[linux-block.git] / include / linux / buffer_head.h

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * 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/blk_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_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_Meta,	/* Buffer contains metadata */
	BH_Prio,	/* Buffer should be submitted with REQ_PRIO */
	BH_Defer_Completion, /* Defer AIO completion to workqueue */

	BH_PrivateStart,/* not a state bit, but the first bit available
			 * for private allocation by other entities
			 */
};

#define MAX_BUF_PER_PAGE (PAGE_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 */
	spinlock_t b_uptodate_lock;	/* Used by the first bh in a page, to
					 * serialise IO completion of other
					 * buffers in the page */
};

/*
 * macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
 * and buffer_foo() functions.
 * To avoid reset buffer flags that are already set, because that causes
 * a costly cache line transition, check the flag first.
 */
#define BUFFER_FNS(bit, name)						\
static __always_inline void set_buffer_##name(struct buffer_head *bh)	\
{									\
	if (!test_bit(BH_##bit, &(bh)->b_state))			\
		set_bit(BH_##bit, &(bh)->b_state);			\
}									\
static __always_inline void clear_buffer_##name(struct buffer_head *bh)	\
{									\
	clear_bit(BH_##bit, &(bh)->b_state);				\
}									\
static __always_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 __always_inline int test_set_buffer_##name(struct buffer_head *bh) \
{									\
	return test_and_set_bit(BH_##bit, &(bh)->b_state);		\
}									\
static __always_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(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)
BUFFER_FNS(Meta, meta)
BUFFER_FNS(Prio, prio)
BUFFER_FNS(Defer_Completion, defer_completion)

static __always_inline void set_buffer_uptodate(struct buffer_head *bh)
{
	/*
	 * make it consistent with folio_mark_uptodate
	 * pairs with smp_load_acquire in buffer_uptodate
	 */
	smp_mb__before_atomic();
	set_bit(BH_Uptodate, &bh->b_state);
}

static __always_inline void clear_buffer_uptodate(struct buffer_head *bh)
{
	clear_bit(BH_Uptodate, &bh->b_state);
}

static __always_inline int buffer_uptodate(const struct buffer_head *bh)
{
	/*
	 * make it consistent with folio_test_uptodate
	 * pairs with smp_mb__before_atomic in set_buffer_uptodate
	 */
	return (smp_load_acquire(&bh->b_state) & (1UL << BH_Uptodate)) != 0;
}

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

/* 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)
#define folio_buffers(folio)		folio_get_private(folio)

void buffer_check_dirty_writeback(struct folio *folio,
				     bool *dirty, bool *writeback);

/*
 * Declarations
 */

void mark_buffer_dirty(struct buffer_head *bh);
void mark_buffer_write_io_error(struct buffer_head *bh);
void touch_buffer(struct buffer_head *bh);
void set_bh_page(struct buffer_head *bh,
		struct page *page, unsigned long offset);
bool try_to_free_buffers(struct folio *);
struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
		bool 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 clean_bdev_aliases(struct block_device *bdev, sector_t block,
			sector_t len);
static inline void clean_bdev_bh_alias(struct buffer_head *bh)
{
	clean_bdev_aliases(bh->b_bdev, bh->b_blocknr, 1);
}

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_gfp(struct block_device *bdev, sector_t block,
				  unsigned size, gfp_t gfp);
void __brelse(struct buffer_head *);
void __bforget(struct buffer_head *);
void __breadahead(struct block_device *, sector_t block, unsigned int size);
void __breadahead_gfp(struct block_device *, sector_t block, unsigned int size,
		  gfp_t gfp);
struct buffer_head *__bread_gfp(struct block_device *,
				sector_t block, unsigned size, gfp_t gfp);
void invalidate_bh_lrus(void);
void invalidate_bh_lrus_cpu(void);
bool has_bh_in_lru(int cpu, void *dummy);
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(blk_opf_t, int, struct buffer_head * bh[]);
int sync_dirty_buffer(struct buffer_head *bh);
int __sync_dirty_buffer(struct buffer_head *bh, blk_opf_t op_flags);
void write_dirty_buffer(struct buffer_head *bh, blk_opf_t op_flags);
int submit_bh(blk_opf_t, 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_invalidate_folio(struct folio *folio, size_t offset, size_t length);
int block_write_full_page(struct page *page, get_block_t *get_block,
				struct writeback_control *wbc);
int __block_write_full_page(struct inode *inode, struct page *page,
			get_block_t *get_block, struct writeback_control *wbc,
			bh_end_io_t *handler);
int block_read_full_folio(struct folio *, get_block_t *);
bool block_is_partially_uptodate(struct folio *, size_t from, size_t count);
int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
		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);
void clean_page_buffers(struct page *page);
int cont_write_begin(struct file *, struct address_space *, loff_t,
			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);
/* Convert errno to return value from ->page_mkwrite() call */
static inline vm_fault_t block_page_mkwrite_return(int err)
{
	if (err == 0)
		return VM_FAULT_LOCKED;
	if (err == -EFAULT || err == -EAGAIN)
		return VM_FAULT_NOPAGE;
	if (err == -ENOMEM)
		return VM_FAULT_OOM;
	/* -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 *);

