[linux-2.6-block.git] / fs / xfs / xfs_buf.h

/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#ifndef __XFS_BUF_H__
#define __XFS_BUF_H__

#include <linux/list.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/buffer_head.h>
#include <linux/uio.h>
#include <linux/list_lru.h>

/*
 *	Base types
 */

#define XFS_BUF_DADDR_NULL	((xfs_daddr_t) (-1LL))

typedef enum {
	XBRW_READ = 1,			/* transfer into target memory */
	XBRW_WRITE = 2,			/* transfer from target memory */
	XBRW_ZERO = 3,			/* Zero target memory */
} xfs_buf_rw_t;

#define XBF_READ	 (1 << 0) /* buffer intended for reading from device */
#define XBF_WRITE	 (1 << 1) /* buffer intended for writing to device */
#define XBF_READ_AHEAD	 (1 << 2) /* asynchronous read-ahead */
#define XBF_ASYNC	 (1 << 4) /* initiator will not wait for completion */
#define XBF_DONE	 (1 << 5) /* all pages in the buffer uptodate */
#define XBF_STALE	 (1 << 6) /* buffer has been staled, do not find it */
#define XBF_WRITE_FAIL	 (1 << 24)/* async writes have failed on this buffer */

/* I/O hints for the BIO layer */
#define XBF_SYNCIO	 (1 << 10)/* treat this buffer as synchronous I/O */
#define XBF_FUA		 (1 << 11)/* force cache write through mode */
#define XBF_FLUSH	 (1 << 12)/* flush the disk cache before a write */

/* flags used only as arguments to access routines */
#define XBF_TRYLOCK	 (1 << 16)/* lock requested, but do not wait */
#define XBF_UNMAPPED	 (1 << 17)/* do not map the buffer */

/* flags used only internally */
#define _XBF_PAGES	 (1 << 20)/* backed by refcounted pages */
#define _XBF_KMEM	 (1 << 21)/* backed by heap memory */
#define _XBF_DELWRI_Q	 (1 << 22)/* buffer on a delwri queue */
#define _XBF_COMPOUND	 (1 << 23)/* compound buffer */

typedef unsigned int xfs_buf_flags_t;

#define XFS_BUF_FLAGS \
	{ XBF_READ,		"READ" }, \
	{ XBF_WRITE,		"WRITE" }, \
	{ XBF_READ_AHEAD,	"READ_AHEAD" }, \
	{ XBF_ASYNC,		"ASYNC" }, \
	{ XBF_DONE,		"DONE" }, \
	{ XBF_STALE,		"STALE" }, \
	{ XBF_WRITE_FAIL,	"WRITE_FAIL" }, \
	{ XBF_SYNCIO,		"SYNCIO" }, \
	{ XBF_FUA,		"FUA" }, \
	{ XBF_FLUSH,		"FLUSH" }, \
	{ XBF_TRYLOCK,		"TRYLOCK" },	/* should never be set */\
	{ XBF_UNMAPPED,		"UNMAPPED" },	/* ditto */\
	{ _XBF_PAGES,		"PAGES" }, \
	{ _XBF_KMEM,		"KMEM" }, \
	{ _XBF_DELWRI_Q,	"DELWRI_Q" }, \
	{ _XBF_COMPOUND,	"COMPOUND" }


/*
 * Internal state flags.
 */
#define XFS_BSTATE_DISPOSE	 (1 << 0)	/* buffer being discarded */

/*
 * The xfs_buftarg contains 2 notions of "sector size" -
 *
 * 1) The metadata sector size, which is the minimum unit and
 *    alignment of IO which will be performed by metadata operations.
 * 2) The device logical sector size
 *
 * The first is specified at mkfs time, and is stored on-disk in the
 * superblock's sb_sectsize.
 *
 * The latter is derived from the underlying device, and controls direct IO
 * alignment constraints.
 */
typedef struct xfs_buftarg {
	dev_t			bt_dev;
	struct block_device	*bt_bdev;
	struct backing_dev_info	*bt_bdi;
	struct xfs_mount	*bt_mount;
	unsigned int		bt_meta_sectorsize;
	size_t			bt_meta_sectormask;
	size_t			bt_logical_sectorsize;
	size_t			bt_logical_sectormask;

	/* LRU control structures */
	struct shrinker		bt_shrinker;
	struct list_lru		bt_lru;
} xfs_buftarg_t;

struct xfs_buf;
typedef void (*xfs_buf_iodone_t)(struct xfs_buf *);


#define XB_PAGES	2

struct xfs_buf_map {
	xfs_daddr_t		bm_bn;	/* block number for I/O */
	int			bm_len;	/* size of I/O */
};

