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 current_is_pdflush(void)
  18 {
  19         return current->flags & PF_FLUSHER;
  20 }
  21
  22 /*
  23  * fs/fs-writeback.c
  24  */
  25 enum 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  */
  36 struct 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  */
  69 void writeback_inodes(struct writeback_control *wbc);
  70 void wake_up_inode(struct inode *inode);
  71 int inode_wait(void *);
  72 void sync_inodes_sb(struct super_block *, int wait);
  73 void sync_inodes(int wait);
  74
  75 /* writeback.h requires fs.h; it, too, is not included from here. */
  76 static 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  */
  86 int wakeup_bdflush(long nr_pages);
  87 void laptop_io_completion(void);
  88 void laptop_sync_completion(void);
  89 void throttle_vm_writeout(void);
  90
  91 /* These are exported to sysctl. */
  92 extern int dirty_background_ratio;
  93 extern int vm_dirty_ratio;
  94 extern int dirty_writeback_centisecs;
  95 extern int dirty_expire_centisecs;
  96 extern int block_dump;
  97 extern int laptop_mode;
  98
  99 struct ctl_table;
 100 struct file;
 101 int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,
 102                                       void __user *, size_t *, loff_t *);
 103
 104 void page_writeback_init(void);
 105 void balance_dirty_pages_ratelimited(struct address_space *mapping);
 106 int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
 107 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 108 int sync_page_range(struct inode *inode, struct address_space *mapping,
 109                         loff_t pos, size_t count);
 110 int sync_page_range_nolock(struct inode *inode, struct address_space
 111                 *mapping, 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 */