/*
* 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_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 */
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)
#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);
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 *, sector_t, int);
struct buffer_head * __getblk(struct block_device *, sector_t, int);
void __brelse(struct buffer_head *);
void __bforget(struct buffer_head *);
void __breadahead(struct block_device *, sector_t block, int size);
struct buffer_head *__bread(struct block_device *, sector_t block, int size);
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_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*,
loff_t *);
int generic_cont_expand(struct inode *inode, loff_t size);
int generic_cont_expand_simple(struct inode *inode, loff_t size);
int block_commit_write(struct page *page, unsigned from, unsigned to);
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_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
int nobh_commit_write(struct file *, struct page *, unsigned, unsigned);
int nobh_truncate_page(struct address_space *, loff_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, int destroy_dirty_buffers) {}
#endif /* CONFIG_BLOCK */
#endif /* _LINUX_BUFFER_HEAD_H */
