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 * fs/fs-writeback.c 18 */ 19 enum writeback_sync_modes { 20 WB_SYNC_NONE, /* Don't wait on anything */ 21 WB_SYNC_ALL, /* Wait on every mapping */ 22 }; 23 24 /* 25 * A control structure which tells the writeback code what to do. These are 26 * always on the stack, and hence need no locking. They are always initialised 27 * in a manner such that unspecified fields are set to zero. 28 */ 29 struct writeback_control { 30 struct backing_dev_info *bdi; /* If !NULL, only write back this 31 queue */ 32 struct super_block *sb; /* if !NULL, only write inodes from 33 this super_block */ 34 enum writeback_sync_modes sync_mode; 35 unsigned long *older_than_this; /* If !NULL, only write back inodes 36 older than this */ 37 long nr_to_write; /* Write this many pages, and decrement 38 this for each page written */ 39 long pages_skipped; /* Pages which were not written */ 40 41 /* 42 * For a_ops->writepages(): is start or end are non-zero then this is 43 * a hint that the filesystem need only write out the pages inside that 44 * byterange. The byte at `end' is included in the writeout request. 45 */ 46 loff_t range_start; 47 loff_t range_end; 48 49 unsigned nonblocking:1; /* Don't get stuck on request queues */ 50 unsigned encountered_congestion:1; /* An output: a queue is full */ 51 unsigned for_kupdate:1; /* A kupdate writeback */ 52 unsigned for_background:1; /* A background writeback */ 53 unsigned for_reclaim:1; /* Invoked from the page allocator */ 54 unsigned range_cyclic:1; /* range_start is cyclic */ 55 unsigned more_io:1; /* more io to be dispatched */ 56 /* 57 * write_cache_pages() won't update wbc->nr_to_write and 58 * mapping->writeback_index if no_nrwrite_index_update 59 * is set. write_cache_pages() may write more than we 60 * requested and we want to make sure nr_to_write and 61 * writeback_index are updated in a consistent manner 62 * so we use a single control to update them 63 */ 64 unsigned no_nrwrite_index_update:1; 65 }; 66 67 /* 68 * fs/fs-writeback.c 69 */ 70 struct bdi_writeback; 71 int inode_wait(void *); 72 void writeback_inodes_sb(struct super_block *); 73 void sync_inodes_sb(struct super_block *); 74 void writeback_inodes_wbc(struct writeback_control *wbc); 75 long wb_do_writeback(struct bdi_writeback *wb, int force_wait); 76 void wakeup_flusher_threads(long nr_pages); 77 78 /* writeback.h requires fs.h; it, too, is not included from here. */ 79 static inline void wait_on_inode(struct inode *inode) 80 { 81 might_sleep(); 82 wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE); 83 } 84 static inline void inode_sync_wait(struct inode *inode) 85 { 86 might_sleep(); 87 wait_on_bit(&inode->i_state, __I_SYNC, inode_wait, 88 TASK_UNINTERRUPTIBLE); 89 } 90 91 92 /* 93 * mm/page-writeback.c 94 */ 95 void laptop_io_completion(void); 96 void laptop_sync_completion(void); 97 void throttle_vm_writeout(gfp_t gfp_mask); 98 99 /* These are exported to sysctl. */ 100 extern int dirty_background_ratio; 101 extern unsigned long dirty_background_bytes; 102 extern int vm_dirty_ratio; 103 extern unsigned long vm_dirty_bytes; 104 extern unsigned int dirty_writeback_interval; 105 extern unsigned int dirty_expire_interval; 106 extern int vm_highmem_is_dirtyable; 107 extern int block_dump; 108 extern int laptop_mode; 109 110 extern unsigned long determine_dirtyable_memory(void); 111 112 extern int dirty_background_ratio_handler(struct ctl_table *table, int write, 113 void __user *buffer, size_t *lenp, 114 loff_t *ppos); 115 extern int dirty_background_bytes_handler(struct ctl_table *table, int write, 116 void __user *buffer, size_t *lenp, 117 loff_t *ppos); 118 extern int dirty_ratio_handler(struct ctl_table *table, int write, 119 void __user *buffer, size_t *lenp, 120 loff_t *ppos); 121 extern int dirty_bytes_handler(struct ctl_table *table, int write, 122 void __user *buffer, size_t *lenp, 123 loff_t *ppos); 124 125 struct ctl_table; 126 int dirty_writeback_centisecs_handler(struct ctl_table *, int, 127 void __user *, size_t *, loff_t *); 128 129 void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty, 130 unsigned long *pbdi_dirty, struct backing_dev_info *bdi); 131 132 void page_writeback_init(void); 133 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping, 134 unsigned long nr_pages_dirtied); 135 136 static inline void 137 balance_dirty_pages_ratelimited(struct address_space *mapping) 138 { 139 balance_dirty_pages_ratelimited_nr(mapping, 1); 140 } 141 142 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc, 143 void *data); 144 145 int generic_writepages(struct address_space *mapping, 146 struct writeback_control *wbc); 147 int write_cache_pages(struct address_space *mapping, 148 struct writeback_control *wbc, writepage_t writepage, 149 void *data); 150 int do_writepages(struct address_space *mapping, struct writeback_control *wbc); 151 void set_page_dirty_balance(struct page *page, int page_mkwrite); 152 void writeback_set_ratelimit(void); 153 154 /* pdflush.c */ 155 extern int nr_pdflush_threads; /* Global so it can be exported to sysctl 156 read-only. */ 157 158 159 #endif /* WRITEBACK_H */ 160