#define DEFINE_SINGLE_BUF_MAP(map, blkno, numblk) \
	struct xfs_buf_map (map) = { .bm_bn = (blkno), .bm_len = (numblk) };

struct xfs_buf_ops {
	void (*verify_read)(struct xfs_buf *);
	void (*verify_write)(struct xfs_buf *);
};

typedef struct xfs_buf {
	/*
	 * first cacheline holds all the fields needed for an uncontended cache
	 * hit to be fully processed. The semaphore straddles the cacheline
	 * boundary, but the counter and lock sits on the first cacheline,
	 * which is the only bit that is touched if we hit the semaphore
	 * fast-path on locking.
	 */
	struct rb_node		b_rbnode;	/* rbtree node */
	xfs_daddr_t		b_bn;		/* block number of buffer */
	int			b_length;	/* size of buffer in BBs */
	atomic_t		b_hold;		/* reference count */
	atomic_t		b_lru_ref;	/* lru reclaim ref count */
	xfs_buf_flags_t		b_flags;	/* status flags */
	struct semaphore	b_sema;		/* semaphore for lockables */

	/*
	 * concurrent access to b_lru and b_lru_flags are protected by
	 * bt_lru_lock and not by b_sema
	 */
	struct list_head	b_lru;		/* lru list */
	spinlock_t		b_lock;		/* internal state lock */
	unsigned int		b_state;	/* internal state flags */
	int			b_io_error;	/* internal IO error state */
	wait_queue_head_t	b_waiters;	/* unpin waiters */
	struct list_head	b_list;
	struct xfs_perag	*b_pag;		/* contains rbtree root */
	xfs_buftarg_t		*b_target;	/* buffer target (device) */
	void			*b_addr;	/* virtual address of buffer */
	struct work_struct	b_ioend_work;
	struct workqueue_struct	*b_ioend_wq;	/* I/O completion wq */
	xfs_buf_iodone_t	b_iodone;	/* I/O completion function */
	struct completion	b_iowait;	/* queue for I/O waiters */
	void			*b_fspriv;
	struct xfs_trans	*b_transp;
	struct page		**b_pages;	/* array of page pointers */
	struct page		*b_page_array[XB_PAGES]; /* inline pages */
	struct xfs_buf_map	*b_maps;	/* compound buffer map */
	struct xfs_buf_map	__b_map;	/* inline compound buffer map */
	int			b_map_count;
	int			b_io_length;	/* IO size in BBs */
	atomic_t		b_pin_count;	/* pin count */
	atomic_t		b_io_remaining;	/* #outstanding I/O requests */
	unsigned int		b_page_count;	/* size of page array */
	unsigned int		b_offset;	/* page offset in first page */
	int			b_error;	/* error code on I/O */
	const struct xfs_buf_ops	*b_ops;

#ifdef XFS_BUF_LOCK_TRACKING
	int			b_last_holder;
#endif
} xfs_buf_t;

/* Finding and Reading Buffers */
struct xfs_buf *_xfs_buf_find(struct xfs_buftarg *target,
			      struct xfs_buf_map *map, int nmaps,
			      xfs_buf_flags_t flags, struct xfs_buf *new_bp);

static inline struct xfs_buf *
xfs_incore(
	struct xfs_buftarg	*target,
	xfs_daddr_t		blkno,
	size_t			numblks,
	xfs_buf_flags_t		flags)
{
	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
	return _xfs_buf_find(target, &map, 1, flags, NULL);
}

struct xfs_buf *_xfs_buf_alloc(struct xfs_buftarg *target,
			       struct xfs_buf_map *map, int nmaps,
			       xfs_buf_flags_t flags);

static inline struct xfs_buf *
xfs_buf_alloc(
	struct xfs_buftarg	*target,
	xfs_daddr_t		blkno,
	size_t			numblks,
	xfs_buf_flags_t		flags)
{
	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
	return _xfs_buf_alloc(target, &map, 1, flags);
}

struct xfs_buf *xfs_buf_get_map(struct xfs_buftarg *target,
			       struct xfs_buf_map *map, int nmaps,
			       xfs_buf_flags_t flags);
struct xfs_buf *xfs_buf_read_map(struct xfs_buftarg *target,
			       struct xfs_buf_map *map, int nmaps,
			       xfs_buf_flags_t flags,
			       const struct xfs_buf_ops *ops);
void xfs_buf_readahead_map(struct xfs_buftarg *target,
			       struct xfs_buf_map *map, int nmaps,
			       const struct xfs_buf_ops *ops);

static inline struct xfs_buf *
xfs_buf_get(
	struct xfs_buftarg	*target,
	xfs_daddr_t		blkno,
	size_t			numblks,
	xfs_buf_flags_t		flags)
{
	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
	return xfs_buf_get_map(target, &map, 1, flags);
}

static inline struct xfs_buf *
xfs_buf_read(
	struct xfs_buftarg	*target,
	xfs_daddr_t		blkno,
	size_t			numblks,
	xfs_buf_flags_t		flags,
	const struct xfs_buf_ops *ops)
{
	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
	return xfs_buf_read_map(target, &map, 1, flags, ops);
}

