[unix-history] / usr / src / sys.386bsd / sys / buf.h

/*
 * Copyright (c) 1982, 1986, 1989 Regents of the University of California.
 * All rights reserved.
 *
 * 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	7.11 (Berkeley) 5/9/90
 */

/*
 * The header for buffers in the buffer pool and otherwise used
 * to describe a block i/o request is given here.
 *
 * Each buffer in the pool is usually doubly linked into 2 lists:
 * hashed into a chain by <dev,blkno> so it can be located in the cache,
 * and (usually) on (one of several) queues.  These lists are circular and
 * doubly linked for easy removal.
 *
 * There are currently three queues for buffers:
 *	one for buffers which must be kept permanently (super blocks)
 * 	one for buffers containing ``useful'' information (the cache)
 *	one for buffers containing ``non-useful'' information
 *		(and empty buffers, pushed onto the front)
 * The latter two queues contain the buffers which are available for
 * reallocation, are kept in lru order.  When not on one of these queues,
 * the buffers are ``checked out'' to drivers which use the available list
 * pointers to keep track of them in their i/o active queues.
 */

/*
 * Bufhd structures used at the head of the hashed buffer queues.
 * We only need three words for these, so this abbreviated
 * definition saves some space.
 */
struct bufhd
{
	long	b_flags;		/* see defines below */
	struct	buf *b_forw, *b_back;	/* fwd/bkwd pointer in chain */
};
struct buf
{
	long	b_flags;		/* too much goes here to describe */
	struct	buf *b_forw, *b_back;	/* hash chain (2 way street) */
	struct	buf *av_forw, *av_back;	/* position on free list if not BUSY */
	struct	buf *b_blockf, **b_blockb;/* associated vnode */
#define	b_actf	av_forw			/* alternate names for driver queue */
#define	b_actl	av_back			/*    head - isn't history wonderful */
	long	b_bcount;		/* transfer count */
	long	b_bufsize;		/* size of allocated buffer */
#define	b_active b_bcount		/* driver queue head: drive active */
	short	b_error;		/* returned after I/O */
	dev_t	b_dev;			/* major+minor device name */
	union {
	    caddr_t b_addr;		/* low order core address */
	    int	*b_words;		/* words for clearing */
	    struct fs *b_fs;		/* superblocks */
	    struct csum *b_cs;		/* superblock summary information */
	    struct cg *b_cg;		/* cylinder group block */
	    struct dinode *b_dino;	/* ilist */
	    daddr_t *b_daddr;		/* indirect block */
	} b_un;
	daddr_t	b_lblkno;		/* logical block number */
	daddr_t	b_blkno;		/* block # on device */
	long	b_resid;		/* words not transferred after error */
#define	b_errcnt b_resid		/* while i/o in progress: # retries */
	struct  proc *b_proc;		/* proc doing physical or swap I/O */
	int	(*b_iodone)();		/* function called by iodone */
	struct	vnode *b_vp;		/* vnode for dev */
	int	b_pfcent;		/* center page when swapping cluster */
	struct	ucred *b_rcred;		/* ref to read credentials */
	struct	ucred *b_wcred;		/* ref to write credendtials */
	int	b_dirtyoff;		/* offset in buffer of dirty region */
	int	b_dirtyend;		/* offset of end of dirty region */
	caddr_t	b_saveaddr;		/* original b_addr for PHYSIO */
};

#define	BQUEUES		4		/* 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 */

#ifdef	KERNEL
#define	BUFHSZ	512
#define RND	(MAXBSIZE/DEV_BSIZE)
#if	((BUFHSZ&(BUFHSZ-1)) == 0)
#define	BUFHASH(dvp, dblkno)	\
	((struct buf *)&bufhash[((int)(dvp)+(((int)(dblkno))/RND))&(BUFHSZ-1)])
#else
#define	BUFHASH(dvp, dblkno)	\
	((struct buf *)&bufhash[((int)(dvp)+(((int)(dblkno))/RND)) % BUFHSZ])
#endif

struct	buf *buf;		/* the buffer pool itself */
char	*buffers;
int	nbuf;			/* number of buffer headers */
int	bufpages;		/* number of memory pages in the buffer pool */
struct	buf *swbuf;		/* swap I/O headers */
int	nswbuf;
struct	bufhd bufhash[BUFHSZ];	/* heads of hash lists */
struct	buf bfreelist[BQUEUES];	/* heads of available lists */
struct	buf bswlist;		/* head of free swap header list */
struct	buf *bclnlist;		/* head of cleaned page list */

void bufinit();
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 bwrite(struct buf *);
void bawrite(struct buf *);
void bdwrite(struct buf *);
void brelse(struct buf *);
struct buf *incore(struct vnode *, daddr_t);
struct buf *getblk(struct vnode *, daddr_t, int);
struct buf *geteblk(int);
int biowait(struct buf *);
int biodone(struct buf *);
void allocbuf(struct buf *, int);

