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 unsigned range_cont:1; 67 }; 68 69 /* 70 * fs/fs-writeback.c 71 */ 72 void writeback_inodes(struct writeback_control *wbc); 73 int inode_wait(void *); 74 void sync_inodes_sb(struct super_block *, int wait); 75 void sync_inodes(int wait); 76 77 /* writeback.h requires fs.h; it, too, is not included from here. */ 78 static inline void wait_on_inode(struct inode *inode) 79 { 80 might_sleep(); 81 wait_on_bit(&inode->i_state, __I_LOCK, inode_wait, 82 TASK_UNINTERRUPTIBLE); 83 } 84 static inline void inode_sync_wait(struct inode *inode) 85 { 86 might_sleep(); 87 wait_on_bit(&inode->i_state, __I_SYNC, inode_wait, 88 TASK_UNINTERRUPTIBLE); 89 } 90 91 92 /* 93 * mm/page-writeback.c 94 */ 95 int wakeup_pdflush(long nr_pages); 96 void laptop_io_completion(void); 97 void laptop_sync_completion(void); 98 void throttle_vm_writeout(gfp_t gfp_mask); 99 100 /* These are exported to sysctl. */ 101 extern int dirty_background_ratio; 102 extern int vm_dirty_ratio; 103 extern int dirty_writeback_interval; 104 extern int dirty_expire_interval; 105 extern int vm_highmem_is_dirtyable; 106 extern int block_dump; 107 extern int laptop_mode; 108 109 extern unsigned long determine_dirtyable_memory(void); 110 111 extern int dirty_ratio_handler(struct ctl_table *table, int write, 112 struct file *filp, void __user *buffer, size_t *lenp, 113 loff_t *ppos); 114 115 struct ctl_table; 116 struct file; 117 int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *, 118 void __user *, size_t *, loff_t *); 119 120 void get_dirty_limits(long *pbackground, long *pdirty, long *pbdi_dirty, 121 struct backing_dev_info *bdi); 122 123 void page_writeback_init(void); 124 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping, 125 unsigned long nr_pages_dirtied); 126 127 static inline void 128 balance_dirty_pages_ratelimited(struct address_space *mapping) 129 { 130 balance_dirty_pages_ratelimited_nr(mapping, 1); 131 } 132 133 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc, 134 void *data); 135 136 int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0); 137 int generic_writepages(struct address_space *mapping, 138 struct writeback_control *wbc); 139 int write_cache_pages(struct address_space *mapping, 140 struct writeback_control *wbc, writepage_t writepage, 141 void *data); 142 int do_writepages(struct address_space *mapping, struct writeback_control *wbc); 143 int sync_page_range(struct inode *inode, struct address_space *mapping, 144 loff_t pos, loff_t count); 145 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping, 146 loff_t pos, loff_t count); 147 void set_page_dirty_balance(struct page *page, int page_mkwrite); 148 void writeback_set_ratelimit(void); 149 150 /* pdflush.c */ 151 extern int nr_pdflush_threads; /* Global so it can be exported to sysctl 152 read-only. */ 153 154 155 #endif /* WRITEBACK_H */ 156