 unsigned nonblocking:1; /* Don't get stuck on request queues */
60 unsigned encountered_congestion:1; /* An output: a queue is full */
61 unsigned for_kupdate:1; /* A kupdate writeback */
62 unsigned for_reclaim:1; /* Invoked from the page allocator */
63 unsigned for_writepages:1; /* This is a writepages() call */
64 unsigned range_cyclic:1; /* range_start is cyclic */
65 unsigned more_io:1; /* more io to be dispatched */
66 };
67
68 /*
69 * fs/fs-writeback.c
70 */
71 void writeback_inodes(struct writeback_control *wbc);
72 int inode_wait(void *);
73 void sync_inodes_sb(struct super_block *, int wait);
74 void sync_inodes(int wait);
75
76 /* writeback.h requires fs.h; it, too, is not included from here. */
77 static inline void wait_on_inode(struct inode *inode)
78 {
79 might_sleep();
80 wait_on_bit(&inode->i_state, __I_LOCK, inode_wait,
81 TASK_UNINTERRUPTIBLE);
82 }
83 static inline void inode_sync_wait(struct inode *inode)
84 {
85 might_sleep();
86 wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
87 TASK_UNINTERRUPTIBLE);
88 }
89
90
91 /*
92 * mm/page-writeback.c
93 */
94 int wakeup_pdflush(long nr_pages);
95 void laptop_io_completion(void);
96 void laptop_sync_completion(void);
97 void throttle_vm_writeout(gfp_t gfp_mask);
98
99 /* These are exported to sysctl. */
100 extern int dirty_background_ratio;
101 extern int vm_dirty_ratio;
102 extern int dirty_writeback_interval;
103 extern int dirty_expire_interval;
104 extern int vm_highmem_is_dirtyable;
105 extern int block_dump;
106 extern int laptop_mode;
107
108 extern int dirty_ratio_handler(struct ctl_table *table, int write,
109 struct file *filp, void __user *buffer, size_t *lenp,
110 loff_t *ppos);
111
112 struct ctl_table;
113 struct file;
114 int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,
115 void __user *, size_t *, loff_t *);
116
117 void page_writeback_init(void);
118 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
119 unsigned long nr_pages_dirtied);
120
121 static inline void
122 balance_dirty_pages_ratelimited(struct address_space *mapping)
123 {
124 balance_dirty_pages_ratelimited_nr(mapping, 1);
125 }
126
127 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
128 void *data);
129
130 int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
131 int generic_writepages(struct address_space *mapping,
132 struct writeback_control *wbc);
133 int write_cache_pages(struct address_space *mapping,
134 struct writeback_control *wbc, writepage_t writepage,
135 void *data);
136 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
137 int sync_page_range(struct inode *inode, struct address_space *mapping,
138 loff_t pos, loff_t count);
139 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
140 loff_t pos, loff_t count);
141 void set_page_dirty_balance(struct page *page, int page_mkwrite);
142 void writeback_set_ratelimit(void);
143
144 /* pdflush.c */
145 extern int nr_pdflush_threads; /* Global so it can be exported to sysctl
146 read-only. */
147
148
149 #endif /* WRITEBACK_H */
150
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