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_wb_list_lock;
  13
  14 /*
  15  * fs/fs-writeback.c
  16  */
  17 enum writeback_sync_modes {
  18         WB_SYNC_NONE,   /* Don't wait on anything */
  19         WB_SYNC_ALL,    /* Wait on every mapping */
  20 };
  21
  22 /*
  23  * A control structure which tells the writeback code what to do.  These are
  24  * always on the stack, and hence need no locking.  They are always initialised
  25  * in a manner such that unspecified fields are set to zero.
  26  */
  27 struct writeback_control {
  28         enum writeback_sync_modes sync_mode;
  29         unsigned long *older_than_this; /* If !NULL, only write back inodes
  30                                            older than this */
  31         unsigned long wb_start;         /* Time writeback_inodes_wb was
  32                                            called. This is needed to avoid
  33                                            extra jobs and livelock */
  34         long nr_to_write;               /* Write this many pages, and decrement
  35                                            this for each page written */
  36         long pages_skipped;             /* Pages which were not written */
  37
  38         /*
  39          * For a_ops->writepages(): is start or end are non-zero then this is
  40          * a hint that the filesystem need only write out the pages inside that
  41          * byterange.  The byte at `end' is included in the writeout request.
  42          */
  43         loff_t range_start;
  44         loff_t range_end;
  45
  46         unsigned nonblocking:1;         /* Don't get stuck on request queues */
  47         unsigned encountered_congestion:1; /* An output: a queue is full */
  48         unsigned for_kupdate:1;         /* A kupdate writeback */
  49         unsigned for_background:1;      /* A background writeback */
  50         unsigned tagged_writepages:1;   /* tag-and-write to avoid livelock */
  51         unsigned for_reclaim:1;         /* Invoked from the page allocator */
  52         unsigned range_cyclic:1;        /* range_start is cyclic */
  53         unsigned more_io:1;             /* more io to be dispatched */
  54 };
  55
  56 /*
  57  * fs/fs-writeback.c
  58  */
  59 struct bdi_writeback;
  60 int inode_wait(void *);
  61 void writeback_inodes_sb(struct super_block *);
  62 void writeback_inodes_sb_nr(struct super_block *, unsigned long nr);
  63 int writeback_inodes_sb_if_idle(struct super_block *);
  64 int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr);
  65 void sync_inodes_sb(struct super_block *);
  66 void writeback_inodes_wb(struct bdi_writeback *wb,
  67                 struct writeback_control *wbc);
  68 long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
  69 void wakeup_flusher_threads(long nr_pages);
  70
  71 /* writeback.h requires fs.h; it, too, is not included from here. */
  72 static inline void wait_on_inode(struct inode *inode)
  73 {
  74         might_sleep();
  75         wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
  76 }
  77 static inline void inode_sync_wait(struct inode *inode)
  78 {
  79         might_sleep();
  80         wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
  81                                                         TASK_UNINTERRUPTIBLE);
  82 }
  83
  84
  85 /*
  86  * mm/page-writeback.c
  87  */
  88 #ifdef CONFIG_BLOCK
  89 void laptop_io_completion(struct backing_dev_info *info);
  90 void laptop_sync_completion(void);
  91 void laptop_mode_sync(struct work_struct *work);
  92 void laptop_mode_timer_fn(unsigned long data);
  93 #else
  94 static inline void laptop_sync_completion(void) { }
  95 #endif
  96 void throttle_vm_writeout(gfp_t gfp_mask);
  97
  98 /* These are exported to sysctl. */
  99 extern int dirty_background_ratio;
 100 extern unsigned long dirty_background_bytes;
 101 extern int vm_dirty_ratio;
 102 extern unsigned long vm_dirty_bytes;
 103 extern unsigned int dirty_writeback_interval;
 104 extern unsigned int dirty_expire_interval;
 105 extern int vm_highmem_is_dirtyable;
 106 extern int block_dump;
 107 extern int laptop_mode;
 108
 109 extern unsigned long determine_dirtyable_memory(void);
 110
 111 extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
 112                 void __user *buffer, size_t *lenp,
 113                 loff_t *ppos);
 114 extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
 115                 void __user *buffer, size_t *lenp,
 116                 loff_t *ppos);
 117 extern int dirty_ratio_handler(struct ctl_table *table, int write,
 118                 void __user *buffer, size_t *lenp,
 119                 loff_t *ppos);
 120 extern int dirty_bytes_handler(struct ctl_table *table, int write,
 121                 void __user *buffer, size_t *lenp,
 122                 loff_t *ppos);
 123
 124 struct ctl_table;
 125 int dirty_writeback_centisecs_handler(struct ctl_table *, int,
 126                                       void __user *, size_t *, loff_t *);
 127
 128 void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
 129 unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
 130                                unsigned long dirty);
 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 void tag_pages_for_writeback(struct address_space *mapping,
 148                              pgoff_t start, pgoff_t end);
 149 int write_cache_pages(struct address_space *mapping,
 150                       struct writeback_control *wbc, writepage_t writepage,
 151                       void *data);
 152 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 153 void set_page_dirty_balance(struct page *page, int page_mkwrite);
 154 void writeback_set_ratelimit(void);
 155 void tag_pages_for_writeback(struct address_space *mapping,
 156                              pgoff_t start, pgoff_t end);
 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 */