fs/xfs/linux-2.6/xfs_buf.h - linux-mtk - Git at Google

 /*
  * 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 <asm/system.h>
 #include <linux/mm.h>
 #include <linux/fs.h>
 #include <linux/buffer_head.h>
 #include <linux/uio.h>

 /*
  *	Base types
  */

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

 #define xfs_buf_ctob(pp)	((pp) * PAGE_CACHE_SIZE)
 #define xfs_buf_btoc(dd)	(((dd) + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT)
 #define xfs_buf_btoct(dd)	((dd) >> PAGE_CACHE_SHIFT)
 #define xfs_buf_poff(aa)	((aa) & ~PAGE_CACHE_MASK)

 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_MAPPED	(1 << 2) /* buffer mapped (b_addr valid) */
 #define XBF_ASYNC	(1 << 4) /* initiator will not wait for completion */
 #define XBF_DONE	(1 << 5) /* all pages in the buffer uptodate */
 #define XBF_DELWRI	(1 << 6) /* buffer has dirty pages */
 #define XBF_STALE	(1 << 7) /* buffer has been staled, do not find it */
 #define XBF_ORDERED	(1 << 11)/* use ordered writes */
 #define XBF_READ_AHEAD	(1 << 12)/* asynchronous read-ahead */
 #define XBF_LOG_BUFFER	(1 << 13)/* this is a buffer used for the log */

 /* flags used only as arguments to access routines */
 #define XBF_LOCK	(1 << 14)/* lock requested */
 #define XBF_TRYLOCK	(1 << 15)/* lock requested, but do not wait */
 #define XBF_DONT_BLOCK	(1 << 16)/* do not block in current thread */

 /* flags used only internally */
 #define _XBF_PAGES	(1 << 18)/* backed by refcounted pages */
 #define	_XBF_RUN_QUEUES	(1 << 19)/* run block device task queue	*/
 #define	_XBF_KMEM	(1 << 20)/* backed by heap memory */
 #define _XBF_DELWRI_Q	(1 << 21)/* buffer on delwri queue */

 typedef unsigned int xfs_buf_flags_t;

 #define XFS_BUF_FLAGS \
 	{ XBF_READ,		"READ" }, \
 	{ XBF_WRITE,		"WRITE" }, \
 	{ XBF_MAPPED,		"MAPPED" }, \
 	{ XBF_ASYNC,		"ASYNC" }, \
 	{ XBF_DONE,		"DONE" }, \
 	{ XBF_DELWRI,		"DELWRI" }, \
 	{ XBF_STALE,		"STALE" }, \
 	{ XBF_ORDERED,		"ORDERED" }, \
 	{ XBF_READ_AHEAD,	"READ_AHEAD" }, \
 	{ XBF_LOCK,		"LOCK" },  	/* should never be set */\
 	{ XBF_TRYLOCK,		"TRYLOCK" }, 	/* ditto */\
 	{ XBF_DONT_BLOCK,	"DONT_BLOCK" },	/* ditto */\
 	{ _XBF_PAGES,		"PAGES" }, \
 	{ _XBF_RUN_QUEUES,	"RUN_QUEUES" }, \
 	{ _XBF_KMEM,		"KMEM" }, \
 	{ _XBF_DELWRI_Q,	"DELWRI_Q" }

 typedef enum {
 	XBT_FORCE_SLEEP = 0,
 	XBT_FORCE_FLUSH = 1,
 } xfs_buftarg_flags_t;

 typedef struct xfs_bufhash {
 	struct list_head	bh_list;
 	spinlock_t		bh_lock;
 } xfs_bufhash_t;

 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_bsize;
 	unsigned int		bt_sshift;
 	size_t			bt_smask;

 	/* per device delwri queue */
 	struct task_struct	*bt_task;
 	struct list_head	bt_delwrite_queue;
 	spinlock_t		bt_delwrite_lock;
 	unsigned long		bt_flags;

