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 DECLARE_PER_CPU(int, dirty_throttle_leaks); 11 12 /* 13 * The 1/4 region under the global dirty thresh is for smooth dirty throttling: 14 * 15 * (thresh - thresh/DIRTY_FULL_SCOPE, thresh) 16 * 17 * Further beyond, all dirtier tasks will enter a loop waiting (possibly long 18 * time) for the dirty pages to drop, unless written enough pages. 19 * 20 * The global dirty threshold is normally equal to the global dirty limit, 21 * except when the system suddenly allocates a lot of anonymous memory and 22 * knocks down the global dirty threshold quickly, in which case the global 23 * dirty limit will follow down slowly to prevent livelocking all dirtier tasks. 24 */ 25 #define DIRTY_SCOPE 8 26 #define DIRTY_FULL_SCOPE (DIRTY_SCOPE / 2) 27 28 struct backing_dev_info; 29 30 /* 31 * fs/fs-writeback.c 32 */ 33 enum writeback_sync_modes { 34 WB_SYNC_NONE, /* Don't wait on anything */ 35 WB_SYNC_ALL, /* Wait on every mapping */ 36 }; 37 38 /* 39 * why some writeback work was initiated 40 */ 41 enum wb_reason { 42 WB_REASON_BACKGROUND, 43 WB_REASON_TRY_TO_FREE_PAGES, 44 WB_REASON_SYNC, 45 WB_REASON_PERIODIC, 46 WB_REASON_LAPTOP_TIMER, 47 WB_REASON_FREE_MORE_MEM, 48 WB_REASON_FS_FREE_SPACE, 49 WB_REASON_FORKER_THREAD, 50 51 WB_REASON_MAX, 52 }; 53 extern const char *wb_reason_name[]; 54 55 /* 56 * A control structure which tells the writeback code what to do. These are 57 * always on the stack, and hence need no locking. They are always initialised 58 * in a manner such that unspecified fields are set to zero. 59 */ 60 struct writeback_control { 61 long nr_to_write; /* Write this many pages, and decrement 62 this for each page written */ 63 long pages_skipped; /* Pages which were not written */ 64 65 /* 66 * For a_ops->writepages(): if start or end are non-zero then this is 67 * a hint that the filesystem need only write out the pages inside that 68 * byterange. The byte at `end' is included in the writeout request. 69 */ 70 loff_t range_start; 71 loff_t range_end; 72 73 enum writeback_sync_modes sync_mode; 74 75 unsigned for_kupdate:1; /* A kupdate writeback */ 76 unsigned for_background:1; /* A background writeback */ 77 unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */ 78 unsigned for_reclaim:1; /* Invoked from the page allocator */ 79 unsigned range_cyclic:1; /* range_start is cyclic */ 80 }; 81 82 /* 83 * fs/fs-writeback.c 84 */ 85 struct bdi_writeback; 86 int inode_wait(void *); 87 void writeback_inodes_sb(struct super_block *, enum wb_reason reason); 88 void writeback_inodes_sb_nr(struct super_block *, unsigned long nr, 89 enum wb_reason reason); 90 int writeback_inodes_sb_if_idle(struct super_block *, enum wb_reason reason); 91 int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr, 92 enum wb_reason reason); 93 void sync_inodes_sb(struct super_block *); 94 long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, 95 enum wb_reason reason); 96 long wb_do_writeback(struct bdi_writeback *wb, int force_wait); 97 void wakeup_flusher_threads(long nr_pages, enum wb_reason reason); 98 void inode_wait_for_writeback(struct inode *inode); 99 100 /* writeback.h requires fs.h; it, too, is not included from here. */ 101 static inline void wait_on_inode(struct inode *inode) 102 { 103 might_sleep(); 104 wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE); 105 } 106 107 108 /* 109 * mm/page-writeback.c 110 */ 111 #ifdef CONFIG_BLOCK 112 void laptop_io_completion(struct backing_dev_info *info); 113 void laptop_sync_completion(void); 114 void laptop_mode_sync(struct work_struct *work); 115 void laptop_mode_timer_fn(unsigned long data); 116 #else 117 static inline void laptop_sync_completion(void) { } 118 #endif 119 void throttle_vm_writeout(gfp_t gfp_mask); 120 bool zone_dirty_ok(struct zone *zone); 121 122 extern unsigned long global_dirty_limit; 123 124 /* These are exported to sysctl. */ 125 extern int dirty_background_ratio; 126 extern unsigned long dirty_background_bytes; 127 extern int vm_dirty_ratio; 128 extern unsigned long vm_dirty_bytes; 129 extern unsigned int dirty_writeback_interval; 130 extern unsigned int dirty_expire_interval; 131 extern int vm_highmem_is_dirtyable; 132 extern int block_dump; 133 extern int laptop_mode; 134 135 extern int dirty_background_ratio_handler(struct ctl_table *table, int write, 136 void __user *buffer, size_t *lenp, 137 loff_t *ppos); 138 extern int dirty_background_bytes_handler(struct ctl_table *table, int write, 139 void __user *buffer, size_t *lenp, 140 loff_t *ppos); 141 extern int dirty_ratio_handler(struct ctl_table *table, int write, 142 void __user *buffer, size_t *lenp, 143 loff_t *ppos); 144 extern int dirty_bytes_handler(struct ctl_table *table, int write, 145 void __user *buffer, size_t *lenp, 146 loff_t *ppos); 147 148 struct ctl_table; 149 int dirty_writeback_centisecs_handler(struct ctl_table *, int, 150 void __user *, size_t *, loff_t *); 151 152 void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty); 153 unsigned long bdi_dirty_limit(struct backing_dev_info *bdi, 154 unsigned long dirty); 155 156 void __bdi_update_bandwidth(struct backing_dev_info *bdi, 157 unsigned long thresh, 158 unsigned long bg_thresh, 159 unsigned long dirty, 160 unsigned long bdi_thresh, 161 unsigned long bdi_dirty, 162 unsigned long start_time); 163 164 void page_writeback_init(void); 165 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping, 166 unsigned long nr_pages_dirtied); 167 168 static inline void 169 balance_dirty_pages_ratelimited(struct address_space *mapping) 170 { 171 balance_dirty_pages_ratelimited_nr(mapping, 1); 172 } 173 174 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc, 175 void *data); 176 177 int generic_writepages(struct address_space *mapping, 178 struct writeback_control *wbc); 179 void tag_pages_for_writeback(struct address_space *mapping, 180 pgoff_t start, pgoff_t end); 181 int write_cache_pages(struct address_space *mapping, 182 struct writeback_control *wbc, writepage_t writepage, 183 void *data); 184 int do_writepages(struct address_space *mapping, struct writeback_control *wbc); 185 void set_page_dirty_balance(struct page *page, int page_mkwrite); 186 void writeback_set_ratelimit(void); 187 void tag_pages_for_writeback(struct address_space *mapping, 188 pgoff_t start, pgoff_t end); 189 190 void account_page_redirty(struct page *page); 191 192 /* pdflush.c */ 193 extern int nr_pdflush_threads; /* Global so it can be exported to sysctl 194 read-only. */ 195 196 197 #endif /* WRITEBACK_H */ 198