[net-next-2.6.git] / fs / xfs / linux-2.6 / 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_FS_MANAGED	(1 << 8) /* filesystem controls freeing memory */
#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_PAGE_CACHE	(1 << 17)/* backed by pagecache */
#define _XBF_PAGES	(1 << 18)/* backed by refcounted pages */
#define	_XBF_RUN_QUEUES	(1 << 19)/* run block device task queue	*/
#define _XBF_DELWRI_Q	(1 << 21)/* buffer on delwri queue */

/*
 * Special flag for supporting metadata blocks smaller than a FSB.
 *
 * In this case we can have multiple xfs_buf_t on a single page and
 * need to lock out concurrent xfs_buf_t readers as they only
 * serialise access to the buffer.
 *
 * If the FSB size >= PAGE_CACHE_SIZE case, we have no serialisation
 * between reads of the page. Hence we can have one thread read the
 * page and modify it, but then race with another thread that thinks
 * the page is not up-to-date and hence reads it again.
 *
 * The result is that the first modifcation to the page is lost.
 * This sort of AGF/AGI reading race can happen when unlinking inodes
 * that require truncation and results in the AGI unlinked list
 * modifications being lost.
 */
#define _XBF_PAGE_LOCKED	(1 << 22)

/*
 * If we try a barrier write, but it fails we have to communicate
 * this to the upper layers.  Unfortunately b_error gets overwritten
 * when the buffer is re-issued so we have to add another flag to
 * keep this information.
 */
#define _XFS_BARRIER_FAILED	(1 << 23)

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_FS_MANAGED,	"FS_MANAGED" }, \
	{ 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_PAGE_CACHE,	"PAGE_CACHE" }, \
	{ _XBF_PAGES,		"PAGES" }, \
	{ _XBF_RUN_QUEUES,	"RUN_QUEUES" }, \
	{ _XBF_DELWRI_Q,	"DELWRI_Q" }, \
	{ _XBF_PAGE_LOCKED,	"PAGE_LOCKED" }, \
	{ _XFS_BARRIER_FAILED,	"BARRIER_FAILED" }


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 address_space	*bt_mapping;
	unsigned int		bt_bsize;
	unsigned int		bt_sshift;
	size_t			bt_smask;

	/* per device buffer hash table */
	uint			bt_hashshift;
	xfs_bufhash_t		*bt_hash;

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

/*
 *	xfs_buf_t:  Buffer structure for pagecache-based buffers
 *
 * This buffer structure is used by the pagecache buffer management routines
 * to refer to an assembly of pages forming a logical buffer.
 *
 * The buffer structure is used on a temporary basis only, and discarded when
 * released.  The real data storage is recorded in the pagecache. Buffers are
 * hashed to the block device on which the file system resides.
 */

struct xfs_buf;
typedef void (*xfs_buf_iodone_t)(struct xfs_buf *);
typedef void (*xfs_buf_relse_t)(struct xfs_buf *);
typedef int (*xfs_buf_bdstrat_t)(struct xfs_buf *);

#define XB_PAGES	2

typedef struct xfs_buf {
	struct semaphore	b_sema;		/* semaphore for lockables */
	unsigned long		b_queuetime;	/* time buffer was queued */
	atomic_t		b_pin_count;	/* pin count */
	wait_queue_head_t	b_waiters;	/* unpin waiters */
	struct list_head	b_list;
	xfs_buf_flags_t		b_flags;	/* status flags */
	struct list_head	b_hash_list;	/* hash table list */
	xfs_bufhash_t		*b_hash;	/* hash table list start */
	xfs_buftarg_t		*b_target;	/* buffer target (device) */
	atomic_t		b_hold;		/* reference count */
	xfs_daddr_t		b_bn;		/* block number for I/O */
	xfs_off_t		b_file_offset;	/* offset in file */
	size_t			b_buffer_length;/* size of buffer in bytes */
	size_t			b_count_desired;/* desired transfer size */
	void			*b_addr;	/* virtual address of buffer */
	struct work_struct	b_iodone_work;
	atomic_t		b_io_remaining;	/* #outstanding I/O requests */
	xfs_buf_iodone_t	b_iodone;	/* I/O completion function */
	xfs_buf_relse_t		b_relse;	/* releasing function */
	struct completion	b_iowait;	/* queue for I/O waiters */
	void			*b_fspriv;
	void			*b_fspriv2;
	struct xfs_mount	*b_mount;
	unsigned short		b_error;	/* error code on I/O */
	unsigned int		b_page_count;	/* size of page array */
	unsigned int		b_offset;	/* page offset in first page */
	struct page		**b_pages;	/* array of page pointers */
	struct page		*b_page_array[XB_PAGES]; /* inline pages */
#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_noaddr(size_t, xfs_buftarg_t *);
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,
				xfs_buf_flags_t);