#ifdef CONFIG_MIGRATION
extern int buffer_migrate_folio(struct address_space *,
		struct folio *dst, struct folio *src, enum migrate_mode);
extern int buffer_migrate_folio_norefs(struct address_space *,
		struct folio *dst, struct folio *src, enum migrate_mode);
#else
#define buffer_migrate_folio NULL
#define buffer_migrate_folio_norefs NULL
#endif

void buffer_init(void);

/*
 * inline definitions
 */

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();
        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_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
}

static inline struct buffer_head *
sb_bread_unmovable(struct super_block *sb, sector_t block)
{
	return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, 0);
}

static inline void
sb_breadahead(struct super_block *sb, sector_t block)
{
	__breadahead(sb->s_bdev, block, sb->s_blocksize);
}

static inline void
sb_breadahead_unmovable(struct super_block *sb, sector_t block)
{
	__breadahead_gfp(sb->s_bdev, block, sb->s_blocksize, 0);
}

static inline struct buffer_head *
sb_getblk(struct super_block *sb, sector_t block)
{
	return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
}


static inline struct buffer_head *
sb_getblk_gfp(struct super_block *sb, sector_t block, gfp_t gfp)
{
	return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, gfp);
}

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;
}

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);
}

static inline struct buffer_head *getblk_unmovable(struct block_device *bdev,
						   sector_t block,
						   unsigned size)
{
	return __getblk_gfp(bdev, block, size, 0);
}

static inline struct buffer_head *__getblk(struct block_device *bdev,
					   sector_t block,
					   unsigned size)
{
	return __getblk_gfp(bdev, block, size, __GFP_MOVABLE);
}

/**
 *  __bread() - reads a specified block and returns the bh
 *  @bdev: the block_device to read from
 *  @block: number of block
 *  @size: size (in bytes) to read
 *
 *  Reads a specified block, and returns buffer head that contains it.
 *  The page cache is allocated from movable area so that it can be migrated.
 *  It returns NULL if the block was unreadable.
 */
static inline struct buffer_head *
__bread(struct block_device *bdev, sector_t block, unsigned size)
{
	return __bread_gfp(bdev, block, size, __GFP_MOVABLE);
}

bool block_dirty_folio(struct address_space *mapping, struct folio *folio);

#else /* CONFIG_BLOCK */

static inline void buffer_init(void) {}
static inline bool try_to_free_buffers(struct folio *folio) { return true; }
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_bh_lrus_cpu(void) {}
static inline bool has_bh_in_lru(int cpu, void *dummy) { return false; }
#define buffer_heads_over_limit 0

