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 }; 34 35 /* 36 * A control structure which tells the writeback code what to do. These are 37 * always on the stack, and hence need no locking. They are always initialised 38 * in a manner such that unspecified fields are set to zero. 39 */ 40 struct writeback_control { 41 struct backing_dev_info *bdi; /* If !NULL, only write back this 42 queue */ 43 enum writeback_sync_modes sync_mode; 44 unsigned long *older_than_this; /* If !NULL, only write back inodes 45 older than this */ 46 long nr_to_write; /* Write this many pages, and decrement 47 this for each page written */ 48 long pages_skipped; /* Pages which were not written */ 49 50 /* 51 * For a_ops->writepages(): is start or end are non-zero then this is 52 * a hint that the filesystem need only write out the pages inside that 53 * byterange. The byte at `end' is included in the writeout request. 54 */ 55 loff_t range_start; 56 loff_t range_end; 57 58 unsigned nonblocking:1; /* Don't get stuck on request queues */ 59 unsigned encountered_congestion:1; /* An output: a queue is full */ 60 unsigned for_kupdate:1; /* A kupdate writeback */ 61 unsigned for_reclaim:1; /* Invoked from the page allocator */ 62 unsigned for_writepages:1; /* This is a writepages() call */ 63 unsigned range_cyclic:1; /* range_start is cyclic */ 64 unsigned more_io:1; /* more io to be dispatched */ 65 /* 66 * write_cache_pages() won't update wbc->nr_to_write and 67 * mapping->writeback_index if no_nrwrite_index_update 68 * is set. write_cache_pages() may write more than we 69 * requested and we want to make sure nr_to_write and 70 * writeback_index are updated in a consistent manner 71 * so we use a single control to update them 72 */ 73 unsigned no_nrwrite_index_update:1; 74 }; 75 76 /* 77 * fs/fs-writeback.c 78 */ 79 void writeback_inodes(struct writeback_control *wbc); 80 int inode_wait(void *); 81 void sync_inodes_sb(struct super_block *, int wait); 82 83 /* writeback.h requires fs.h; it, too, is not included from here. */ 84 static inline void wait_on_inode(struct inode *inode) 85 { 86 might_sleep(); 87 wait_on_bit(&inode->i_state, __I_LOCK, inode_wait, 88 TASK_UNINTERRUPTIBLE); 89 } 90 static inline void inode_sync_wait(struct inode *inode) 91 { 92 might_sleep(); 93 wait_on_bit(&inode->i_state, __I_SYNC, inode_wait, 94 TASK_UNINTERRUPTIBLE); 95 } 96 97 98 /* 99 * mm/page-writeback.c 100 */ 101 int wakeup_pdflush(long nr_pages); 102 void laptop_io_completion(void); 103 void laptop_sync_completion(void); 104 void throttle_vm_writeout(gfp_t gfp_mask); 105 106 /* These are exported to sysctl. */ 107 extern int dirty_background_ratio; 108 extern unsigned long dirty_background_bytes; 109 extern int vm_dirty_ratio; 110 extern unsigned long vm_dirty_bytes; 111 extern unsigned int dirty_writeback_interval; 112 extern unsigned 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_background_ratio_handler(struct ctl_table *table, int write, 120 struct file *filp, void __user *buffer, size_t *lenp, 121 loff_t *ppos); 122 extern int dirty_background_bytes_handler(struct ctl_table *table, int write, 123 struct file *filp, void __user *buffer, size_t *lenp, 124 loff_t *ppos); 125 extern int dirty_ratio_handler(struct ctl_table *table, int write, 126 struct file *filp, void __user *buffer, size_t *lenp, 127 loff_t *ppos); 128 extern int dirty_bytes_handler(struct ctl_table *table, int write, 129 struct file *filp, void __user *buffer, size_t *lenp, 130 loff_t *ppos); 131 132 struct ctl_table; 133 struct file; 134 int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *, 135 void __user *, size_t *, loff_t *); 136 137 void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty, 138 unsigned long *pbdi_dirty, struct backing_dev_info *bdi); 139 140 void page_writeback_init(void); 141 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping, 142 unsigned long nr_pages_dirtied); 143 144 static inline void 145 balance_dirty_pages_ratelimited(struct address_space *mapping) 146 { 147 balance_dirty_pages_ratelimited_nr(mapping, 1); 148 } 149 150 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc, 151 void *data); 152 153 int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0); 154 int generic_writepages(struct address_space *mapping, 155 struct writeback_control *wbc); 156 int write_cache_pages(struct address_space *mapping, 157 struct writeback_control *wbc, writepage_t writepage, 158 void *data); 159 int do_writepages(struct address_space *mapping, struct writeback_control *wbc); 160 int sync_page_range(struct inode *inode, struct address_space *mapping, 161 loff_t pos, loff_t count); 162 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping, 163 loff_t pos, loff_t count); 164 void set_page_dirty_balance(struct page *page, int page_mkwrite); 165 void writeback_set_ratelimit(void); 166 167 /* pdflush.c */ 168 extern int nr_pdflush_threads; /* Global so it can be exported to sysctl 169 read-only. */ 170 171 172 #endif /* WRITEBACK_H */ 173