static inline void
xfs_buf_readahead(
	struct xfs_buftarg	*target,
	xfs_daddr_t		blkno,
	size_t			numblks,
	const struct xfs_buf_ops *ops)
{
	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
	return xfs_buf_readahead_map(target, &map, 1, ops);
}

struct xfs_buf *xfs_buf_get_empty(struct xfs_buftarg *target, size_t numblks);
void xfs_buf_set_empty(struct xfs_buf *bp, size_t numblks);
int xfs_buf_associate_memory(struct xfs_buf *bp, void *mem, size_t length);

struct xfs_buf *xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks,
				int flags);
int xfs_buf_read_uncached(struct xfs_buftarg *target, xfs_daddr_t daddr,
			  size_t numblks, int flags, struct xfs_buf **bpp,
			  const struct xfs_buf_ops *ops);
void xfs_buf_hold(struct xfs_buf *bp);

/* Releasing Buffers */
extern void xfs_buf_free(xfs_buf_t *);
extern void xfs_buf_rele(xfs_buf_t *);

/* Locking and Unlocking Buffers */
extern int xfs_buf_trylock(xfs_buf_t *);
extern void xfs_buf_lock(xfs_buf_t *);
extern void xfs_buf_unlock(xfs_buf_t *);
#define xfs_buf_islocked(bp) \
	((bp)->b_sema.count <= 0)

/* Buffer Read and Write Routines */
extern int xfs_bwrite(struct xfs_buf *bp);
extern void xfs_buf_ioend(struct xfs_buf *bp);
extern void xfs_buf_ioerror(xfs_buf_t *, int);
extern void xfs_buf_ioerror_alert(struct xfs_buf *, const char *func);
extern void xfs_buf_submit(struct xfs_buf *bp);
extern int xfs_buf_submit_wait(struct xfs_buf *bp);
extern void xfs_buf_iomove(xfs_buf_t *, size_t, size_t, void *,
				xfs_buf_rw_t);
#define xfs_buf_zero(bp, off, len) \
	    xfs_buf_iomove((bp), (off), (len), NULL, XBRW_ZERO)

/* Buffer Utility Routines */
extern void *xfs_buf_offset(struct xfs_buf *, size_t);

/* Delayed Write Buffer Routines */
extern bool xfs_buf_delwri_queue(struct xfs_buf *, struct list_head *);
extern int xfs_buf_delwri_submit(struct list_head *);
extern int xfs_buf_delwri_submit_nowait(struct list_head *);

/* Buffer Daemon Setup Routines */
extern int xfs_buf_init(void);
extern void xfs_buf_terminate(void);

#define XFS_BUF_ZEROFLAGS(bp) \
	((bp)->b_flags &= ~(XBF_READ|XBF_WRITE|XBF_ASYNC| \
			    XBF_SYNCIO|XBF_FUA|XBF_FLUSH| \
			    XBF_WRITE_FAIL))

void xfs_buf_stale(struct xfs_buf *bp);
#define XFS_BUF_UNSTALE(bp)	((bp)->b_flags &= ~XBF_STALE)
#define XFS_BUF_ISSTALE(bp)	((bp)->b_flags & XBF_STALE)

#define XFS_BUF_DONE(bp)	((bp)->b_flags |= XBF_DONE)
#define XFS_BUF_UNDONE(bp)	((bp)->b_flags &= ~XBF_DONE)
#define XFS_BUF_ISDONE(bp)	((bp)->b_flags & XBF_DONE)

#define XFS_BUF_ASYNC(bp)	((bp)->b_flags |= XBF_ASYNC)
#define XFS_BUF_UNASYNC(bp)	((bp)->b_flags &= ~XBF_ASYNC)
#define XFS_BUF_ISASYNC(bp)	((bp)->b_flags & XBF_ASYNC)

#define XFS_BUF_READ(bp)	((bp)->b_flags |= XBF_READ)
#define XFS_BUF_UNREAD(bp)	((bp)->b_flags &= ~XBF_READ)
#define XFS_BUF_ISREAD(bp)	((bp)->b_flags & XBF_READ)

#define XFS_BUF_WRITE(bp)	((bp)->b_flags |= XBF_WRITE)
#define XFS_BUF_UNWRITE(bp)	((bp)->b_flags &= ~XBF_WRITE)
#define XFS_BUF_ISWRITE(bp)	((bp)->b_flags & XBF_WRITE)

