/*	$OpenBSD: buf.h,v 1.45 2004/01/21 21:00:14 tedu Exp $	*/
/*	$NetBSD: buf.h,v 1.25 1997/04/09 21:12:17 mycroft Exp $	*/

/*
 * Copyright (c) 1982, 1986, 1989, 1993
 *	The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)buf.h	8.7 (Berkeley) 1/21/94
 */

#ifndef _SYS_BUF_H_
#define	_SYS_BUF_H_
#include <sys/queue.h>

#define NOLIST ((struct buf *)0x87654321)

struct buf;
struct vnode;

/*
 * To avoid including <ufs/ffs/softdep.h>
 */

LIST_HEAD(workhead, worklist);

/*
 * These are currently used only by the soft dependency code, hence
 * are stored once in a global variable. If other subsystems wanted
 * to use these hooks, a pointer to a set of bio_ops could be added
 * to each buffer.
 */
extern struct bio_ops {
	void	(*io_start)(struct buf *);
	void	(*io_complete)(struct buf *);
	void	(*io_deallocate)(struct buf *);
	void	(*io_movedeps)(struct buf *, struct buf *);
	int	(*io_countdeps)(struct buf *, int, int);
} bioops;

/*
 * The buffer header describes an I/O operation in the kernel.
 */
struct buf {
	LIST_ENTRY(buf) b_hash;		/* Hash chain. */
	LIST_ENTRY(buf) b_vnbufs;	/* Buffer's associated vnode. */
	TAILQ_ENTRY(buf) b_freelist;	/* Free list position if not active. */
	TAILQ_ENTRY(buf) b_synclist;	/* List of dirty buffers to be written out */
	long b_synctime;		/* Time this buffer should be flushed */
	struct	buf *b_actf, **b_actb;	/* Device driver queue when active. */
	struct  proc *b_proc;		/* Associated proc; NULL if kernel. */
	volatile long	b_flags;	/* B_* flags. */
	int	b_error;		/* Errno value. */
	long	b_bufsize;		/* Allocated buffer size. */
	long	b_bcount;		/* Valid bytes in buffer. */
	size_t	b_resid;		/* Remaining I/O. */
	dev_t	b_dev;			/* Device associated with buffer. */
	struct {
		caddr_t	b_addr;		/* Memory, superblocks, indirect etc. */
	} b_un;
	void	*b_saveaddr;		/* Original b_addr for physio. */
	daddr_t	b_lblkno;		/* Logical block number. */
	daddr_t	b_blkno;		/* Underlying physical block number. */
					/* Function to call upon completion.
					 * Will be called at splbio(). */
	void	(*b_iodone)(struct buf *);
	struct	vnode *b_vp;		/* Device vnode. */
	int	b_dirtyoff;		/* Offset in buffer of dirty region. */
	int	b_dirtyend;		/* Offset of end of dirty region. */
	int	b_validoff;		/* Offset in buffer of valid region. */
	int	b_validend;		/* Offset of end of valid region. */
 	struct	workhead b_dep;		/* List of filesystem dependencies. */
};

/*
 * bufq
 * flexible buffer queue routines
 */
struct bufq {
	void (*bufq_free)(struct bufq *);
	void (*bufq_add)(struct bufq *, struct buf *);
	struct buf *(*bufq_get)(struct bufq *);
};

struct bufq_default {
	struct bufq bufq;
	struct buf bufq_head[3];
};

#define	BUFQ_ALLOC(_type)	bufq_default_alloc()	/* XXX */
#define	BUFQ_FREE(_bufq)	(_bufq)->bufq_free(_bufq)
#define	BUFQ_ADD(_bufq, _bp)	(_bufq)->bufq_add(_bufq, _bp)
#define	BUFQ_GET(_bufq)		(_bufq)->bufq_get(_bufq)

struct bufq *bufq_default_alloc(void);
void bufq_default_free(struct bufq *);
void bufq_default_add(struct bufq *, struct buf *);
struct buf *bufq_default_get(struct bufq *);

/*
 * For portability with historic industry practice, the cylinder number has
 * to be maintained in the `b_resid' field.
 */
#define	b_cylinder b_resid		/* Cylinder number for disksort(). */

/* Device driver compatibility definitions. */
#define	b_active b_bcount		/* Driver queue head: drive active. */
#define	b_data	 b_un.b_addr		/* b_un.b_addr is not changeable. */
#define	b_errcnt b_resid		/* Retry count while I/O in progress. */

