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;
  13extern struct list_head inode_in_use;
  14extern struct list_head inode_unused;
  15
  16/*
  17 * fs/fs-writeback.c
  18 */
  19enum 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 */
  29struct 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 */     
  73struct bdi_writeback;
  74int inode_wait(void *);
  75void writeback_inodes_sb(struct super_block *);
  76int writeback_inodes_sb_if_idle(struct super_block *);
  77void sync_inodes_sb(struct super_block *);
  78void writeback_inodes_wbc(struct writeback_control *wbc);
  79long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
  80void wakeup_flusher_threads(long nr_pages);
  81
  82/* writeback.h requires fs.h; it, too, is not included from here. */
  83static 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}
  88static 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 */
  99void laptop_io_completion(void);
 100void laptop_sync_completion(void);
 101void throttle_vm_writeout(gfp_t gfp_mask);
 102
 103/* These are exported to sysctl. */
 104extern int dirty_background_ratio;
 105extern unsigned long dirty_background_bytes;
 106extern int vm_dirty_ratio;
 107extern unsigned long vm_dirty_bytes;
 108extern unsigned int dirty_writeback_interval;
 109extern unsigned int dirty_expire_interval;
 110extern int vm_highmem_is_dirtyable;
 111extern int block_dump;
 112extern int laptop_mode;
 113
 114extern unsigned long determine_dirtyable_memory(void);
 115
 116extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
 117                void __user *buffer, size_t *lenp,
 118                loff_t *ppos);
 119extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
 120                void __user *buffer, size_t *lenp,
 121                loff_t *ppos);
 122extern int dirty_ratio_handler(struct ctl_table *table, int write,
 123                void __user *buffer, size_t *lenp,
 124                loff_t *ppos);
 125extern int dirty_bytes_handler(struct ctl_table *table, int write,
 126                void __user *buffer, size_t *lenp,
 127                loff_t *ppos);
 128
 129struct ctl_table;
 130int dirty_writeback_centisecs_handler(struct ctl_table *, int,
 131                                      void __user *, size_t *, loff_t *);
 132
 133void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
 134                      unsigned long *pbdi_dirty, struct backing_dev_info *bdi);
 135
 136void page_writeback_init(void);
 137void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 138                                        unsigned long nr_pages_dirtied);
 139
 140static inline void
 141balance_dirty_pages_ratelimited(struct address_space *mapping)
 142{
 143        balance_dirty_pages_ratelimited_nr(mapping, 1);
 144}
 145
 146typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
 147                                void *data);
 148
 149int generic_writepages(struct address_space *mapping,
 150                       struct writeback_control *wbc);
 151int write_cache_pages(struct address_space *mapping,
 152                      struct writeback_control *wbc, writepage_t writepage,
 153                      void *data);
 154int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 155void set_page_dirty_balance(struct page *page, int page_mkwrite);
 156void writeback_set_ratelimit(void);
 157
 158/* pdflush.c */
 159extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
 160                                   read-only. */
 161
 162
 163#endif          /* WRITEBACK_H */
 164