/* 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);

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))

#define XFS_BUF_STALE(bp)	((bp)->b_flags |= XBF_STALE)
#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_UNMANAGE(bp)	((bp)->b_flags &= ~XBF_FS_MANAGED)

#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_SET_BRELSE_FUNC(bp, func)	((bp)->b_relse = (func))

#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))

#define XFS_BUF_SET_VTYPE_REF(bp, type, ref)	do { } while (0)
#define XFS_BUF_SET_VTYPE(bp, type)		do { } while (0)
#define XFS_BUF_SET_REF(bp, ref)		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)
{
	if (!bp->b_relse)
		xfs_buf_unlock(bp);
	xfs_buf_rele(bp);
}

#define xfs_biodone(bp)		xfs_buf_ioend(bp, 0)

#define xfs_biomove(bp, off, len, data, rw) \
	    xfs_buf_iomove((bp), (off), (len), (data), \
		((rw) == XBF_WRITE) ? XBRW_WRITE : XBRW_READ)

#define xfs_biozero(bp, off, len) \
	    xfs_buf_iomove((bp), (off), (len), NULL, XBRW_ZERO)

#define xfs_iowait(bp)	xfs_buf_iowait(bp)

#define xfs_baread(target, rablkno, ralen)  \
	xfs_buf_readahead((target), (rablkno), (ralen), XBF_DONT_BLOCK)


