[apple/libc.git] / db / hash / hash_buf.c

/*
 * Copyright (c) 2003 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_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. 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_HEADER_END@
 */
/*-
 * Copyright (c) 1990, 1993, 1994
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Margo Seltzer.
 *
 * 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)hash_buf.c	8.5 (Berkeley) 7/15/94";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>

/*
 * PACKAGE: hash
 *
 * DESCRIPTION:
 *	Contains buffer management
 *
 * ROUTINES:
 * External
 *	__buf_init
 *	__get_buf
 *	__buf_free
 *	__reclaim_buf
 * Internal
 *	newbuf
 */

#include <sys/param.h>

#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>

#ifdef DEBUG
#include <assert.h>
#endif

#include <db.h>
#include "hash.h"
#include "page.h"
#include "extern.h"

static BUFHEAD *newbuf(HTAB *, u_int32_t, BUFHEAD *);

/* Unlink B from its place in the lru */
#define BUF_REMOVE(B) { \
	(B)->prev->next = (B)->next; \
	(B)->next->prev = (B)->prev; \
}

/* Insert B after P */
#define BUF_INSERT(B, P) { \
	(B)->next = (P)->next; \
	(B)->prev = (P); \
	(P)->next = (B); \
	(B)->next->prev = (B); \
}

#define	MRU	hashp->bufhead.next
#define	LRU	hashp->bufhead.prev

#define MRU_INSERT(B)	BUF_INSERT((B), &hashp->bufhead)
#define LRU_INSERT(B)	BUF_INSERT((B), LRU)

/*
 * We are looking for a buffer with address "addr".  If prev_bp is NULL, then
 * address is a bucket index.  If prev_bp is not NULL, then it points to the
 * page previous to an overflow page that we are trying to find.
 *
 * CAVEAT:  The buffer header accessed via prev_bp's ovfl field may no longer
 * be valid.  Therefore, you must always verify that its address matches the
 * address you are seeking.
 */
extern BUFHEAD *
__get_buf(hashp, addr, prev_bp, newpage)
	HTAB *hashp;
	u_int32_t addr;
	BUFHEAD *prev_bp;
	int newpage;	/* If prev_bp set, indicates a new overflow page. */
{
	BUFHEAD *bp;
	u_int32_t is_disk_mask;
	int is_disk, segment_ndx;
	SEGMENT segp;

	is_disk = 0;
	is_disk_mask = 0;
	if (prev_bp) {
		bp = prev_bp->ovfl;
		if (!bp || (bp->addr != addr))
			bp = NULL;
		if (!newpage)
			is_disk = BUF_DISK;
	} else {
		/* Grab buffer out of directory */
		segment_ndx = addr & (hashp->SGSIZE - 1);

		/* valid segment ensured by __call_hash() */
		segp = hashp->dir[addr >> hashp->SSHIFT];
#ifdef DEBUG
		assert(segp != NULL);
#endif
		bp = PTROF(segp[segment_ndx]);
		is_disk_mask = ISDISK(segp[segment_ndx]);
		is_disk = is_disk_mask || !hashp->new_file;
	}

	if (!bp) {
		bp = newbuf(hashp, addr, prev_bp);
		if (!bp ||
		    __get_page(hashp, bp->page, addr, !prev_bp, is_disk, 0))
			return (NULL);
		if (!prev_bp)
			segp[segment_ndx] =
			    (BUFHEAD *)((ptrdiff_t)bp | is_disk_mask);
	} else {
		BUF_REMOVE(bp);
		MRU_INSERT(bp);
	}
	return (bp);
}

/*
 * We need a buffer for this page. Either allocate one, or evict a resident
 * one (if we have as many buffers as we're allowed) and put this one in.
 *
 * If newbuf finds an error (returning NULL), it also sets errno.
 */
static BUFHEAD *
newbuf(hashp, addr, prev_bp)
	HTAB *hashp;
	u_int32_t addr;
	BUFHEAD *prev_bp;
{
	BUFHEAD *bp;		/* The buffer we're going to use */
	BUFHEAD *xbp;		/* Temp pointer */
	BUFHEAD *next_xbp;
	SEGMENT segp;
	int segment_ndx;
	u_int16_t oaddr, *shortp;

