/* * 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 <linux/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_Unwritten,	/* Buffer is allocated on disk but not written */	BH_Quiet,	/* Buffer Error Prinks to be quiet */ 	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)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(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 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);void end_buffer_async_write(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 __wait_on_buffer(struct buffer_head *);wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);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 unlock_buffer(struct buffer_head *bh);void __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 __sync_dirty_buffer(struct buffer_head *bh, int rw);void write_dirty_buffer(struct buffer_head *bh, int rw);int submit_bh(int, struct buffer_head *);void write_boundary_block(struct block_device *bdev,			sector_t bblock, unsigned blocksize);int bh_uptodate_or_lock(struct buffer_head *bh);int bh_submit_read(struct buffer_head *bh); 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_write_full_page_endio(struct page *page, get_block_t *get_block,			struct writeback_control *wbc, bh_end_io_t *handler);int block_read_full_page(struct page*, get_block_t*);int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,				unsigned long from);int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,		unsigned flags, struct page **pagep, get_block_t *get_block);int __block_write_begin(struct page *page, loff_t pos, unsigned len,		get_block_t *get_block);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 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 vm_fault *vmf,				get_block_t get_block);int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,				get_block_t get_block);/* Convert errno to return value from ->page_mkwrite() call */static inline int block_page_mkwrite_return(int err){	if (err == 0)		return VM_FAULT_LOCKED;	if (err == -EFAULT)		return VM_FAULT_NOPAGE;	if (err == -ENOMEM)		return VM_FAULT_OOM;	if (err == -EAGAIN)		return VM_FAULT_RETRY;	/* -ENOSPC, -EDQUOT, -EIO ... */	return VM_FAULT_SIGBUS;}sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);int block_truncate_page(struct address_space *, loff_t, get_block_t *);int nobh_write_begin(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 voidsb_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 voidmap_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;} static inline void wait_on_buffer(struct buffer_head *bh){	might_sleep();	if (buffer_locked(bh))		__wait_on_buffer(bh);} static inline int trylock_buffer(struct buffer_head *bh){	return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));} static inline void lock_buffer(struct buffer_head *bh){	might_sleep();	if (!trylock_buffer(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 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; } #endif /* CONFIG_BLOCK */#endif /* _LINUX_BUFFER_HEAD_H */