/*
 * These flags are kept in b_flags.
 */
#define	B_AGE		0x00000001	/* Move to age queue when I/O done. */
#define	B_NEEDCOMMIT	0x00000002	/* Needs committing to stable storage */
#define	B_ASYNC		0x00000004	/* Start I/O, do not wait. */
#define	B_BAD		0x00000008	/* Bad block revectoring in progress. */
#define	B_BUSY		0x00000010	/* I/O in progress. */
#define	B_CACHE		0x00000020	/* Bread found us in the cache. */
#define	B_CALL		0x00000040	/* Call b_iodone from biodone. */
#define	B_DELWRI	0x00000080	/* Delay I/O until buffer reused. */
#define	B_DIRTY		0x00000100	/* Dirty page to be pushed out async. */
#define	B_DONE		0x00000200	/* I/O completed. */
#define	B_EINTR		0x00000400	/* I/O was interrupted */
#define	B_ERROR		0x00000800	/* I/O error occurred. */
#define	B_GATHERED	0x00001000	/* LFS: already in a segment. */
#define	B_INVAL		0x00002000	/* Does not contain valid info. */
#define	B_LOCKED	0x00004000	/* Locked in core (not reusable). */
#define	B_NOCACHE	0x00008000	/* Do not cache block after use. */
#define	B_PAGET		0x00010000	/* Page in/out of page table space. */
#define	B_PGIN		0x00020000	/* Pagein op, so swap() can count it. */
#define	B_PHYS		0x00040000	/* I/O to user memory. */
#define	B_RAW		0x00080000	/* Set by physio for raw transfers. */
#define	B_READ		0x00100000	/* Read buffer. */
#define	B_TAPE		0x00200000	/* Magnetic tape I/O. */
#define	B_UAREA		0x00400000	/* Buffer describes Uarea I/O. */
#define	B_WANTED	0x00800000	/* Process wants this buffer. */
#define	B_WRITE		0x00000000	/* Write buffer (pseudo flag). */
#define	B_WRITEINPROG	0x01000000	/* Write in progress. */
#define	B_XXX		0x02000000	/* Debugging flag. */
#define	B_DEFERRED	0x04000000	/* Skipped over for cleaning */
#define	B_SCANNED	0x08000000	/* Block already pushed during sync */
#define B_PDAEMON	0x10000000	/* I/O started by pagedaemon */

/*
 * This structure describes a clustered I/O.  It is stored in the b_saveaddr
 * field of the buffer on which I/O is done.  At I/O completion, cluster
 * callback uses the structure to parcel I/O's to individual buffers, and
 * then free's this structure.
 */
struct cluster_save {
	long	bs_bcount;		/* Saved b_bcount. */
	long	bs_bufsize;		/* Saved b_bufsize. */
	void	*bs_saveaddr;		/* Saved b_addr. */
	int	bs_nchildren;		/* Number of associated buffers. */
	struct buf **bs_children;	/* List of associated buffers. */
};

/*
 * Zero out the buffer's data area.
 */
#define	clrbuf(bp) {							\
	bzero((bp)->b_data, (u_int)(bp)->b_bcount);			\
	(bp)->b_resid = 0;						\
}


/* Flags to low-level allocation routines. */
#define B_CLRBUF	0x01	/* Request allocated buffer be cleared. */
#define B_SYNC		0x02	/* Do all allocations synchronously. */

struct cluster_info {
	daddr_t	ci_lastr;			/* last read (read-ahead) */
	daddr_t	ci_lastw;			/* last write (write cluster) */
	daddr_t	ci_cstart;			/* start block of cluster */
	daddr_t	ci_lasta;			/* last allocation */
	int	ci_clen;			/* length of current cluster */
	int	ci_ralen;			/* Read-ahead length */
	daddr_t	ci_maxra;			/* last readahead block */
};

#ifdef _KERNEL
__BEGIN_DECLS
extern int nbuf;		/* The number of buffer headers */
extern struct buf *buf;		/* The buffer headers. */
extern char *buffers;		/* The buffer contents. */
extern int bufpages;		/* Number of memory pages in the buffer pool. */

extern struct pool bufpool;

void	allocbuf(struct buf *, int);
void	bawrite(struct buf *);
void	bdwrite(struct buf *);
void	biodone(struct buf *);
int	biowait(struct buf *);
int	bread(struct vnode *, daddr_t, int,
		   struct ucred *, struct buf **);
int	breada(struct vnode *, daddr_t, int, daddr_t, int,
		    struct ucred *, struct buf **);
int	breadn(struct vnode *, daddr_t, int, daddr_t *, int *, int,
		    struct ucred *, struct buf **);
void	brelse(struct buf *);
void	bremfree(struct buf *);
void	bufinit(void);
void	buf_dirty(struct buf *);
void    buf_undirty(struct buf *);
int	bwrite(struct buf *);
struct buf *getblk(struct vnode *, daddr_t, int, int, int);
struct buf *geteblk(int);
struct buf *incore(struct vnode *, daddr_t);

void	minphys(struct buf *bp);
int	physio(void (*strategy)(struct buf *), struct buf *bp, dev_t dev,
	    int flags, void (*minphys)(struct buf *), struct uio *uio);
void  brelvp(struct buf *);
void  reassignbuf(struct buf *);
void  bgetvp(struct vnode *, struct buf *);

void  buf_replacevnode(struct buf *, struct vnode *);
void  buf_daemon(struct proc *);

#ifdef DEBUG
void buf_print(struct buf *);
#endif

static __inline void
buf_start(struct buf *bp)
{
	if (bioops.io_start)
		(*bioops.io_start)(bp);
}

static __inline void
buf_complete(struct buf *bp)
{
	if (bioops.io_complete)
		(*bioops.io_complete)(bp);
}

static __inline void
buf_deallocate(struct buf *bp)
{
	if (bioops.io_deallocate)
		(*bioops.io_deallocate)(bp);
}

static __inline void
buf_movedeps(struct buf *bp, struct buf *bp2)
{
	if (bioops.io_movedeps)
		(*bioops.io_movedeps)(bp, bp2);
}

static __inline int
buf_countdeps(struct buf *bp, int i, int islocked)
{
	if (bioops.io_countdeps)
		return ((*bioops.io_countdeps)(bp, i, islocked));
	else
		return (0);
}

int	cluster_read(struct vnode *, struct cluster_info *,
	    u_quad_t, daddr_t, long, struct ucred *, struct buf **);
void	cluster_write(struct buf *, struct cluster_info *, u_quad_t);

__END_DECLS
#endif
#endif /* !_SYS_BUF_H_ */
