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 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
83 /* writeback.h requires fs.h; it, too, is not included from here. */
84 static inline void wait_on_inode(struct inode *inode)
85 {
86 might_sleep();
87 wait_on_bit(&inode->i_state, __I_LOCK, inode_wait,
88 TASK_UNINTERRUPTIBLE);
89 }
90 static inline void inode_sync_wait(struct inode *inode)
91 {
92 might_sleep();
93 wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
94 TASK_UNINTERRUPTIBLE);
95 }
96
97
98 /*
99 * mm/page-writeback.c
100 */
101 int wakeup_pdflush(long nr_pages);
102 void laptop_io_completion(void);
103 void laptop_sync_completion(void);
104 void throttle_vm_writeout(gfp_t gfp_mask);
105
106 /* These are exported to sysctl. */
107 extern int dirty_background_ratio;
108 extern unsigned long dirty_background_bytes;
109 extern int vm_dirty_ratio;
110 extern unsigned long vm_dirty_bytes;
111 extern unsigned int dirty_writeback_interval;
112 extern unsigned int dirty_expire_interval;
113 extern int vm_highmem_is_dirtyable;
114 extern int block_dump;
115 extern int laptop_mode;
116
117 extern unsigned long determine_dirtyable_memory(void);
118
119 extern int dirty_background_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_background_bytes_handler(struct ctl_table *table, int write,
123 struct file *filp, void __user *buffer, size_t *lenp,
124 loff_t *ppos);
125 extern int dirty_ratio_handler(struct ctl_table *table, int write,
126 struct file *filp, void __user *buffer, size_t *lenp,
127 loff_t *ppos);
128 extern int dirty_bytes_handler(struct ctl_table *table, int write,
129 struct file *filp, void __user *buffer, size_t *lenp,
130 loff_t *ppos);
131
132 struct ctl_table;
133 struct file;
134 int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,
135 void __user *, size_t *, loff_t *);
136
137 void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
138 unsigned long *pbdi_dirty, struct backing_dev_info *bdi);
139
140 void page_writeback_init(void);
141 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
142 unsigned long nr_pages_dirtied);
143
144 static inline void
145 balance_dirty_pages_ratelimited(struct address_space *mapping)
146 {
147 balance_dirty_pages_ratelimited_nr(mapping, 1);
148 }
149
150 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
151 void *data);
152
153 int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
154 int generic_writepages(struct address_space *mapping,
155 struct writeback_control *wbc);
156 int write_cache_pages(struct address_space *mapping,
157 struct writeback_control *wbc, writepage_t writepage,
158 void *data);
159 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
160 int sync_page_range(struct inode *inode, struct address_space *mapping,
161 loff_t pos, loff_t count);
162 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
163 loff_t pos, loff_t count);
164 void set_page_dirty_balance(struct page *page, int page_mkwrite);
165 void writeback_set_ratelimit(void);
166
167 /* pdflush.c */
168 extern int nr_pdflush_threads; /* Global so it can be exported to sysctl
169 read-only. */
170
171
172 #endif /* WRITEBACK_H */
173
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