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 14 /* 15 * fs/fs-writeback.c 16 */ 17 enum writeback_sync_modes { 18 WB_SYNC_NONE, /* Don't wait on anything */ 19 WB_SYNC_ALL, /* Wait on every mapping */ 20 }; 21 22 /* 23 * A control structure which tells the writeback code what to do. These are 24 * always on the stack, and hence need no locking. They are always initialised 25 * in a manner such that unspecified fields are set to zero. 26 */ 27 struct writeback_control { 28 enum writeback_sync_modes sync_mode; 29 unsigned long *older_than_this; /* If !NULL, only write back inodes 30 older than this */ 31 unsigned long wb_start; /* Time writeback_inodes_wb was 32 called. This is needed to avoid 33 extra jobs and livelock */ 34 long nr_to_write; /* Write this many pages, and decrement 35 this for each page written */ 36 long pages_skipped; /* Pages which were not written */ 37 38 /* 39 * For a_ops->writepages(): is start or end are non-zero then this is 40 * a hint that the filesystem need only write out the pages inside that 41 * byterange. The byte at `end' is included in the writeout request. 42 */ 43 loff_t range_start; 44 loff_t range_end; 45 46 unsigned nonblocking:1; /* Don't get stuck on request queues */ 47 unsigned encountered_congestion:1; /* An output: a queue is full */ 48 unsigned for_kupdate:1; /* A kupdate writeback */ 49 unsigned for_background:1; /* A background writeback */ 50 unsigned for_reclaim:1; /* Invoked from the page allocator */ 51 unsigned range_cyclic:1; /* range_start is cyclic */ 52 unsigned more_io:1; /* more io to be dispatched */ 53 }; 54 55 /* 56 * fs/fs-writeback.c 57 */ 58 struct bdi_writeback; 59 int inode_wait(void *); 60 void writeback_inodes_sb(struct super_block *); 61 int writeback_inodes_sb_if_idle(struct super_block *); 62 void sync_inodes_sb(struct super_block *); 63 void writeback_inodes_wb(struct bdi_writeback *wb, 64 struct writeback_control *wbc); 65 long wb_do_writeback(struct bdi_writeback *wb, int force_wait); 66 void wakeup_flusher_threads(long nr_pages); 67 68 /* writeback.h requires fs.h; it, too, is not included from here. */ 69 static inline void wait_on_inode(struct inode *inode) 70 { 71 might_sleep(); 72 wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE); 73 } 74 static inline void inode_sync_wait(struct inode *inode) 75 { 76 might_sleep(); 77 wait_on_bit(&inode->i_state, __I_SYNC, inode_wait, 78 TASK_UNINTERRUPTIBLE); 79 } 80 81 82 /* 83 * mm/page-writeback.c 84 */ 85 #ifdef CONFIG_BLOCK 86 void laptop_io_completion(struct backing_dev_info *info); 87 void laptop_sync_completion(void); 88 void laptop_mode_sync(struct work_struct *work); 89 void laptop_mode_timer_fn(unsigned long data); 90 #else 91 static inline void laptop_sync_completion(void) { } 92 #endif 93 void throttle_vm_writeout(gfp_t gfp_mask); 94 95 /* These are exported to sysctl. */ 96 extern int dirty_background_ratio; 97 extern unsigned long dirty_background_bytes; 98 extern int vm_dirty_ratio; 99 extern unsigned long vm_dirty_bytes; 100 extern unsigned int dirty_writeback_interval; 101 extern unsigned int dirty_expire_interval; 102 extern int vm_highmem_is_dirtyable; 103 extern int block_dump; 104 extern int laptop_mode; 105 106 extern unsigned long determine_dirtyable_memory(void); 107 108 extern int dirty_background_ratio_handler(struct ctl_table *table, int write, 109 void __user *buffer, size_t *lenp, 110 loff_t *ppos); 111 extern int dirty_background_bytes_handler(struct ctl_table *table, int write, 112 void __user *buffer, size_t *lenp, 113 loff_t *ppos); 114 extern int dirty_ratio_handler(struct ctl_table *table, int write, 115 void __user *buffer, size_t *lenp, 116 loff_t *ppos); 117 extern int dirty_bytes_handler(struct ctl_table *table, int write, 118 void __user *buffer, size_t *lenp, 119 loff_t *ppos); 120 121 struct ctl_table; 122 int dirty_writeback_centisecs_handler(struct ctl_table *, int, 123 void __user *, size_t *, loff_t *); 124 125 void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty); 126 unsigned long bdi_dirty_limit(struct backing_dev_info *bdi, 127 unsigned long dirty); 128 129 void page_writeback_init(void); 130 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping, 131 unsigned long nr_pages_dirtied); 132 133 static inline void 134 balance_dirty_pages_ratelimited(struct address_space *mapping) 135 { 136 balance_dirty_pages_ratelimited_nr(mapping, 1); 137 } 138 139 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc, 140 void *data); 141 142 int generic_writepages(struct address_space *mapping, 143 struct writeback_control *wbc); 144 int write_cache_pages(struct address_space *mapping, 145 struct writeback_control *wbc, writepage_t writepage, 146 void *data); 147 int do_writepages(struct address_space *mapping, struct writeback_control *wbc); 148 void set_page_dirty_balance(struct page *page, int page_mkwrite); 149 void writeback_set_ratelimit(void); 150 void tag_pages_for_writeback(struct address_space *mapping, 151 pgoff_t start, pgoff_t end); 152 153 /* pdflush.c */ 154 extern int nr_pdflush_threads; /* Global so it can be exported to sysctl 155 read-only. */ 156 157 158 #endif /* WRITEBACK_H */ 159