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   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 extern struct list_head inode_in_use;
  14 extern struct list_head inode_unused;
  15
  16 /*
  17  * Yes, writeback.h requires sched.h
  18  * No, sched.h is not included from here.
  19  */
  20 static inline int task_is_pdflush(struct task_struct *task)
  21 {
  22         return task->flags & PF_FLUSHER;
  23 }
  24
  25 #define current_is_pdflush()    task_is_pdflush(current)
  26
  27 /*
  28  * fs/fs-writeback.c
  29  */
  30 enum writeback_sync_modes {
  31         WB_SYNC_NONE,   /* Don't wait on anything */
  32         WB_SYNC_ALL,    /* Wait on every mapping */
  33         WB_SYNC_HOLD,   /* Hold the inode on sb_dirty for sys_sync() */
  34 };
  35
  36 /*
  37  * A control structure which tells the writeback code what to do.  These are
  38  * always on the stack, and hence need no locking.  They are always initialised
  39  * in a manner such that unspecified fields are set to zero.
  40  */
  41 struct writeback_control {
  42         struct backing_dev_info *bdi;   /* If !NULL, only write back this
  43                                            queue */
  44         enum writeback_sync_modes sync_mode;
  45         unsigned long *older_than_this; /* If !NULL, only write back inodes
  46                                            older than this */
  47         long nr_to_write;               /* Write this many pages, and decrement
  48                                            this for each page written */
  49         long pages_skipped;             /* Pages which were not written */
  50
  51         /*
  52          * For a_ops->writepages(): is start or end are non-zero then this is
  53          * a hint that the filesystem need only write out the pages inside that
  54          * byterange.  The byte at `end' is included in the writeout request.
  55          */
  56         loff_t range_start;
  57         loff_t range_end;
  58
  59         unsigned nonblocking:1;         /* Don't get stuck on request queues */
  60         unsigned encountered_congestion:1; /* An output: a queue is full */
  61         unsigned for_kupdate:1;         /* A kupdate writeback */
  62         unsigned for_reclaim:1;         /* Invoked from the page allocator */
  63         unsigned for_writepages:1;      /* This is a writepages() call */
  64         unsigned range_cyclic:1;        /* range_start is cyclic */
  65         unsigned more_io:1;             /* more io to be dispatched */
  66 };
  67
  68 /*
  69  * fs/fs-writeback.c
  70  */
  71 void writeback_inodes(struct writeback_control *wbc);
  72 int inode_wait(void *);
  73 void sync_inodes_sb(struct super_block *, int wait);
  74 void sync_inodes(int wait);
  75
  76 /* writeback.h requires fs.h; it, too, is not included from here. */
  77 static inline void wait_on_inode(struct inode *inode)
  78 {
  79         might_sleep();
  80         wait_on_bit(&inode->i_state, __I_LOCK, inode_wait,
  81                                                         TASK_UNINTERRUPTIBLE);
  82 }
  83 static inline void inode_sync_wait(struct inode *inode)
  84 {
  85         might_sleep();
  86         wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
  87                                                         TASK_UNINTERRUPTIBLE);
  88 }
  89
  90
  91 /*
  92  * mm/page-writeback.c
  93  */
  94 int wakeup_pdflush(long nr_pages);
  95 void laptop_io_completion(void);
  96 void laptop_sync_completion(void);
  97 void throttle_vm_writeout(gfp_t gfp_mask);
  98
  99 /* These are exported to sysctl. */
 100 extern int dirty_background_ratio;
 101 extern int vm_dirty_ratio;
 102 extern int dirty_writeback_interval;
 103 extern int dirty_expire_interval;
 104 extern int block_dump;
 105 extern int laptop_mode;
 106
 107 extern int dirty_ratio_handler(struct ctl_table *table, int write,
 108                 struct file *filp, void __user *buffer, size_t *lenp,
 109                 loff_t *ppos);
 110
 111 struct ctl_table;
 112 struct file;
 113 int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,
 114                                       void __user *, size_t *, loff_t *);
 115
 116 void page_writeback_init(void);
 117 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 118                                         unsigned long nr_pages_dirtied);
 119
 120 static inline void
 121 balance_dirty_pages_ratelimited(struct address_space *mapping)
 122 {
 123         balance_dirty_pages_ratelimited_nr(mapping, 1);
 124 }
 125
 126 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
 127                                 void *data);
 128
 129 int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
 130 int generic_writepages(struct address_space *mapping,
 131                        struct writeback_control *wbc);
 132 int write_cache_pages(struct address_space *mapping,
 133                       struct writeback_control *wbc, writepage_t writepage,
 134                       void *data);
 135 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 136 int sync_page_range(struct inode *inode, struct address_space *mapping,
 137                         loff_t pos, loff_t count);
 138 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
 139                            loff_t pos, loff_t count);
 140 void set_page_dirty_balance(struct page *page, int page_mkwrite);
 141 void writeback_set_ratelimit(void);
 142
 143 /* pdflush.c */
 144 extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
 145                                    read-only. */
 146
 147
 148 #endif          /* WRITEBACK_H */