 	/* LRU control structures */
 	struct shrinker		bt_shrinker;
 	struct list_head	bt_lru;
 	spinlock_t		bt_lru_lock;
 	unsigned int		bt_lru_nr;
 } xfs_buftarg_t;

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

 #define XB_PAGES	2

 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_off_t		b_file_offset;	/* offset in file */
 	size_t			b_buffer_length;/* size of buffer in bytes */
 	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 */

 	struct list_head	b_lru;		/* lru list */
 	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) */
 	xfs_daddr_t		b_bn;		/* block number for I/O */
 	size_t			b_count_desired;/* desired transfer size */
 	void			*b_addr;	/* virtual address of buffer */
 	struct work_struct	b_iodone_work;
 	xfs_buf_iodone_t	b_iodone;	/* I/O completion function */
 	struct completion	b_iowait;	/* queue for I/O waiters */
 	void			*b_fspriv;
 	void			*b_fspriv2;
 	struct page		**b_pages;	/* array of page pointers */
 	struct page		*b_page_array[XB_PAGES]; /* inline pages */
 	unsigned long		b_queuetime;	/* time buffer was queued */
 	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 */
 	unsigned short		b_error;	/* error code on I/O */
 #ifdef XFS_BUF_LOCK_TRACKING
 	int			b_last_holder;
 #endif
 } xfs_buf_t;


 /* Finding and Reading Buffers */
 extern xfs_buf_t *_xfs_buf_find(xfs_buftarg_t *, xfs_off_t, size_t,
 				xfs_buf_flags_t, xfs_buf_t *);
 #define xfs_incore(buftarg,blkno,len,lockit) \
 	_xfs_buf_find(buftarg, blkno ,len, lockit, NULL)

 extern xfs_buf_t *xfs_buf_get(xfs_buftarg_t *, xfs_off_t, size_t,
 				xfs_buf_flags_t);
 extern xfs_buf_t *xfs_buf_read(xfs_buftarg_t *, xfs_off_t, size_t,
 				xfs_buf_flags_t);

 extern xfs_buf_t *xfs_buf_get_empty(size_t, xfs_buftarg_t *);
 extern xfs_buf_t *xfs_buf_get_uncached(struct xfs_buftarg *, size_t, int);
 extern int xfs_buf_associate_memory(xfs_buf_t *, void *, size_t);
 extern void xfs_buf_hold(xfs_buf_t *);
 extern void xfs_buf_readahead(xfs_buftarg_t *, xfs_off_t, size_t);
 struct xfs_buf *xfs_buf_read_uncached(struct xfs_mount *mp,
 				struct xfs_buftarg *target,
 				xfs_daddr_t daddr, size_t length, int flags);

 /* 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_cond_lock(xfs_buf_t *);
 extern int xfs_buf_lock_value(xfs_buf_t *);
 extern void xfs_buf_lock(xfs_buf_t *);
 extern void xfs_buf_unlock(xfs_buf_t *);

 /* Buffer Read and Write Routines */
 extern int xfs_bwrite(struct xfs_mount *mp, struct xfs_buf *bp);
 extern void xfs_bdwrite(void *mp, xfs_buf_t *bp);

 extern void xfsbdstrat(struct xfs_mount *, struct xfs_buf *);
 extern int xfs_bdstrat_cb(struct xfs_buf *);

 extern void xfs_buf_ioend(xfs_buf_t *,	int);
 extern void xfs_buf_ioerror(xfs_buf_t *, int);
 extern int xfs_buf_iorequest(xfs_buf_t *);
 extern int xfs_buf_iowait(xfs_buf_t *);
 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)

 static inline int xfs_buf_geterror(xfs_buf_t *bp)
 {
 	return bp ? bp->b_error : ENOMEM;
 }

 /* Buffer Utility Routines */
 extern xfs_caddr_t xfs_buf_offset(xfs_buf_t *, size_t);

 /* Delayed Write Buffer Routines */
 extern void xfs_buf_delwri_dequeue(xfs_buf_t *);
 extern void xfs_buf_delwri_promote(xfs_buf_t *);