/*
 * These macros use the IO block map rather than b_bn. b_bn is now really
 * just for the buffer cache index for cached buffers. As IO does not use b_bn
 * anymore, uncached buffers do not use b_bn at all and hence must modify the IO
 * map directly. Uncached buffers are not allowed to be discontiguous, so this
 * is safe to do.
 *
 * In future, uncached buffers will pass the block number directly to the io
 * request function and hence these macros will go away at that point.
 */
#define XFS_BUF_ADDR(bp)		((bp)->b_maps[0].bm_bn)
#define XFS_BUF_SET_ADDR(bp, bno)	((bp)->b_maps[0].bm_bn = (xfs_daddr_t)(bno))

static inline void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
{
	atomic_set(&bp->b_lru_ref, lru_ref);
}

static inline int xfs_buf_ispinned(struct xfs_buf *bp)
{
	return atomic_read(&bp->b_pin_count);
}

static inline void xfs_buf_relse(xfs_buf_t *bp)
{
	xfs_buf_unlock(bp);
	xfs_buf_rele(bp);
}

static inline int
xfs_buf_verify_cksum(struct xfs_buf *bp, unsigned long cksum_offset)
{
	return xfs_verify_cksum(bp->b_addr, BBTOB(bp->b_length),
				cksum_offset);
}

static inline void
xfs_buf_update_cksum(struct xfs_buf *bp, unsigned long cksum_offset)
{
	xfs_update_cksum(bp->b_addr, BBTOB(bp->b_length),
			 cksum_offset);
}

/*
 *	Handling of buftargs.
 */
extern xfs_buftarg_t *xfs_alloc_buftarg(struct xfs_mount *,
			struct block_device *);
extern void xfs_free_buftarg(struct xfs_mount *, struct xfs_buftarg *);
extern void xfs_wait_buftarg(xfs_buftarg_t *);
extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int);

#define xfs_getsize_buftarg(buftarg)	block_size((buftarg)->bt_bdev)
#define xfs_readonly_buftarg(buftarg)	bdev_read_only((buftarg)->bt_bdev)