#endif /* CONFIG_BLOCK */
#endif /* _LINUX_BUFFER_HEAD_H */
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
1da177e4 LT	2	/*
	3	* include/linux/buffer_head.h
	4	*
	5	* Everything to do with buffer_heads.
	6	*/
	7
	8	#ifndef _LINUX_BUFFER_HEAD_H
	9	#define _LINUX_BUFFER_HEAD_H
	10
	11	#include <linux/types.h>
3ae72869	12	#include <linux/blk_types.h>
1da177e4 LT	13	#include <linux/fs.h>
	14	#include <linux/linkage.h>
	15	#include <linux/pagemap.h>
	16	#include <linux/wait.h>
60063497	17	#include <linux/atomic.h>
1da177e4	18
9361401e DH	19	#ifdef CONFIG_BLOCK
9361401e DH	20
1da177e4 LT	21	enum bh_state_bits {
	22	BH_Uptodate, /* Contains valid data */
	23	BH_Dirty, /* Is dirty */
	24	BH_Lock, /* Is locked */
	25	BH_Req, /* Has been submitted for I/O */
	26
	27	BH_Mapped, /* Has a disk mapping */
	28	BH_New, /* Disk mapping was newly created by get_block */
	29	BH_Async_Read, /* Is under end_buffer_async_read I/O */
	30	BH_Async_Write, /* Is under end_buffer_async_write I/O */
	31	BH_Delay, /* Buffer is not yet allocated on disk */
	32	BH_Boundary, /* Block is followed by a discontiguity */
	33	BH_Write_EIO, /* I/O error on write */
33a266dd	34	BH_Unwritten, /* Buffer is allocated on disk but not written */
08bafc03	35	BH_Quiet, /* Buffer Error Prinks to be quiet */
877f962c TT	36	BH_Meta, /* Buffer contains metadata */
877f962c TT	37	BH_Prio, /* Buffer should be submitted with REQ_PRIO */
7b7a8665	38	BH_Defer_Completion, /* Defer AIO completion to workqueue */
1da177e4 LT	39
	40	BH_PrivateStart,/* not a state bit, but the first bit available
	41	* for private allocation by other entities
	42	*/
	43	};
	44
09cbfeaf	45	#define MAX_BUF_PER_PAGE (PAGE_SIZE / 512)
1da177e4 LT	46
	47	struct page;
	48	struct buffer_head;
	49	struct address_space;
	50	typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
	51
	52	/*
205f87f6 BP	53	* Historically, a buffer_head was used to map a single block
	54	* within a page, and of course as the unit of I/O through the
	55	* filesystem and block layers. Nowadays the basic I/O unit
	56	* is the bio, and buffer_heads are used for extracting block
	57	* mappings (via a get_block_t call), for tracking state within
	58	* a page (via a page_mapping) and for wrapping bio submission
	59	* for backward compatibility reasons (e.g. submit_bh).
1da177e4 LT	60	*/
1da177e4 LT	61	struct buffer_head {
1da177e4 LT	62	unsigned long b_state; /* buffer state bitmap (see above) */
	63	struct buffer_head b_this_page;/ circular list of page's buffers */
	64	struct page b_page; / the page this bh is mapped to */
1da177e4	65
205f87f6 BP	66	sector_t b_blocknr; /* start block number */
	67	size_t b_size; /* size of mapping */
	68	char b_data; / pointer to data within the page */
1da177e4 LT	69
	70	struct block_device *b_bdev;
	71	bh_end_io_t b_end_io; / I/O completion */
	72	void b_private; / reserved for b_end_io */
	73	struct list_head b_assoc_buffers; /* associated with another mapping */
58ff407b JK	74	struct address_space b_assoc_map; / mapping this buffer is
58ff407b JK	75	associated with */
205f87f6	76	atomic_t b_count; /* users using this buffer_head */
f1e67e35 TG	77	spinlock_t b_uptodate_lock; /* Used by the first bh in a page, to
	78	* serialise IO completion of other
	79	* buffers in the page */
1da177e4 LT	80	};
	81
	82	/*
	83	* macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
	84	* and buffer_foo() functions.
60f91826 KW	85	* To avoid reset buffer flags that are already set, because that causes
60f91826 KW	86	* a costly cache line transition, check the flag first.