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

 #define xfs_buf_target_name(target)	\
 	({ char __b[BDEVNAME_SIZE]; bdevname((target)->bt_bdev, __b); __b; })


 #define XFS_BUF_BFLAGS(bp)	((bp)->b_flags)
 #define XFS_BUF_ZEROFLAGS(bp)	((bp)->b_flags &= \
 		~(XBF_READ|XBF_WRITE|XBF_ASYNC|XBF_DELWRI|XBF_ORDERED))

 void xfs_buf_stale(struct xfs_buf *bp);
 #define XFS_BUF_STALE(bp)	xfs_buf_stale(bp);
 #define XFS_BUF_UNSTALE(bp)	((bp)->b_flags &= ~XBF_STALE)
 #define XFS_BUF_ISSTALE(bp)	((bp)->b_flags & XBF_STALE)
 #define XFS_BUF_SUPER_STALE(bp)	do {				\
 					XFS_BUF_STALE(bp);	\
 					xfs_buf_delwri_dequeue(bp);	\
 					XFS_BUF_DONE(bp);	\
 				} while (0)

 #define XFS_BUF_DELAYWRITE(bp)		((bp)->b_flags |= XBF_DELWRI)
 #define XFS_BUF_UNDELAYWRITE(bp)	xfs_buf_delwri_dequeue(bp)
 #define XFS_BUF_ISDELAYWRITE(bp)	((bp)->b_flags & XBF_DELWRI)

 #define XFS_BUF_ERROR(bp,no)	xfs_buf_ioerror(bp,no)
 #define XFS_BUF_GETERROR(bp)	xfs_buf_geterror(bp)
 #define XFS_BUF_ISERROR(bp)	(xfs_buf_geterror(bp) ? 1 : 0)

 #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_BUSY(bp)	do { } while (0)
 #define XFS_BUF_UNBUSY(bp)	do { } while (0)
 #define XFS_BUF_ISBUSY(bp)	(1)

 #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_ORDERED(bp)	((bp)->b_flags |= XBF_ORDERED)
 #define XFS_BUF_UNORDERED(bp)	((bp)->b_flags &= ~XBF_ORDERED)
 #define XFS_BUF_ISORDERED(bp)	((bp)->b_flags & XBF_ORDERED)

 #define XFS_BUF_HOLD(bp)	xfs_buf_hold(bp)
 #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)

 #define XFS_BUF_IODONE_FUNC(bp)			((bp)->b_iodone)
 #define XFS_BUF_SET_IODONE_FUNC(bp, func)	((bp)->b_iodone = (func))
 #define XFS_BUF_CLR_IODONE_FUNC(bp)		((bp)->b_iodone = NULL)

 #define XFS_BUF_FSPRIVATE(bp, type)		((type)(bp)->b_fspriv)
 #define XFS_BUF_SET_FSPRIVATE(bp, val)		((bp)->b_fspriv = (void*)(val))
 #define XFS_BUF_FSPRIVATE2(bp, type)		((type)(bp)->b_fspriv2)
 #define XFS_BUF_SET_FSPRIVATE2(bp, val)		((bp)->b_fspriv2 = (void*)(val))
 #define XFS_BUF_SET_START(bp)			do { } while (0)

 #define XFS_BUF_PTR(bp)			(xfs_caddr_t)((bp)->b_addr)
 #define XFS_BUF_SET_PTR(bp, val, cnt)	xfs_buf_associate_memory(bp, val, cnt)
 #define XFS_BUF_ADDR(bp)		((bp)->b_bn)
 #define XFS_BUF_SET_ADDR(bp, bno)	((bp)->b_bn = (xfs_daddr_t)(bno))
 #define XFS_BUF_OFFSET(bp)		((bp)->b_file_offset)
 #define XFS_BUF_SET_OFFSET(bp, off)	((bp)->b_file_offset = (off))
 #define XFS_BUF_COUNT(bp)		((bp)->b_count_desired)
 #define XFS_BUF_SET_COUNT(bp, cnt)	((bp)->b_count_desired = (cnt))
 #define XFS_BUF_SIZE(bp)		((bp)->b_buffer_length)
 #define XFS_BUF_SET_SIZE(bp, cnt)	((bp)->b_buffer_length = (cnt))

