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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         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          * For WB_SYNC_ALL, the sb must always be pinned. For WB_SYNC_NONE,
  71          * the writeback code will pin the sb for the caller. However,
  72          * for eg umount, the caller does WB_SYNC_NONE but already has
  73          * the sb pinned. If the below is set, caller already has the
  74          * sb pinned.
  75          */
  76         unsigned sb_pinned:1;
  77 };
  78
  79 /*
  80  * fs/fs-writeback.c
  81  */
  82 struct bdi_writeback;
  83 int inode_wait(void *);
  84 void writeback_inodes_sb(struct super_block *);
  85 void writeback_inodes_sb_locked(struct super_block *);
  86 int writeback_inodes_sb_if_idle(struct super_block *);
  87 void sync_inodes_sb(struct super_block *);
  88 void writeback_inodes_wbc(struct writeback_control *wbc);
  89 long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
  90 void wakeup_flusher_threads(long nr_pages);
  91
  92 /* writeback.h requires fs.h; it, too, is not included from here. */
  93 static inline void wait_on_inode(struct inode *inode)
  94 {
  95         might_sleep();
  96         wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
  97 }
  98 static inline void inode_sync_wait(struct inode *inode)
  99 {
 100         might_sleep();
 101         wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
 102                                                         TASK_UNINTERRUPTIBLE);
 103 }
 104
 105
 106 /*
 107  * mm/page-writeback.c
 108  */
 109 #ifdef CONFIG_BLOCK
 110 void laptop_io_completion(struct backing_dev_info *info);
 111 void laptop_sync_completion(void);
 112 void laptop_mode_sync(struct work_struct *work);
 113 void laptop_mode_timer_fn(unsigned long data);
 114 #else
 115 static inline void laptop_sync_completion(void) { }
 116 #endif
 117 void throttle_vm_writeout(gfp_t gfp_mask);
 118
 119 /* These are exported to sysctl. */
 120 extern int dirty_background_ratio;
 121 extern unsigned long dirty_background_bytes;
 122 extern int vm_dirty_ratio;
 123 extern unsigned long vm_dirty_bytes;
 124 extern unsigned int dirty_writeback_interval;
 125 extern unsigned int dirty_expire_interval;
 126 extern int vm_highmem_is_dirtyable;
 127 extern int block_dump;
 128 extern int laptop_mode;
 129
 130 extern unsigned long determine_dirtyable_memory(void);
 131
 132 extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
 133                 void __user *buffer, size_t *lenp,
 134                 loff_t *ppos);
 135 extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
 136                 void __user *buffer, size_t *lenp,
 137                 loff_t *ppos);
 138 extern int dirty_ratio_handler(struct ctl_table *table, int write,
 139                 void __user *buffer, size_t *lenp,
 140                 loff_t *ppos);
 141 extern int dirty_bytes_handler(struct ctl_table *table, int write,
 142                 void __user *buffer, size_t *lenp,
 143                 loff_t *ppos);
 144
 145 struct ctl_table;
 146 int dirty_writeback_centisecs_handler(struct ctl_table *, int,
 147                                       void __user *, size_t *, loff_t *);
 148
 149 void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
 150                       unsigned long *pbdi_dirty, struct backing_dev_info *bdi);
 151
 152 void page_writeback_init(void);
 153 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 154                                         unsigned long nr_pages_dirtied);
 155
 156 static inline void
 157 balance_dirty_pages_ratelimited(struct address_space *mapping)
 158 {
 159         balance_dirty_pages_ratelimited_nr(mapping, 1);
 160 }
 161
 162 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
 163                                 void *data);
 164
 165 int generic_writepages(struct address_space *mapping,
 166                        struct writeback_control *wbc);
 167 int write_cache_pages(struct address_space *mapping,
 168                       struct writeback_control *wbc, writepage_t writepage,
 169                       void *data);
 170 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 171 void set_page_dirty_balance(struct page *page, int page_mkwrite);
 172 void writeback_set_ratelimit(void);
 173
 174 /* pdflush.c */
 175 extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
 176                                    read-only. */
 177
 178
 179 #endif          /* WRITEBACK_H */