1 /* 2 * include/linux/writeback.h. 3 */ 4 #ifndef WRITEBACK_H 5 #define WRITEBACK_H 6 7 struct backing_dev_info; 8 9 extern spinlock_t inode_lock; 10 extern struct list_head inode_in_use; 11 extern struct list_head inode_unused; 12 13 /* 14 * Yes, writeback.h requires sched.h 15 * No, sched.h is not included from here. 16 */ 17 static inline int task_is_pdflush(struct task_struct *task) 18 { 19 return task->flags & PF_FLUSHER; 20 } 21 22 #define current_is_pdflush() task_is_pdflush(current) 23 24 /* 25 * fs/fs-writeback.c 26 */ 27 enum writeback_sync_modes { 28 WB_SYNC_NONE, /* Don't wait on anything */ 29 WB_SYNC_ALL, /* Wait on every mapping */ 30 WB_SYNC_HOLD, /* Hold the inode on sb_dirty for sys_sync() */ 31 }; 32 33 /* 34 * A control structure which tells the writeback code what to do. These are 35 * always on the stack, and hence need no locking. They are always initialised 36 * in a manner such that unspecified fields are set to zero. 37 */ 38 struct writeback_control { 39 struct backing_dev_info *bdi; /* If !NULL, only write back this 40 queue */ 41 enum writeback_sync_modes sync_mode; 42 unsigned long *older_than_this; /* If !NULL, only write back inodes 43 older than this */ 44 long nr_to_write; /* Write this many pages, and decrement 45 this for each page written */ 46 long pages_skipped; /* Pages which were not written */ 47 48 /* 49 * For a_ops->writepages(): is start or end are non-zero then this is 50 * a hint that the filesystem need only write out the pages inside that 51 * byterange. The byte at `end' is included in the writeout request. 52 */ 53 loff_t start; 54 loff_t end; 55 56 unsigned nonblocking:1; /* Don't get stuck on request queues */ 57 unsigned encountered_congestion:1; /* An output: a queue is full */ 58 unsigned for_kupdate:1; /* A kupdate writeback */ 59 unsigned for_reclaim:1; /* Invoked from the page allocator */ 60 }; 61 62 /* 63 * ->writepage() return values (make these much larger than a pagesize, in 64 * case some fs is returning number-of-bytes-written from writepage) 65 */ 66 #define WRITEPAGE_ACTIVATE 0x80000 /* IO was not started: activate page */ 67 68 /* 69 * fs/fs-writeback.c 70 */ 71 void writeback_inodes(struct writeback_control *wbc); 72 void wake_up_inode(struct inode *inode); 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 85 /* 86 * mm/page-writeback.c 87 */ 88 int wakeup_pdflush(long nr_pages); 89 void laptop_io_completion(void); 90 void laptop_sync_completion(void); 91 void throttle_vm_writeout(void); 92 93 /* These are exported to sysctl. */ 94 extern int dirty_background_ratio; 95 extern int vm_dirty_ratio; 96 extern int dirty_writeback_centisecs; 97 extern int dirty_expire_centisecs; 98 extern int block_dump; 99 extern int laptop_mode; 100 101 struct ctl_table; 102 struct file; 103 int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *, 104 void __user *, size_t *, loff_t *); 105 106 void page_writeback_init(void); 107 void balance_dirty_pages_ratelimited(struct address_space *mapping); 108 int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0); 109 int do_writepages(struct address_space *mapping, struct writeback_control *wbc); 110 int sync_page_range(struct inode *inode, struct address_space *mapping, 111 loff_t pos, size_t count); 112 int sync_page_range_nolock(struct inode *inode, struct address_space 113 *mapping, loff_t pos, size_t count); 114 115 /* pdflush.c */ 116 extern int nr_pdflush_threads; /* Global so it can be exported to sysctl 117 read-only. */ 118 119 120 #endif /* WRITEBACK_H */ 121