 static inline void
 xfs_buf_set_ref(
 	struct xfs_buf	*bp,
 	int		lru_ref)
 {
 	atomic_set(&bp->b_lru_ref, lru_ref);
 }
 #define XFS_BUF_SET_VTYPE_REF(bp, type, ref)	xfs_buf_set_ref(bp, ref)
 #define XFS_BUF_SET_VTYPE(bp, type)		do { } while (0)

 #define XFS_BUF_ISPINNED(bp)	atomic_read(&((bp)->b_pin_count))

 #define XFS_BUF_VALUSEMA(bp)	xfs_buf_lock_value(bp)
 #define XFS_BUF_CPSEMA(bp)	(xfs_buf_cond_lock(bp) == 0)
 #define XFS_BUF_VSEMA(bp)	xfs_buf_unlock(bp)
 #define XFS_BUF_PSEMA(bp,x)	xfs_buf_lock(bp)
 #define XFS_BUF_FINISH_IOWAIT(bp)	complete(&bp->b_iowait);

 #define XFS_BUF_SET_TARGET(bp, target)	((bp)->b_target = (target))
 #define XFS_BUF_TARGET(bp)		((bp)->b_target)
 #define XFS_BUFTARG_NAME(target)	xfs_buf_target_name(target)

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

 /*
  *	Handling of buftargs.
  */
 extern xfs_buftarg_t *xfs_alloc_buftarg(struct xfs_mount *,
 			struct block_device *, int, const char *);
 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, unsigned int);
 extern int xfs_flush_buftarg(xfs_buftarg_t *, int);

 #ifdef CONFIG_KDB_MODULES
 extern struct list_head *xfs_get_buftarg_list(void);
 #endif

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

 #define xfs_binval(buftarg)		xfs_flush_buftarg(buftarg, 1)
 #define XFS_bflush(buftarg)		xfs_flush_buftarg(buftarg, 1)

 #endif	/* __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 <asm/system.h>
	#include <linux/mm.h>
	#include <linux/fs.h>
	#include <linux/buffer_head.h>
	#include <linux/uio.h>

	/*
	* Base types
	*/

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

	#define xfs_buf_ctob(pp) ((pp) * PAGE_CACHE_SIZE)
	#define xfs_buf_btoc(dd) (((dd) + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT)
	#define xfs_buf_btoct(dd) ((dd) >> PAGE_CACHE_SHIFT)
	#define xfs_buf_poff(aa) ((aa) & ~PAGE_CACHE_MASK)

	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_MAPPED (1 << 2) /* buffer mapped (b_addr valid) */
	#define XBF_ASYNC (1 << 4) /* initiator will not wait for completion */
	#define XBF_DONE (1 << 5) /* all pages in the buffer uptodate */
	#define XBF_DELWRI (1 << 6) /* buffer has dirty pages */
	#define XBF_STALE (1 << 7) /* buffer has been staled, do not find it */
	#define XBF_ORDERED (1 << 11)/* use ordered writes */
	#define XBF_READ_AHEAD (1 << 12)/* asynchronous read-ahead */
	#define XBF_LOG_BUFFER (1 << 13)/* this is a buffer used for the log */

	/* flags used only as arguments to access routines */
	#define XBF_LOCK (1 << 14)/* lock requested */
	#define XBF_TRYLOCK (1 << 15)/* lock requested, but do not wait */
	#define XBF_DONT_BLOCK (1 << 16)/* do not block in current thread */