/*
 *	Handling of buftargs.
 */
extern xfs_buftarg_t *xfs_alloc_buftarg(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__ */
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>
	24	#include <asm/system.h>
	25	#include <linux/mm.h>
	26	#include <linux/fs.h>
	27	#include <linux/buffer_head.h>
	28	#include <linux/uio.h>
	29
	30	/*
	31	* Base types
	32	*/
	33
ce8e922c NS	34	#define XFS_BUF_DADDR_NULL ((xfs_daddr_t) (-1LL))
	35
	36	#define xfs_buf_ctob(pp) ((pp) * PAGE_CACHE_SIZE)
	37	#define xfs_buf_btoc(dd) (((dd) + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT)
	38	#define xfs_buf_btoct(dd) ((dd) >> PAGE_CACHE_SHIFT)
	39	#define xfs_buf_poff(aa) ((aa) & ~PAGE_CACHE_MASK)
	40
	41	typedef enum {
	42	XBRW_READ = 1, /* transfer into target memory */
	43	XBRW_WRITE = 2, /* transfer from target memory */
	44	XBRW_ZERO = 3, /* Zero target memory */
	45	} xfs_buf_rw_t;
	46
807cbbdb CH	47	#define XBF_READ (1 << 0) /* buffer intended for reading from device */
	48	#define XBF_WRITE (1 << 1) /* buffer intended for writing to device */
	49	#define XBF_MAPPED (1 << 2) /* buffer mapped (b_addr valid) */
	50	#define XBF_ASYNC (1 << 4) /* initiator will not wait for completion */
	51	#define XBF_DONE (1 << 5) /* all pages in the buffer uptodate */
	52	#define XBF_DELWRI (1 << 6) /* buffer has dirty pages */
	53	#define XBF_STALE (1 << 7) /* buffer has been staled, do not find it */
	54	#define XBF_FS_MANAGED (1 << 8) /* filesystem controls freeing memory */
	55	#define XBF_ORDERED (1 << 11)/* use ordered writes */
	56	#define XBF_READ_AHEAD (1 << 12)/* asynchronous read-ahead */
	57	#define XBF_LOG_BUFFER (1 << 13)/* this is a buffer used for the log */
1da177e4	58
807cbbdb CH	59	/* flags used only as arguments to access routines */
	60	#define XBF_LOCK (1 << 14)/* lock requested */
	61	#define XBF_TRYLOCK (1 << 15)/* lock requested, but do not wait */
	62	#define XBF_DONT_BLOCK (1 << 16)/* do not block in current thread */
1da177e4	63
807cbbdb CH	64	/* flags used only internally */
	65	#define _XBF_PAGE_CACHE (1 << 17)/* backed by pagecache */
	66	#define _XBF_PAGES (1 << 18)/* backed by refcounted pages */
	67	#define _XBF_RUN_QUEUES (1 << 19)/* run block device task queue */
	68	#define _XBF_DELWRI_Q (1 << 21)/* buffer on delwri queue */
6ab455ee	69
807cbbdb CH	70	/*
	71	* Special flag for supporting metadata blocks smaller than a FSB.
	72	*
	73	* In this case we can have multiple xfs_buf_t on a single page and
	74	* need to lock out concurrent xfs_buf_t readers as they only
	75	* serialise access to the buffer.
	76	*
	77	* If the FSB size >= PAGE_CACHE_SIZE case, we have no serialisation
	78	* between reads of the page. Hence we can have one thread read the
	79	* page and modify it, but then race with another thread that thinks
	80	* the page is not up-to-date and hence reads it again.
	81	*
	82	* The result is that the first modifcation to the page is lost.
	83	* This sort of AGF/AGI reading race can happen when unlinking inodes
	84	* that require truncation and results in the AGI unlinked list
	85	* modifications being lost.
	86	*/
	87	#define _XBF_PAGE_LOCKED (1 << 22)
	88
	89	/*
	90	* If we try a barrier write, but it fails we have to communicate
	91	* this to the upper layers. Unfortunately b_error gets overwritten
