78b1e4684cc958387c6133dfc302a7e2eee804eb
[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  * fs/fs-writeback.c
18  */
19 enum 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  */
29 struct 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         long nr_to_write;               /* Write this many pages, and decrement
38                                            this for each page written */
39         long pages_skipped;             /* Pages which were not written */
40
41         /*
42          * For a_ops->writepages(): is start or end are non-zero then this is
43          * a hint that the filesystem need only write out the pages inside that
44          * byterange.  The byte at `end' is included in the writeout request.
45          */
46         loff_t range_start;
47         loff_t range_end;
48
49         unsigned nonblocking:1;         /* Don't get stuck on request queues */
50         unsigned encountered_congestion:1; /* An output: a queue is full */
51         unsigned for_kupdate:1;         /* A kupdate writeback */
52         unsigned for_reclaim:1;         /* Invoked from the page allocator */
53         unsigned for_writepages:1;      /* This is a writepages() call */
54         unsigned range_cyclic:1;        /* range_start is cyclic */
55         unsigned more_io:1;             /* more io to be dispatched */
56         /*
57          * write_cache_pages() won't update wbc->nr_to_write and
58          * mapping->writeback_index if no_nrwrite_index_update
59          * is set.  write_cache_pages() may write more than we
60          * requested and we want to make sure nr_to_write and
61          * writeback_index are updated in a consistent manner
62          * so we use a single control to update them
63          */
64         unsigned no_nrwrite_index_update:1;
65 };
66
67 /*
68  * fs/fs-writeback.c
69  */     
70 struct bdi_writeback;
71 int inode_wait(void *);
72 long writeback_inodes_sb(struct super_block *);
73 long sync_inodes_sb(struct super_block *);
74 void writeback_inodes_wbc(struct writeback_control *wbc);
75 long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
76 void wakeup_flusher_threads(long nr_pages);
77
78 /* writeback.h requires fs.h; it, too, is not included from here. */
79 static inline void wait_on_inode(struct inode *inode)
80 {
81         might_sleep();
82         wait_on_bit(&inode->i_state, __I_LOCK, inode_wait,
83                                                         TASK_UNINTERRUPTIBLE);
84 }
85 static inline void inode_sync_wait(struct inode *inode)
86 {
87         might_sleep();
88         wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
89                                                         TASK_UNINTERRUPTIBLE);
90 }
91
92
93 /*
94  * mm/page-writeback.c
95  */
96 void laptop_io_completion(void);
97 void laptop_sync_completion(void);
98 void throttle_vm_writeout(gfp_t gfp_mask);
99
100 /* These are exported to sysctl. */
101 extern int dirty_background_ratio;
102 extern unsigned long dirty_background_bytes;
103 extern int vm_dirty_ratio;
104 extern unsigned long vm_dirty_bytes;
105 extern unsigned int dirty_writeback_interval;
106 extern unsigned int dirty_expire_interval;
107 extern int vm_highmem_is_dirtyable;
108 extern int block_dump;
109 extern int laptop_mode;
110
111 extern unsigned long determine_dirtyable_memory(void);
112
113 extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
114                 struct file *filp, void __user *buffer, size_t *lenp,
115                 loff_t *ppos);
116 extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
117                 struct file *filp, void __user *buffer, size_t *lenp,
118                 loff_t *ppos);
119 extern int dirty_ratio_handler(struct ctl_table *table, int write,
120                 struct file *filp, void __user *buffer, size_t *lenp,
121                 loff_t *ppos);
122 extern int dirty_bytes_handler(struct ctl_table *table, int write,
123                 struct file *filp, void __user *buffer, size_t *lenp,
124                 loff_t *ppos);
125
126 struct ctl_table;
127 struct file;
128 int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,
129                                       void __user *, size_t *, loff_t *);
130
131 void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
132                       unsigned long *pbdi_dirty, struct backing_dev_info *bdi);
133
134 void page_writeback_init(void);
135 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
136                                         unsigned long nr_pages_dirtied);
137
138 static inline void
139 balance_dirty_pages_ratelimited(struct address_space *mapping)
140 {
141         balance_dirty_pages_ratelimited_nr(mapping, 1);
142 }
143
144 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
145                                 void *data);
146
147 int generic_writepages(struct address_space *mapping,
148                        struct writeback_control *wbc);
149 int write_cache_pages(struct address_space *mapping,
150                       struct writeback_control *wbc, writepage_t writepage,
151                       void *data);
152 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
153 int sync_page_range(struct inode *inode, struct address_space *mapping,
154                         loff_t pos, loff_t count);
155 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
156                            loff_t pos, loff_t count);
157 void set_page_dirty_balance(struct page *page, int page_mkwrite);
158 void writeback_set_ratelimit(void);
159
160 /* pdflush.c */
161 extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
162                                    read-only. */
163
164
165 #endif          /* WRITEBACK_H */