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/*

 * include/linux/buffer_head.h

 *

 * Everything to do with buffer_heads.

 */

#ifndef _LINUX_BUFFER_HEAD_H

#define _LINUX_BUFFER_HEAD_H

#include <linux/types.h>

#include <linux/fs.h>

#include <linux/linkage.h>

#include <linux/pagemap.h>

#include <linux/wait.h>

#include <asm/atomic.h>

#ifdef CONFIG_BLOCK

enum bh_state_bits {

        BH_Uptodate,    /* Contains valid data */

        BH_Dirty,       /* Is dirty */

        BH_Lock,        /* Is locked */

        BH_Req,         /* Has been submitted for I/O */

        BH_Uptodate_Lock,/* Used by the first bh in a page, to serialise

                          * IO completion of other buffers in the page

                          */

        BH_Mapped,      /* Has a disk mapping */

        BH_New,         /* Disk mapping was newly created by get_block */

        BH_Async_Read,  /* Is under end_buffer_async_read I/O */

        BH_Async_Write, /* Is under end_buffer_async_write I/O */

        BH_Delay,       /* Buffer is not yet allocated on disk */

        BH_Boundary,    /* Block is followed by a discontiguity */

        BH_Write_EIO,   /* I/O error on write */

        BH_Ordered,     /* ordered write */

        BH_Eopnotsupp,  /* operation not supported (barrier) */

        BH_Unwritten,   /* Buffer is allocated on disk but not written */

        BH_PrivateStart,/* not a state bit, but the first bit available

                         * for private allocation by other entities

                         */

};

#define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)

struct page;

struct buffer_head;

struct address_space;

typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);

/*

 * Historically, a buffer_head was used to map a single block

 * within a page, and of course as the unit of I/O through the

 * filesystem and block layers.  Nowadays the basic I/O unit

 * is the bio, and buffer_heads are used for extracting block

 * mappings (via a get_block_t call), for tracking state within

 * a page (via a page_mapping) and for wrapping bio submission

 * for backward compatibility reasons (e.g. submit_bh).

 */

struct buffer_head {

        unsigned long b_state;          /* buffer state bitmap (see above) */

        struct buffer_head *b_this_page;/* circular list of page's buffers */

        struct page *b_page;            /* the page this bh is mapped to */

        sector_t b_blocknr;             /* start block number */

        size_t b_size;                  /* size of mapping */

        char *b_data;                   /* pointer to data within the page */

        struct block_device *b_bdev;

        bh_end_io_t *b_end_io;          /* I/O completion */

        void *b_private;                /* reserved for b_end_io */

        struct list_head b_assoc_buffers; /* associated with another mapping */

        struct address_space *b_assoc_map;      /* mapping this buffer is

                                                   associated with */

        atomic_t b_count;               /* users using this buffer_head */

};

/*

 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()

 * and buffer_foo() functions.

 */

#define BUFFER_FNS(bit, name)                                           \

static inline void set_buffer_##name(struct buffer_head *bh)            \

{                                                                       \

        set_bit(BH_##bit, &(bh)->b_state);                              \

}                                                                       \

static inline void clear_buffer_##name(struct buffer_head *bh)          \

{                                                                       \

        clear_bit(BH_##bit, &(bh)->b_state);                            \

}                                                                       \

static inline int buffer_##name(const struct buffer_head *bh)           \

{                                                                       \

        return test_bit(BH_##bit, &(bh)->b_state);                      \

}

/*

 * test_set_buffer_foo() and test_clear_buffer_foo()

 */

#define TAS_BUFFER_FNS(bit, name)                                       \

static inline int test_set_buffer_##name(struct buffer_head *bh)        \

{                                                                       \

        return test_and_set_bit(BH_##bit, &(bh)->b_state);              \

}                                                                       \

static inline int test_clear_buffer_##name(struct buffer_head *bh)      \

{                                                                       \

        return test_and_clear_bit(BH_##bit, &(bh)->b_state);            \

}                                                                       \

/*

 * Emit the buffer bitops functions.   Note that there are also functions

 * of the form "mark_buffer_foo()".  These are higher-level functions which

 * do something in addition to setting a b_state bit.

