xnu-792.12.6.tar.gz

[apple/xnu.git] / bsd / sys / buf_internal.h

/*
 * Copyright (c) 2006 Apple Computer, Inc. All Rights Reserved.
 * 
 * @APPLE_LICENSE_OSREFERENCE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code 
 * as defined in and that are subject to the Apple Public Source License 
 * Version 2.0 (the 'License'). You may not use this file except in 
 * compliance with the License.  The rights granted to you under the 
 * License may not be used to create, or enable the creation or 
 * redistribution of, unlawful or unlicensed copies of an Apple operating 
 * system, or to circumvent, violate, or enable the circumvention or 
 * violation of, any terms of an Apple operating system software license 
 * agreement.
 *
 * Please obtain a copy of the License at 
 * http://www.opensource.apple.com/apsl/ and read it before using this 
 * file.
 *
 * The Original Code and all software distributed under the License are 
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, 
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. 
 * Please see the License for the specific language governing rights and 
 * limitations under the License.
 *
 * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
 */
/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
/*
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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	8.9 (Berkeley) 3/30/95
 */

#ifndef _SYS_BUF_INTERNAL_H_
#define	_SYS_BUF_INTERNAL_H_

#include <sys/appleapiopts.h>

#ifdef KERNEL
#include <sys/queue.h>
#include <sys/errno.h>
#include <sys/vm.h>
#include <sys/cdefs.h>
#include <sys/buf.h>
#include <sys/lock.h>


extern lck_mtx_t    *buf_mtxp;
#define NOLIST ((struct buf *)0x87654321)

/*
 * 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. */
	int	b_timestamp;		/* timestamp for queuing operation */
	long	b_whichq;		/* the free list the buffer belongs to */
	volatile long	b_flags;	/* B_* flags. */
	volatile long	b_lflags;	/* BL_BUSY | BL_WANTED flags... protected by buf_mtx */
	int	b_error;		/* errno value. */
	long	b_bufsize;		/* Allocated buffer size. */
	long	b_bcount;		/* Valid bytes in buffer. */
	long	b_resid;		/* Remaining I/O. */
	dev_t	b_dev;			/* Device associated with buffer. */
        uintptr_t	b_datap;	/* Memory, superblocks, indirect etc.*/
	daddr64_t	b_lblkno;	/* Logical block number. */
	daddr64_t	b_blkno;	/* Underlying physical block number. */
	void	(*b_iodone)(buf_t, void *);	/* Function to call upon completion. */
	vnode_t	b_vp;			/* Device vnode. */
	struct	ucred *b_rcred;		/* Read credentials reference. */
	struct	ucred *b_wcred;		/* Write credentials reference. */
	void *	b_upl;			/* Pointer to UPL */
	buf_t	b_real_bp;		/* used to track bp generated through cluster_bp */
	TAILQ_ENTRY(buf)	b_act;	/* Device driver queue when active */
	void *	b_drvdata;		/* Device driver private use */
        void *  b_fsprivate;		/* filesystem private use */
	void *	b_transaction;		/* journal private use */
	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. */
	proc_t 	b_proc;			/* Associated proc; NULL if kernel. */
#ifdef JOE_DEBUG
        void *	b_owner;
        int     b_tag;
        void *  b_lastbrelse;
        int	b_stackbrelse[6];
        int	b_stackgetblk[6];
#endif
};


/* cluster_io definitions for use with io bufs */
#define b_uploffset  b_bufsize
#define b_trans_head b_freelist.tqe_prev
#define b_trans_next b_freelist.tqe_next
#define b_iostate    b_rcred

/*
 * These flags are kept in b_lflags... 
 * buf_mtxp must be held before examining/updating
 */
#define	BL_BUSY		0x00000001	/* I/O in progress. */
#define	BL_WANTED	0x00000002	/* Process wants this buffer. */
#define BL_IOBUF	0x00000004	/* buffer allocated via 'buf_alloc' */


/*
 * mask used by buf_flags... these are the readable external flags
 */
#define BUF_X_RDFLAGS (B_CLUSTER | B_PHYS | B_LOCKED | B_DELWRI | B_ASYNC |\
                       B_READ | B_WRITE | B_META | B_PAGEIO)
/*
 * mask used by buf_clearflags/buf_setflags... these are the writable external flags
 */
#define BUF_X_WRFLAGS (B_LOCKED | B_NOCACHE | B_ASYNC | B_READ | B_WRITE | B_PAGEIO)

