writeback: introduce writeback_control.more_io to indicate more io
[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         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 void wake_up_inode(struct inode *inode);
73 int inode_wait(void *);
74 void sync_inodes_sb(struct super_block *, int wait);
75 void sync_inodes(int wait);
76
77 /* writeback.h requires fs.h; it, too, is not included from here. */
78 static inline void wait_on_inode(struct inode *inode)
79 {
80         might_sleep();
81         wait_on_bit(&inode->i_state, __I_LOCK, inode_wait,
82                                                         TASK_UNINTERRUPTIBLE);
83 }
84
85 /*
86  * mm/page-writeback.c
87  */
88 int wakeup_pdflush(long nr_pages);
89 void laptop_io_completion(void);
90 void laptop_sync_completion(void);
91 void throttle_vm_writeout(gfp_t gfp_mask);
92
93 /* These are exported to sysctl. */
94 extern int dirty_background_ratio;
95 extern int vm_dirty_ratio;
96 extern int dirty_writeback_interval;
97 extern int dirty_expire_interval;
98 extern int block_dump;
99 extern int laptop_mode;
100
101 extern int dirty_ratio_handler(struct ctl_table *table, int write,
102                 struct file *filp, void __user *buffer, size_t *lenp,
103                 loff_t *ppos);
104
105 struct ctl_table;
106 struct file;
107 int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,
108                                       void __user *, size_t *, loff_t *);
109
110 void page_writeback_init(void);
111 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
112                                         unsigned long nr_pages_dirtied);
113
114 static inline void
115 balance_dirty_pages_ratelimited(struct address_space *mapping)
116 {
117         balance_dirty_pages_ratelimited_nr(mapping, 1);
118 }
119
120 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
121                                 void *data);
122
123 int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
124 int generic_writepages(struct address_space *mapping,
125                        struct writeback_control *wbc);
126 int write_cache_pages(struct address_space *mapping,
127                       struct writeback_control *wbc, writepage_t writepage,
128                       void *data);
129 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
130 int sync_page_range(struct inode *inode, struct address_space *mapping,
131                         loff_t pos, loff_t count);
132 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
133                            loff_t pos, loff_t count);
134 void set_page_dirty_balance(struct page *page, int page_mkwrite);
135 void writeback_set_ratelimit(void);
136
137 /* pdflush.c */
138 extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
139                                    read-only. */
140
141
142 #endif          /* WRITEBACK_H */