1da177e4 LT	87	*/
1da177e4 LT	88	#define BUFFER_FNS(bit, name) \
ee91ef61	89	static __always_inline void set_buffer_##name(struct buffer_head *bh) \
1da177e4	90	{ \
60f91826 KW	91	if (!test_bit(BH_##bit, &(bh)->b_state)) \
60f91826 KW	92	set_bit(BH_##bit, &(bh)->b_state); \
1da177e4	93	} \
ee91ef61	94	static __always_inline void clear_buffer_##name(struct buffer_head *bh) \
1da177e4 LT	95	{ \
	96	clear_bit(BH_##bit, &(bh)->b_state); \
	97	} \
ee91ef61	98	static __always_inline int buffer_##name(const struct buffer_head *bh) \
1da177e4 LT	99	{ \
	100	return test_bit(BH_##bit, &(bh)->b_state); \
	101	}
	102
	103	/*
	104	* test_set_buffer_foo() and test_clear_buffer_foo()
	105	*/
	106	#define TAS_BUFFER_FNS(bit, name) \
ee91ef61	107	static __always_inline int test_set_buffer_##name(struct buffer_head *bh) \
1da177e4 LT	108	{ \
	109	return test_and_set_bit(BH_##bit, &(bh)->b_state); \
	110	} \
ee91ef61	111	static __always_inline int test_clear_buffer_##name(struct buffer_head *bh) \
1da177e4 LT	112	{ \
	113	return test_and_clear_bit(BH_##bit, &(bh)->b_state); \
	114	} \
	115
	116	/*
	117	* Emit the buffer bitops functions. Note that there are also functions
	118	* of the form "mark_buffer_foo()". These are higher-level functions which
	119	* do something in addition to setting a b_state bit.
	120	*/
1da177e4 LT	121	BUFFER_FNS(Dirty, dirty)
	122	TAS_BUFFER_FNS(Dirty, dirty)
	123	BUFFER_FNS(Lock, locked)
1da177e4 LT	124	BUFFER_FNS(Req, req)
	125	TAS_BUFFER_FNS(Req, req)
	126	BUFFER_FNS(Mapped, mapped)
	127	BUFFER_FNS(New, new)
	128	BUFFER_FNS(Async_Read, async_read)
	129	BUFFER_FNS(Async_Write, async_write)
	130	BUFFER_FNS(Delay, delay)
	131	BUFFER_FNS(Boundary, boundary)
	132	BUFFER_FNS(Write_EIO, write_io_error)
33a266dd	133	BUFFER_FNS(Unwritten, unwritten)
877f962c TT	134	BUFFER_FNS(Meta, meta)
877f962c TT	135	BUFFER_FNS(Prio, prio)
7b7a8665	136	BUFFER_FNS(Defer_Completion, defer_completion)
1da177e4	137
d4252071 MP	138	static __always_inline void set_buffer_uptodate(struct buffer_head *bh)
	139	{
	140	/*
	141	* make it consistent with folio_mark_uptodate
	142	* pairs with smp_load_acquire in buffer_uptodate
	143	*/
	144	smp_mb__before_atomic();
	145	set_bit(BH_Uptodate, &bh->b_state);
	146	}
	147
	148	static __always_inline void clear_buffer_uptodate(struct buffer_head *bh)
	149	{
	150	clear_bit(BH_Uptodate, &bh->b_state);
	151	}
	152
	153	static __always_inline int buffer_uptodate(const struct buffer_head *bh)
	154	{
	155	/*
	156	* make it consistent with folio_test_uptodate
	157	* pairs with smp_mb__before_atomic in set_buffer_uptodate
	158	*/
	159	return (smp_load_acquire(&bh->b_state) & (1UL << BH_Uptodate)) != 0;
	160	}
	161
1da177e4	162	#define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
1da177e4 LT	163
	164	/* If we know page->private refers to buffer_heads */
	165	#define page_buffers(page) \
	166	({ \
4c21e2f2 HD	167	BUG_ON(!PagePrivate(page)); \
4c21e2f2 HD	168	((struct buffer_head *)page_private(page)); \
1da177e4 LT	169	})
1da177e4 LT	170	#define page_has_buffers(page) PagePrivate(page)
cd1067be	171	#define folio_buffers(folio) folio_get_private(folio)
1da177e4	172
520f301c	173	void buffer_check_dirty_writeback(struct folio *folio,
b4597226 MG	174	bool dirty, bool writeback);
b4597226 MG	175
1da177e4 LT	176	/*
	177	* Declarations
	178	*/
	179
b3c97528	180	void mark_buffer_dirty(struct buffer_head *bh);
87354e5d	181	void mark_buffer_write_io_error(struct buffer_head *bh);
f0059afd	182	void touch_buffer(struct buffer_head *bh);
