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