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/workqueue.h>
   9#include <linux/fs.h>
  10
  11DECLARE_PER_CPU(int, dirty_throttle_leaks);
  12
  13/*
  14 * The 1/4 region under the global dirty thresh is for smooth dirty throttling:
  15 *
  16 *      (thresh - thresh/DIRTY_FULL_SCOPE, thresh)
  17 *
  18 * Further beyond, all dirtier tasks will enter a loop waiting (possibly long
  19 * time) for the dirty pages to drop, unless written enough pages.
  20 *
  21 * The global dirty threshold is normally equal to the global dirty limit,
  22 * except when the system suddenly allocates a lot of anonymous memory and
  23 * knocks down the global dirty threshold quickly, in which case the global
  24 * dirty limit will follow down slowly to prevent livelocking all dirtier tasks.
  25 */
  26#define DIRTY_SCOPE             8
  27#define DIRTY_FULL_SCOPE        (DIRTY_SCOPE / 2)
  28
  29struct backing_dev_info;
  30
  31/*
  32 * fs/fs-writeback.c
  33 */
  34enum writeback_sync_modes {
  35        WB_SYNC_NONE,   /* Don't wait on anything */
  36        WB_SYNC_ALL,    /* Wait on every mapping */
  37};
  38
  39/*
  40 * why some writeback work was initiated
  41 */
  42enum wb_reason {
  43        WB_REASON_BACKGROUND,
  44        WB_REASON_TRY_TO_FREE_PAGES,
  45        WB_REASON_SYNC,
  46        WB_REASON_PERIODIC,
  47        WB_REASON_LAPTOP_TIMER,
  48        WB_REASON_FREE_MORE_MEM,
  49        WB_REASON_FS_FREE_SPACE,
  50        WB_REASON_FORKER_THREAD,
  51
  52        WB_REASON_MAX,
  53};
  54extern const char *wb_reason_name[];
  55
  56/*
  57 * A control structure which tells the writeback code what to do.  These are
  58 * always on the stack, and hence need no locking.  They are always initialised
  59 * in a manner such that unspecified fields are set to zero.
  60 */
  61struct writeback_control {
  62        long nr_to_write;               /* Write this many pages, and decrement
  63                                           this for each page written */
  64        long pages_skipped;             /* Pages which were not written */
  65
  66        /*
  67         * For a_ops->writepages(): if start or end are non-zero then this is
  68         * a hint that the filesystem need only write out the pages inside that
  69         * byterange.  The byte at `end' is included in the writeout request.
  70         */
  71        loff_t range_start;
  72        loff_t range_end;
  73
  74        enum writeback_sync_modes sync_mode;
  75
  76        unsigned for_kupdate:1;         /* A kupdate writeback */
  77        unsigned for_background:1;      /* A background writeback */
  78        unsigned tagged_writepages:1;   /* tag-and-write to avoid livelock */
  79        unsigned for_reclaim:1;         /* Invoked from the page allocator */
  80        unsigned range_cyclic:1;        /* range_start is cyclic */
  81};
  82
  83/*
  84 * fs/fs-writeback.c
  85 */     
  86struct bdi_writeback;
  87int inode_wait(void *);
  88void writeback_inodes_sb(struct super_block *, enum wb_reason reason);
  89void writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
  90                                                        enum wb_reason reason);
  91int try_to_writeback_inodes_sb(struct super_block *, enum wb_reason reason);
  92int try_to_writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
  93                                  enum wb_reason reason);
  94void sync_inodes_sb(struct super_block *);
  95long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages,
  96                                enum wb_reason reason);
  97long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
  98void wakeup_flusher_threads(long nr_pages, enum wb_reason reason);
  99void inode_wait_for_writeback(struct inode *inode);
 100
 101/* writeback.h requires fs.h; it, too, is not included from here. */
 102static inline void wait_on_inode(struct inode *inode)
 103{
 104        might_sleep();
 105        wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
 106}
 107
 108/*
 109 * mm/page-writeback.c
 110 */
 111#ifdef CONFIG_BLOCK
 112void laptop_io_completion(struct backing_dev_info *info);
 113void laptop_sync_completion(void);
 114void laptop_mode_sync(struct work_struct *work);
 115void laptop_mode_timer_fn(unsigned long data);
 116#else
 117static inline void laptop_sync_completion(void) { }
 118#endif
 119void throttle_vm_writeout(gfp_t gfp_mask);
 120bool zone_dirty_ok(struct zone *zone);
 121
 122extern unsigned long global_dirty_limit;
 123
 124/* These are exported to sysctl. */
 125extern int dirty_background_ratio;
 126extern unsigned long dirty_background_bytes;
 127extern int vm_dirty_ratio;
 128extern unsigned long vm_dirty_bytes;
 129extern unsigned int dirty_writeback_interval;
 130extern unsigned int dirty_expire_interval;
 131extern int vm_highmem_is_dirtyable;
 132extern int block_dump;
 133extern int laptop_mode;
 134
 135extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
 136                void __user *buffer, size_t *lenp,
 137                loff_t *ppos);
 138extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
 139                void __user *buffer, size_t *lenp,
 140                loff_t *ppos);
 141extern int dirty_ratio_handler(struct ctl_table *table, int write,
 142                void __user *buffer, size_t *lenp,
 143                loff_t *ppos);
 144extern int dirty_bytes_handler(struct ctl_table *table, int write,
 145                void __user *buffer, size_t *lenp,
 146                loff_t *ppos);
 147
 148struct ctl_table;
 149int dirty_writeback_centisecs_handler(struct ctl_table *, int,
 150                                      void __user *, size_t *, loff_t *);
 151
 152void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
 153unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
 154                               unsigned long dirty);
 155
 156void __bdi_update_bandwidth(struct backing_dev_info *bdi,
 157                            unsigned long thresh,
 158                            unsigned long bg_thresh,
 159                            unsigned long dirty,
 160                            unsigned long bdi_thresh,
 161                            unsigned long bdi_dirty,
 162                            unsigned long start_time);
 163
 164void page_writeback_init(void);
 165void balance_dirty_pages_ratelimited(struct address_space *mapping);
 166
 167typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
 168                                void *data);
 169
 170int generic_writepages(struct address_space *mapping,
 171                       struct writeback_control *wbc);
 172void tag_pages_for_writeback(struct address_space *mapping,
 173                             pgoff_t start, pgoff_t end);
 174int write_cache_pages(struct address_space *mapping,
 175                      struct writeback_control *wbc, writepage_t writepage,
 176                      void *data);
 177int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 178void set_page_dirty_balance(struct page *page, int page_mkwrite);
 179void writeback_set_ratelimit(void);
 180void tag_pages_for_writeback(struct address_space *mapping,
 181                             pgoff_t start, pgoff_t end);
 182
 183void account_page_redirty(struct page *page);
 184
 185#endif          /* WRITEBACK_H */
 186