2 * include/linux/writeback.h
7 #include <linux/sched.h>
8 #include <linux/workqueue.h>
11 DECLARE_PER_CPU(int, dirty_throttle_leaks
);
14 * The 1/4 region under the global dirty thresh is for smooth dirty throttling:
16 * (thresh - thresh/DIRTY_FULL_SCOPE, thresh)
18 * Further beyond, all dirtier tasks will enter a loop waiting (possibly long
19 * time) for the dirty pages to drop, unless written enough pages.
21 * The global dirty threshold is normally equal to the global dirty limit,
22 * except when the system suddenly allocates a lot of anonymous memory and
23 * knocks down the global dirty threshold quickly, in which case the global
24 * dirty limit will follow down slowly to prevent livelocking all dirtier tasks.
27 #define DIRTY_FULL_SCOPE (DIRTY_SCOPE / 2)
29 struct backing_dev_info
;
34 enum writeback_sync_modes
{
35 WB_SYNC_NONE
, /* Don't wait on anything */
36 WB_SYNC_ALL
, /* Wait on every mapping */
40 * why some writeback work was initiated
44 WB_REASON_TRY_TO_FREE_PAGES
,
47 WB_REASON_LAPTOP_TIMER
,
48 WB_REASON_FREE_MORE_MEM
,
49 WB_REASON_FS_FREE_SPACE
,
51 * There is no bdi forker thread any more and works are done
52 * by emergency worker, however, this is TPs userland visible
53 * and we'll be exposing exactly the same information,
54 * so it has a mismatch name.
56 WB_REASON_FORKER_THREAD
,
62 * A control structure which tells the writeback code what to do. These are
63 * always on the stack, and hence need no locking. They are always initialised
64 * in a manner such that unspecified fields are set to zero.
66 struct writeback_control
{
67 long nr_to_write
; /* Write this many pages, and decrement
68 this for each page written */
69 long pages_skipped
; /* Pages which were not written */
72 * For a_ops->writepages(): if start or end are non-zero then this is
73 * a hint that the filesystem need only write out the pages inside that
74 * byterange. The byte at `end' is included in the writeout request.
79 enum writeback_sync_modes sync_mode
;
81 unsigned for_kupdate
:1; /* A kupdate writeback */
82 unsigned for_background
:1; /* A background writeback */
83 unsigned tagged_writepages
:1; /* tag-and-write to avoid livelock */
84 unsigned for_reclaim
:1; /* Invoked from the page allocator */
85 unsigned range_cyclic
:1; /* range_start is cyclic */
86 unsigned for_sync
:1; /* sync(2) WB_SYNC_ALL writeback */
93 void writeback_inodes_sb(struct super_block
*, enum wb_reason reason
);
94 void writeback_inodes_sb_nr(struct super_block
*, unsigned long nr
,
95 enum wb_reason reason
);
96 int try_to_writeback_inodes_sb(struct super_block
*, enum wb_reason reason
);
97 int try_to_writeback_inodes_sb_nr(struct super_block
*, unsigned long nr
,
98 enum wb_reason reason
);
99 void sync_inodes_sb(struct super_block
*);
100 void wakeup_flusher_threads(long nr_pages
, enum wb_reason reason
);
101 void inode_wait_for_writeback(struct inode
*inode
);
103 /* writeback.h requires fs.h; it, too, is not included from here. */
104 static inline void wait_on_inode(struct inode
*inode
)
107 wait_on_bit(&inode
->i_state
, __I_NEW
, TASK_UNINTERRUPTIBLE
);
111 * mm/page-writeback.c
114 void laptop_io_completion(struct backing_dev_info
*info
);
115 void laptop_sync_completion(void);
116 void laptop_mode_sync(struct work_struct
*work
);
117 void laptop_mode_timer_fn(unsigned long data
);
119 static inline void laptop_sync_completion(void) { }
121 void throttle_vm_writeout(gfp_t gfp_mask
);
122 bool zone_dirty_ok(struct zone
*zone
);
124 extern unsigned long global_dirty_limit
;
126 /* These are exported to sysctl. */
127 extern int dirty_background_ratio
;
128 extern unsigned long dirty_background_bytes
;
129 extern int vm_dirty_ratio
;
130 extern unsigned long vm_dirty_bytes
;
131 extern unsigned int dirty_writeback_interval
;
132 extern unsigned int dirty_expire_interval
;
133 extern int vm_highmem_is_dirtyable
;
134 extern int block_dump
;
135 extern int laptop_mode
;
137 extern int dirty_background_ratio_handler(struct ctl_table
*table
, int write
,
138 void __user
*buffer
, size_t *lenp
,
140 extern int dirty_background_bytes_handler(struct ctl_table
*table
, int write
,
141 void __user
*buffer
, size_t *lenp
,
143 extern int dirty_ratio_handler(struct ctl_table
*table
, int write
,
144 void __user
*buffer
, size_t *lenp
,
146 extern int dirty_bytes_handler(struct ctl_table
*table
, int write
,
147 void __user
*buffer
, size_t *lenp
,
151 int dirty_writeback_centisecs_handler(struct ctl_table
*, int,
152 void __user
*, size_t *, loff_t
*);
154 void global_dirty_limits(unsigned long *pbackground
, unsigned long *pdirty
);
155 unsigned long bdi_dirty_limit(struct backing_dev_info
*bdi
,
156 unsigned long dirty
);
158 void __bdi_update_bandwidth(struct backing_dev_info
*bdi
,
159 unsigned long thresh
,
160 unsigned long bg_thresh
,
162 unsigned long bdi_thresh
,
163 unsigned long bdi_dirty
,
164 unsigned long start_time
);
166 void page_writeback_init(void);
167 void balance_dirty_pages_ratelimited(struct address_space
*mapping
);
169 typedef int (*writepage_t
)(struct page
*page
, struct writeback_control
*wbc
,
172 int generic_writepages(struct address_space
*mapping
,
173 struct writeback_control
*wbc
);
174 void tag_pages_for_writeback(struct address_space
*mapping
,
175 pgoff_t start
, pgoff_t end
);
176 int write_cache_pages(struct address_space
*mapping
,
177 struct writeback_control
*wbc
, writepage_t writepage
,
179 int do_writepages(struct address_space
*mapping
, struct writeback_control
*wbc
);
180 void writeback_set_ratelimit(void);
181 void tag_pages_for_writeback(struct address_space
*mapping
,
182 pgoff_t start
, pgoff_t end
);
184 void account_page_redirty(struct page
*page
);
186 #endif /* WRITEBACK_H */