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 current_is_pdflush(void) 18 { 19 return current->flags & PF_FLUSHER; 20 } 21 22 /* 23 * fs/fs-writeback.c 24 */ 25 enum writeback_sync_modes { 26 WB_SYNC_NONE, /* Don't wait on anything */ 27 WB_SYNC_ALL, /* Wait on every mapping */ 28 WB_SYNC_HOLD, /* Hold the inode on sb_dirty for sys_sync() */ 29 }; 30 31 /* 32 * A control structure which tells the writeback code what to do. These are 33 * always on the stack, and hence need no locking. They are always initialised 34 * in a manner such that unspecified fields are set to zero. 35 */ 36 struct writeback_control { 37 struct backing_dev_info *bdi; /* If !NULL, only write back this 38 queue */ 39 enum writeback_sync_modes sync_mode; 40 unsigned long *older_than_this; /* If !NULL, only write back inodes 41 older than this */ 42 long nr_to_write; /* Write this many pages, and decrement 43 this for each page written */ 44 long pages_skipped; /* Pages which were not written */ 45 46 /* 47 * For a_ops->writepages(): is start or end are non-zero then this is 48 * a hint that the filesystem need only write out the pages inside that 49 * byterange. The byte at `end' is included in the writeout request. 50 */ 51 loff_t start; 52 loff_t end; 53 54 unsigned nonblocking:1; /* Don't get stuck on request queues */ 55 unsigned encountered_congestion:1; /* An output: a queue is full */ 56 unsigned for_kupdate:1; /* A kupdate writeback */ 57 unsigned for_reclaim:1; /* Invoked from the page allocator */ 58 }; 59 60 /* 61 * ->writepage() return values (make these much larger than a pagesize, in 62 * case some fs is returning number-of-bytes-written from writepage) 63 */ 64 #define WRITEPAGE_ACTIVATE 0x80000 /* IO was not started: activate page */ 65 66 /* 67 * fs/fs-writeback.c 68 */ 69 void writeback_inodes(struct writeback_control *wbc); 70 void wake_up_inode(struct inode *inode); 71 int inode_wait(void *); 72 void sync_inodes_sb(struct super_block *, int wait); 73 void sync_inodes(int wait); 74 75 /* writeback.h requires fs.h; it, too, is not included from here. */ 76 static inline void wait_on_inode(struct inode *inode) 77 { 78 might_sleep(); 79 wait_on_bit(&inode->i_state, __I_LOCK, inode_wait, 80 TASK_UNINTERRUPTIBLE); 81 } 82 83 /* 84 * mm/page-writeback.c 85 */ 86 int wakeup_bdflush(long nr_pages); 87 void laptop_io_completion(void); 88 void laptop_sync_completion(void); 89 void throttle_vm_writeout(void); 90 91 /* These are exported to sysctl. */ 92 extern int dirty_background_ratio; 93 extern int vm_dirty_ratio; 94 extern int dirty_writeback_centisecs; 95 extern int dirty_expire_centisecs; 96 extern int block_dump; 97 extern int laptop_mode; 98 99 struct ctl_table; 100 struct file; 101 int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *, 102 void __user *, size_t *, loff_t *); 103 104 void page_writeback_init(void); 105 void balance_dirty_pages_ratelimited(struct address_space *mapping); 106 int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0); 107 int do_writepages(struct address_space *mapping, struct writeback_control *wbc); 108 int sync_page_range(struct inode *inode, struct address_space *mapping, 109 loff_t pos, size_t count); 110 int sync_page_range_nolock(struct inode *inode, struct address_space 111 *mapping, loff_t pos, size_t count); 112 113 /* pdflush.c */ 114 extern int nr_pdflush_threads; /* Global so it can be exported to sysctl 115 read-only. */ 116 117 118 #endif /* WRITEBACK_H */ 119