writeback: pay attention to wbc->nr_to_write in write_cache_pages
[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         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
61 /*
62  * fs/fs-writeback.c
63  */     
64 struct bdi_writeback;
65 int inode_wait(void *);
66 void writeback_inodes_sb(struct super_block *);
67 int writeback_inodes_sb_if_idle(struct super_block *);
68 void sync_inodes_sb(struct super_block *);
69 void writeback_inodes_wbc(struct writeback_control *wbc);
70 long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
71 void wakeup_flusher_threads(long nr_pages);
72
73 /* writeback.h requires fs.h; it, too, is not included from here. */
74 static inline void wait_on_inode(struct inode *inode)
75 {
76         might_sleep();
77         wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
78 }
79 static inline void inode_sync_wait(struct inode *inode)
80 {
81         might_sleep();
82         wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
83                                                         TASK_UNINTERRUPTIBLE);
84 }
85
86
87 /*
88  * mm/page-writeback.c
89  */
90 #ifdef CONFIG_BLOCK
91 void laptop_io_completion(struct backing_dev_info *info);
92 void laptop_sync_completion(void);
93 void laptop_mode_sync(struct work_struct *work);
94 void laptop_mode_timer_fn(unsigned long data);
95 #else
96 static inline void laptop_sync_completion(void) { }
97 #endif
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                 void __user *buffer, size_t *lenp,
115                 loff_t *ppos);
116 extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
117                 void __user *buffer, size_t *lenp,
118                 loff_t *ppos);
119 extern int dirty_ratio_handler(struct ctl_table *table, int write,
120                 void __user *buffer, size_t *lenp,
121                 loff_t *ppos);
122 extern int dirty_bytes_handler(struct ctl_table *table, int write,
123                 void __user *buffer, size_t *lenp,
124                 loff_t *ppos);
125
126 struct ctl_table;
127 int dirty_writeback_centisecs_handler(struct ctl_table *, int,
128                                       void __user *, size_t *, loff_t *);
129
130 void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
131                       unsigned long *pbdi_dirty, struct backing_dev_info *bdi);
132
133 void page_writeback_init(void);
134 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
135                                         unsigned long nr_pages_dirtied);
136
137 static inline void
138 balance_dirty_pages_ratelimited(struct address_space *mapping)
139 {
140         balance_dirty_pages_ratelimited_nr(mapping, 1);
141 }
142
143 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
144                                 void *data);
145
146 int generic_writepages(struct address_space *mapping,
147                        struct writeback_control *wbc);
148 int write_cache_pages(struct address_space *mapping,
149                       struct writeback_control *wbc, writepage_t writepage,
150                       void *data);
151 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
152 void set_page_dirty_balance(struct page *page, int page_mkwrite);
153 void writeback_set_ratelimit(void);
154
155 /* pdflush.c */
156 extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
157                                    read-only. */
158
159
160 #endif          /* WRITEBACK_H */