/*
 * These flags are kept in b_flags... access is lockless
 * External flags are defined in buf.h and cannot overlap
 * the internal flags
 * 
 * these flags are internal... there definition may change
 */
#define	B_CACHE		0x00010000	/* getblk found us in the cache. */
#define	B_DONE		0x00020000	/* I/O completed. */
#define	B_INVAL		0x00040000	/* Does not contain valid info. */
#define	B_ERROR		0x00080000	/* I/O error occurred. */
#define	B_EINTR		0x00100000	/* I/O was interrupted */
#define	B_AGE		0x00200000	/* Move to age queue when I/O done. */
#define B_FILTER	0x00400000	/* call b_iodone from biodone as an in-line filter */
#define	B_CALL		0x00800000	/* Call b_iodone from biodone, assumes b_iodone consumes bp */
#define	B_RAW		0x01000000	/* Set by physio for raw transfers. */
#define	B_WASDIRTY	0x02000000	/* page was found dirty in the VM cache */
#define	B_HDRALLOC	0x04000000	/* zone allocated buffer header */
#define	B_ZALLOC	0x08000000	/* b_datap is zalloc()ed */
/*
 * private flags used by the journal layer
 */
#define	B_NORELSE	0x10000000	/* don't brelse() in bwrite() */
/*
 * private flags used by by the cluster layer
 */
#define B_NEED_IODONE   0x20000000	/* need biodone on the real_bp associated with a cluster_io */
#define B_COMMIT_UPL    0x40000000	/* commit/abort the UPL on I/O success/failure */
/*
 * can we deprecate?
 */
#define	B_TAPE		0x80000000	/* Magnetic tape I/O. */


/* Flags to low-level allocation routines. */
#define B_CLRBUF	0x01	/* Request allocated buffer be cleared. */
#define B_SYNC		0x02	/* Do all allocations synchronously. */
#define B_NOBUFF	0x04	/* Do not allocate struct buf */


extern int niobuf;		/* The number of IO buffer headers for cluster IO */
extern int nbuf;		/* The number of buffer headers */
extern struct buf *buf;		/* The buffer headers. */


/*
 * Definitions for the buffer free lists.
 */
#define	BQUEUES		6		/* number of free buffer queues */

#define	BQ_LOCKED	0		/* super-blocks &c */
#define	BQ_LRU		1		/* lru, useful buffers */
#define	BQ_AGE		2		/* rubbish */
#define	BQ_EMPTY	3		/* buffer headers with no memory */
#define BQ_META		4		/* buffer containing metadata */
#define BQ_LAUNDRY	5		/* buffers that need cleaning */


__BEGIN_DECLS

buf_t	alloc_io_buf(vnode_t, int);
void	free_io_buf(buf_t);

int	allocbuf(struct buf *, int);
void	bufinit(void);

void	buf_setfilter(buf_t, void (*)(buf_t, void *), void *, void **, void **);

/*
 * Flags for buf_acquire
 */
#define BAC_NOWAIT		0x01	/* Don't wait if buffer is busy */
#define BAC_REMOVE		0x02	/* Remove from free list once buffer is acquired */
#define BAC_SKIP_NONLOCKED	0x04	/* Don't return LOCKED buffers */
#define BAC_SKIP_LOCKED		0x08	/* Only return LOCKED buffers */

void	cluster_init(void);
void	buf_drop(buf_t);
errno_t	buf_acquire(buf_t, int, int, int);

int	count_busy_buffers(void);
int	count_lock_queue(void);


__END_DECLS


/*
 *	Stats on usefulness of the buffer cache
 */
struct bufstats {
	long	bufs_incore;		/* found incore */
	long	bufs_busyincore;	/* found incore. was busy */
	long	bufs_vmhits;		/* not incore. found in VM */
	long	bufs_miss;			/* not incore. not in VM */
	long	bufs_sleeps;		/* buffer starvation */
	long	bufs_eblk;			/* Calls to geteblk */
	long	bufs_iobufmax;		/* Max. number of IO buffers used */
	long	bufs_iobufinuse;	/* number of IO buffers in use */
	long	bufs_iobufsleeps;	/* IO buffer starvation */
};

#endif /* KERNEL */
#endif /* !_SYS_BUF_H_ */