	92	* when the buffer is re-issued so we have to add another flag to
	93	* keep this information.
	94	*/
	95	#define _XFS_BARRIER_FAILED (1 << 23)
73f6aa4d	96
807cbbdb	97	typedef unsigned int xfs_buf_flags_t;
1da177e4	98
0b1b213f CH	99	#define XFS_BUF_FLAGS \
	100	{ XBF_READ, "READ" }, \
	101	{ XBF_WRITE, "WRITE" }, \
	102	{ XBF_MAPPED, "MAPPED" }, \
	103	{ XBF_ASYNC, "ASYNC" }, \
	104	{ XBF_DONE, "DONE" }, \
	105	{ XBF_DELWRI, "DELWRI" }, \
	106	{ XBF_STALE, "STALE" }, \
	107	{ XBF_FS_MANAGED, "FS_MANAGED" }, \
	108	{ XBF_ORDERED, "ORDERED" }, \
	109	{ XBF_READ_AHEAD, "READ_AHEAD" }, \
	110	{ XBF_LOCK, "LOCK" }, /* should never be set */\
	111	{ XBF_TRYLOCK, "TRYLOCK" }, /* ditto */\
	112	{ XBF_DONT_BLOCK, "DONT_BLOCK" }, /* ditto */\
	113	{ _XBF_PAGE_CACHE, "PAGE_CACHE" }, \
	114	{ _XBF_PAGES, "PAGES" }, \
	115	{ _XBF_RUN_QUEUES, "RUN_QUEUES" }, \
	116	{ _XBF_DELWRI_Q, "DELWRI_Q" }, \
	117	{ _XBF_PAGE_LOCKED, "PAGE_LOCKED" }, \
	118	{ _XFS_BARRIER_FAILED, "BARRIER_FAILED" }
	119
	120
ce8e922c	121	typedef enum {
5e6a07df DC	122	XBT_FORCE_SLEEP = 0,
5e6a07df DC	123	XBT_FORCE_FLUSH = 1,
ce8e922c	124	} xfs_buftarg_flags_t;
1da177e4 LT	125
	126	typedef struct xfs_bufhash {
	127	struct list_head bh_list;
	128	spinlock_t bh_lock;
	129	} xfs_bufhash_t;
	130
	131	typedef struct xfs_buftarg {
ce8e922c NS	132	dev_t bt_dev;
	133	struct block_device *bt_bdev;
	134	struct address_space *bt_mapping;
	135	unsigned int bt_bsize;
	136	unsigned int bt_sshift;
	137	size_t bt_smask;
	138
	139	/* per device buffer hash table */
1da177e4 LT	140	uint bt_hashshift;
1da177e4 LT	141	xfs_bufhash_t *bt_hash;
a6867a68 DC	142
	143	/* per device delwri queue */
	144	struct task_struct *bt_task;
	145	struct list_head bt_list;
	146	struct list_head bt_delwrite_queue;
	147	spinlock_t bt_delwrite_lock;
ce8e922c	148	unsigned long bt_flags;
1da177e4 LT	149	} xfs_buftarg_t;
	150
	151	/*
ce8e922c	152	* xfs_buf_t: Buffer structure for pagecache-based buffers
1da177e4	153	*
ce8e922c NS	154	* This buffer structure is used by the pagecache buffer management routines
	155	* to refer to an assembly of pages forming a logical buffer.
	156	*
	157	* The buffer structure is used on a temporary basis only, and discarded when
	158	* released. The real data storage is recorded in the pagecache. Buffers are
1da177e4 LT	159	* hashed to the block device on which the file system resides.
	160	*/
	161
	162	struct xfs_buf;
ce8e922c NS	163	typedef void (xfs_buf_iodone_t)(struct xfs_buf );
	164	typedef void (xfs_buf_relse_t)(struct xfs_buf );
	165	typedef int (xfs_buf_bdstrat_t)(struct xfs_buf );
1da177e4	166
ce8e922c	167	#define XB_PAGES 2
1da177e4 LT	168
1da177e4 LT	169	typedef struct xfs_buf {
ce8e922c NS	170	struct semaphore b_sema; /* semaphore for lockables */
	171	unsigned long b_queuetime; /* time buffer was queued */
	172	atomic_t b_pin_count; /* pin count */
	173	wait_queue_head_t b_waiters; /* unpin waiters */
	174	struct list_head b_list;
	175	xfs_buf_flags_t b_flags; /* status flags */
	176	struct list_head b_hash_list; /* hash table list */
	177	xfs_bufhash_t b_hash; / hash table list start */
	178	xfs_buftarg_t b_target; / buffer target (device) */
	179	atomic_t b_hold; /* reference count */
	180	xfs_daddr_t b_bn; /* block number for I/O */
