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 * Yes, writeback.h requires sched.h 18 * No, sched.h is not included from here. 19 */ 20 static inline int task_is_pdflush(struct task_struct *task) 21 { 22 return task->flags & PF_FLUSHER; 23 } 24 25 #define current_is_pdflush() task_is_pdflush(current) 26 27 /* 28 * fs/fs-writeback.c 29 */ 30 enum writeback_sync_modes { 31 WB_SYNC_NONE, /* Don't wait on anything */ 32 WB_SYNC_ALL, /* Wait on every mapping */ 33 WB_SYNC_HOLD, /* Hold the inode on sb_dirty for sys_sync() */ 34 }; 35 36 /* 37 * A control structure which tells the writeback code what to do. These are 38 * always on the stack, and hence need no locking. They are always initialised 39 * in a manner such that unspecified fields are set to zero. 40 */ 41 struct writeback_control { 42 struct backing_dev_info *bdi; /* If !NULL, only write back this 43 queue */ 44 enum writeback_sync_modes sync_mode; 45 unsigned long *older_than_this; /* If !NULL, only write back inodes 46 older than this */ 47 long nr_to_write; /* Write this many pages, and decrement 48 this for each page written */ 49 long pages_skipped; /* Pages which were not written */ 50 51 /* 52 * For a_ops->writepages(): is start or end are non-zero then this is 53 * a hint that the filesystem need only write out the pages inside that 54 * byterange. The byte at `end' is included in the writeout request. 55 */ 56 loff_t range_start; 57 loff_t range_end; 58 59 unsigned nonblocking:1; /* Don't get stuck on request queues */ 60 unsigned encountered_congestion:1; /* An output: a queue is full */ 61 unsigned for_kupdate:1; /* A kupdate writeback */ 62 unsigned for_reclaim:1; /* Invoked from the page allocator */ 63 unsigned for_writepages:1; /* This is a writepages() call */ 64 unsigned range_cyclic:1; /* range_start is cyclic */ 65 unsigned more_io:1; /* more io to be dispatched */ 66 /* 67 * write_cache_pages() won't update wbc->nr_to_write and 68 * mapping->writeback_index if no_nrwrite_index_update 69 * is set. write_cache_pages() may write more than we 70 * requested and we want to make sure nr_to_write and 71 * writeback_index are updated in a consistent manner 72 * so we use a single control to update them 73 */ 74 unsigned no_nrwrite_index_update:1; 75 }; 76 77 /* 78 * fs/fs-writeback.c 79 */ 80 void writeback_inodes(struct writeback_control *wbc); 81 int inode_wait(void *); 82 void sync_inodes_sb(struct super_block *, int wait); 83 void sync_inodes(int wait); 84 85 /* writeback.h requires fs.h; it, too, is not included from here. */ 86 static inline void wait_on_inode(struct inode *inode) 87 { 88 might_sleep(); 89 wait_on_bit(&inode->i_state, __I_LOCK, inode_wait, 90 TASK_UNINTERRUPTIBLE); 91 } 92 static inline void inode_sync_wait(struct inode *inode) 93 { 94 might_sleep(); 95 wait_on_bit(&inode->i_state, __I_SYNC, inode_wait, 96 TASK_UNINTERRUPTIBLE); 97 } 98 99 100 /* 101 * mm/page-writeback.c 102 */ 103 int wakeup_pdflush(long nr_pages); 104 void laptop_io_completion(void); 105 void laptop_sync_completion(void); 106 void throttle_vm_writeout(gfp_t gfp_mask); 107 108 /* These are exported to sysctl. */ 109 extern int dirty_background_ratio; 110 extern int vm_dirty_ratio; 111 extern int dirty_writeback_interval; 112 extern int dirty_expire_interval; 113 extern int vm_highmem_is_dirtyable; 114 extern int block_dump; 115 extern int laptop_mode; 116 117 extern unsigned long determine_dirtyable_memory(void); 118 119 extern int dirty_ratio_handler(struct ctl_table *table, int write, 120 struct file *filp, void __user *buffer, size_t *lenp, 121 loff_t *ppos); 122 123 struct ctl_table; 124 struct file; 125 int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *, 126 void __user *, size_t *, loff_t *); 127 128 void get_dirty_limits(long *pbackground, long *pdirty, long *pbdi_dirty, 129 struct backing_dev_info *bdi); 130 131 void page_writeback_init(void); 132 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping, 133 unsigned long nr_pages_dirtied); 134 135 static inline void 136 balance_dirty_pages_ratelimited(struct address_space *mapping) 137 { 138 balance_dirty_pages_ratelimited_nr(mapping, 1); 139 } 140 141 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc, 142 void *data); 143 144 int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0); 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 int sync_page_range(struct inode *inode, struct address_space *mapping, 152 loff_t pos, loff_t count); 153 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping, 154 loff_t pos, loff_t count); 155 void set_page_dirty_balance(struct page *page, int page_mkwrite); 156 void writeback_set_ratelimit(void); 157 158 /* pdflush.c */ 159 extern int nr_pdflush_threads; /* Global so it can be exported to sysctl 160 read-only. */ 161 162 163 #endif /* WRITEBACK_H */ 164