1da177e4 LT	183	void set_bh_page(struct buffer_head *bh,
1da177e4 LT	184	struct page *page, unsigned long offset);
68189fef	185	bool try_to_free_buffers(struct folio *);
1da177e4	186	struct buffer_head alloc_page_buffers(struct page page, unsigned long size,
640ab98f	187	bool retry);
1da177e4 LT	188	void create_empty_buffers(struct page *, unsigned long,
	189	unsigned long b_state);
	190	void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
	191	void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
35c80d5f	192	void end_buffer_async_write(struct buffer_head *bh, int uptodate);
1da177e4 LT	193
	194	/* Things to do with buffers at mapping->private_list */
	195	void mark_buffer_dirty_inode(struct buffer_head bh, struct inode inode);
	196	int inode_has_buffers(struct inode *);
	197	void invalidate_inode_buffers(struct inode *);
	198	int remove_inode_buffers(struct inode *inode);
	199	int sync_mapping_buffers(struct address_space *mapping);
29f3ad7d JK	200	void clean_bdev_aliases(struct block_device *bdev, sector_t block,
29f3ad7d JK	201	sector_t len);
e64855c6 JK	202	static inline void clean_bdev_bh_alias(struct buffer_head *bh)
	203	{
	204	clean_bdev_aliases(bh->b_bdev, bh->b_blocknr, 1);
	205	}
1da177e4 LT	206
1da177e4 LT	207	void mark_buffer_async_write(struct buffer_head *bh);
1da177e4 LT	208	void __wait_on_buffer(struct buffer_head *);
1da177e4 LT	209	wait_queue_head_t bh_waitq_head(struct buffer_head bh);
3991d3bd TK	210	struct buffer_head __find_get_block(struct block_device bdev, sector_t block,
3991d3bd TK	211	unsigned size);
3b5e6454 GK	212	struct buffer_head __getblk_gfp(struct block_device bdev, sector_t block,
3b5e6454 GK	213	unsigned size, gfp_t gfp);
1da177e4 LT	214	void __brelse(struct buffer_head *);
1da177e4 LT	215	void __bforget(struct buffer_head *);
3991d3bd	216	void __breadahead(struct block_device *, sector_t block, unsigned int size);
d87f6392 RG	217	void __breadahead_gfp(struct block_device *, sector_t block, unsigned int size,
d87f6392 RG	218	gfp_t gfp);
3b5e6454 GK	219	struct buffer_head __bread_gfp(struct block_device ,
3b5e6454 GK	220	sector_t block, unsigned size, gfp_t gfp);
f9a14399	221	void invalidate_bh_lrus(void);
243418e3	222	void invalidate_bh_lrus_cpu(void);
8cc621d2	223	bool has_bh_in_lru(int cpu, void *dummy);
dd0fc66f	224	struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
1da177e4	225	void free_buffer_head(struct buffer_head * bh);
b3c97528 HH	226	void unlock_buffer(struct buffer_head *bh);
b3c97528 HH	227	void __lock_buffer(struct buffer_head *bh);
1420c4a5	228	void ll_rw_block(blk_opf_t, int, struct buffer_head * bh[]);
1da177e4	229	int sync_dirty_buffer(struct buffer_head *bh);
3ae72869 BVA	230	int __sync_dirty_buffer(struct buffer_head *bh, blk_opf_t op_flags);
3ae72869 BVA	231	void write_dirty_buffer(struct buffer_head *bh, blk_opf_t op_flags);
1420c4a5	232	int submit_bh(blk_opf_t, struct buffer_head *);
1da177e4 LT	233	void write_boundary_block(struct block_device *bdev,
1da177e4 LT	234	sector_t bblock, unsigned blocksize);
389d1b08 AK	235	int bh_uptodate_or_lock(struct buffer_head *bh);
389d1b08 AK	236	int bh_submit_read(struct buffer_head *bh);
1da177e4 LT	237
	238	extern int buffer_heads_over_limit;
	239
	240	/*
	241	* Generic address_space_operations implementations for buffer_head-backed
	242	* address_spaces.
	243	*/
7ba13abb	244	void block_invalidate_folio(struct folio *folio, size_t offset, size_t length);
1da177e4 LT	245	int block_write_full_page(struct page page, get_block_t get_block,
1da177e4 LT	246	struct writeback_control *wbc);
