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 */
task_is_pdflush(struct task_struct * task)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 enum writeback_sync_modes sync_mode;
44 unsigned long *older_than_this; /* If !NULL, only write back inodes
45 older than this */
46 long nr_to_write; /* Write this many pages, and decrement
47 this for each page written */
48 long pages_skipped; /* Pages which were not written */
49
50 /*
51 * For a_ops->writepages(): is start or end are non-zero then this is
52 * a hint that the filesystem need only write out the pages inside that
53 * byterange. The byte at `end' is included in the writeout request.
54 */
55 loff_t range_start;
56 loff_t range_end;
57
58 unsigned nonblocking:1; /* Don't get stuck on request queues */
59 unsigned encountered_congestion:1; /* An output: a queue is full */
60 unsigned for_kupdate:1; /* A kupdate writeback */
61 unsigned for_reclaim:1; /* Invoked from the page allocator */
62 unsigned for_writepages:1; /* This is a writepages() call */
63 unsigned range_cyclic:1; /* range_start is cyclic */
64 unsigned more_io:1; /* more io to be dispatched */
65 /*
66 * write_cache_pages() won't update wbc->nr_to_write and
67 * mapping->writeback_index if no_nrwrite_index_update
68 * is set. write_cache_pages() may write more than we
69 * requested and we want to make sure nr_to_write and
70 * writeback_index are updated in a consistent manner
71 * so we use a single control to update them
72 */
73 unsigned no_nrwrite_index_update:1;
74 };
75
76 /*
77 * fs/fs-writeback.c
78 */
79 void writeback_inodes(struct writeback_control *wbc);
80 int inode_wait(void *);
81 void sync_inodes_sb(struct super_block *, int wait);
82 void sync_inodes(int wait);
83
84 /* writeback.h requires fs.h; it, too, is not included from here. */
wait_on_inode(struct inode * inode)85 static inline void wait_on_inode(struct inode *inode)
86 {
87 might_sleep();
88 wait_on_bit(&inode->i_state, __I_LOCK, inode_wait,
89 TASK_UNINTERRUPTIBLE);
90 }
inode_sync_wait(struct inode * inode)91 static inline void inode_sync_wait(struct inode *inode)
92 {
93 might_sleep();
94 wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
95 TASK_UNINTERRUPTIBLE);
96 }
97
98
99 /*
100 * mm/page-writeback.c
101 */
102 int wakeup_pdflush(long nr_pages);
103 void laptop_io_completion(void);
104 void laptop_sync_completion(void);
105 void throttle_vm_writeout(gfp_t gfp_mask);
106
107 /* These are exported to sysctl. */
108 extern int dirty_background_ratio;
109 extern unsigned long dirty_background_bytes;
110 extern int vm_dirty_ratio;
111 extern unsigned long vm_dirty_bytes;
112 extern int dirty_writeback_interval;
113 extern int dirty_expire_interval;
114 extern int vm_highmem_is_dirtyable;
115 extern int block_dump;
116 extern int laptop_mode;
117
118 extern unsigned long determine_dirtyable_memory(void);
119
120 extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
121 struct file *filp, void __user *buffer, size_t *lenp,
122 loff_t *ppos);
123 extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
124 struct file *filp, void __user *buffer, size_t *lenp,
125 loff_t *ppos);
126 extern int dirty_ratio_handler(struct ctl_table *table, int write,
127 struct file *filp, void __user *buffer, size_t *lenp,
128 loff_t *ppos);
129 extern int dirty_bytes_handler(struct ctl_table *table, int write,
130 struct file *filp, void __user *buffer, size_t *lenp,
131 loff_t *ppos);
132
133 struct ctl_table;
134 struct file;
135 int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,
136 void __user *, size_t *, loff_t *);
137
138 void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
139 unsigned long *pbdi_dirty, struct backing_dev_info *bdi);
140
141 void page_writeback_init(void);
142 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
143 unsigned long nr_pages_dirtied);
144
145 static inline void
balance_dirty_pages_ratelimited(struct address_space * mapping)146 balance_dirty_pages_ratelimited(struct address_space *mapping)
147 {
148 balance_dirty_pages_ratelimited_nr(mapping, 1);
149 }
150
151 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
152 void *data);
153
154 int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
155 int generic_writepages(struct address_space *mapping,
156 struct writeback_control *wbc);
157 int write_cache_pages(struct address_space *mapping,
158 struct writeback_control *wbc, writepage_t writepage,
159 void *data);
160 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
161 int sync_page_range(struct inode *inode, struct address_space *mapping,
162 loff_t pos, loff_t count);
163 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
164 loff_t pos, loff_t count);
165 void set_page_dirty_balance(struct page *page, int page_mkwrite);
166 void writeback_set_ratelimit(void);
167
168 /* pdflush.c */
169 extern int nr_pdflush_threads; /* Global so it can be exported to sysctl
170 read-only. */
171
172
173 #endif /* WRITEBACK_H */
174