	181	xfs_off_t b_file_offset; /* offset in file */
	182	size_t b_buffer_length;/* size of buffer in bytes */
	183	size_t b_count_desired;/* desired transfer size */
	184	void b_addr; / virtual address of buffer */
	185	struct work_struct b_iodone_work;
	186	atomic_t b_io_remaining; /* #outstanding I/O requests */
	187	xfs_buf_iodone_t b_iodone; /* I/O completion function */
	188	xfs_buf_relse_t b_relse; /* releasing function */
b4dd330b	189	struct completion b_iowait; /* queue for I/O waiters */
ce8e922c NS	190	void *b_fspriv;
ce8e922c NS	191	void *b_fspriv2;
15ac08a8	192	struct xfs_mount *b_mount;
ce8e922c	193	unsigned short b_error; /* error code on I/O */
ce8e922c NS	194	unsigned int b_page_count; /* size of page array */
	195	unsigned int b_offset; /* page offset in first page */
	196	struct page *b_pages; / array of page pointers */
	197	struct page b_page_array[XB_PAGES]; / inline pages */
	198	#ifdef XFS_BUF_LOCK_TRACKING
	199	int b_last_holder;
1da177e4 LT	200	#endif
	201	} xfs_buf_t;
	202
	203
	204	/* Finding and Reading Buffers */
ce8e922c NS	205	extern xfs_buf_t _xfs_buf_find(xfs_buftarg_t , xfs_off_t, size_t,
ce8e922c NS	206	xfs_buf_flags_t, xfs_buf_t *);
1da177e4	207	#define xfs_incore(buftarg,blkno,len,lockit) \
ce8e922c	208	_xfs_buf_find(buftarg, blkno ,len, lockit, NULL)
1da177e4	209
6ad112bf	210	extern xfs_buf_t xfs_buf_get(xfs_buftarg_t , xfs_off_t, size_t,
ce8e922c	211	xfs_buf_flags_t);
6ad112bf	212	extern xfs_buf_t xfs_buf_read(xfs_buftarg_t , xfs_off_t, size_t,
ce8e922c	213	xfs_buf_flags_t);
1da177e4	214
ce8e922c NS	215	extern xfs_buf_t xfs_buf_get_empty(size_t, xfs_buftarg_t );
	216	extern xfs_buf_t xfs_buf_get_noaddr(size_t, xfs_buftarg_t );
	217	extern int xfs_buf_associate_memory(xfs_buf_t , void , size_t);
	218	extern void xfs_buf_hold(xfs_buf_t *);
	219	extern void xfs_buf_readahead(xfs_buftarg_t *, xfs_off_t, size_t,
	220	xfs_buf_flags_t);
1da177e4 LT	221
1da177e4 LT	222	/* Releasing Buffers */
ce8e922c NS	223	extern void xfs_buf_free(xfs_buf_t *);
ce8e922c NS	224	extern void xfs_buf_rele(xfs_buf_t *);
1da177e4 LT	225
1da177e4 LT	226	/* Locking and Unlocking Buffers */
ce8e922c NS	227	extern int xfs_buf_cond_lock(xfs_buf_t *);
	228	extern int xfs_buf_lock_value(xfs_buf_t *);
	229	extern void xfs_buf_lock(xfs_buf_t *);
	230	extern void xfs_buf_unlock(xfs_buf_t *);
1da177e4 LT	231
1da177e4 LT	232	/* Buffer Read and Write Routines */
64e0bc7d	233	extern int xfs_bwrite(struct xfs_mount mp, struct xfs_buf bp);
5d765b97	234	extern void xfs_bdwrite(void mp, xfs_buf_t bp);
4e23471a CH	235
	236	extern void xfsbdstrat(struct xfs_mount , struct xfs_buf );
	237	extern int xfs_bdstrat_cb(struct xfs_buf *);
	238
ce8e922c NS	239	extern void xfs_buf_ioend(xfs_buf_t *, int);
ce8e922c NS	240	extern void xfs_buf_ioerror(xfs_buf_t *, int);
ce8e922c NS	241	extern int xfs_buf_iorequest(xfs_buf_t *);
ce8e922c NS	242	extern int xfs_buf_iowait(xfs_buf_t *);
b9c48649	243	extern void xfs_buf_iomove(xfs_buf_t , size_t, size_t, void ,
ce8e922c NS	244	xfs_buf_rw_t);
ce8e922c NS	245
ce8e922c	246	static inline int xfs_buf_geterror(xfs_buf_t *bp)
1da177e4	247	{
ce8e922c	248	return bp ? bp->b_error : ENOMEM;
1da177e4 LT	249	}
	250
	251	/* Buffer Utility Routines */
ce8e922c	252	extern xfs_caddr_t xfs_buf_offset(xfs_buf_t *, size_t);