#endif

/*
 * These flags are kept in b_flags.
 */
#define	B_WRITE		0x000000	/* non-read pseudo-flag */
#define	B_READ		0x000001	/* read when I/O occurs */
#define	B_DONE		0x000002	/* transaction finished */
#define	B_ERROR		0x000004	/* transaction aborted */
#define	B_BUSY		0x000008	/* not on av_forw/back list */
#define	B_PHYS		0x000010	/* physical IO */
#define	B_XXX		0x000020	/* was B_MAP, alloc UNIBUS on pdp-11 */
#define	B_WANTED	0x000040	/* issue wakeup when BUSY goes off */
#define	B_AGE		0x000080	/* delayed write for correct aging */
#define	B_ASYNC		0x000100	/* don't wait for I/O completion */
#define	B_DELWRI	0x000200	/* write at exit of avail list */
#define	B_TAPE		0x000400	/* this is a magtape (no bdwrite) */
#define	B_VMPAGE	0x000800	/* buffer from virtual memory */
#define	B_MALLOC	0x001000	/* buffer from malloc space */
#define	B_DIRTY		0x002000	/* dirty page to be pushed out async */
#define	B_PGIN		0x004000	/* pagein op, so swap() can count it */
#define	B_CACHE		0x008000	/* did bread find us in the cache ? */
#define	B_INVAL		0x010000	/* does not contain valid info  */
#define	B_LOCKED	0x020000	/* locked in core (not reusable) */
#define	B_HEAD		0x040000	/* a buffer header, not a buffer */
#define	B_BAD		0x100000	/* bad block revectoring in progress */
#define	B_CALL		0x200000	/* call b_iodone from iodone */
#define	B_RAW		0x400000	/* set by physio for raw transfers */
#define	B_NOCACHE	0x800000	/* do not cache block after use */

/*
 * Insq/Remq for the buffer hash lists.
 */
#define	bremhash(bp) { \
	(bp)->b_back->b_forw = (bp)->b_forw; \
	(bp)->b_forw->b_back = (bp)->b_back; \
}
#define	binshash(bp, dp) { \
	(bp)->b_forw = (dp)->b_forw; \
	(bp)->b_back = (dp); \
	(dp)->b_forw->b_back = (bp); \
	(dp)->b_forw = (bp); \
}

/*
 * Insq/Remq for the buffer free lists.
 */
#define	bremfree(bp) { \
	(bp)->av_back->av_forw = (bp)->av_forw; \
	(bp)->av_forw->av_back = (bp)->av_back; \
}
#define	binsheadfree(bp, dp) { \
	(dp)->av_forw->av_back = (bp); \
	(bp)->av_forw = (dp)->av_forw; \
	(dp)->av_forw = (bp); \
	(bp)->av_back = (dp); \
}
#define	binstailfree(bp, dp) { \
	(dp)->av_back->av_forw = (bp); \
	(bp)->av_back = (dp)->av_back; \
	(dp)->av_back = (bp); \
	(bp)->av_forw = (dp); \
}

