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 /* 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. 55 */ 56 WB_REASON_FORKER_THREAD, 57 58 WB_REASON_MAX, 59 }; 60 61 /* 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. 65 */ 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 */ 70 71 /* 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. 75 */ 76 loff_t range_start; 77 loff_t range_end; 78 79 enum writeback_sync_modes sync_mode; 80 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 */ 87 }; 88 89 /* 90 * fs/fs-writeback.c 91 */ 92 struct bdi_writeback; 93 int inode_wait(void *); 94 void writeback_inodes_sb(struct super_block *, enum wb_reason reason); 95 void writeback_inodes_sb_nr(struct super_block *, unsigned long nr, 96 enum wb_reason reason); 97 int try_to_writeback_inodes_sb(struct super_block *, enum wb_reason reason); 98 int try_to_writeback_inodes_sb_nr(struct super_block *, unsigned long nr, 99 enum wb_reason reason); 100 void sync_inodes_sb(struct super_block *); 101 long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, 102 enum wb_reason reason); 103 void wakeup_flusher_threads(long nr_pages, enum wb_reason reason); 104 void inode_wait_for_writeback(struct inode *inode); 105 106 /* writeback.h requires fs.h; it, too, is not included from here. */ 107 static inline void wait_on_inode(struct inode *inode) 108 { 109 might_sleep(); 110 wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE); 111 } 112 113 /* 114 * mm/page-writeback.c 115 */ 116 #ifdef CONFIG_BLOCK 117 void laptop_io_completion(struct backing_dev_info *info); 118 void laptop_sync_completion(void); 119 void laptop_mode_sync(struct work_struct *work); 120 void laptop_mode_timer_fn(unsigned long data); 121 #else 122 static inline void laptop_sync_completion(void) { } 123 #endif 124 void throttle_vm_writeout(gfp_t gfp_mask); 125 bool zone_dirty_ok(struct zone *zone); 126 127 extern unsigned long global_dirty_limit; 128 129 /* These are exported to sysctl. */ 130 extern int dirty_background_ratio; 131 extern unsigned long dirty_background_bytes; 132 extern int vm_dirty_ratio; 133 extern unsigned long vm_dirty_bytes; 134 extern unsigned int dirty_writeback_interval; 135 extern unsigned int dirty_expire_interval; 136 extern int vm_highmem_is_dirtyable; 137 extern int block_dump; 138 extern int laptop_mode; 139 140 extern int dirty_background_ratio_handler(struct ctl_table *table, int write, 141 void __user *buffer, size_t *lenp, 142 loff_t *ppos); 143 extern int dirty_background_bytes_handler(struct ctl_table *table, int write, 144 void __user *buffer, size_t *lenp, 145 loff_t *ppos); 146 extern int dirty_ratio_handler(struct ctl_table *table, int write, 147 void __user *buffer, size_t *lenp, 148 loff_t *ppos); 149 extern int dirty_bytes_handler(struct ctl_table *table, int write, 150 void __user *buffer, size_t *lenp, 151 loff_t *ppos); 152 153 struct ctl_table; 154 int dirty_writeback_centisecs_handler(struct ctl_table *, int, 155 void __user *, size_t *, loff_t *); 156 157 void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty); 158 unsigned long bdi_dirty_limit(struct backing_dev_info *bdi, 159 unsigned long dirty); 160 161 void __bdi_update_bandwidth(struct backing_dev_info *bdi, 162 unsigned long thresh, 163 unsigned long bg_thresh, 164 unsigned long dirty, 165 unsigned long bdi_thresh, 166 unsigned long bdi_dirty, 167 unsigned long start_time); 168 169 void page_writeback_init(void); 170 void balance_dirty_pages_ratelimited(struct address_space *mapping); 171 172 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc, 173 void *data); 174 175 int generic_writepages(struct address_space *mapping, 176 struct writeback_control *wbc); 177 void tag_pages_for_writeback(struct address_space *mapping, 178 pgoff_t start, pgoff_t end); 179 int write_cache_pages(struct address_space *mapping, 180 struct writeback_control *wbc, writepage_t writepage, 181 void *data); 182 int do_writepages(struct address_space *mapping, struct writeback_control *wbc); 183 void set_page_dirty_balance(struct page *page, int page_mkwrite); 184 void writeback_set_ratelimit(void); 185 void tag_pages_for_writeback(struct address_space *mapping, 186 pgoff_t start, pgoff_t end); 187 188 void account_page_redirty(struct page *page); 189 190 #endif /* WRITEBACK_H */ 191