#endif	/* __XFS_BUF_H__ */
Commit	Line	Data
1da177e4	1	/*
7b718769 NS	2	* Copyright (c) 2000-2005 Silicon Graphics, Inc.
7b718769 NS	3	* All Rights Reserved.
1da177e4	4	*
7b718769 NS	5	* This program is free software; you can redistribute it and/or
7b718769 NS	6	* modify it under the terms of the GNU General Public License as
1da177e4 LT	7	* published by the Free Software Foundation.
1da177e4 LT	8	*
7b718769 NS	9	* This program is distributed in the hope that it would be useful,
	10	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	12	* GNU General Public License for more details.
1da177e4	13	*
7b718769 NS	14	* You should have received a copy of the GNU General Public License
	15	* along with this program; if not, write the Free Software Foundation,
	16	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
1da177e4	17	*/
1da177e4 LT	18	#ifndef __XFS_BUF_H__
	19	#define __XFS_BUF_H__
	20
1da177e4 LT	21	#include <linux/list.h>
	22	#include <linux/types.h>
	23	#include <linux/spinlock.h>
1da177e4 LT	24	#include <linux/mm.h>
	25	#include <linux/fs.h>
	26	#include <linux/buffer_head.h>
	27	#include <linux/uio.h>
e80dfa19	28	#include <linux/list_lru.h>
1da177e4 LT	29
	30	/*
	31	* Base types
	32	*/
	33
ce8e922c NS	34	#define XFS_BUF_DADDR_NULL ((xfs_daddr_t) (-1LL))
ce8e922c NS	35
ce8e922c NS	36	typedef enum {
	37	XBRW_READ = 1, /* transfer into target memory */
	38	XBRW_WRITE = 2, /* transfer from target memory */
	39	XBRW_ZERO = 3, /* Zero target memory */
	40	} xfs_buf_rw_t;
	41
6fb8a90a CM	42	#define XBF_READ (1 << 0) /* buffer intended for reading from device */
	43	#define XBF_WRITE (1 << 1) /* buffer intended for writing to device */
	44	#define XBF_READ_AHEAD (1 << 2) /* asynchronous read-ahead */
	45	#define XBF_ASYNC (1 << 4) /* initiator will not wait for completion */
	46	#define XBF_DONE (1 << 5) /* all pages in the buffer uptodate */
	47	#define XBF_STALE (1 << 6) /* buffer has been staled, do not find it */
ac8809f9	48	#define XBF_WRITE_FAIL (1 << 24)/* async writes have failed on this buffer */
1d5ae5df CH	49
1d5ae5df CH	50	/* I/O hints for the BIO layer */
6fb8a90a CM	51	#define XBF_SYNCIO (1 << 10)/* treat this buffer as synchronous I/O */
	52	#define XBF_FUA (1 << 11)/* force cache write through mode */
	53	#define XBF_FLUSH (1 << 12)/* flush the disk cache before a write */
1da177e4	54
807cbbdb	55	/* flags used only as arguments to access routines */
6fb8a90a CM	56	#define XBF_TRYLOCK (1 << 16)/* lock requested, but do not wait */
6fb8a90a CM	57	#define XBF_UNMAPPED (1 << 17)/* do not map the buffer */
1da177e4	58
807cbbdb	59	/* flags used only internally */
6fb8a90a CM	60	#define _XBF_PAGES (1 << 20)/* backed by refcounted pages */
	61	#define _XBF_KMEM (1 << 21)/* backed by heap memory */
	62	#define _XBF_DELWRI_Q (1 << 22)/* buffer on a delwri queue */
	63	#define _XBF_COMPOUND (1 << 23)/* compound buffer */
6ab455ee	64
807cbbdb	65	typedef unsigned int xfs_buf_flags_t;
1da177e4	66
0b1b213f CH	67	#define XFS_BUF_FLAGS \
	68	{ XBF_READ, "READ" }, \
	69	{ XBF_WRITE, "WRITE" }, \
1d5ae5df	70	{ XBF_READ_AHEAD, "READ_AHEAD" }, \
0b1b213f CH	71	{ XBF_ASYNC, "ASYNC" }, \
0b1b213f CH	72	{ XBF_DONE, "DONE" }, \
0b1b213f	73	{ XBF_STALE, "STALE" }, \
ac8809f9	74	{ XBF_WRITE_FAIL, "WRITE_FAIL" }, \
1d5ae5df CH	75	{ XBF_SYNCIO, "SYNCIO" }, \
	76	{ XBF_FUA, "FUA" }, \
	77	{ XBF_FLUSH, "FLUSH" }, \
6fb8a90a	78	{ XBF_TRYLOCK, "TRYLOCK" }, /* should never be set */\
611c9946	79	{ XBF_UNMAPPED, "UNMAPPED" }, /* ditto */\
0b1b213f	80	{ _XBF_PAGES, "PAGES" }, \
0e6e847f	81	{ _XBF_KMEM, "KMEM" }, \
cbb7baab	82	{ _XBF_DELWRI_Q, "DELWRI_Q" }, \
a4082357 DC	83	{ _XBF_COMPOUND, "COMPOUND" }
a4082357 DC	84
ac8809f9	85
a4082357 DC	86	/*
	87	* Internal state flags.
	88	*/
	89	#define XFS_BSTATE_DISPOSE (1 << 0) /* buffer being discarded */
0b1b213f	90
7c71ee78 ES	91	/*
	92	* The xfs_buftarg contains 2 notions of "sector size" -
	93	*
	94	* 1) The metadata sector size, which is the minimum unit and
	95	* alignment of IO which will be performed by metadata operations.
	96	* 2) The device logical sector size
	97	*
