include/linux/writeback.h

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