	oaddr = 0;
	bp = LRU;
	/*
	 * If LRU buffer is pinned, the buffer pool is too small. We need to
	 * allocate more buffers.
	 */
	if (hashp->nbufs || (bp->flags & BUF_PIN)) {
		/* Allocate a new one */
		if ((bp = (BUFHEAD *)malloc(sizeof(BUFHEAD))) == NULL)
			return (NULL);
#ifdef PURIFY
		memset(bp, 0xff, sizeof(BUFHEAD));
#endif
		if ((bp->page = (char *)malloc(hashp->BSIZE)) == NULL) {
			free(bp);
			return (NULL);
		}
#ifdef PURIFY
		memset(bp->page, 0xff, hashp->BSIZE);
#endif
		if (hashp->nbufs)
			hashp->nbufs--;
	} else {
		/* Kick someone out */
		BUF_REMOVE(bp);
		/*
		 * If this is an overflow page with addr 0, it's already been
		 * flushed back in an overflow chain and initialized.
		 */
		if ((bp->addr != 0) || (bp->flags & BUF_BUCKET)) {
			/*
			 * Set oaddr before __put_page so that you get it
			 * before bytes are swapped.
			 */
			shortp = (u_int16_t *)bp->page;
			if (shortp[0])
				oaddr = shortp[shortp[0] - 1];
			if ((bp->flags & BUF_MOD) && __put_page(hashp, bp->page,
			    bp->addr, (int)IS_BUCKET(bp->flags), 0))
				return (NULL);
			/*
			 * Update the pointer to this page (i.e. invalidate it).
			 *
			 * If this is a new file (i.e. we created it at open
			 * time), make sure that we mark pages which have been
			 * written to disk so we retrieve them from disk later,
			 * rather than allocating new pages.
			 */
			if (IS_BUCKET(bp->flags)) {
				segment_ndx = bp->addr & (hashp->SGSIZE - 1);
				segp = hashp->dir[bp->addr >> hashp->SSHIFT];
#ifdef DEBUG
				assert(segp != NULL);
#endif

				if (hashp->new_file &&
				    ((bp->flags & BUF_MOD) ||
				    ISDISK(segp[segment_ndx])))
					segp[segment_ndx] = (BUFHEAD *)BUF_DISK;
				else
					segp[segment_ndx] = NULL;
			}
			/*
			 * Since overflow pages can only be access by means of
			 * their bucket, free overflow pages associated with
			 * this bucket.
			 */
			for (xbp = bp; xbp->ovfl;) {
				next_xbp = xbp->ovfl;
				xbp->ovfl = 0;
				xbp = next_xbp;

				/* Check that ovfl pointer is up date. */
				if (IS_BUCKET(xbp->flags) ||
				    (oaddr != xbp->addr))
					break;

				shortp = (u_int16_t *)xbp->page;
				if (shortp[0])
					/* set before __put_page */
					oaddr = shortp[shortp[0] - 1];
				if ((xbp->flags & BUF_MOD) && __put_page(hashp,
				    xbp->page, xbp->addr, 0, 0))
					return (NULL);
				xbp->addr = 0;
				xbp->flags = 0;
				BUF_REMOVE(xbp);
				LRU_INSERT(xbp);
			}
		}
	}

	/* Now assign this buffer */
	bp->addr = addr;
#ifdef DEBUG1
	(void)fprintf(stderr, "NEWBUF1: %d->ovfl was %d is now %d\n",
	    bp->addr, (bp->ovfl ? bp->ovfl->addr : 0), 0);
#endif
	bp->ovfl = NULL;
	if (prev_bp) {
		/*
		 * If prev_bp is set, this is an overflow page, hook it in to
		 * the buffer overflow links.
		 */
#ifdef DEBUG1
		(void)fprintf(stderr, "NEWBUF2: %d->ovfl was %d is now %d\n",
		    prev_bp->addr, (prev_bp->ovfl ? bp->ovfl->addr : 0),
		    (bp ? bp->addr : 0));
#endif
		prev_bp->ovfl = bp;
		bp->flags = 0;
	} else
		bp->flags = BUF_BUCKET;
	MRU_INSERT(bp);
	return (bp);
}

extern void
__buf_init(hashp, nbytes)
	HTAB *hashp;
	int nbytes;
{
	BUFHEAD *bfp;
	int npages;

	bfp = &(hashp->bufhead);
	npages = (nbytes + hashp->BSIZE - 1) >> hashp->BSHIFT;
	npages = MAX(npages, MIN_BUFFERS);

	hashp->nbufs = npages;
	bfp->next = bfp;
	bfp->prev = bfp;
	/*
	 * This space is calloc'd so these are already null.
	 *
	 * bfp->ovfl = NULL;
	 * bfp->flags = 0;
	 * bfp->page = NULL;
	 * bfp->addr = 0;
	 */
}

extern int
__buf_free(hashp, do_free, to_disk)
	HTAB *hashp;
	int do_free, to_disk;
{
	BUFHEAD *bp;

