cef75527a14c9bf50bb94c010e5394533022123d
[linux-2.6.git] / include / linux / writeback.h
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 };
34
35 /*
36  * A control structure which tells the writeback code what to do.  These are
37  * always on the stack, and hence need no locking.  They are always initialised
38  * in a manner such that unspecified fields are set to zero.
39  */
40 struct writeback_control {
41         struct backing_dev_info *bdi;   /* If !NULL, only write back this
42                                            queue */
43         struct super_block *sb;         /* if !NULL, only write inodes from
44                                            this super_block */
45         enum writeback_sync_modes sync_mode;
46         unsigned long *older_than_this; /* If !NULL, only write back inodes
47                                            older than this */
48         long nr_to_write;               /* Write this many pages, and decrement
49                                            this for each page written */
50         long pages_skipped;             /* Pages which were not written */
51
52         /*
53          * For a_ops->writepages(): is start or end are non-zero then this is
54          * a hint that the filesystem need only write out the pages inside that
55          * byterange.  The byte at `end' is included in the writeout request.
56          */
57         loff_t range_start;
58         loff_t range_end;
59
60         unsigned nonblocking:1;         /* Don't get stuck on request queues */
61         unsigned encountered_congestion:1; /* An output: a queue is full */
62         unsigned for_kupdate:1;         /* A kupdate writeback */
63         unsigned for_reclaim:1;         /* Invoked from the page allocator */
64         unsigned for_writepages:1;      /* This is a writepages() call */
65         unsigned range_cyclic:1;        /* range_start is cyclic */
66         unsigned more_io:1;             /* more io to be dispatched */
67         /*
68          * write_cache_pages() won't update wbc->nr_to_write and
69          * mapping->writeback_index if no_nrwrite_index_update
70          * is set.  write_cache_pages() may write more than we
71          * requested and we want to make sure nr_to_write and
72          * writeback_index are updated in a consistent manner
73          * so we use a single control to update them
74          */
75         unsigned no_nrwrite_index_update:1;
76 };
77
78 /*
79  * fs/fs-writeback.c
80  */     
81 struct bdi_writeback;
82 int inode_wait(void *);
83 long writeback_inodes_sb(struct super_block *);
84 long sync_inodes_sb(struct super_block *);
85 void writeback_inodes_wbc(struct writeback_control *wbc);
86 long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
87 void wakeup_flusher_threads(long nr_pages);
88
89 /* writeback.h requires fs.h; it, too, is not included from here. */
90 static inline void wait_on_inode(struct inode *inode)
91 {
92         might_sleep();
93         wait_on_bit(&inode->i_state, __I_LOCK, inode_wait,
94                                                         TASK_UNINTERRUPTIBLE);
95 }
96 static inline void inode_sync_wait(struct inode *inode)
97 {
98         might_sleep();
99         wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
100                                                         TASK_UNINTERRUPTIBLE);
101 }
102
103
104 /*
105  * mm/page-writeback.c
106  */
107 void laptop_io_completion(void);
108 void laptop_sync_completion(void);
109 void throttle_vm_writeout(gfp_t gfp_mask);
110
111 /* These are exported to sysctl. */
112 extern int dirty_background_ratio;
113 extern unsigned long dirty_background_bytes;
114 extern int vm_dirty_ratio;
115 extern unsigned long vm_dirty_bytes;
116 extern unsigned int dirty_writeback_interval;
117 extern unsigned int dirty_expire_interval;
118 extern int vm_highmem_is_dirtyable;
119 extern int block_dump;
120 extern int laptop_mode;
121
122 extern unsigned long determine_dirtyable_memory(void);
123
124 extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
125                 struct file *filp, void __user *buffer, size_t *lenp,
126                 loff_t *ppos);
127 extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
128                 struct file *filp, void __user *buffer, size_t *lenp,
129                 loff_t *ppos);
130 extern int dirty_ratio_handler(struct ctl_table *table, int write,
131                 struct file *filp, void __user *buffer, size_t *lenp,
132                 loff_t *ppos);
133 extern int dirty_bytes_handler(struct ctl_table *table, int write,
134                 struct file *filp, void __user *buffer, size_t *lenp,
135                 loff_t *ppos);
136
137 struct ctl_table;
138 struct file;
139 int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,
140                                       void __user *, size_t *, loff_t *);
141
142 void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
143                       unsigned long *pbdi_dirty, struct backing_dev_info *bdi);
144
145 void page_writeback_init(void);
146 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
147                                         unsigned long nr_pages_dirtied);
148
149 static inline void
150 balance_dirty_pages_ratelimited(struct address_space *mapping)
151 {
152         balance_dirty_pages_ratelimited_nr(mapping, 1);
153 }
154
155 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
156                                 void *data);
157
158 int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
159 int generic_writepages(struct address_space *mapping,
160                        struct writeback_control *wbc);
161 int write_cache_pages(struct address_space *mapping,
162                       struct writeback_control *wbc, writepage_t writepage,
163                       void *data);
164 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
165 int sync_page_range(struct inode *inode, struct address_space *mapping,
166                         loff_t pos, loff_t count);
167 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
168                            loff_t pos, loff_t count);
169 void set_page_dirty_balance(struct page *page, int page_mkwrite);
170 void writeback_set_ratelimit(void);
171
172 /* pdflush.c */
173 extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
174                                    read-only. */
175
176
177 #endif          /* WRITEBACK_H */