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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  * 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_reclaim:1;         /* Invoked from the page allocator */
  53         unsigned range_cyclic:1;        /* range_start is cyclic */
  54         unsigned more_io:1;             /* more io to be dispatched */
  55         /*
  56          * write_cache_pages() won't update wbc->nr_to_write and
  57          * mapping->writeback_index if no_nrwrite_index_update
  58          * is set.  write_cache_pages() may write more than we
  59          * requested and we want to make sure nr_to_write and
  60          * writeback_index are updated in a consistent manner
  61          * so we use a single control to update them
  62          */
  63         unsigned no_nrwrite_index_update:1;
  64 };
  65
  66 /*
  67  * fs/fs-writeback.c
  68  */
  69 struct bdi_writeback;
  70 int inode_wait(void *);
  71 void writeback_inodes_sb(struct super_block *);
  72 void sync_inodes_sb(struct super_block *);
  73 void writeback_inodes_wbc(struct writeback_control *wbc);
  74 long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
  75 void wakeup_flusher_threads(long nr_pages);
  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 static inline void inode_sync_wait(struct inode *inode)
  85 {
  86         might_sleep();
  87         wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
  88                                                         TASK_UNINTERRUPTIBLE);
  89 }
  90
  91
  92 /*
  93  * mm/page-writeback.c
  94  */
  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 unsigned long dirty_background_bytes;
 102 extern int vm_dirty_ratio;
 103 extern unsigned long vm_dirty_bytes;
 104 extern unsigned int dirty_writeback_interval;
 105 extern unsigned int dirty_expire_interval;
 106 extern int vm_highmem_is_dirtyable;
 107 extern int block_dump;
 108 extern int laptop_mode;
 109
 110 extern unsigned long determine_dirtyable_memory(void);
 111
 112 extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
 113                 void __user *buffer, size_t *lenp,
 114                 loff_t *ppos);
 115 extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
 116                 void __user *buffer, size_t *lenp,
 117                 loff_t *ppos);
 118 extern int dirty_ratio_handler(struct ctl_table *table, int write,
 119                 void __user *buffer, size_t *lenp,
 120                 loff_t *ppos);
 121 extern int dirty_bytes_handler(struct ctl_table *table, int write,
 122                 void __user *buffer, size_t *lenp,
 123                 loff_t *ppos);
 124
 125 struct ctl_table;
 126 int dirty_writeback_centisecs_handler(struct ctl_table *, int,
 127                                       void __user *, size_t *, loff_t *);
 128
 129 void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
 130                       unsigned long *pbdi_dirty, struct backing_dev_info *bdi);
 131
 132 void page_writeback_init(void);
 133 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 134                                         unsigned long nr_pages_dirtied);
 135
 136 static inline void
 137 balance_dirty_pages_ratelimited(struct address_space *mapping)
 138 {
 139         balance_dirty_pages_ratelimited_nr(mapping, 1);
 140 }
 141
 142 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
 143                                 void *data);
 144
 145 int generic_writepages(struct address_space *mapping,
 146                        struct writeback_control *wbc);
 147 int write_cache_pages(struct address_space *mapping,
 148                       struct writeback_control *wbc, writepage_t writepage,
 149                       void *data);
 150 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 151 void set_page_dirty_balance(struct page *page, int page_mkwrite);
 152 void writeback_set_ratelimit(void);
 153
 154 /* pdflush.c */
 155 extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
 156                                    read-only. */
 157
 158
 159 #endif          /* WRITEBACK_H */