LXR linux-bk/include/linux/writeback.h

   1/*
   2 * include/linux/writeback.h.
   3 */
   4#ifndef WRITEBACK_H
   5#define WRITEBACK_H
   6
   7struct backing_dev_info;
   8
   9extern spinlock_t inode_lock;
  10extern struct list_head inode_in_use;
  11extern struct list_head inode_unused;
  12
  13/*
  14 * Yes, writeback.h requires sched.h
  15 * No, sched.h is not included from here.
  16 */
  17static inline int current_is_pdflush(void)
  18{
  19        return current->flags & PF_FLUSHER;
  20}
  21
  22/*
  23 * fs/fs-writeback.c
  24 */
  25enum 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 */
  36struct 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 */     
  69void writeback_inodes(struct writeback_control *wbc);
  70void wake_up_inode(struct inode *inode);
  71int inode_wait(void *);
  72void sync_inodes_sb(struct super_block *, int wait);
  73void sync_inodes(int wait);
  74
  75/* writeback.h requires fs.h; it, too, is not included from here. */
  76static 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 */
  86int wakeup_bdflush(long nr_pages);
  87void laptop_io_completion(void);
  88void laptop_sync_completion(void);
  89
  90/* These are exported to sysctl. */
  91extern int dirty_background_ratio;
  92extern int vm_dirty_ratio;
  93extern int dirty_writeback_centisecs;
  94extern int dirty_expire_centisecs;
  95extern int block_dump;
  96extern int laptop_mode;
  97
  98struct ctl_table;
  99struct file;
 100int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,
 101                                      void __user *, size_t *, loff_t *);
 102
 103void page_writeback_init(void);
 104void balance_dirty_pages_ratelimited(struct address_space *mapping);
 105int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
 106int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 107int sync_page_range(struct inode *inode, struct address_space *mapping,
 108                        loff_t pos, size_t count);
 109int sync_page_range_nolock(struct inode *inode, struct address_space
 110                *mapping, loff_t pos, size_t count);
 111
 112/* pdflush.c */
 113extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
 114                                   read-only. */
 115
 116
 117#endif          /* WRITEBACK_H */
 118