	/* flags used only internally */
	#define _XBF_PAGES (1 << 18)/* backed by refcounted pages */
	#define _XBF_RUN_QUEUES (1 << 19)/* run block device task queue */
	#define _XBF_KMEM (1 << 20)/* backed by heap memory */
	#define _XBF_DELWRI_Q (1 << 21)/* buffer on delwri queue */

	typedef unsigned int xfs_buf_flags_t;

	#define XFS_BUF_FLAGS \
	{ XBF_READ, "READ" }, \
	{ XBF_WRITE, "WRITE" }, \
	{ XBF_MAPPED, "MAPPED" }, \
	{ XBF_ASYNC, "ASYNC" }, \
	{ XBF_DONE, "DONE" }, \
	{ XBF_DELWRI, "DELWRI" }, \
	{ XBF_STALE, "STALE" }, \
	{ XBF_ORDERED, "ORDERED" }, \
	{ XBF_READ_AHEAD, "READ_AHEAD" }, \
	{ XBF_LOCK, "LOCK" }, /* should never be set */\
	{ XBF_TRYLOCK, "TRYLOCK" }, /* ditto */\
	{ XBF_DONT_BLOCK, "DONT_BLOCK" }, /* ditto */\
	{ _XBF_PAGES, "PAGES" }, \
	{ _XBF_RUN_QUEUES, "RUN_QUEUES" }, \
	{ _XBF_KMEM, "KMEM" }, \
	{ _XBF_DELWRI_Q, "DELWRI_Q" }

	typedef enum {
	XBT_FORCE_SLEEP = 0,
	XBT_FORCE_FLUSH = 1,
	} xfs_buftarg_flags_t;

	typedef struct xfs_bufhash {
	struct list_head bh_list;
	spinlock_t bh_lock;
	} xfs_bufhash_t;

	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_bsize;
	unsigned int bt_sshift;
	size_t bt_smask;

	/* per device delwri queue */
	struct task_struct *bt_task;
	struct list_head bt_delwrite_queue;
	spinlock_t bt_delwrite_lock;
	unsigned long bt_flags;

	/* LRU control structures */
	struct shrinker bt_shrinker;
	struct list_head bt_lru;
	spinlock_t bt_lru_lock;
	unsigned int bt_lru_nr;
	} xfs_buftarg_t;

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

	#define XB_PAGES 2

	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_off_t b_file_offset; /* offset in file */
	size_t b_buffer_length;/* size of buffer in bytes */
	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 */

	struct list_head b_lru; /* lru list */
	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) */
	xfs_daddr_t b_bn; /* block number for I/O */
	size_t b_count_desired;/* desired transfer size */
	void b_addr; / virtual address of buffer */
	struct work_struct b_iodone_work;
	xfs_buf_iodone_t b_iodone; /* I/O completion function */
	struct completion b_iowait; /* queue for I/O waiters */
	void *b_fspriv;
	void *b_fspriv2;
	struct page *b_pages; / array of page pointers */
	struct page b_page_array[XB_PAGES]; / inline pages */
	unsigned long b_queuetime; /* time buffer was queued */
	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 */
	unsigned short b_error; /* error code on I/O */
	#ifdef XFS_BUF_LOCK_TRACKING
	int b_last_holder;
	#endif
	} xfs_buf_t;


	/* Finding and Reading Buffers */
	extern xfs_buf_t _xfs_buf_find(xfs_buftarg_t , xfs_off_t, size_t,
	xfs_buf_flags_t, xfs_buf_t *);
	#define xfs_incore(buftarg,blkno,len,lockit) \
	_xfs_buf_find(buftarg, blkno ,len, lockit, NULL)

	extern xfs_buf_t xfs_buf_get(xfs_buftarg_t , xfs_off_t, size_t,
	xfs_buf_flags_t);
	extern xfs_buf_t xfs_buf_read(xfs_buftarg_t , xfs_off_t, size_t,
	xfs_buf_flags_t);

	extern xfs_buf_t xfs_buf_get_empty(size_t, xfs_buftarg_t );
	extern xfs_buf_t xfs_buf_get_uncached(struct xfs_buftarg , size_t, int);
	extern int xfs_buf_associate_memory(xfs_buf_t , void , size_t);
	extern void xfs_buf_hold(xfs_buf_t *);
	extern void xfs_buf_readahead(xfs_buftarg_t *, xfs_off_t, size_t);
	struct xfs_buf xfs_buf_read_uncached(struct xfs_mount mp,
	struct xfs_buftarg *target,
	xfs_daddr_t daddr, size_t length, int flags);