b4bba389 BM	247	int __block_write_full_page(struct inode inode, struct page page,
	248	get_block_t get_block, struct writeback_control wbc,
	249	bh_end_io_t *handler);
2c69e205	250	int block_read_full_folio(struct folio , get_block_t );
2e7e80f7	251	bool block_is_partially_uptodate(struct folio *, size_t from, size_t count);
155130a4	252	int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
b3992d1e	253	struct page *pagep, get_block_t get_block);
6e1db88d CH	254	int __block_write_begin(struct page *page, loff_t pos, unsigned len,
6e1db88d CH	255	get_block_t *get_block);
afddba49 NP	256	int block_write_end(struct file , struct address_space ,
	257	loff_t, unsigned, unsigned,
	258	struct page , void );
	259	int generic_write_end(struct file , struct address_space ,
	260	loff_t, unsigned, unsigned,
	261	struct page , void );
	262	void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
f892760a	263	void clean_page_buffers(struct page *page);
89e10787	264	int cont_write_begin(struct file , struct address_space , loff_t,
be3bbbc5	265	unsigned, struct page , void ,
89e10787	266	get_block_t , loff_t );
05eb0b51	267	int generic_cont_expand_simple(struct inode *inode, loff_t size);
1da177e4	268	int block_commit_write(struct page *page, unsigned from, unsigned to);
c2ec175c	269	int block_page_mkwrite(struct vm_area_struct vma, struct vm_fault vmf,
54171690	270	get_block_t get_block);
24da4fab	271	/* Convert errno to return value from ->page_mkwrite() call */
401b25aa	272	static inline vm_fault_t block_page_mkwrite_return(int err)
24da4fab JK	273	{
	274	if (err == 0)
	275	return VM_FAULT_LOCKED;
0911d004	276	if (err == -EFAULT \|\| err == -EAGAIN)
24da4fab JK	277	return VM_FAULT_NOPAGE;
	278	if (err == -ENOMEM)
	279	return VM_FAULT_OOM;
	280	/* -ENOSPC, -EDQUOT, -EIO ... */
	281	return VM_FAULT_SIGBUS;
	282	}
1da177e4	283	sector_t generic_block_bmap(struct address_space , sector_t, get_block_t );
1da177e4	284	int block_truncate_page(struct address_space , loff_t, get_block_t );
1da177e4	285
67235182 MWO	286	#ifdef CONFIG_MIGRATION
	287	extern int buffer_migrate_folio(struct address_space *,
	288	struct folio dst, struct folio src, enum migrate_mode);
	289	extern int buffer_migrate_folio_norefs(struct address_space *,
	290	struct folio dst, struct folio src, enum migrate_mode);
	291	#else
	292	#define buffer_migrate_folio NULL
	293	#define buffer_migrate_folio_norefs NULL
	294	#endif
1da177e4	295
b6cd0b77	296	void buffer_init(void);
1da177e4 LT	297
	298	/*
	299	* inline definitions
	300	*/
	301
1da177e4 LT	302	static inline void get_bh(struct buffer_head *bh)
	303	{
	304	atomic_inc(&bh->b_count);
	305	}
	306
	307	static inline void put_bh(struct buffer_head *bh)
	308	{
4e857c58	309	smp_mb__before_atomic();
1da177e4 LT	310	atomic_dec(&bh->b_count);
	311	}
	312
	313	static inline void brelse(struct buffer_head *bh)
	314	{
	315	if (bh)
	316	__brelse(bh);
	317	}
	318
	319	static inline void bforget(struct buffer_head *bh)
	320	{
	321	if (bh)
	322	__bforget(bh);
	323	}
	324
	325	static inline struct buffer_head *
	326	sb_bread(struct super_block *sb, sector_t block)
	327	{
3b5e6454 GK	328	return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
	329	}
	330
	331	static inline struct buffer_head *
	332	sb_bread_unmovable(struct super_block *sb, sector_t block)
	333	{
	334	return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, 0);
1da177e4 LT	335	}
	336
	337	static inline void
	338	sb_breadahead(struct super_block *sb, sector_t block)
	339	{
	340	__breadahead(sb->s_bdev, block, sb->s_blocksize);
