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 * Yes, writeback.h requires sched.h
  18 * No, sched.h is not included from here.
  19 */
  20static inline int task_is_pdflush(struct task_struct *task)
  21{
  22        return task->flags & PF_FLUSHER;
  23}
  24
  25#define current_is_pdflush()    task_is_pdflush(current)
  26
  27/*
  28 * fs/fs-writeback.c
  29 */
  30enum writeback_sync_modes {
  31        WB_SYNC_NONE,   /* Don't wait on anything */
  32        WB_SYNC_ALL,    /* Wait on every mapping */
  33        WB_SYNC_HOLD,   /* Hold the inode on sb_dirty for sys_sync() */
  34};
  35
  36/*
  37 * A control structure which tells the writeback code what to do.  These are
  38 * always on the stack, and hence need no locking.  They are always initialised
  39 * in a manner such that unspecified fields are set to zero.
  40 */
  41struct writeback_control {
  42        struct backing_dev_info *bdi;   /* If !NULL, only write back this
  43                                           queue */
  44        enum writeback_sync_modes sync_mode;
  45        unsigned long *older_than_this; /* If !NULL, only write back inodes
  46                                           older than this */
  47        long nr_to_write;               /* Write this many pages, and decrement
  48                                           this for each page written */
  49        long pages_skipped;             /* Pages which were not written */
  50
  51        /*
  52         * For a_ops->writepages(): is start or end are non-zero then this is
  53         * a hint that the filesystem need only write out the pages inside that
  54         * byterange.  The byte at `end' is included in the writeout request.
  55         */
  56        loff_t range_start;
  57        loff_t range_end;
  58
  59        unsigned nonblocking:1;         /* Don't get stuck on request queues */
  60        unsigned encountered_congestion:1; /* An output: a queue is full */
  61        unsigned for_kupdate:1;         /* A kupdate writeback */
  62        unsigned for_reclaim:1;         /* Invoked from the page allocator */
  63        unsigned for_writepages:1;      /* This is a writepages() call */
  64        unsigned range_cyclic:1;        /* range_start is cyclic */
  65        unsigned more_io:1;             /* more io to be dispatched */
  66};
  67
  68/*
  69 * fs/fs-writeback.c
  70 */     
  71void writeback_inodes(struct writeback_control *wbc);
  72int inode_wait(void *);
  73void sync_inodes_sb(struct super_block *, int wait);
  74void sync_inodes(int wait);
  75
  76/* writeback.h requires fs.h; it, too, is not included from here. */
  77static inline void wait_on_inode(struct inode *inode)
  78{
  79        might_sleep();
  80        wait_on_bit(&inode->i_state, __I_LOCK, inode_wait,
  81                                                        TASK_UNINTERRUPTIBLE);
  82}
  83static inline void inode_sync_wait(struct inode *inode)
  84{
  85        might_sleep();
  86        wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
  87                                                        TASK_UNINTERRUPTIBLE);
  88}
  89
  90
  91/*
  92 * mm/page-writeback.c
  93 */
  94int wakeup_pdflush(long nr_pages);
  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 int vm_dirty_ratio;
 102extern int dirty_writeback_interval;
 103extern int dirty_expire_interval;
 104extern int vm_highmem_is_dirtyable;
 105extern int block_dump;
 106extern int laptop_mode;
 107
 108extern int dirty_ratio_handler(struct ctl_table *table, int write,
 109                struct file *filp, void __user *buffer, size_t *lenp,
 110                loff_t *ppos);
 111
 112struct ctl_table;
 113struct file;
 114int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,
 115                                      void __user *, size_t *, loff_t *);
 116
 117void get_dirty_limits(long *pbackground, long *pdirty, long *pbdi_dirty,
 118                 struct backing_dev_info *bdi);
 119
 120void page_writeback_init(void);
 121void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 122                                        unsigned long nr_pages_dirtied);
 123
 124static inline void
 125balance_dirty_pages_ratelimited(struct address_space *mapping)
 126{
 127        balance_dirty_pages_ratelimited_nr(mapping, 1);
 128}
 129
 130typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
 131                                void *data);
 132
 133int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
 134int generic_writepages(struct address_space *mapping,
 135                       struct writeback_control *wbc);
 136int write_cache_pages(struct address_space *mapping,
 137                      struct writeback_control *wbc, writepage_t writepage,
 138                      void *data);
 139int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 140int sync_page_range(struct inode *inode, struct address_space *mapping,
 141                        loff_t pos, loff_t count);
 142int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
 143                           loff_t pos, loff_t count);
 144void set_page_dirty_balance(struct page *page, int page_mkwrite);
 145void writeback_set_ratelimit(void);
 146
 147/* pdflush.c */
 148extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
 149                                   read-only. */
 150
 151
 152#endif          /* WRITEBACK_H */
 153