	98	* The first is specified at mkfs time, and is stored on-disk in the
	99	* superblock's sb_sectsize.
	100	*
	101	* The latter is derived from the underlying device, and controls direct IO
	102	* alignment constraints.
	103	*/
1da177e4	104	typedef struct xfs_buftarg {
ce8e922c NS	105	dev_t bt_dev;
ce8e922c NS	106	struct block_device *bt_bdev;
0e6e847f	107	struct backing_dev_info *bt_bdi;
ebad861b	108	struct xfs_mount *bt_mount;
6da54179 ES	109	unsigned int bt_meta_sectorsize;
6da54179 ES	110	size_t bt_meta_sectormask;
7c71ee78 ES	111	size_t bt_logical_sectorsize;
7c71ee78 ES	112	size_t bt_logical_sectormask;
ce8e922c	113
ff57ab21 DC	114	/* LRU control structures */
ff57ab21 DC	115	struct shrinker bt_shrinker;
e80dfa19	116	struct list_lru bt_lru;
1da177e4 LT	117	} xfs_buftarg_t;
1da177e4 LT	118
1da177e4	119	struct xfs_buf;
ce8e922c	120	typedef void (xfs_buf_iodone_t)(struct xfs_buf );
1da177e4	121
c3f8fc73	122
ce8e922c	123	#define XB_PAGES 2
1da177e4	124
cbb7baab DC	125	struct xfs_buf_map {
	126	xfs_daddr_t bm_bn; /* block number for I/O */
	127	int bm_len; /* size of I/O */
	128	};
	129
3e85c868 DC	130	#define DEFINE_SINGLE_BUF_MAP(map, blkno, numblk) \
	131	struct xfs_buf_map (map) = { .bm_bn = (blkno), .bm_len = (numblk) };
	132
1813dd64 DC	133	struct xfs_buf_ops {
	134	void (verify_read)(struct xfs_buf );
	135	void (verify_write)(struct xfs_buf );
	136	};
	137
1da177e4	138	typedef struct xfs_buf {
50f59e8e DC	139	/*
	140	* first cacheline holds all the fields needed for an uncontended cache
	141	* hit to be fully processed. The semaphore straddles the cacheline
	142	* boundary, but the counter and lock sits on the first cacheline,
	143	* which is the only bit that is touched if we hit the semaphore
	144	* fast-path on locking.
	145	*/
	146	struct rb_node b_rbnode; /* rbtree node */
cbb7baab	147	xfs_daddr_t b_bn; /* block number of buffer */
4e94b71b	148	int b_length; /* size of buffer in BBs */
50f59e8e	149	atomic_t b_hold; /* reference count */
430cbeb8	150	atomic_t b_lru_ref; /* lru reclaim ref count */
50f59e8e	151	xfs_buf_flags_t b_flags; /* status flags */
ce8e922c	152	struct semaphore b_sema; /* semaphore for lockables */
50f59e8e	153
6fb8a90a CM	154	/*
	155	* concurrent access to b_lru and b_lru_flags are protected by
	156	* bt_lru_lock and not by b_sema
	157	*/
430cbeb8	158	struct list_head b_lru; /* lru list */
a4082357 DC	159	spinlock_t b_lock; /* internal state lock */
a4082357 DC	160	unsigned int b_state; /* internal state flags */
61be9c52	161	int b_io_error; /* internal IO error state */
ce8e922c NS	162	wait_queue_head_t b_waiters; /* unpin waiters */
ce8e922c NS	163	struct list_head b_list;
74f75a0c	164	struct xfs_perag b_pag; / contains rbtree root */
ce8e922c	165	xfs_buftarg_t b_target; / buffer target (device) */
ce8e922c	166	void b_addr; / virtual address of buffer */
b29c70f5 BF	167	struct work_struct b_ioend_work;
b29c70f5 BF	168	struct workqueue_struct b_ioend_wq; / I/O completion wq */
ce8e922c	169	xfs_buf_iodone_t b_iodone; /* I/O completion function */
b4dd330b	170	struct completion b_iowait; /* queue for I/O waiters */
ce8e922c	171	void *b_fspriv;
bf9d9013	172	struct xfs_trans *b_transp;
ce8e922c NS	173	struct page *b_pages; / array of page pointers */
ce8e922c NS	174	struct page b_page_array[XB_PAGES]; / inline pages */
3e85c868	175	struct xfs_buf_map b_maps; / compound buffer map */
d44d9bc6	176	struct xfs_buf_map __b_map; /* inline compound buffer map */
3e85c868	177	int b_map_count;
aa0e8833	178	int b_io_length; /* IO size in BBs */
50f59e8e DC	179	atomic_t b_pin_count; /* pin count */
	180	atomic_t b_io_remaining; /* #outstanding I/O requests */
	181	unsigned int b_page_count; /* size of page array */
	182	unsigned int b_offset; /* page offset in first page */
2451337d	183	int b_error; /* error code on I/O */
1813dd64	184	const struct xfs_buf_ops *b_ops;
cfb02852	185
ce8e922c NS	186	#ifdef XFS_BUF_LOCK_TRACKING
ce8e922c NS	187	int b_last_holder;
1da177e4 LT	188	#endif
	189	} xfs_buf_t;
	190
1da177e4	191	/* Finding and Reading Buffers */
3e85c868 DC	192	struct xfs_buf _xfs_buf_find(struct xfs_buftarg target,
