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        long nr_to_write;               /* Write this many pages, and decrement
  38                                           this for each page written */
  39        long pages_skipped;             /* Pages which were not written */
  40
  41        /*
  42         * For a_ops->writepages(): is start or end are non-zero then this is
  43         * a hint that the filesystem need only write out the pages inside that
  44         * byterange.  The byte at `end' is included in the writeout request.
  45         */
  46        loff_t range_start;
  47        loff_t range_end;
  48
  49        unsigned nonblocking:1;         /* Don't get stuck on request queues */
  50        unsigned encountered_congestion:1; /* An output: a queue is full */
  51        unsigned for_kupdate:1;         /* A kupdate writeback */
  52        unsigned for_reclaim:1;         /* Invoked from the page allocator */
  53        unsigned range_cyclic:1;        /* range_start is cyclic */
  54        unsigned more_io:1;             /* more io to be dispatched */
  55        /*
  56         * write_cache_pages() won't update wbc->nr_to_write and
  57         * mapping->writeback_index if no_nrwrite_index_update
  58         * is set.  write_cache_pages() may write more than we
  59         * requested and we want to make sure nr_to_write and
  60         * writeback_index are updated in a consistent manner
  61         * so we use a single control to update them
  62         */
  63        unsigned no_nrwrite_index_update:1;
  64};
  65
  66/*
  67 * fs/fs-writeback.c
  68 */     
  69struct bdi_writeback;
  70int inode_wait(void *);
  71void writeback_inodes_sb(struct super_block *);
  72void sync_inodes_sb(struct super_block *);
  73void writeback_inodes_wbc(struct writeback_control *wbc);
  74long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
  75void wakeup_flusher_threads(long nr_pages);
  76
  77/* writeback.h requires fs.h; it, too, is not included from here. */
  78static inline void wait_on_inode(struct inode *inode)
  79{
  80        might_sleep();
  81        wait_on_bit(&inode->i_state, __I_LOCK, inode_wait,
  82                                                        TASK_UNINTERRUPTIBLE);
  83}
  84static inline void inode_sync_wait(struct inode *inode)
  85{
  86        might_sleep();
  87        wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
  88                                                        TASK_UNINTERRUPTIBLE);
  89}
  90
  91
  92/*
  93 * mm/page-writeback.c
  94 */
  95void laptop_io_completion(void);
  96void laptop_sync_completion(void);
  97void throttle_vm_writeout(gfp_t gfp_mask);
  98
  99/* These are exported to sysctl. */
 100extern int dirty_background_ratio;
 101extern unsigned long dirty_background_bytes;
 102extern int vm_dirty_ratio;
 103extern unsigned long vm_dirty_bytes;
 104extern unsigned int dirty_writeback_interval;
 105extern unsigned int dirty_expire_interval;
 106extern int vm_highmem_is_dirtyable;
 107extern int block_dump;
 108extern int laptop_mode;
 109
 110extern unsigned long determine_dirtyable_memory(void);
 111
 112extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
 113                void __user *buffer, size_t *lenp,
 114                loff_t *ppos);
 115extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
 116                void __user *buffer, size_t *lenp,
 117                loff_t *ppos);
 118extern int dirty_ratio_handler(struct ctl_table *table, int write,
 119                void __user *buffer, size_t *lenp,
 120                loff_t *ppos);
 121extern int dirty_bytes_handler(struct ctl_table *table, int write,
 122                void __user *buffer, size_t *lenp,
 123                loff_t *ppos);
 124
 125struct ctl_table;
 126int dirty_writeback_centisecs_handler(struct ctl_table *, int,
 127                                      void __user *, size_t *, loff_t *);
 128
 129void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
 130                      unsigned long *pbdi_dirty, struct backing_dev_info *bdi);
 131
 132void page_writeback_init(void);
 133void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 134                                        unsigned long nr_pages_dirtied);
 135
 136static inline void
 137balance_dirty_pages_ratelimited(struct address_space *mapping)
 138{
 139        balance_dirty_pages_ratelimited_nr(mapping, 1);
 140}
 141
 142typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
 143                                void *data);
 144
 145int generic_writepages(struct address_space *mapping,
 146                       struct writeback_control *wbc);
 147int write_cache_pages(struct address_space *mapping,
 148                      struct writeback_control *wbc, writepage_t writepage,
 149                      void *data);
 150int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 151void set_page_dirty_balance(struct page *page, int page_mkwrite);
 152void writeback_set_ratelimit(void);
 153
 154/* pdflush.c */
 155extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
 156                                   read-only. */
 157
 158
 159#endif          /* WRITEBACK_H */
 160