 */

BUFFER_FNS(Uptodate, uptodate)

BUFFER_FNS(Dirty, dirty)

TAS_BUFFER_FNS(Dirty, dirty)

BUFFER_FNS(Lock, locked)

TAS_BUFFER_FNS(Lock, locked)

BUFFER_FNS(Req, req)

TAS_BUFFER_FNS(Req, req)

BUFFER_FNS(Mapped, mapped)

BUFFER_FNS(New, new)

BUFFER_FNS(Async_Read, async_read)

BUFFER_FNS(Async_Write, async_write)

BUFFER_FNS(Delay, delay)

BUFFER_FNS(Boundary, boundary)

BUFFER_FNS(Write_EIO, write_io_error)

BUFFER_FNS(Ordered, ordered)

BUFFER_FNS(Eopnotsupp, eopnotsupp)

BUFFER_FNS(Unwritten, unwritten)

#define bh_offset(bh)           ((unsigned long)(bh)->b_data & ~PAGE_MASK)

#define touch_buffer(bh)        mark_page_accessed(bh->b_page)

/* If we *know* page->private refers to buffer_heads */

#define page_buffers(page)                                      \

        ({                                                      \

                BUG_ON(!PagePrivate(page));                     \

                ((struct buffer_head *)page_private(page));     \

        })

#define page_has_buffers(page)  PagePrivate(page)

/*

 * Declarations

 */

void FASTCALL(mark_buffer_dirty(struct buffer_head *bh));

void init_buffer(struct buffer_head *, bh_end_io_t *, void *);

void set_bh_page(struct buffer_head *bh,

                struct page *page, unsigned long offset);

int try_to_free_buffers(struct page *);

struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,

                int retry);

void create_empty_buffers(struct page *, unsigned long,

                        unsigned long b_state);

void end_buffer_read_sync(struct buffer_head *bh, int uptodate);

void end_buffer_write_sync(struct buffer_head *bh, int uptodate);

/* Things to do with buffers at mapping->private_list */

void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);

int inode_has_buffers(struct inode *);

void invalidate_inode_buffers(struct inode *);

int remove_inode_buffers(struct inode *inode);

int sync_mapping_buffers(struct address_space *mapping);

void unmap_underlying_metadata(struct block_device *bdev, sector_t block);

void mark_buffer_async_write(struct buffer_head *bh);

void invalidate_bdev(struct block_device *);

int sync_blockdev(struct block_device *bdev);

void __wait_on_buffer(struct buffer_head *);

wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);

int fsync_bdev(struct block_device *);

struct super_block *freeze_bdev(struct block_device *);

void thaw_bdev(struct block_device *, struct super_block *);

int fsync_super(struct super_block *);

int fsync_no_super(struct block_device *);

struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,

                        unsigned size);

struct buffer_head *__getblk(struct block_device *bdev, sector_t block,

                        unsigned size);

void __brelse(struct buffer_head *);

void __bforget(struct buffer_head *);

void __breadahead(struct block_device *, sector_t block, unsigned int size);

struct buffer_head *__bread(struct block_device *, sector_t block, unsigned size);

void invalidate_bh_lrus(void);

struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);

void free_buffer_head(struct buffer_head * bh);

void FASTCALL(unlock_buffer(struct buffer_head *bh));

void FASTCALL(__lock_buffer(struct buffer_head *bh));

void ll_rw_block(int, int, struct buffer_head * bh[]);

int sync_dirty_buffer(struct buffer_head *bh);

int submit_bh(int, struct buffer_head *);

void write_boundary_block(struct block_device *bdev,

                        sector_t bblock, unsigned blocksize);

extern int buffer_heads_over_limit;

/*

 * Generic address_space_operations implementations for buffer_head-backed

 * address_spaces.