	193	struct xfs_buf_map *map, int nmaps,
	194	xfs_buf_flags_t flags, struct xfs_buf *new_bp);
	195
	196	static inline struct xfs_buf *
	197	xfs_incore(
	198	struct xfs_buftarg *target,
	199	xfs_daddr_t blkno,
	200	size_t numblks,
	201	xfs_buf_flags_t flags)
	202	{
	203	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
	204	return _xfs_buf_find(target, &map, 1, flags, NULL);
	205	}
	206
	207	struct xfs_buf _xfs_buf_alloc(struct xfs_buftarg target,
	208	struct xfs_buf_map *map, int nmaps,
	209	xfs_buf_flags_t flags);
	210
	211	static inline struct xfs_buf *
	212	xfs_buf_alloc(
	213	struct xfs_buftarg *target,
	214	xfs_daddr_t blkno,
	215	size_t numblks,
	216	xfs_buf_flags_t flags)
	217	{
	218	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
	219	return _xfs_buf_alloc(target, &map, 1, flags);
	220	}
1da177e4	221
6dde2707 DC	222	struct xfs_buf xfs_buf_get_map(struct xfs_buftarg target,
	223	struct xfs_buf_map *map, int nmaps,
	224	xfs_buf_flags_t flags);
	225	struct xfs_buf xfs_buf_read_map(struct xfs_buftarg target,
	226	struct xfs_buf_map *map, int nmaps,
1813dd64 DC	227	xfs_buf_flags_t flags,
1813dd64 DC	228	const struct xfs_buf_ops *ops);
6dde2707	229	void xfs_buf_readahead_map(struct xfs_buftarg *target,
c3f8fc73	230	struct xfs_buf_map *map, int nmaps,
1813dd64	231	const struct xfs_buf_ops *ops);
6dde2707 DC	232
	233	static inline struct xfs_buf *
	234	xfs_buf_get(
	235	struct xfs_buftarg *target,
	236	xfs_daddr_t blkno,
	237	size_t numblks,
	238	xfs_buf_flags_t flags)
	239	{
	240	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
	241	return xfs_buf_get_map(target, &map, 1, flags);
	242	}
	243
	244	static inline struct xfs_buf *
	245	xfs_buf_read(
	246	struct xfs_buftarg *target,
	247	xfs_daddr_t blkno,
	248	size_t numblks,
c3f8fc73	249	xfs_buf_flags_t flags,
1813dd64	250	const struct xfs_buf_ops *ops)
6dde2707 DC	251	{
6dde2707 DC	252	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
1813dd64	253	return xfs_buf_read_map(target, &map, 1, flags, ops);
6dde2707 DC	254	}
	255
	256	static inline void
	257	xfs_buf_readahead(
	258	struct xfs_buftarg *target,
	259	xfs_daddr_t blkno,
c3f8fc73	260	size_t numblks,
1813dd64	261	const struct xfs_buf_ops *ops)
6dde2707 DC	262	{
6dde2707 DC	263	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
1813dd64	264	return xfs_buf_readahead_map(target, &map, 1, ops);
6dde2707	265	}
e70b73f8 DC	266
e70b73f8 DC	267	struct xfs_buf xfs_buf_get_empty(struct xfs_buftarg target, size_t numblks);
e70b73f8 DC	268	void xfs_buf_set_empty(struct xfs_buf *bp, size_t numblks);
	269	int xfs_buf_associate_memory(struct xfs_buf bp, void mem, size_t length);
	270
	271	struct xfs_buf xfs_buf_get_uncached(struct xfs_buftarg target, size_t numblks,
	272	int flags);
ba372674 DC	273	int xfs_buf_read_uncached(struct xfs_buftarg *target, xfs_daddr_t daddr,
	274	size_t numblks, int flags, struct xfs_buf **bpp,
	275	const struct xfs_buf_ops *ops);
e70b73f8	276	void xfs_buf_hold(struct xfs_buf *bp);
1da177e4 LT	277
1da177e4 LT	278	/* Releasing Buffers */
ce8e922c NS	279	extern void xfs_buf_free(xfs_buf_t *);
ce8e922c NS	280	extern void xfs_buf_rele(xfs_buf_t *);
1da177e4 LT	281
1da177e4 LT	282	/* Locking and Unlocking Buffers */
0c842ad4	283	extern int xfs_buf_trylock(xfs_buf_t *);
ce8e922c NS	284	extern void xfs_buf_lock(xfs_buf_t *);
ce8e922c NS	285	extern void xfs_buf_unlock(xfs_buf_t *);
0c842ad4 CH	286	#define xfs_buf_islocked(bp) \
0c842ad4 CH	287	((bp)->b_sema.count <= 0)
1da177e4 LT	288
1da177e4 LT	289	/* Buffer Read and Write Routines */
c2b006c1	290	extern int xfs_bwrite(struct xfs_buf *bp);
e8aaba9a	291	extern void xfs_buf_ioend(struct xfs_buf *bp);
ce8e922c	292	extern void xfs_buf_ioerror(xfs_buf_t *, int);
901796af	293	extern void xfs_buf_ioerror_alert(struct xfs_buf , const char func);
595bff75 DC	294	extern void xfs_buf_submit(struct xfs_buf *bp);
595bff75 DC	295	extern int xfs_buf_submit_wait(struct xfs_buf *bp);
b9c48649	296	extern void xfs_buf_iomove(xfs_buf_t , size_t, size_t, void ,
ce8e922c	297	xfs_buf_rw_t);