	/* Need to make sure that buffer manager has been initialized */
	if (!LRU)
		return (0);
	for (bp = LRU; bp != &hashp->bufhead;) {
		/* Check that the buffer is valid */
		if (bp->addr || IS_BUCKET(bp->flags)) {
			if (to_disk && (bp->flags & BUF_MOD) &&
			    __put_page(hashp, bp->page,
			    bp->addr, IS_BUCKET(bp->flags), 0))
				return (-1);
		}
		/* Check if we are freeing stuff */
		if (do_free) {
			if (bp->page)
				free(bp->page);
			BUF_REMOVE(bp);
			free(bp);
			bp = LRU;
		} else
			bp = bp->prev;
	}
	return (0);
}

extern void
__reclaim_buf(hashp, bp)
	HTAB *hashp;
	BUFHEAD *bp;
{
	bp->ovfl = 0;
	bp->addr = 0;
	bp->flags = 0;
	BUF_REMOVE(bp);
	LRU_INSERT(bp);
}
Commit	Line	Data
e9ce8d39	1	/*
9385eb3d	2	* Copyright (c) 2003 Apple Computer, Inc. All rights reserved.
e9ce8d39 A	3	*
	4	* @APPLE_LICENSE_HEADER_START@
	5	*
734aad71 A	6	* This file contains Original Code and/or Modifications of Original Code
	7	* as defined in and that are subject to the Apple Public Source License
	8	* Version 2.0 (the 'License'). You may not use this file except in
	9	* compliance with the License. Please obtain a copy of the License at
	10	* http://www.opensource.apple.com/apsl/ and read it before using this
	11	* file.
	12	*
	13	* The Original Code and all software distributed under the License are
	14	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
e9ce8d39 A	15	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
e9ce8d39 A	16	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
734aad71 A	17	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	18	* Please see the License for the specific language governing rights and
	19	* limitations under the License.
e9ce8d39 A	20	*
	21	* @APPLE_LICENSE_HEADER_END@
	22	*/
9385eb3d A	23	/*-
9385eb3d A	24	* Copyright (c) 1990, 1993, 1994
e9ce8d39 A	25	* The Regents of the University of California. All rights reserved.
	26	*
	27	* This code is derived from software contributed to Berkeley by
	28	* Margo Seltzer.
	29	*
	30	* Redistribution and use in source and binary forms, with or without
	31	* modification, are permitted provided that the following conditions
	32	* are met:
	33	* 1. Redistributions of source code must retain the above copyright
	34	* notice, this list of conditions and the following disclaimer.
	35	* 2. Redistributions in binary form must reproduce the above copyright
	36	* notice, this list of conditions and the following disclaimer in the
	37	* documentation and/or other materials provided with the distribution.
	38	* 3. All advertising materials mentioning features or use of this software
	39	* must display the following acknowledgement:
	40	* This product includes software developed by the University of
	41	* California, Berkeley and its contributors.
	42	* 4. Neither the name of the University nor the names of its contributors
	43	* may be used to endorse or promote products derived from this software
	44	* without specific prior written permission.
	45	*
	46	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	47	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	48	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	49	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	50	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	51	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	52	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	53	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	54	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	55	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	56	* SUCH DAMAGE.
	57	*/
	58
9385eb3d A	59	#if defined(LIBC_SCCS) && !defined(lint)
