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 unsigned long wb_start; /* Time writeback_inodes_wb was 38 called. This is needed to avoid 39 extra jobs and livelock */ 40 long nr_to_write; /* Write this many pages, and decrement 41 this for each page written */ 42 long pages_skipped; /* Pages which were not written */ 43 44 /* 45 * For a_ops->writepages(): is start or end are non-zero then this is 46 * a hint that the filesystem need only write out the pages inside that 47 * byterange. The byte at `end' is included in the writeout request. 48 */ 49 loff_t range_start; 50 loff_t range_end; 51 52 unsigned nonblocking:1; /* Don't get stuck on request queues */ 53 unsigned encountered_congestion:1; /* An output: a queue is full */ 54 unsigned for_kupdate:1; /* A kupdate writeback */ 55 unsigned for_background:1; /* A background writeback */ 56 unsigned for_reclaim:1; /* Invoked from the page allocator */ 57 unsigned range_cyclic:1; /* range_start is cyclic */ 58 unsigned more_io:1; /* more io to be dispatched */ 59 /* 60 * write_cache_pages() won't update wbc->nr_to_write and 61 * mapping->writeback_index if no_nrwrite_index_update 62 * is set. write_cache_pages() may write more than we 63 * requested and we want to make sure nr_to_write and 64 * writeback_index are updated in a consistent manner 65 * so we use a single control to update them 66 */ 67 unsigned no_nrwrite_index_update:1; 68 69 /* 70 * For WB_SYNC_ALL, the sb must always be pinned. For WB_SYNC_NONE, 71 * the writeback code will pin the sb for the caller. However, 72 * for eg umount, the caller does WB_SYNC_NONE but already has 73 * the sb pinned. If the below is set, caller already has the 74 * sb pinned. 75 */ 76 unsigned sb_pinned:1; 77 }; 78 79 /* 80 * fs/fs-writeback.c 81 */ 82 struct bdi_writeback; 83 int inode_wait(void *); 84 void writeback_inodes_sb(struct super_block *); 85 void writeback_inodes_sb_locked(struct super_block *); 86 int writeback_inodes_sb_if_idle(struct super_block *); 87 void sync_inodes_sb(struct super_block *); 88 void writeback_inodes_wbc(struct writeback_control *wbc); 89 long wb_do_writeback(struct bdi_writeback *wb, int force_wait); 90 void wakeup_flusher_threads(long nr_pages); 91 92 /* writeback.h requires fs.h; it, too, is not included from here. */ 93 static inline void wait_on_inode(struct inode *inode) 94 { 95 might_sleep(); 96 wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE); 97 } 98 static inline void inode_sync_wait(struct inode *inode) 99 { 100 might_sleep(); 101 wait_on_bit(&inode->i_state, __I_SYNC, inode_wait, 102 TASK_UNINTERRUPTIBLE); 103 } 104 105 106 /* 107 * mm/page-writeback.c 108 */ 109 #ifdef CONFIG_BLOCK 110 void laptop_io_completion(struct backing_dev_info *info); 111 void laptop_sync_completion(void); 112 void laptop_mode_sync(struct work_struct *work); 113 void laptop_mode_timer_fn(unsigned long data); 114 #else 115 static inline void laptop_sync_completion(void) { } 116 #endif 117 void throttle_vm_writeout(gfp_t gfp_mask); 118 119 /* These are exported to sysctl. */ 120 extern int dirty_background_ratio; 121 extern unsigned long dirty_background_bytes; 122 extern int vm_dirty_ratio; 123 extern unsigned long vm_dirty_bytes; 124 extern unsigned int dirty_writeback_interval; 125 extern unsigned int dirty_expire_interval; 126 extern int vm_highmem_is_dirtyable; 127 extern int block_dump; 128 extern int laptop_mode; 129 130 extern unsigned long determine_dirtyable_memory(void); 131 132 extern int dirty_background_ratio_handler(struct ctl_table *table, int write, 133 void __user *buffer, size_t *lenp, 134 loff_t *ppos); 135 extern int dirty_background_bytes_handler(struct ctl_table *table, int write, 136 void __user *buffer, size_t *lenp, 137 loff_t *ppos); 138 extern int dirty_ratio_handler(struct ctl_table *table, int write, 139 void __user *buffer, size_t *lenp, 140 loff_t *ppos); 141 extern int dirty_bytes_handler(struct ctl_table *table, int write, 142 void __user *buffer, size_t *lenp, 143 loff_t *ppos); 144 145 struct ctl_table; 146 int dirty_writeback_centisecs_handler(struct ctl_table *, int, 147 void __user *, size_t *, loff_t *); 148 149 void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty, 150 unsigned long *pbdi_dirty, struct backing_dev_info *bdi); 151 152 void page_writeback_init(void); 153 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping, 154 unsigned long nr_pages_dirtied); 155 156 static inline void 157 balance_dirty_pages_ratelimited(struct address_space *mapping) 158 { 159 balance_dirty_pages_ratelimited_nr(mapping, 1); 160 } 161 162 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc, 163 void *data); 164 165 int generic_writepages(struct address_space *mapping, 166 struct writeback_control *wbc); 167 int write_cache_pages(struct address_space *mapping, 168 struct writeback_control *wbc, writepage_t writepage, 169 void *data); 170 int do_writepages(struct address_space *mapping, struct writeback_control *wbc); 171 void set_page_dirty_balance(struct page *page, int page_mkwrite); 172 void writeback_set_ratelimit(void); 173 174 /* pdflush.c */ 175 extern int nr_pdflush_threads; /* Global so it can be exported to sysctl 176 read-only. */ 177 178 179 #endif /* WRITEBACK_H */ 180