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_background:1;      /* A background writeback */
  53        unsigned for_reclaim:1;         /* Invoked from the page allocator */
  54        unsigned range_cyclic:1;        /* range_start is cyclic */
  55        unsigned more_io:1;             /* more io to be dispatched */
  56        /*
  57         * write_cache_pages() won't update wbc->nr_to_write and
  58         * mapping->writeback_index if no_nrwrite_index_update
  59         * is set.  write_cache_pages() may write more than we
  60         * requested and we want to make sure nr_to_write and
  61         * writeback_index are updated in a consistent manner
  62         * so we use a single control to update them
  63         */
  64        unsigned no_nrwrite_index_update:1;
  65};
  66
  67/*
  68 * fs/fs-writeback.c
  69 */     
  70struct bdi_writeback;
  71int inode_wait(void *);
  72void writeback_inodes_sb(struct super_block *);
  73int writeback_inodes_sb_if_idle(struct super_block *);
  74void sync_inodes_sb(struct super_block *);
  75void writeback_inodes_wbc(struct writeback_control *wbc);
  76long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
  77void wakeup_flusher_threads(long nr_pages);
  78
  79/* writeback.h requires fs.h; it, too, is not included from here. */
  80static inline void wait_on_inode(struct inode *inode)
  81{
  82        might_sleep();
  83        wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
  84}
  85static inline void inode_sync_wait(struct inode *inode)
  86{
  87        might_sleep();
  88        wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
  89                                                        TASK_UNINTERRUPTIBLE);
  90}
  91
  92
  93/*
  94 * mm/page-writeback.c
  95 */
  96void laptop_io_completion(void);
  97void laptop_sync_completion(void);
  98void throttle_vm_writeout(gfp_t gfp_mask);
  99
 100/* These are exported to sysctl. */
 101extern int dirty_background_ratio;
 102extern unsigned long dirty_background_bytes;
 103extern int vm_dirty_ratio;
 104extern unsigned long vm_dirty_bytes;
 105extern unsigned int dirty_writeback_interval;
 106extern unsigned int dirty_expire_interval;
 107extern int vm_highmem_is_dirtyable;
 108extern int block_dump;
 109extern int laptop_mode;
 110
 111extern unsigned long determine_dirtyable_memory(void);
 112
 113extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
 114                void __user *buffer, size_t *lenp,
 115                loff_t *ppos);
 116extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
 117                void __user *buffer, size_t *lenp,
 118                loff_t *ppos);
 119extern int dirty_ratio_handler(struct ctl_table *table, int write,
 120                void __user *buffer, size_t *lenp,
 121                loff_t *ppos);
 122extern int dirty_bytes_handler(struct ctl_table *table, int write,
 123                void __user *buffer, size_t *lenp,
 124                loff_t *ppos);
 125
 126struct ctl_table;
 127int dirty_writeback_centisecs_handler(struct ctl_table *, int,
 128                                      void __user *, size_t *, loff_t *);
 129
 130void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
 131                      unsigned long *pbdi_dirty, struct backing_dev_info *bdi);
 132
 133void page_writeback_init(void);
 134void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 135                                        unsigned long nr_pages_dirtied);
 136
 137static inline void
 138balance_dirty_pages_ratelimited(struct address_space *mapping)
 139{
 140        balance_dirty_pages_ratelimited_nr(mapping, 1);
 141}
 142
 143typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
 144                                void *data);
 145
 146int generic_writepages(struct address_space *mapping,
 147                       struct writeback_control *wbc);
 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);
 154
 155/* pdflush.c */
 156extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
 157                                   read-only. */
 158
 159
 160#endif          /* WRITEBACK_H */
 161