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         unsigned long wb_start;         /* Time writeback_inodes_wb was
  38                                            called. This is needed to avoid
  39                                            extra jobs and livelock */
  40         long nr_to_write;               /* Write this many pages, and decrement
  41                                            this for each page written */
  42         long pages_skipped;             /* Pages which were not written */
  43
  44         /*
  45          * For a_ops->writepages(): is start or end are non-zero then this is
  46          * a hint that the filesystem need only write out the pages inside that
  47          * byterange.  The byte at `end' is included in the writeout request.
  48          */
  49         loff_t range_start;
  50         loff_t range_end;
  51
  52         unsigned nonblocking:1;         /* Don't get stuck on request queues */
  53         unsigned encountered_congestion:1; /* An output: a queue is full */
  54         unsigned for_kupdate:1;         /* A kupdate writeback */
  55         unsigned for_background:1;      /* A background writeback */
  56         unsigned for_reclaim:1;         /* Invoked from the page allocator */
  57         unsigned range_cyclic:1;        /* range_start is cyclic */
  58         unsigned more_io:1;             /* more io to be dispatched */
  59         /*
  60          * write_cache_pages() won't update wbc->nr_to_write and
  61          * mapping->writeback_index if no_nrwrite_index_update
  62          * is set.  write_cache_pages() may write more than we
  63          * requested and we want to make sure nr_to_write and
  64          * writeback_index are updated in a consistent manner
  65          * so we use a single control to update them
  66          */
  67         unsigned no_nrwrite_index_update:1;
  68 };
  69
  70 /*
  71  * fs/fs-writeback.c
  72  */
  73 struct bdi_writeback;
  74 int inode_wait(void *);
  75 void writeback_inodes_sb(struct super_block *);
  76 int writeback_inodes_sb_if_idle(struct super_block *);
  77 void sync_inodes_sb(struct super_block *);
  78 void writeback_inodes_wbc(struct writeback_control *wbc);
  79 long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
  80 void wakeup_flusher_threads(long nr_pages);
  81
  82 /* writeback.h requires fs.h; it, too, is not included from here. */
  83 static inline void wait_on_inode(struct inode *inode)
  84 {
  85         might_sleep();
  86         wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
  87 }
  88 static inline void inode_sync_wait(struct inode *inode)
  89 {
  90         might_sleep();
  91         wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
  92                                                         TASK_UNINTERRUPTIBLE);
  93 }
  94
  95
  96 /*
  97  * mm/page-writeback.c
  98  */
  99 void laptop_io_completion(void);
 100 void laptop_sync_completion(void);
 101 void throttle_vm_writeout(gfp_t gfp_mask);
 102
 103 /* These are exported to sysctl. */
 104 extern int dirty_background_ratio;
 105 extern unsigned long dirty_background_bytes;
 106 extern int vm_dirty_ratio;
 107 extern unsigned long vm_dirty_bytes;
 108 extern unsigned int dirty_writeback_interval;
 109 extern unsigned int dirty_expire_interval;
 110 extern int vm_highmem_is_dirtyable;
 111 extern int block_dump;
 112 extern int laptop_mode;
 113
 114 extern unsigned long determine_dirtyable_memory(void);
 115
 116 extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
 117                 void __user *buffer, size_t *lenp,
 118                 loff_t *ppos);
 119 extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
 120                 void __user *buffer, size_t *lenp,
 121                 loff_t *ppos);
 122 extern int dirty_ratio_handler(struct ctl_table *table, int write,
 123                 void __user *buffer, size_t *lenp,
 124                 loff_t *ppos);
 125 extern int dirty_bytes_handler(struct ctl_table *table, int write,
 126                 void __user *buffer, size_t *lenp,
 127                 loff_t *ppos);
 128
 129 struct ctl_table;
 130 int dirty_writeback_centisecs_handler(struct ctl_table *, int,
 131                                       void __user *, size_t *, loff_t *);
 132
 133 void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
 134                       unsigned long *pbdi_dirty, struct backing_dev_info *bdi);
 135
 136 void page_writeback_init(void);
 137 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 138                                         unsigned long nr_pages_dirtied);
 139
 140 static inline void
 141 balance_dirty_pages_ratelimited(struct address_space *mapping)
 142 {
 143         balance_dirty_pages_ratelimited_nr(mapping, 1);
 144 }
 145
 146 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
 147                                 void *data);
 148
 149 int generic_writepages(struct address_space *mapping,
 150                        struct writeback_control *wbc);
 151 int write_cache_pages(struct address_space *mapping,
 152                       struct writeback_control *wbc, writepage_t writepage,
 153                       void *data);
 154 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 155 void set_page_dirty_balance(struct page *page, int page_mkwrite);
 156 void writeback_set_ratelimit(void);
 157
 158 /* pdflush.c */
 159 extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
 160                                    read-only. */
 161
 162
 163 #endif          /* WRITEBACK_H */