#define	iodone	biodone
#define	iowait	biowait

/*
 * Zero out a buffer's data portion.
 */
#define	clrbuf(bp) { \
	bzero((bp)->b_un.b_addr, (unsigned)(bp)->b_bcount); \
	(bp)->b_resid = 0; \
}
#define B_CLRBUF	0x1	/* request allocated buffer be cleared */
#define B_SYNC		0x2	/* do all allocations synchronously */
Commit	Line	Data
f4566079 WJ	1	/*
	2	* Copyright (c) 1982, 1986, 1989 Regents of the University of California.
	3	* All rights reserved.
	4	*
	5	* Redistribution and use in source and binary forms, with or without
	6	* modification, are permitted provided that the following conditions
	7	* are met:
	8	* 1. Redistributions of source code must retain the above copyright
	9	* notice, this list of conditions and the following disclaimer.
	10	* 2. Redistributions in binary form must reproduce the above copyright
	11	* notice, this list of conditions and the following disclaimer in the
	12	* documentation and/or other materials provided with the distribution.
	13	* 3. All advertising materials mentioning features or use of this software
	14	* must display the following acknowledgement:
	15	* This product includes software developed by the University of
	16	* California, Berkeley and its contributors.
	17	* 4. Neither the name of the University nor the names of its contributors
	18	* may be used to endorse or promote products derived from this software
	19	* without specific prior written permission.
	20	*
	21	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	22	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	23	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	24	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	25	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	26	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	27	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	28	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	29	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	30	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	31	* SUCH DAMAGE.
	32	*
	33	* @(#)buf.h 7.11 (Berkeley) 5/9/90
	34	*/
	35
	36	/*
	37	* The header for buffers in the buffer pool and otherwise used
	38	* to describe a block i/o request is given here.
	39	*
	40	* Each buffer in the pool is usually doubly linked into 2 lists:
	41	* hashed into a chain by <dev,blkno> so it can be located in the cache,
	42	* and (usually) on (one of several) queues. These lists are circular and
	43	* doubly linked for easy removal.
	44	*
	45	* There are currently three queues for buffers:
	46	* one for buffers which must be kept permanently (super blocks)
	47	* one for buffers containing ``useful'' information (the cache)
	48	* one for buffers containing ``non-useful'' information
	49	* (and empty buffers, pushed onto the front)
	50	* The latter two queues contain the buffers which are available for
	51	* reallocation, are kept in lru order. When not on one of these queues,
	52	* the buffers are ``checked out'' to drivers which use the available list
	53	* pointers to keep track of them in their i/o active queues.
	54	*/
	55
	56	/*
	57	* Bufhd structures used at the head of the hashed buffer queues.
	58	* We only need three words for these, so this abbreviated
	59	* definition saves some space.
	60	*/
	61	struct bufhd
	62	{
	63	long b_flags; /* see defines below */
	64	struct buf b_forw, b_back; /* fwd/bkwd pointer in chain */
65	};
66	struct buf
67	{
68	long b_flags; /* too much goes here to describe */
69	struct buf b_forw, b_back; /* hash chain (2 way street) */
70	struct buf av_forw, av_back; /* position on free list if not BUSY */
71	struct buf b_blockf, b_blockb;/ associated vnode */
72	#define b_actf av_forw /* alternate names for driver queue */
73	#define b_actl av_back /* head - isn't history wonderful */
74	long b_bcount; /* transfer count */
75	long b_bufsize; /* size of allocated buffer */
76	#define b_active b_bcount /* driver queue head: drive active */
77	short b_error; /* returned after I/O */
78	dev_t b_dev; /* major+minor device name */
79	union {
80	caddr_t b_addr; /* low order core address */
81	int b_words; / words for clearing */
82	struct fs b_fs; / superblocks */
83	struct csum b_cs; / superblock summary information */
84	struct cg b_cg; / cylinder group block */
85	struct dinode b_dino; / ilist */
86	daddr_t b_daddr; / indirect block */
87	} b_un;
88	daddr_t b_lblkno; /* logical block number */
89	daddr_t b_blkno; /* block # on device */
90	long b_resid; /* words not transferred after error */
91	#define b_errcnt b_resid /* while i/o in progress: # retries */
92	struct proc b_proc; / proc doing physical or swap I/O */
93	int (b_iodone)(); / function called by iodone */
94	struct vnode b_vp; / vnode for dev */
95	int b_pfcent; /* center page when swapping cluster */