	/* 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_cond_lock(xfs_buf_t *);
	extern int xfs_buf_lock_value(xfs_buf_t *);
	extern void xfs_buf_lock(xfs_buf_t *);
	extern void xfs_buf_unlock(xfs_buf_t *);

	/* Buffer Read and Write Routines */
	extern int xfs_bwrite(struct xfs_mount mp, struct xfs_buf bp);
	extern void xfs_bdwrite(void mp, xfs_buf_t bp);

	extern void xfsbdstrat(struct xfs_mount , struct xfs_buf );
	extern int xfs_bdstrat_cb(struct xfs_buf *);

	extern void xfs_buf_ioend(xfs_buf_t *, int);
	extern void xfs_buf_ioerror(xfs_buf_t *, int);
	extern int xfs_buf_iorequest(xfs_buf_t *);
	extern int xfs_buf_iowait(xfs_buf_t *);
	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)

	static inline int xfs_buf_geterror(xfs_buf_t *bp)
	{
	return bp ? bp->b_error : ENOMEM;
	}

	/* Buffer Utility Routines */
	extern xfs_caddr_t xfs_buf_offset(xfs_buf_t *, size_t);

	/* Delayed Write Buffer Routines */
	extern void xfs_buf_delwri_dequeue(xfs_buf_t *);
	extern void xfs_buf_delwri_promote(xfs_buf_t *);

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

	#define xfs_buf_target_name(target) \
	({ char __b[BDEVNAME_SIZE]; bdevname((target)->bt_bdev, __b); __b; })


	#define XFS_BUF_BFLAGS(bp) ((bp)->b_flags)
	#define XFS_BUF_ZEROFLAGS(bp) ((bp)->b_flags &= \
	~(XBF_READ\|XBF_WRITE\|XBF_ASYNC\|XBF_DELWRI\|XBF_ORDERED))

	void xfs_buf_stale(struct xfs_buf *bp);
	#define XFS_BUF_STALE(bp) xfs_buf_stale(bp);
	#define XFS_BUF_UNSTALE(bp) ((bp)->b_flags &= ~XBF_STALE)
	#define XFS_BUF_ISSTALE(bp) ((bp)->b_flags & XBF_STALE)
	#define XFS_BUF_SUPER_STALE(bp) do { \
	XFS_BUF_STALE(bp); \
	xfs_buf_delwri_dequeue(bp); \
	XFS_BUF_DONE(bp); \
	} while (0)

	#define XFS_BUF_DELAYWRITE(bp) ((bp)->b_flags \|= XBF_DELWRI)
	#define XFS_BUF_UNDELAYWRITE(bp) xfs_buf_delwri_dequeue(bp)
	#define XFS_BUF_ISDELAYWRITE(bp) ((bp)->b_flags & XBF_DELWRI)

	#define XFS_BUF_ERROR(bp,no) xfs_buf_ioerror(bp,no)
	#define XFS_BUF_GETERROR(bp) xfs_buf_geterror(bp)
	#define XFS_BUF_ISERROR(bp) (xfs_buf_geterror(bp) ? 1 : 0)

	#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_BUSY(bp) do { } while (0)
	#define XFS_BUF_UNBUSY(bp) do { } while (0)
	#define XFS_BUF_ISBUSY(bp) (1)

	#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_ORDERED(bp) ((bp)->b_flags \|= XBF_ORDERED)
	#define XFS_BUF_UNORDERED(bp) ((bp)->b_flags &= ~XBF_ORDERED)
	#define XFS_BUF_ISORDERED(bp) ((bp)->b_flags & XBF_ORDERED)