 */

void block_invalidatepage(struct page *page, unsigned long offset);

int block_write_full_page(struct page *page, get_block_t *get_block,

                                struct writeback_control *wbc);

int block_read_full_page(struct page*, get_block_t*);

int block_write_begin(struct file *, struct address_space *,

                                loff_t, unsigned, unsigned,

                                struct page **, void **, get_block_t*);

int block_write_end(struct file *, struct address_space *,

                                loff_t, unsigned, unsigned,

                                struct page *, void *);

int generic_write_end(struct file *, struct address_space *,

                                loff_t, unsigned, unsigned,

                                struct page *, void *);

void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);

int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);

int cont_write_begin(struct file *, struct address_space *, loff_t,

                        unsigned, unsigned, struct page **, void **,

                        get_block_t *, loff_t *);

int generic_cont_expand_simple(struct inode *inode, loff_t size);

int block_commit_write(struct page *page, unsigned from, unsigned to);

int block_page_mkwrite(struct vm_area_struct *vma, struct page *page,

                                get_block_t get_block);

void block_sync_page(struct page *);

sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);

int generic_commit_write(struct file *, struct page *, unsigned, unsigned);

int block_truncate_page(struct address_space *, loff_t, get_block_t *);

int file_fsync(struct file *, struct dentry *, int);

int nobh_write_begin(struct file *, struct address_space *,

                                loff_t, unsigned, unsigned,

                                struct page **, void **, get_block_t*);

int nobh_write_end(struct file *, struct address_space *,

                                loff_t, unsigned, unsigned,

                                struct page *, void *);

int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);

int nobh_writepage(struct page *page, get_block_t *get_block,

                        struct writeback_control *wbc);

void buffer_init(void);

/*

 * inline definitions

 */

static inline void attach_page_buffers(struct page *page,

                struct buffer_head *head)

{

        page_cache_get(page);

        SetPagePrivate(page);

        set_page_private(page, (unsigned long)head);

}

static inline void get_bh(struct buffer_head *bh)

{

        atomic_inc(&bh->b_count);

}

static inline void put_bh(struct buffer_head *bh)

{

        smp_mb__before_atomic_dec();

        atomic_dec(&bh->b_count);

}

static inline void brelse(struct buffer_head *bh)

{

        if (bh)

                __brelse(bh);

}

static inline void bforget(struct buffer_head *bh)

{

        if (bh)

                __bforget(bh);

}

static inline struct buffer_head *

sb_bread(struct super_block *sb, sector_t block)

{

        return __bread(sb->s_bdev, block, sb->s_blocksize);

}

static inline void

sb_breadahead(struct super_block *sb, sector_t block)

{

        __breadahead(sb->s_bdev, block, sb->s_blocksize);

}

static inline struct buffer_head *

sb_getblk(struct super_block *sb, sector_t block)

{

        return __getblk(sb->s_bdev, block, sb->s_blocksize);

}

static inline struct buffer_head *

sb_find_get_block(struct super_block *sb, sector_t block)

{

        return __find_get_block(sb->s_bdev, block, sb->s_blocksize);

}

static inline void

map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)

{

        set_buffer_mapped(bh);

        bh->b_bdev = sb->s_bdev;

        bh->b_blocknr = block;

        bh->b_size = sb->s_blocksize;

}

/*

 * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into

 * __wait_on_buffer() just to trip a debug check.  Because debug code in inline

 * functions is bloaty.

 */

static inline void wait_on_buffer(struct buffer_head *bh)

{

        might_sleep();

        if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0)

                __wait_on_buffer(bh);

}

static inline void lock_buffer(struct buffer_head *bh)

{

        might_sleep();

        if (test_set_buffer_locked(bh))

                __lock_buffer(bh);

}

extern int __set_page_dirty_buffers(struct page *page);

#else /* CONFIG_BLOCK */

static inline void buffer_init(void) {}

static inline int try_to_free_buffers(struct page *page) { return 1; }

static inline int sync_blockdev(struct block_device *bdev) { return 0; }

static inline int inode_has_buffers(struct inode *inode) { return 0; }

static inline void invalidate_inode_buffers(struct inode *inode) {}

static inline int remove_inode_buffers(struct inode *inode) { return 1; }

static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }

static inline void invalidate_bdev(struct block_device *bdev) {}

#endif /* CONFIG_BLOCK */

#endif /* _LINUX_BUFFER_HEAD_H */