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/*
 * include/linux/writeback.h.
 */
#ifndef WRITEBACK_H
#define WRITEBACK_H

struct backing_dev_info;

extern spinlock_t inode_lock;
extern struct list_head inode_in_use;
extern struct list_head inode_unused;

/*
 * Yes, writeback.h requires sched.h
 * No, sched.h is not included from here.
 */
static inline int current_is_pdflush(void)
{
        return current->flags & PF_FLUSHER;
}

/*
 * fs/fs-writeback.c
 */
enum writeback_sync_modes {
        WB_SYNC_NONE,   /* Don't wait on anything */
        WB_SYNC_ALL,    /* Wait on every mapping */
        WB_SYNC_HOLD,   /* Hold the inode on sb_dirty for sys_sync() */
};

/*
 * A control structure which tells the writeback code what to do
 */
struct writeback_control {
        struct backing_dev_info *bdi;   /* If !NULL, only write back this
                                           queue */
        enum writeback_sync_modes sync_mode;
        unsigned long *older_than_this; /* If !NULL, only write back inodes
                                           older than this */
        long nr_to_write;               /* Write this many pages, and decrement
                                           this for each page written */
        int nonblocking;                /* Don't get stuck on request queues */
        int encountered_congestion;     /* An output: a queue is full */
        int for_kupdate;                /* A kupdate writeback */
        int for_reclaim;                /* Invoked from the page allocator */
};

/*
 * ->writepage() return values (make these much larger than a pagesize, in
 * case some fs is returning number-of-bytes-written from writepage)
 */
#define WRITEPAGE_ACTIVATE      0x80000 /* IO was not started: activate page */

/*
 * fs/fs-writeback.c
 */    
void writeback_inodes(struct writeback_control *wbc);
void wake_up_inode(struct inode *inode);
void __wait_on_inode(struct inode * inode);
void sync_inodes_sb(struct super_block *, int wait);
void sync_inodes(int wait);

/* writeback.h requires fs.h; it, too, is not included from here. */
static inline void wait_on_inode(struct inode *inode)
{
        if (inode->i_state & I_LOCK)
                __wait_on_inode(inode);
}

/*
 * mm/page-writeback.c
 */
int wakeup_bdflush(long nr_pages);

/* These 5 are exported to sysctl. */
extern int dirty_background_ratio;
extern int vm_dirty_ratio;
extern int dirty_writeback_centisecs;
extern int dirty_expire_centisecs;

struct ctl_table;
struct file;
int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,
                                      void __user *, size_t *);

void page_writeback_init(void);
void balance_dirty_pages_ratelimited(struct address_space *mapping);
int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
int do_writepages(struct address_space *mapping, struct writeback_control *wbc);

/* pdflush.c */
extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
                                   read-only. */


#endif          /* WRITEBACK_H */