1a1a3e97 CH	298	#define xfs_buf_zero(bp, off, len) \
1a1a3e97 CH	299	xfs_buf_iomove((bp), (off), (len), NULL, XBRW_ZERO)
ce8e922c	300
1da177e4	301	/* Buffer Utility Routines */
88ee2df7	302	extern void xfs_buf_offset(struct xfs_buf , size_t);
1da177e4	303
1da177e4	304	/* Delayed Write Buffer Routines */
43ff2122 CH	305	extern bool xfs_buf_delwri_queue(struct xfs_buf , struct list_head );
	306	extern int xfs_buf_delwri_submit(struct list_head *);
	307	extern int xfs_buf_delwri_submit_nowait(struct list_head *);
1da177e4 LT	308
1da177e4 LT	309	/* Buffer Daemon Setup Routines */
ce8e922c NS	310	extern int xfs_buf_init(void);
ce8e922c NS	311	extern void xfs_buf_terminate(void);
1da177e4	312
1d5ae5df	313	#define XFS_BUF_ZEROFLAGS(bp) \
43ff2122	314	((bp)->b_flags &= ~(XBF_READ\|XBF_WRITE\|XBF_ASYNC\| \
ac8809f9 DC	315	XBF_SYNCIO\|XBF_FUA\|XBF_FLUSH\| \
ac8809f9 DC	316	XBF_WRITE_FAIL))
ce8e922c	317
430cbeb8	318	void xfs_buf_stale(struct xfs_buf *bp);
0cadda1c CH	319	#define XFS_BUF_UNSTALE(bp) ((bp)->b_flags &= ~XBF_STALE)
0cadda1c CH	320	#define XFS_BUF_ISSTALE(bp) ((bp)->b_flags & XBF_STALE)
1da177e4	321
ce8e922c NS	322	#define XFS_BUF_DONE(bp) ((bp)->b_flags \|= XBF_DONE)
	323	#define XFS_BUF_UNDONE(bp) ((bp)->b_flags &= ~XBF_DONE)
	324	#define XFS_BUF_ISDONE(bp) ((bp)->b_flags & XBF_DONE)
	325
ce8e922c NS	326	#define XFS_BUF_ASYNC(bp) ((bp)->b_flags \|= XBF_ASYNC)
	327	#define XFS_BUF_UNASYNC(bp) ((bp)->b_flags &= ~XBF_ASYNC)
	328	#define XFS_BUF_ISASYNC(bp) ((bp)->b_flags & XBF_ASYNC)
	329
ce8e922c NS	330	#define XFS_BUF_READ(bp) ((bp)->b_flags \|= XBF_READ)
	331	#define XFS_BUF_UNREAD(bp) ((bp)->b_flags &= ~XBF_READ)
	332	#define XFS_BUF_ISREAD(bp) ((bp)->b_flags & XBF_READ)
	333
	334	#define XFS_BUF_WRITE(bp) ((bp)->b_flags \|= XBF_WRITE)
	335	#define XFS_BUF_UNWRITE(bp) ((bp)->b_flags &= ~XBF_WRITE)
	336	#define XFS_BUF_ISWRITE(bp) ((bp)->b_flags & XBF_WRITE)
	337
cbb7baab DC	338	/*
	339	* These macros use the IO block map rather than b_bn. b_bn is now really
	340	* just for the buffer cache index for cached buffers. As IO does not use b_bn
	341	* anymore, uncached buffers do not use b_bn at all and hence must modify the IO
	342	* map directly. Uncached buffers are not allowed to be discontiguous, so this
	343	* is safe to do.
	344	*
	345	* In future, uncached buffers will pass the block number directly to the io
	346	* request function and hence these macros will go away at that point.
	347	*/
d44d9bc6 MT	348	#define XFS_BUF_ADDR(bp) ((bp)->b_maps[0].bm_bn)
d44d9bc6 MT	349	#define XFS_BUF_SET_ADDR(bp, bno) ((bp)->b_maps[0].bm_bn = (xfs_daddr_t)(bno))
ce8e922c	350
38f23232	351	static inline void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
821eb21d DC	352	{
	353	atomic_set(&bp->b_lru_ref, lru_ref);
	354	}
ce8e922c	355
811e64c7 CS	356	static inline int xfs_buf_ispinned(struct xfs_buf *bp)
	357	{
	358	return atomic_read(&bp->b_pin_count);
	359	}
ce8e922c	360
ce8e922c	361	static inline void xfs_buf_relse(xfs_buf_t *bp)
1da177e4	362	{
bfc60177	363	xfs_buf_unlock(bp);
ce8e922c	364	xfs_buf_rele(bp);
1da177e4 LT	365	}
1da177e4 LT	366
51582170 ES	367	static inline int
	368	xfs_buf_verify_cksum(struct xfs_buf *bp, unsigned long cksum_offset)
	369	{
	370	return xfs_verify_cksum(bp->b_addr, BBTOB(bp->b_length),
	371	cksum_offset);
	372	}
	373
f1dbcd7e ES	374	static inline void
	375	xfs_buf_update_cksum(struct xfs_buf *bp, unsigned long cksum_offset)
	376	{
	377	xfs_update_cksum(bp->b_addr, BBTOB(bp->b_length),
	378	cksum_offset);
	379	}
	380
1da177e4 LT	381	/*
	382	* Handling of buftargs.
	383	*/
ebad861b	384	extern xfs_buftarg_t xfs_alloc_buftarg(struct xfs_mount ,
34dcefd7	385	struct block_device *);
c141b292	386	extern void xfs_free_buftarg(struct xfs_mount , struct xfs_buftarg );
1da177e4	387	extern void xfs_wait_buftarg(xfs_buftarg_t *);
a96c4151	388	extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int);
d808f617	389
ce8e922c NS	390	#define xfs_getsize_buftarg(buftarg) block_size((buftarg)->bt_bdev)
	391	#define xfs_readonly_buftarg(buftarg) bdev_read_only((buftarg)->bt_bdev)
	392
1da177e4	393	#endif /* __XFS_BUF_H__ */