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/*

 * include/linux/writeback.h

 */

#ifndef WRITEBACK_H

#define WRITEBACK_H

#include <linux/sched.h>

#include <linux/fs.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 task_is_pdflush(struct task_struct *task)

{

        return task->flags & PF_FLUSHER;

}

#define current_is_pdflush()    task_is_pdflush(current)

/*

 * 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.  These are

 * always on the stack, and hence need no locking.  They are always initialised

 * in a manner such that unspecified fields are set to zero.

 */

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 */

        long pages_skipped;             /* Pages which were not written */

        /*

         * For a_ops->writepages(): is start or end are non-zero then this is

         * a hint that the filesystem need only write out the pages inside that

         * byterange.  The byte at `end' is included in the writeout request.

         */

        loff_t range_start;

        loff_t range_end;

        unsigned nonblocking:1;         /* Don't get stuck on request queues */

        unsigned encountered_congestion:1; /* An output: a queue is full */

        unsigned for_kupdate:1;         /* A kupdate writeback */

        unsigned for_reclaim:1;         /* Invoked from the page allocator */

        unsigned for_writepages:1;      /* This is a writepages() call */

        unsigned range_cyclic:1;        /* range_start is cyclic */

};

/*

 * fs/fs-writeback.c

 */

void writeback_inodes(struct writeback_control *wbc);

int inode_wait(void *);

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)

{

        might_sleep();

        wait_on_bit(&inode->i_state, __I_LOCK, inode_wait,

                                                        TASK_UNINTERRUPTIBLE);

}

static inline void inode_sync_wait(struct inode *inode)

{

        might_sleep();

        wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,

                                                        TASK_UNINTERRUPTIBLE);

}

/*

 * mm/page-writeback.c

 */

int wakeup_pdflush(long nr_pages);

void laptop_io_completion(void);

void laptop_sync_completion(void);

void throttle_vm_writeout(gfp_t gfp_mask);

/* These are exported to sysctl. */

extern int dirty_background_ratio;

extern int vm_dirty_ratio;

extern int dirty_writeback_interval;

extern int dirty_expire_interval;

extern int block_dump;

extern int laptop_mode;

extern int dirty_ratio_handler(struct ctl_table *table, int write,

                struct file *filp, void __user *buffer, size_t *lenp,

                loff_t *ppos);

struct ctl_table;

struct file;

int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,

                                      void __user *, size_t *, loff_t *);

void page_writeback_init(void);

void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,

                                        unsigned long nr_pages_dirtied);

static inline void

balance_dirty_pages_ratelimited(struct address_space *mapping)

{

        balance_dirty_pages_ratelimited_nr(mapping, 1);

}

typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,

                                void *data);

int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);

int generic_writepages(struct address_space *mapping,

                       struct writeback_control *wbc);

int write_cache_pages(struct address_space *mapping,

                      struct writeback_control *wbc, writepage_t writepage,

                      void *data);

int do_writepages(struct address_space *mapping, struct writeback_control *wbc);

int sync_page_range(struct inode *inode, struct address_space *mapping,

                        loff_t pos, loff_t count);

int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,

                           loff_t pos, loff_t count);

void set_page_dirty_balance(struct page *page, int page_mkwrite);

void writeback_set_ratelimit(void);

/* pdflush.c */

extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl

                                   read-only. */

#endif          /* WRITEBACK_H */