1da177e4	253
1da177e4	254	/* Delayed Write Buffer Routines */
ce8e922c	255	extern void xfs_buf_delwri_dequeue(xfs_buf_t *);
d808f617	256	extern void xfs_buf_delwri_promote(xfs_buf_t *);
1da177e4 LT	257
1da177e4 LT	258	/* Buffer Daemon Setup Routines */
ce8e922c NS	259	extern int xfs_buf_init(void);
ce8e922c NS	260	extern void xfs_buf_terminate(void);
1da177e4	261
ce8e922c NS	262	#define xfs_buf_target_name(target) \
ce8e922c NS	263	({ char __b[BDEVNAME_SIZE]; bdevname((target)->bt_bdev, __b); __b; })
1da177e4 LT	264
1da177e4 LT	265
ce8e922c	266	#define XFS_BUF_BFLAGS(bp) ((bp)->b_flags)
f5faad79 NS	267	#define XFS_BUF_ZEROFLAGS(bp) ((bp)->b_flags &= \
f5faad79 NS	268	~(XBF_READ\|XBF_WRITE\|XBF_ASYNC\|XBF_DELWRI\|XBF_ORDERED))
ce8e922c	269
0cadda1c CH	270	#define XFS_BUF_STALE(bp) ((bp)->b_flags \|= XBF_STALE)
	271	#define XFS_BUF_UNSTALE(bp) ((bp)->b_flags &= ~XBF_STALE)
	272	#define XFS_BUF_ISSTALE(bp) ((bp)->b_flags & XBF_STALE)
ce8e922c NS	273	#define XFS_BUF_SUPER_STALE(bp) do { \
	274	XFS_BUF_STALE(bp); \
	275	xfs_buf_delwri_dequeue(bp); \
	276	XFS_BUF_DONE(bp); \
	277	} while (0)
1da177e4	278
ce8e922c NS	279	#define XFS_BUF_UNMANAGE(bp) ((bp)->b_flags &= ~XBF_FS_MANAGED)
	280
	281	#define XFS_BUF_DELAYWRITE(bp) ((bp)->b_flags \|= XBF_DELWRI)
	282	#define XFS_BUF_UNDELAYWRITE(bp) xfs_buf_delwri_dequeue(bp)
	283	#define XFS_BUF_ISDELAYWRITE(bp) ((bp)->b_flags & XBF_DELWRI)
	284
	285	#define XFS_BUF_ERROR(bp,no) xfs_buf_ioerror(bp,no)
	286	#define XFS_BUF_GETERROR(bp) xfs_buf_geterror(bp)
	287	#define XFS_BUF_ISERROR(bp) (xfs_buf_geterror(bp) ? 1 : 0)
	288
	289	#define XFS_BUF_DONE(bp) ((bp)->b_flags \|= XBF_DONE)
	290	#define XFS_BUF_UNDONE(bp) ((bp)->b_flags &= ~XBF_DONE)
	291	#define XFS_BUF_ISDONE(bp) ((bp)->b_flags & XBF_DONE)
	292
	293	#define XFS_BUF_BUSY(bp) do { } while (0)
	294	#define XFS_BUF_UNBUSY(bp) do { } while (0)
	295	#define XFS_BUF_ISBUSY(bp) (1)
	296
	297	#define XFS_BUF_ASYNC(bp) ((bp)->b_flags \|= XBF_ASYNC)
	298	#define XFS_BUF_UNASYNC(bp) ((bp)->b_flags &= ~XBF_ASYNC)
	299	#define XFS_BUF_ISASYNC(bp) ((bp)->b_flags & XBF_ASYNC)
	300
	301	#define XFS_BUF_ORDERED(bp) ((bp)->b_flags \|= XBF_ORDERED)
	302	#define XFS_BUF_UNORDERED(bp) ((bp)->b_flags &= ~XBF_ORDERED)
	303	#define XFS_BUF_ISORDERED(bp) ((bp)->b_flags & XBF_ORDERED)
ce8e922c NS	304
	305	#define XFS_BUF_HOLD(bp) xfs_buf_hold(bp)
	306	#define XFS_BUF_READ(bp) ((bp)->b_flags \|= XBF_READ)
	307	#define XFS_BUF_UNREAD(bp) ((bp)->b_flags &= ~XBF_READ)
	308	#define XFS_BUF_ISREAD(bp) ((bp)->b_flags & XBF_READ)
	309
	310	#define XFS_BUF_WRITE(bp) ((bp)->b_flags \|= XBF_WRITE)
	311	#define XFS_BUF_UNWRITE(bp) ((bp)->b_flags &= ~XBF_WRITE)
	312	#define XFS_BUF_ISWRITE(bp) ((bp)->b_flags & XBF_WRITE)
	313
ce8e922c NS	314	#define XFS_BUF_IODONE_FUNC(bp) ((bp)->b_iodone)
	315	#define XFS_BUF_SET_IODONE_FUNC(bp, func) ((bp)->b_iodone = (func))
	316	#define XFS_BUF_CLR_IODONE_FUNC(bp) ((bp)->b_iodone = NULL)
ce8e922c NS	317
	318	#define XFS_BUF_FSPRIVATE(bp, type) ((type)(bp)->b_fspriv)
	319	#define XFS_BUF_SET_FSPRIVATE(bp, val) ((bp)->b_fspriv = (void*)(val))
	320	#define XFS_BUF_FSPRIVATE2(bp, type) ((type)(bp)->b_fspriv2)
	321	#define XFS_BUF_SET_FSPRIVATE2(bp, val) ((bp)->b_fspriv2 = (void*)(val))