	#define XFS_BUF_HOLD(bp) xfs_buf_hold(bp)
	#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)

	#define XFS_BUF_IODONE_FUNC(bp) ((bp)->b_iodone)
	#define XFS_BUF_SET_IODONE_FUNC(bp, func) ((bp)->b_iodone = (func))
	#define XFS_BUF_CLR_IODONE_FUNC(bp) ((bp)->b_iodone = NULL)

	#define XFS_BUF_FSPRIVATE(bp, type) ((type)(bp)->b_fspriv)
	#define XFS_BUF_SET_FSPRIVATE(bp, val) ((bp)->b_fspriv = (void*)(val))
	#define XFS_BUF_FSPRIVATE2(bp, type) ((type)(bp)->b_fspriv2)
	#define XFS_BUF_SET_FSPRIVATE2(bp, val) ((bp)->b_fspriv2 = (void*)(val))
	#define XFS_BUF_SET_START(bp) do { } while (0)

	#define XFS_BUF_PTR(bp) (xfs_caddr_t)((bp)->b_addr)
	#define XFS_BUF_SET_PTR(bp, val, cnt) xfs_buf_associate_memory(bp, val, cnt)
	#define XFS_BUF_ADDR(bp) ((bp)->b_bn)
	#define XFS_BUF_SET_ADDR(bp, bno) ((bp)->b_bn = (xfs_daddr_t)(bno))
	#define XFS_BUF_OFFSET(bp) ((bp)->b_file_offset)
	#define XFS_BUF_SET_OFFSET(bp, off) ((bp)->b_file_offset = (off))
	#define XFS_BUF_COUNT(bp) ((bp)->b_count_desired)
	#define XFS_BUF_SET_COUNT(bp, cnt) ((bp)->b_count_desired = (cnt))
	#define XFS_BUF_SIZE(bp) ((bp)->b_buffer_length)
	#define XFS_BUF_SET_SIZE(bp, cnt) ((bp)->b_buffer_length = (cnt))

	static inline void
	xfs_buf_set_ref(
	struct xfs_buf *bp,
	int lru_ref)
	{
	atomic_set(&bp->b_lru_ref, lru_ref);
	}
	#define XFS_BUF_SET_VTYPE_REF(bp, type, ref) xfs_buf_set_ref(bp, ref)
	#define XFS_BUF_SET_VTYPE(bp, type) do { } while (0)

	#define XFS_BUF_ISPINNED(bp) atomic_read(&((bp)->b_pin_count))

	#define XFS_BUF_VALUSEMA(bp) xfs_buf_lock_value(bp)
	#define XFS_BUF_CPSEMA(bp) (xfs_buf_cond_lock(bp) == 0)
	#define XFS_BUF_VSEMA(bp) xfs_buf_unlock(bp)
	#define XFS_BUF_PSEMA(bp,x) xfs_buf_lock(bp)
	#define XFS_BUF_FINISH_IOWAIT(bp) complete(&bp->b_iowait);

	#define XFS_BUF_SET_TARGET(bp, target) ((bp)->b_target = (target))
	#define XFS_BUF_TARGET(bp) ((bp)->b_target)
	#define XFS_BUFTARG_NAME(target) xfs_buf_target_name(target)

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

	/*
	* Handling of buftargs.
	*/
	extern xfs_buftarg_t xfs_alloc_buftarg(struct xfs_mount ,
	struct block_device , int, const char );
	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, unsigned int);
	extern int xfs_flush_buftarg(xfs_buftarg_t *, int);

	#ifdef CONFIG_KDB_MODULES
	extern struct list_head *xfs_get_buftarg_list(void);
	#endif

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

	#define xfs_binval(buftarg) xfs_flush_buftarg(buftarg, 1)
	#define XFS_bflush(buftarg) xfs_flush_buftarg(buftarg, 1)

	#endif /* __XFS_BUF_H__ */