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  * Passed into wb_writeback(), essentially a subset of writeback_control
  26  */
  27 struct wb_writeback_args {
  28         long nr_pages;
  29         struct super_block *sb;
  30         enum writeback_sync_modes sync_mode;
  31         int for_kupdate:1;
  32         int range_cyclic:1;
  33         int for_background:1;
  34 };
  35
  36 /*
  37  * Work items for the bdi_writeback threads
  38  */
  39 struct bdi_work {
  40         struct list_head list;          /* pending work list */
  41         struct rcu_head rcu_head;       /* for RCU free/clear of work */
  42
  43         unsigned long seen;             /* threads that have seen this work */
  44         atomic_t pending;               /* number of threads still to do work */
  45
  46         struct wb_writeback_args args;  /* writeback arguments */
  47
  48         unsigned long state;            /* flag bits, see WS_* */
  49 };
  50
  51 /*
  52  * A control structure which tells the writeback code what to do.  These are
  53  * always on the stack, and hence need no locking.  They are always initialised
  54  * in a manner such that unspecified fields are set to zero.
  55  */
  56 struct writeback_control {
  57         struct backing_dev_info *bdi;   /* If !NULL, only write back this
  58                                            queue */
  59         struct super_block *sb;         /* if !NULL, only write inodes from
  60                                            this super_block */
  61         enum writeback_sync_modes sync_mode;
  62         unsigned long *older_than_this; /* If !NULL, only write back inodes
  63                                            older than this */
  64         long nr_to_write;               /* Write this many pages, and decrement
  65                                            this for each page written */
  66         long pages_skipped;             /* Pages which were not written */
  67
  68         /*
  69          * For a_ops->writepages(): is start or end are non-zero then this is
  70          * a hint that the filesystem need only write out the pages inside that
  71          * byterange.  The byte at `end' is included in the writeout request.
  72          */
  73         loff_t range_start;
  74         loff_t range_end;
  75
  76         unsigned nonblocking:1;         /* Don't get stuck on request queues */
  77         unsigned encountered_congestion:1; /* An output: a queue is full */
  78         unsigned for_kupdate:1;         /* A kupdate writeback */
  79         unsigned for_background:1;      /* A background writeback */
  80         unsigned for_reclaim:1;         /* Invoked from the page allocator */
  81         unsigned range_cyclic:1;        /* range_start is cyclic */
  82         unsigned more_io:1;             /* more io to be dispatched */
  83         /*
  84          * write_cache_pages() won't update wbc->nr_to_write and
  85          * mapping->writeback_index if no_nrwrite_index_update
  86          * is set.  write_cache_pages() may write more than we
  87          * requested and we want to make sure nr_to_write and
  88          * writeback_index are updated in a consistent manner
  89          * so we use a single control to update them
  90          */
  91         unsigned no_nrwrite_index_update:1;
  92 };
  93
  94 /*
  95  * fs/fs-writeback.c
  96  */
  97 struct bdi_writeback;
  98 int inode_wait(void *);
  99 void writeback_inodes_sb(struct super_block *);
 100 void sync_inodes_sb(struct super_block *);
 101 void writeback_inodes_wbc(struct writeback_control *wbc);
 102 long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
 103 void wakeup_flusher_threads(long nr_pages);
 104
 105 #define inode_to_bdi(inode)     ((inode)->i_mapping->backing_dev_info)
 106
 107 /* writeback.h requires fs.h; it, too, is not included from here. */
 108 static inline void wait_on_inode(struct inode *inode)
 109 {
 110         might_sleep();
 111         wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
 112 }
 113 static inline void inode_sync_wait(struct inode *inode)
 114 {
 115         might_sleep();
 116         wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
 117                                                         TASK_UNINTERRUPTIBLE);
 118 }
 119
 120
 121 /*
 122  * mm/page-writeback.c
 123  */
 124 void laptop_io_completion(void);
 125 void laptop_sync_completion(void);
 126 void throttle_vm_writeout(gfp_t gfp_mask);
 127
 128 /* These are exported to sysctl. */
 129 extern int dirty_background_ratio;
 130 extern unsigned long dirty_background_bytes;
 131 extern int vm_dirty_ratio;
 132 extern unsigned long vm_dirty_bytes;
 133 extern unsigned int dirty_writeback_interval;
 134 extern unsigned int dirty_expire_interval;
 135 extern int vm_highmem_is_dirtyable;
 136 extern int block_dump;
 137 extern int laptop_mode;
 138
 139 extern unsigned long determine_dirtyable_memory(void);
 140
 141 extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
 142                 void __user *buffer, size_t *lenp,
 143                 loff_t *ppos);
 144 extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
 145                 void __user *buffer, size_t *lenp,
 146                 loff_t *ppos);
 147 extern int dirty_ratio_handler(struct ctl_table *table, int write,
 148                 void __user *buffer, size_t *lenp,
 149                 loff_t *ppos);
 150 extern int dirty_bytes_handler(struct ctl_table *table, int write,
 151                 void __user *buffer, size_t *lenp,
 152                 loff_t *ppos);
 153
 154 struct ctl_table;
 155 int dirty_writeback_centisecs_handler(struct ctl_table *, int,
 156                                       void __user *, size_t *, loff_t *);
 157
 158 void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
 159                       unsigned long *pbdi_dirty, struct backing_dev_info *bdi);
 160
 161 void page_writeback_init(void);
 162 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 163                                         unsigned long nr_pages_dirtied);
 164
 165 static inline void
 166 balance_dirty_pages_ratelimited(struct address_space *mapping)
 167 {
 168         balance_dirty_pages_ratelimited_nr(mapping, 1);
 169 }
 170
 171 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
 172                                 void *data);
 173
 174 int generic_writepages(struct address_space *mapping,
 175                        struct writeback_control *wbc);
 176 int write_cache_pages(struct address_space *mapping,
 177                       struct writeback_control *wbc, writepage_t writepage,
 178                       void *data);
 179 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 180 void set_page_dirty_balance(struct page *page, int page_mkwrite);
 181 void writeback_set_ratelimit(void);
 182
 183 /* pdflush.c */
 184 extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
 185                                    read-only. */
 186
 187
 188 #endif          /* WRITEBACK_H */