96	struct ucred b_rcred; / ref to read credentials */
97	struct ucred b_wcred; / ref to write credendtials */
98	int b_dirtyoff; /* offset in buffer of dirty region */
99	int b_dirtyend; /* offset of end of dirty region */
100	caddr_t b_saveaddr; /* original b_addr for PHYSIO */
101	};
102
103	#define BQUEUES 4 /* number of free buffer queues */
104
105	#define BQ_LOCKED 0 /* super-blocks &c */
106	#define BQ_LRU 1 /* lru, useful buffers */
107	#define BQ_AGE 2 /* rubbish */
108	#define BQ_EMPTY 3 /* buffer headers with no memory */
109
110	#ifdef KERNEL
111	#define BUFHSZ 512
112	#define RND (MAXBSIZE/DEV_BSIZE)
113	#if ((BUFHSZ&(BUFHSZ-1)) == 0)
114	#define BUFHASH(dvp, dblkno) \
115	((struct buf *)&bufhash[((int)(dvp)+(((int)(dblkno))/RND))&(BUFHSZ-1)])
116	#else
117	#define BUFHASH(dvp, dblkno) \
118	((struct buf *)&bufhash[((int)(dvp)+(((int)(dblkno))/RND)) % BUFHSZ])
119	#endif
120
121	struct buf buf; / the buffer pool itself */
122	char *buffers;
123	int nbuf; /* number of buffer headers */
124	int bufpages; /* number of memory pages in the buffer pool */
125	struct buf swbuf; / swap I/O headers */
126	int nswbuf;
127	struct bufhd bufhash[BUFHSZ]; /* heads of hash lists */
128	struct buf bfreelist[BQUEUES]; /* heads of available lists */
129	struct buf bswlist; /* head of free swap header list */
130	struct buf bclnlist; / head of cleaned page list */
131
132	void bufinit();
133	int bread(struct vnode , daddr_t, int, struct ucred , struct buf **);
134	int breada(struct vnode , daddr_t, int, daddr_t, int, struct ucred ,
135	struct buf **);
136	int bwrite(struct buf *);
137	void bawrite(struct buf *);
138	void bdwrite(struct buf *);
139	void brelse(struct buf *);
140	struct buf incore(struct vnode , daddr_t);
141	struct buf getblk(struct vnode , daddr_t, int);
142	struct buf *geteblk(int);
143	int biowait(struct buf *);
144	int biodone(struct buf *);
145	void allocbuf(struct buf *, int);
146
147	#endif
148
149	/*
150	* These flags are kept in b_flags.
151	*/
152	#define B_WRITE 0x000000 /* non-read pseudo-flag */
153	#define B_READ 0x000001 /* read when I/O occurs */
154	#define B_DONE 0x000002 /* transaction finished */
155	#define B_ERROR 0x000004 /* transaction aborted */
156	#define B_BUSY 0x000008 /* not on av_forw/back list */
157	#define B_PHYS 0x000010 /* physical IO */
158	#define B_XXX 0x000020 /* was B_MAP, alloc UNIBUS on pdp-11 */
159	#define B_WANTED 0x000040 /* issue wakeup when BUSY goes off */
160	#define B_AGE 0x000080 /* delayed write for correct aging */
161	#define B_ASYNC 0x000100 /* don't wait for I/O completion */
162	#define B_DELWRI 0x000200 /* write at exit of avail list */
163	#define B_TAPE 0x000400 /* this is a magtape (no bdwrite) */
164	#define B_VMPAGE 0x000800 /* buffer from virtual memory */
165	#define B_MALLOC 0x001000 /* buffer from malloc space */
166	#define B_DIRTY 0x002000 /* dirty page to be pushed out async */
167	#define B_PGIN 0x004000 /* pagein op, so swap() can count it */
168	#define B_CACHE 0x008000 /* did bread find us in the cache ? */
169	#define B_INVAL 0x010000 /* does not contain valid info */
170	#define B_LOCKED 0x020000 /* locked in core (not reusable) */
171	#define B_HEAD 0x040000 /* a buffer header, not a buffer */
172	#define B_BAD 0x100000 /* bad block revectoring in progress */
173	#define B_CALL 0x200000 /* call b_iodone from iodone */
174	#define B_RAW 0x400000 /* set by physio for raw transfers */
175	#define B_NOCACHE 0x800000 /* do not cache block after use */
176
177	/*
178	* Insq/Remq for the buffer hash lists.
179	*/
180	#define bremhash(bp) { \
181	(bp)->b_back->b_forw = (bp)->b_forw; \
182	(bp)->b_forw->b_back = (bp)->b_back; \
183	}
184	#define binshash(bp, dp) { \
185	(bp)->b_forw = (dp)->b_forw; \
186	(bp)->b_back = (dp); \
187	(dp)->b_forw->b_back = (bp); \
188	(dp)->b_forw = (bp); \
189	}
190
191	/*
192	* Insq/Remq for the buffer free lists.
193	*/
194	#define bremfree(bp) { \
195	(bp)->av_back->av_forw = (bp)->av_forw; \
196	(bp)->av_forw->av_back = (bp)->av_back; \
197	}
198	#define binsheadfree(bp, dp) { \
199	(dp)->av_forw->av_back = (bp); \
200	(bp)->av_forw = (dp)->av_forw; \
201	(dp)->av_forw = (bp); \
202	(bp)->av_back = (dp); \
203	}
204	#define binstailfree(bp, dp) { \
205	(dp)->av_back->av_forw = (bp); \
206	(bp)->av_back = (dp)->av_back; \
207	(dp)->av_back = (bp); \
208	(bp)->av_forw = (dp); \
209	}
210
211	#define iodone biodone
212	#define iowait biowait
213
214	/*
215	* Zero out a buffer's data portion.
216	*/
217	#define clrbuf(bp) { \
218	bzero((bp)->b_un.b_addr, (unsigned)(bp)->b_bcount); \
219	(bp)->b_resid = 0; \
220	}
221	#define B_CLRBUF 0x1 /* request allocated buffer be cleared */
222	#define B_SYNC 0x2 /* do all allocations synchronously */