1 /* 2 * include/linux/writeback.h 3 */ 4 #ifndef WRITEBACK_H 5 #define WRITEBACK_H 6 7 #include <linux/sched.h> 8 #include <linux/workqueue.h> 9 #include <linux/fs.h> 10 11 DECLARE_PER_CPU(int, dirty_throttle_leaks); 12 13 /* 14 * The 1/4 region under the global dirty thresh is for smooth dirty throttling: 15 * 16 * (thresh - thresh/DIRTY_FULL_SCOPE, thresh) 17 * 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. 20 * 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. 25 */ 26 #define DIRTY_SCOPE 8 27 #define DIRTY_FULL_SCOPE (DIRTY_SCOPE / 2) 28 29 struct backing_dev_info; 30 31 /* 32 * fs/fs-writeback.c 33 */ 34 enum writeback_sync_modes { 35 WB_SYNC_NONE, /* Don't wait on anything */ 36 WB_SYNC_ALL, /* Wait on every mapping */ 37 }; 38 39 /* 40 * why some writeback work was initiated 41 */ 42 enum wb_reason { 43 WB_REASON_BACKGROUND, 44 WB_REASON_TRY_TO_FREE_PAGES, 45 WB_REASON_SYNC, 46 WB_REASON_PERIODIC, 47 WB_REASON_LAPTOP_TIMER, 48 WB_REASON_FREE_MORE_MEM, 49 WB_REASON_FS_FREE_SPACE, 50 WB_REASON_FORKER_THREAD, 51 52 WB_REASON_MAX, 53 }; 54 extern const char *wb_reason_name[]; 55 56 /* 57 * A control structure which tells the writeback code what to do. These are 58 * always on the stack, and hence need no locking. They are always initialised 59 * in a manner such that unspecified fields are set to zero. 60 */ 61 struct writeback_control { 62 long nr_to_write; /* Write this many pages, and decrement 63 this for each page written */ 64 long pages_skipped; /* Pages which were not written */ 65 66 /* 67 * For a_ops->writepages(): if start or end are non-zero then this is 68 * a hint that the filesystem need only write out the pages inside that 69 * byterange. The byte at `end' is included in the writeout request. 70 */ 71 loff_t range_start; 72 loff_t range_end; 73 74 enum writeback_sync_modes sync_mode; 75 76 unsigned for_kupdate:1; /* A kupdate writeback */ 77 unsigned for_background:1; /* A background writeback */ 78 unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */ 79 unsigned for_reclaim:1; /* Invoked from the page allocator */ 80 unsigned range_cyclic:1; /* range_start is cyclic */ 81 unsigned for_sync:1; /* sync(2) WB_SYNC_ALL writeback */ 82 }; 83 84 /* 85 * fs/fs-writeback.c 86 */ 87 struct bdi_writeback; 88 int inode_wait(void *); 89 void writeback_inodes_sb(struct super_block *, enum wb_reason reason); 90 void writeback_inodes_sb_nr(struct super_block *, unsigned long nr, 91 enum wb_reason reason); 92 int try_to_writeback_inodes_sb(struct super_block *, enum wb_reason reason); 93 int try_to_writeback_inodes_sb_nr(struct super_block *, unsigned long nr, 94 enum wb_reason reason); 95 void sync_inodes_sb(struct super_block *); 96 long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, 97 enum wb_reason reason); 98 long wb_do_writeback(struct bdi_writeback *wb, int force_wait); 99 void wakeup_flusher_threads(long nr_pages, enum wb_reason reason); 100 void inode_wait_for_writeback(struct inode *inode); 101 102 /* writeback.h requires fs.h; it, too, is not included from here. */ 103 static inline void wait_on_inode(struct inode *inode) 104 { 105 might_sleep(); 106 wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE); 107 } 108 109 /* 110 * mm/page-writeback.c 111 */ 112 #ifdef CONFIG_BLOCK 113 void laptop_io_completion(struct backing_dev_info *info); 114 void laptop_sync_completion(void); 115 void laptop_mode_sync(struct work_struct *work); 116 void laptop_mode_timer_fn(unsigned long data); 117 #else 118 static inline void laptop_sync_completion(void) { } 119 #endif 120 void throttle_vm_writeout(gfp_t gfp_mask); 121 bool zone_dirty_ok(struct zone *zone); 122 123 extern unsigned long global_dirty_limit; 124 125 /* These are exported to sysctl. */ 126 extern int dirty_background_ratio; 127 extern unsigned long dirty_background_bytes; 128 extern int vm_dirty_ratio; 129 extern unsigned long vm_dirty_bytes; 130 extern unsigned int dirty_writeback_interval; 131 extern unsigned int dirty_expire_interval; 132 extern int vm_highmem_is_dirtyable; 133 extern int block_dump; 134 extern int laptop_mode; 135 136 extern int dirty_background_ratio_handler(struct ctl_table *table, int write, 137 void __user *buffer, size_t *lenp, 138 loff_t *ppos); 139 extern int dirty_background_bytes_handler(struct ctl_table *table, int write, 140 void __user *buffer, size_t *lenp, 141 loff_t *ppos); 142 extern int dirty_ratio_handler(struct ctl_table *table, int write, 143 void __user *buffer, size_t *lenp, 144 loff_t *ppos); 145 extern int dirty_bytes_handler(struct ctl_table *table, int write, 146 void __user *buffer, size_t *lenp, 147 loff_t *ppos); 148 149 struct ctl_table; 150 int dirty_writeback_centisecs_handler(struct ctl_table *, int, 151 void __user *, size_t *, loff_t *); 152 153 void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty); 154 unsigned long bdi_dirty_limit(struct backing_dev_info *bdi, 155 unsigned long dirty); 156 157 void __bdi_update_bandwidth(struct backing_dev_info *bdi, 158 unsigned long thresh, 159 unsigned long bg_thresh, 160 unsigned long dirty, 161 unsigned long bdi_thresh, 162 unsigned long bdi_dirty, 163 unsigned long start_time); 164 165 void page_writeback_init(void); 166 void balance_dirty_pages_ratelimited(struct address_space *mapping); 167 168 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc, 169 void *data); 170 171 int generic_writepages(struct address_space *mapping, 172 struct writeback_control *wbc); 173 void tag_pages_for_writeback(struct address_space *mapping, 174 pgoff_t start, pgoff_t end); 175 int write_cache_pages(struct address_space *mapping, 176 struct writeback_control *wbc, writepage_t writepage, 177 void *data); 178 int do_writepages(struct address_space *mapping, struct writeback_control *wbc); 179 void set_page_dirty_balance(struct page *page, int page_mkwrite); 180 void writeback_set_ratelimit(void); 181 void tag_pages_for_writeback(struct address_space *mapping, 182 pgoff_t start, pgoff_t end); 183 184 void account_page_redirty(struct page *page); 185 186 #endif /* WRITEBACK_H */ 187