include/linux/writeback.h

   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 /*
  13  * fs/fs-writeback.c
  14  */
  15 enum writeback_sync_modes {
  16         WB_SYNC_NONE,   /* Don't wait on anything */
  17         WB_SYNC_ALL,    /* Wait on every mapping */
  18 };
  19
  20 /*
  21  * A control structure which tells the writeback code what to do.  These are
  22  * always on the stack, and hence need no locking.  They are always initialised
  23  * in a manner such that unspecified fields are set to zero.
  24  */
  25 struct writeback_control {
  26         enum writeback_sync_modes sync_mode;
  27         long nr_to_write;               /* Write this many pages, and decrement
  28                                            this for each page written */
  29         long pages_skipped;             /* Pages which were not written */
  30
  31         /*
  32          * For a_ops->writepages(): is start or end are non-zero then this is
  33          * a hint that the filesystem need only write out the pages inside that
  34          * byterange.  The byte at `end' is included in the writeout request.
  35          */
  36         loff_t range_start;
  37         loff_t range_end;
  38
  39         unsigned for_kupdate:1;         /* A kupdate writeback */
  40         unsigned for_background:1;      /* A background writeback */
  41         unsigned tagged_writepages:1;   /* tag-and-write to avoid livelock */
  42         unsigned for_reclaim:1;         /* Invoked from the page allocator */
  43         unsigned range_cyclic:1;        /* range_start is cyclic */
  44 };
  45
  46 /*
  47  * fs/fs-writeback.c
  48  */
  49 struct bdi_writeback;
  50 int inode_wait(void *);
  51 void writeback_inodes_sb(struct super_block *);
  52 void writeback_inodes_sb_nr(struct super_block *, unsigned long nr);
  53 int writeback_inodes_sb_if_idle(struct super_block *);
  54 int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr);
  55 void sync_inodes_sb(struct super_block *);
  56 long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages);
  57 long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
  58 void wakeup_flusher_threads(long nr_pages);
  59
  60 /* writeback.h requires fs.h; it, too, is not included from here. */
  61 static inline void wait_on_inode(struct inode *inode)
  62 {
  63         might_sleep();
  64         wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
  65 }
  66 static inline void inode_sync_wait(struct inode *inode)
  67 {
  68         might_sleep();
  69         wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
  70                                                         TASK_UNINTERRUPTIBLE);
  71 }
  72
  73
  74 /*
  75  * mm/page-writeback.c
  76  */
  77 #ifdef CONFIG_BLOCK
  78 void laptop_io_completion(struct backing_dev_info *info);
  79 void laptop_sync_completion(void);
  80 void laptop_mode_sync(struct work_struct *work);
  81 void laptop_mode_timer_fn(unsigned long data);
  82 #else
  83 static inline void laptop_sync_completion(void) { }
  84 #endif
  85 void throttle_vm_writeout(gfp_t gfp_mask);
  86
  87 extern unsigned long global_dirty_limit;
  88
  89 /* These are exported to sysctl. */
  90 extern int dirty_background_ratio;
  91 extern unsigned long dirty_background_bytes;
  92 extern int vm_dirty_ratio;
  93 extern unsigned long vm_dirty_bytes;
  94 extern unsigned int dirty_writeback_interval;
  95 extern unsigned int dirty_expire_interval;
  96 extern int vm_highmem_is_dirtyable;
  97 extern int block_dump;
  98 extern int laptop_mode;
  99
 100 extern unsigned long determine_dirtyable_memory(void);
 101
 102 extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
 103                 void __user *buffer, size_t *lenp,
 104                 loff_t *ppos);
 105 extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
 106                 void __user *buffer, size_t *lenp,
 107                 loff_t *ppos);
 108 extern int dirty_ratio_handler(struct ctl_table *table, int write,
 109                 void __user *buffer, size_t *lenp,
 110                 loff_t *ppos);
 111 extern int dirty_bytes_handler(struct ctl_table *table, int write,
 112                 void __user *buffer, size_t *lenp,
 113                 loff_t *ppos);
 114
 115 struct ctl_table;
 116 int dirty_writeback_centisecs_handler(struct ctl_table *, int,
 117                                       void __user *, size_t *, loff_t *);
 118
 119 void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
 120 unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
 121                                unsigned long dirty);
 122
 123 void __bdi_update_bandwidth(struct backing_dev_info *bdi,
 124                             unsigned long thresh,
 125                             unsigned long dirty,
 126                             unsigned long bdi_thresh,
 127                             unsigned long bdi_dirty,
 128                             unsigned long start_time);
 129
 130 void page_writeback_init(void);
 131 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 132                                         unsigned long nr_pages_dirtied);
 133
 134 static inline void
 135 balance_dirty_pages_ratelimited(struct address_space *mapping)
 136 {
 137         balance_dirty_pages_ratelimited_nr(mapping, 1);
 138 }
 139
 140 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
 141                                 void *data);
 142
 143 int generic_writepages(struct address_space *mapping,
 144                        struct writeback_control *wbc);
 145 void tag_pages_for_writeback(struct address_space *mapping,
 146                              pgoff_t start, pgoff_t end);
 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 void set_page_dirty_balance(struct page *page, int page_mkwrite);
 152 void writeback_set_ratelimit(void);
 153 void tag_pages_for_writeback(struct address_space *mapping,
 154                              pgoff_t start, pgoff_t end);
 155
 156 /* pdflush.c */
 157 extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
 158                                    read-only. */
 159
 160
 161 #endif          /* WRITEBACK_H */