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 #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  * fs/fs-writeback.c
  18  */
  19 enum writeback_sync_modes {
  20         WB_SYNC_NONE,   /* Don't wait on anything */
  21         WB_SYNC_ALL,    /* Wait on every mapping */
  22 };
  23
  24 /*
  25  * A control structure which tells the writeback code what to do.  These are
  26  * always on the stack, and hence need no locking.  They are always initialised
  27  * in a manner such that unspecified fields are set to zero.
  28  */
  29 struct writeback_control {
  30         struct backing_dev_info *bdi;   /* If !NULL, only write back this
  31                                            queue */
  32         struct super_block *sb;         /* if !NULL, only write inodes from
  33                                            this super_block */
  34         enum writeback_sync_modes sync_mode;
  35         unsigned long *older_than_this; /* If !NULL, only write back inodes
  36                                            older than this */
  37         long nr_to_write;               /* Write this many pages, and decrement
  38                                            this for each page written */
  39         long pages_skipped;             /* Pages which were not written */
  40
  41         /*
  42          * For a_ops->writepages(): is start or end are non-zero then this is
  43          * a hint that the filesystem need only write out the pages inside that
  44          * byterange.  The byte at `end' is included in the writeout request.
  45          */
  46         loff_t range_start;
  47         loff_t range_end;
  48
  49         unsigned nonblocking:1;         /* Don't get stuck on request queues */
  50         unsigned encountered_congestion:1; /* An output: a queue is full */
  51         unsigned for_kupdate:1;         /* A kupdate writeback */
  52         unsigned for_background:1;      /* A background writeback */
  53         unsigned for_reclaim:1;         /* Invoked from the page allocator */
  54         unsigned range_cyclic:1;        /* range_start is cyclic */
  55         unsigned more_io:1;             /* more io to be dispatched */
  56         /*
  57          * write_cache_pages() won't update wbc->nr_to_write and
  58          * mapping->writeback_index if no_nrwrite_index_update
  59          * is set.  write_cache_pages() may write more than we
  60          * requested and we want to make sure nr_to_write and
  61          * writeback_index are updated in a consistent manner
  62          * so we use a single control to update them
  63          */
  64         unsigned no_nrwrite_index_update:1;
  65 };
  66
  67 /*
  68  * fs/fs-writeback.c
  69  */
  70 struct bdi_writeback;
  71 int inode_wait(void *);
  72 void writeback_inodes_sb(struct super_block *);
  73 void sync_inodes_sb(struct super_block *);
  74 void writeback_inodes_wbc(struct writeback_control *wbc);
  75 long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
  76 void wakeup_flusher_threads(long nr_pages);
  77
  78 /* writeback.h requires fs.h; it, too, is not included from here. */
  79 static inline void wait_on_inode(struct inode *inode)
  80 {
  81         might_sleep();
  82         wait_on_bit(&inode->i_state, __I_LOCK, inode_wait,
  83                                                         TASK_UNINTERRUPTIBLE);
  84 }
  85 static inline void inode_sync_wait(struct inode *inode)
  86 {
  87         might_sleep();
  88         wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
  89                                                         TASK_UNINTERRUPTIBLE);
  90 }
  91
  92
  93 /*
  94  * mm/page-writeback.c
  95  */
  96 void laptop_io_completion(void);
  97 void laptop_sync_completion(void);
  98 void throttle_vm_writeout(gfp_t gfp_mask);
  99
 100 /* These are exported to sysctl. */
 101 extern int dirty_background_ratio;
 102 extern unsigned long dirty_background_bytes;
 103 extern int vm_dirty_ratio;
 104 extern unsigned long vm_dirty_bytes;
 105 extern unsigned int dirty_writeback_interval;
 106 extern unsigned int dirty_expire_interval;
 107 extern int vm_highmem_is_dirtyable;
 108 extern int block_dump;
 109 extern int laptop_mode;
 110
 111 extern unsigned long determine_dirtyable_memory(void);
 112
 113 extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
 114                 void __user *buffer, size_t *lenp,
 115                 loff_t *ppos);
 116 extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
 117                 void __user *buffer, size_t *lenp,
 118                 loff_t *ppos);
 119 extern int dirty_ratio_handler(struct ctl_table *table, int write,
 120                 void __user *buffer, size_t *lenp,
 121                 loff_t *ppos);
 122 extern int dirty_bytes_handler(struct ctl_table *table, int write,
 123                 void __user *buffer, size_t *lenp,
 124                 loff_t *ppos);
 125
 126 struct ctl_table;
 127 int dirty_writeback_centisecs_handler(struct ctl_table *, int,
 128                                       void __user *, size_t *, loff_t *);
 129
 130 void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
 131                       unsigned long *pbdi_dirty, struct backing_dev_info *bdi);
 132
 133 void page_writeback_init(void);
 134 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 135                                         unsigned long nr_pages_dirtied);
 136
 137 static inline void
 138 balance_dirty_pages_ratelimited(struct address_space *mapping)
 139 {
 140         balance_dirty_pages_ratelimited_nr(mapping, 1);
 141 }
 142
 143 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
 144                                 void *data);
 145
 146 int generic_writepages(struct address_space *mapping,
 147                        struct writeback_control *wbc);
 148 int write_cache_pages(struct address_space *mapping,
 149                       struct writeback_control *wbc, writepage_t writepage,
 150                       void *data);
 151 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 152 void set_page_dirty_balance(struct page *page, int page_mkwrite);
 153 void writeback_set_ratelimit(void);
 154
 155 /* pdflush.c */
 156 extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
 157                                    read-only. */
 158
 159
 160 #endif          /* WRITEBACK_H */