LXR linux/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
  10struct backing_dev_info;
  11
  12extern spinlock_t inode_lock;
  13
  14/*
  15 * fs/fs-writeback.c
  16 */
  17enum 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 */
  27struct 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 for_reclaim:1;         /* Invoked from the page allocator */
  51        unsigned range_cyclic:1;        /* range_start is cyclic */
  52        unsigned more_io:1;             /* more io to be dispatched */
  53};
  54
  55/*
  56 * fs/fs-writeback.c
  57 */     
  58struct bdi_writeback;
  59int inode_wait(void *);
  60void writeback_inodes_sb(struct super_block *);
  61void writeback_inodes_sb_nr(struct super_block *, unsigned long nr);
  62int writeback_inodes_sb_if_idle(struct super_block *);
  63int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr);
  64void sync_inodes_sb(struct super_block *);
  65void writeback_inodes_wb(struct bdi_writeback *wb,
  66                struct writeback_control *wbc);
  67long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
  68void wakeup_flusher_threads(long nr_pages);
  69
  70/* writeback.h requires fs.h; it, too, is not included from here. */
  71static inline void wait_on_inode(struct inode *inode)
  72{
  73        might_sleep();
  74        wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
  75}
  76static inline void inode_sync_wait(struct inode *inode)
  77{
  78        might_sleep();
  79        wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
  80                                                        TASK_UNINTERRUPTIBLE);
  81}
  82
  83
  84/*
  85 * mm/page-writeback.c
  86 */
  87#ifdef CONFIG_BLOCK
  88void laptop_io_completion(struct backing_dev_info *info);
  89void laptop_sync_completion(void);
  90void laptop_mode_sync(struct work_struct *work);
  91void laptop_mode_timer_fn(unsigned long data);
  92#else
  93static inline void laptop_sync_completion(void) { }
  94#endif
  95void throttle_vm_writeout(gfp_t gfp_mask);
  96
  97/* These are exported to sysctl. */
  98extern int dirty_background_ratio;
  99extern unsigned long dirty_background_bytes;
 100extern int vm_dirty_ratio;
 101extern unsigned long vm_dirty_bytes;
 102extern unsigned int dirty_writeback_interval;
 103extern unsigned int dirty_expire_interval;
 104extern int vm_highmem_is_dirtyable;
 105extern int block_dump;
 106extern int laptop_mode;
 107
 108extern unsigned long determine_dirtyable_memory(void);
 109
 110extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
 111                void __user *buffer, size_t *lenp,
 112                loff_t *ppos);
 113extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
 114                void __user *buffer, size_t *lenp,
 115                loff_t *ppos);
 116extern int dirty_ratio_handler(struct ctl_table *table, int write,
 117                void __user *buffer, size_t *lenp,
 118                loff_t *ppos);
 119extern int dirty_bytes_handler(struct ctl_table *table, int write,
 120                void __user *buffer, size_t *lenp,
 121                loff_t *ppos);
 122
 123struct ctl_table;
 124int dirty_writeback_centisecs_handler(struct ctl_table *, int,
 125                                      void __user *, size_t *, loff_t *);
 126
 127void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
 128unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
 129                               unsigned long dirty);
 130
 131void page_writeback_init(void);
 132void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 133                                        unsigned long nr_pages_dirtied);
 134
 135static inline void
 136balance_dirty_pages_ratelimited(struct address_space *mapping)
 137{
 138        balance_dirty_pages_ratelimited_nr(mapping, 1);
 139}
 140
 141typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
 142                                void *data);
 143
 144int generic_writepages(struct address_space *mapping,
 145                       struct writeback_control *wbc);
 146void tag_pages_for_writeback(struct address_space *mapping,
 147                             pgoff_t start, pgoff_t end);
 148int write_cache_pages(struct address_space *mapping,
 149                      struct writeback_control *wbc, writepage_t writepage,
 150                      void *data);
 151int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 152void set_page_dirty_balance(struct page *page, int page_mkwrite);
 153void writeback_set_ratelimit(void);
 154void tag_pages_for_writeback(struct address_space *mapping,
 155                             pgoff_t start, pgoff_t end);
 156
 157/* pdflush.c */
 158extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
 159                                   read-only. */
 160
 161
 162#endif          /* WRITEBACK_H */
 163