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
   9 struct backing_dev_info;
  10
  11 extern spinlock_t inode_lock;
  12 extern struct list_head inode_in_use;
  13 extern struct list_head inode_unused;
  14
  15 /*
  16  * Yes, writeback.h requires sched.h
  17  * No, sched.h is not included from here.
  18  */
  19 static inline int task_is_pdflush(struct task_struct *task)
  20 {
  21         return task->flags & PF_FLUSHER;
  22 }
  23
  24 #define current_is_pdflush()    task_is_pdflush(current)
  25
  26 /*
  27  * fs/fs-writeback.c
  28  */
  29 enum writeback_sync_modes {
  30         WB_SYNC_NONE,   /* Don't wait on anything */
  31         WB_SYNC_ALL,    /* Wait on every mapping */
  32         WB_SYNC_HOLD,   /* Hold the inode on sb_dirty for sys_sync() */
  33 };
  34
  35 /*
  36  * A control structure which tells the writeback code what to do.  These are
  37  * always on the stack, and hence need no locking.  They are always initialised
  38  * in a manner such that unspecified fields are set to zero.
  39  */
  40 struct writeback_control {
  41         struct backing_dev_info *bdi;   /* If !NULL, only write back this
  42                                            queue */
  43         enum writeback_sync_modes sync_mode;
  44         unsigned long *older_than_this; /* If !NULL, only write back inodes
  45                                            older than this */
  46         long nr_to_write;               /* Write this many pages, and decrement
  47                                            this for each page written */
  48         long pages_skipped;             /* Pages which were not written */
  49
  50         /*
  51          * For a_ops->writepages(): is start or end are non-zero then this is
  52          * a hint that the filesystem need only write out the pages inside that
  53          * byterange.  The byte at `end' is included in the writeout request.
  54          */
  55         loff_t range_start;
  56         loff_t range_end;
  57
  58         unsigned nonblocking:1;         /* Don't get stuck on request queues */
  59         unsigned encountered_congestion:1; /* An output: a queue is full */
  60         unsigned for_kupdate:1;         /* A kupdate writeback */
  61         unsigned for_reclaim:1;         /* Invoked from the page allocator */
  62         unsigned for_writepages:1;      /* This is a writepages() call */
  63         unsigned range_cyclic:1;        /* range_start is cyclic */
  64
  65         void *fs_private;               /* For use by ->writepages() */
  66 };
  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(gfp_t gfp_mask);
  92
  93 /* These are exported to sysctl. */
  94 extern int dirty_background_ratio;
  95 extern int vm_dirty_ratio;
  96 extern int dirty_writeback_interval;
  97 extern int dirty_expire_interval;
  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_nr(struct address_space *mapping,
 108                                         unsigned long nr_pages_dirtied);
 109
 110 static inline void
 111 balance_dirty_pages_ratelimited(struct address_space *mapping)
 112 {
 113         balance_dirty_pages_ratelimited_nr(mapping, 1);
 114 }
 115
 116 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
 117                                 void *data);
 118
 119 int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
 120 int generic_writepages(struct address_space *mapping,
 121                        struct writeback_control *wbc);
 122 int write_cache_pages(struct address_space *mapping,
 123                       struct writeback_control *wbc, writepage_t writepage,
 124                       void *data);
 125 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 126 int sync_page_range(struct inode *inode, struct address_space *mapping,
 127                         loff_t pos, loff_t count);
 128 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
 129                            loff_t pos, loff_t count);
 130 void set_page_dirty_balance(struct page *page);
 131 void writeback_set_ratelimit(void);
 132
 133 /* pdflush.c */
 134 extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
 135                                    read-only. */
 136
 137
 138 #endif          /* WRITEBACK_H */