ce8e922c NS	322	#define XFS_BUF_SET_START(bp) do { } while (0)
	323	#define XFS_BUF_SET_BRELSE_FUNC(bp, func) ((bp)->b_relse = (func))
	324
	325	#define XFS_BUF_PTR(bp) (xfs_caddr_t)((bp)->b_addr)
	326	#define XFS_BUF_SET_PTR(bp, val, cnt) xfs_buf_associate_memory(bp, val, cnt)
	327	#define XFS_BUF_ADDR(bp) ((bp)->b_bn)
	328	#define XFS_BUF_SET_ADDR(bp, bno) ((bp)->b_bn = (xfs_daddr_t)(bno))
	329	#define XFS_BUF_OFFSET(bp) ((bp)->b_file_offset)
	330	#define XFS_BUF_SET_OFFSET(bp, off) ((bp)->b_file_offset = (off))
	331	#define XFS_BUF_COUNT(bp) ((bp)->b_count_desired)
	332	#define XFS_BUF_SET_COUNT(bp, cnt) ((bp)->b_count_desired = (cnt))
	333	#define XFS_BUF_SIZE(bp) ((bp)->b_buffer_length)
	334	#define XFS_BUF_SET_SIZE(bp, cnt) ((bp)->b_buffer_length = (cnt))
	335
	336	#define XFS_BUF_SET_VTYPE_REF(bp, type, ref) do { } while (0)
	337	#define XFS_BUF_SET_VTYPE(bp, type) do { } while (0)
	338	#define XFS_BUF_SET_REF(bp, ref) do { } while (0)
	339
4d16e924	340	#define XFS_BUF_ISPINNED(bp) atomic_read(&((bp)->b_pin_count))
ce8e922c NS	341
	342	#define XFS_BUF_VALUSEMA(bp) xfs_buf_lock_value(bp)
	343	#define XFS_BUF_CPSEMA(bp) (xfs_buf_cond_lock(bp) == 0)
	344	#define XFS_BUF_VSEMA(bp) xfs_buf_unlock(bp)
	345	#define XFS_BUF_PSEMA(bp,x) xfs_buf_lock(bp)
b4dd330b	346	#define XFS_BUF_FINISH_IOWAIT(bp) complete(&bp->b_iowait);
ce8e922c NS	347
	348	#define XFS_BUF_SET_TARGET(bp, target) ((bp)->b_target = (target))
	349	#define XFS_BUF_TARGET(bp) ((bp)->b_target)
	350	#define XFS_BUFTARG_NAME(target) xfs_buf_target_name(target)
	351
ce8e922c	352	static inline void xfs_buf_relse(xfs_buf_t *bp)
1da177e4	353	{
ce8e922c NS	354	if (!bp->b_relse)
	355	xfs_buf_unlock(bp);
	356	xfs_buf_rele(bp);
1da177e4 LT	357	}
1da177e4 LT	358
ce8e922c	359	#define xfs_biodone(bp) xfs_buf_ioend(bp, 0)
1da177e4	360
ce8e922c NS	361	#define xfs_biomove(bp, off, len, data, rw) \
ce8e922c NS	362	xfs_buf_iomove((bp), (off), (len), (data), \
0cadda1c	363	((rw) == XBF_WRITE) ? XBRW_WRITE : XBRW_READ)
1da177e4	364
ce8e922c NS	365	#define xfs_biozero(bp, off, len) \
ce8e922c NS	366	xfs_buf_iomove((bp), (off), (len), NULL, XBRW_ZERO)
1da177e4	367
ce8e922c	368	#define xfs_iowait(bp) xfs_buf_iowait(bp)
1da177e4 LT	369
1da177e4 LT	370	#define xfs_baread(target, rablkno, ralen) \
ce8e922c	371	xfs_buf_readahead((target), (rablkno), (ralen), XBF_DONT_BLOCK)
1da177e4 LT	372
	373
	374	/*
	375	* Handling of buftargs.
	376	*/
e2a07812	377	extern xfs_buftarg_t xfs_alloc_buftarg(struct block_device , int, const char *);
c141b292	378	extern void xfs_free_buftarg(struct xfs_mount , struct xfs_buftarg );
1da177e4 LT	379	extern void xfs_wait_buftarg(xfs_buftarg_t *);
1da177e4 LT	380	extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int, unsigned int);
1da177e4	381	extern int xfs_flush_buftarg(xfs_buftarg_t *, int);
d808f617	382
e6a0e9cd TS	383	#ifdef CONFIG_KDB_MODULES
	384	extern struct list_head *xfs_get_buftarg_list(void);
	385	#endif
1da177e4	386
ce8e922c NS	387	#define xfs_getsize_buftarg(buftarg) block_size((buftarg)->bt_bdev)
	388	#define xfs_readonly_buftarg(buftarg) bdev_read_only((buftarg)->bt_bdev)
	389
	390	#define xfs_binval(buftarg) xfs_flush_buftarg(buftarg, 1)
	391	#define XFS_bflush(buftarg) xfs_flush_buftarg(buftarg, 1)
1da177e4 LT	392
1da177e4 LT	393	#endif /* __XFS_BUF_H__ */