	341	}
	342
d87f6392 RG	343	static inline void
	344	sb_breadahead_unmovable(struct super_block *sb, sector_t block)
	345	{
	346	__breadahead_gfp(sb->s_bdev, block, sb->s_blocksize, 0);
	347	}
	348
1da177e4 LT	349	static inline struct buffer_head *
	350	sb_getblk(struct super_block *sb, sector_t block)
	351	{
3b5e6454	352	return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
1da177e4 LT	353	}
1da177e4 LT	354
bd7ade3c NB	355
	356	static inline struct buffer_head *
	357	sb_getblk_gfp(struct super_block *sb, sector_t block, gfp_t gfp)
	358	{
	359	return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, gfp);
	360	}
	361
1da177e4 LT	362	static inline struct buffer_head *
	363	sb_find_get_block(struct super_block *sb, sector_t block)
	364	{
	365	return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
	366	}
	367
	368	static inline void
	369	map_bh(struct buffer_head bh, struct super_block sb, sector_t block)
	370	{
	371	set_buffer_mapped(bh);
	372	bh->b_bdev = sb->s_bdev;
	373	bh->b_blocknr = block;
b0cf2321	374	bh->b_size = sb->s_blocksize;
1da177e4 LT	375	}
1da177e4 LT	376
1da177e4 LT	377	static inline void wait_on_buffer(struct buffer_head *bh)
	378	{
	379	might_sleep();
a9877cc2	380	if (buffer_locked(bh))
1da177e4 LT	381	__wait_on_buffer(bh);
	382	}
	383
ca5de404 NP	384	static inline int trylock_buffer(struct buffer_head *bh)
ca5de404 NP	385	{
51b07fc3	386	return likely(!test_and_set_bit_lock(BH_Lock, &bh->b_state));
ca5de404 NP	387	}
ca5de404 NP	388
1da177e4 LT	389	static inline void lock_buffer(struct buffer_head *bh)
	390	{
	391	might_sleep();
ca5de404	392	if (!trylock_buffer(bh))
1da177e4 LT	393	__lock_buffer(bh);
	394	}
	395
3b5e6454 GK	396	static inline struct buffer_head getblk_unmovable(struct block_device bdev,
	397	sector_t block,
	398	unsigned size)
	399	{
	400	return __getblk_gfp(bdev, block, size, 0);
	401	}
	402
	403	static inline struct buffer_head __getblk(struct block_device bdev,
	404	sector_t block,
	405	unsigned size)
	406	{
	407	return __getblk_gfp(bdev, block, size, __GFP_MOVABLE);
	408	}
	409
	410	/**
	411	* __bread() - reads a specified block and returns the bh
	412	* @bdev: the block_device to read from
	413	* @block: number of block
	414	* @size: size (in bytes) to read
	415	*
	416	* Reads a specified block, and returns buffer head that contains it.
	417	* The page cache is allocated from movable area so that it can be migrated.
	418	* It returns NULL if the block was unreadable.
	419	*/
	420	static inline struct buffer_head *
	421	__bread(struct block_device *bdev, sector_t block, unsigned size)
	422	{
	423	return __bread_gfp(bdev, block, size, __GFP_MOVABLE);
	424	}
	425
e621900a	426	bool block_dirty_folio(struct address_space mapping, struct folio folio);
9361401e DH	427
	428	#else /* CONFIG_BLOCK */
	429
	430	static inline void buffer_init(void) {}
68189fef	431	static inline bool try_to_free_buffers(struct folio *folio) { return true; }
9361401e DH	432	static inline int inode_has_buffers(struct inode *inode) { return 0; }
	433	static inline void invalidate_inode_buffers(struct inode *inode) {}
	434	static inline int remove_inode_buffers(struct inode *inode) { return 1; }
	435	static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
243418e3	436	static inline void invalidate_bh_lrus_cpu(void) {}
6de522d1	437	static inline bool has_bh_in_lru(int cpu, void *dummy) { return false; }
d2de7ea4	438	#define buffer_heads_over_limit 0
9361401e DH	439
9361401e DH	440	#endif /* CONFIG_BLOCK */
1da177e4	441	#endif /* _LINUX_BUFFER_HEAD_H */