	60	static char sccsid[] = "@(#)hash_buf.c 8.5 (Berkeley) 7/15/94";
	61	#endif /* LIBC_SCCS and not lint */
	62	#include <sys/cdefs.h>
e9ce8d39 A	63
	64	/*
	65	* PACKAGE: hash
	66	*
	67	* DESCRIPTION:
	68	* Contains buffer management
	69	*
	70	* ROUTINES:
	71	* External
	72	* __buf_init
	73	* __get_buf
	74	* __buf_free
	75	* __reclaim_buf
	76	* Internal
	77	* newbuf
	78	*/
	79
	80	#include <sys/param.h>
	81
9385eb3d	82	#include <stddef.h>
e9ce8d39 A	83	#include <stdio.h>
e9ce8d39 A	84	#include <stdlib.h>
9385eb3d	85
e9ce8d39 A	86	#ifdef DEBUG
	87	#include <assert.h>
	88	#endif
	89
	90	#include <db.h>
	91	#include "hash.h"
	92	#include "page.h"
	93	#include "extern.h"
	94
9385eb3d	95	static BUFHEAD newbuf(HTAB , u_int32_t, BUFHEAD *);
e9ce8d39 A	96
	97	/* Unlink B from its place in the lru */
	98	#define BUF_REMOVE(B) { \
	99	(B)->prev->next = (B)->next; \
	100	(B)->next->prev = (B)->prev; \
	101	}
	102
	103	/* Insert B after P */
	104	#define BUF_INSERT(B, P) { \
	105	(B)->next = (P)->next; \
	106	(B)->prev = (P); \
	107	(P)->next = (B); \
	108	(B)->next->prev = (B); \
	109	}
	110
	111	#define MRU hashp->bufhead.next
	112	#define LRU hashp->bufhead.prev
	113
	114	#define MRU_INSERT(B) BUF_INSERT((B), &hashp->bufhead)
	115	#define LRU_INSERT(B) BUF_INSERT((B), LRU)
	116
	117	/*
	118	* We are looking for a buffer with address "addr". If prev_bp is NULL, then
	119	* address is a bucket index. If prev_bp is not NULL, then it points to the
	120	* page previous to an overflow page that we are trying to find.
	121	*
	122	* CAVEAT: The buffer header accessed via prev_bp's ovfl field may no longer
	123	* be valid. Therefore, you must always verify that its address matches the
	124	* address you are seeking.
	125	*/
	126	extern BUFHEAD *
	127	__get_buf(hashp, addr, prev_bp, newpage)
	128	HTAB *hashp;
9385eb3d	129	u_int32_t addr;
e9ce8d39 A	130	BUFHEAD *prev_bp;
	131	int newpage; /* If prev_bp set, indicates a new overflow page. */
	132	{
9385eb3d A	133	BUFHEAD *bp;
	134	u_int32_t is_disk_mask;
	135	int is_disk, segment_ndx;
e9ce8d39 A	136	SEGMENT segp;
	137
	138	is_disk = 0;
	139	is_disk_mask = 0;
	140	if (prev_bp) {
	141	bp = prev_bp->ovfl;
	142	if (!bp \|\| (bp->addr != addr))
	143	bp = NULL;
	144	if (!newpage)
	145	is_disk = BUF_DISK;
	146	} else {
	147	/* Grab buffer out of directory */
	148	segment_ndx = addr & (hashp->SGSIZE - 1);
	149
	150	/* valid segment ensured by __call_hash() */
	151	segp = hashp->dir[addr >> hashp->SSHIFT];
	152	#ifdef DEBUG
	153	assert(segp != NULL);
	154	#endif
	155	bp = PTROF(segp[segment_ndx]);
	156	is_disk_mask = ISDISK(segp[segment_ndx]);
	157	is_disk = is_disk_mask \|\| !hashp->new_file;
	158	}
	159
	160	if (!bp) {
	161	bp = newbuf(hashp, addr, prev_bp);
	162	if (!bp \|\|
	163	__get_page(hashp, bp->page, addr, !prev_bp, is_disk, 0))
	164	return (NULL);
	165	if (!prev_bp)
	166	segp[segment_ndx] =
9385eb3d	167	(BUFHEAD *)((ptrdiff_t)bp \| is_disk_mask);
e9ce8d39 A	168	} else {
	169	BUF_REMOVE(bp);
	170	MRU_INSERT(bp);
	171	}
	172	return (bp);
	173	}
	174
	175	/*
	176	* We need a buffer for this page. Either allocate one, or evict a resident
	177	* one (if we have as many buffers as we're allowed) and put this one in.
	178	*
	179	* If newbuf finds an error (returning NULL), it also sets errno.
	180	*/
	181	static BUFHEAD *
	182	newbuf(hashp, addr, prev_bp)
	183	HTAB *hashp;
9385eb3d	184	u_int32_t addr;
e9ce8d39 A	185	BUFHEAD *prev_bp;
e9ce8d39 A	186	{
9385eb3d A	187	BUFHEAD bp; / The buffer we're going to use */
	188	BUFHEAD xbp; / Temp pointer */
	189	BUFHEAD *next_xbp;
e9ce8d39 A	190	SEGMENT segp;
e9ce8d39 A	191	int segment_ndx;
9385eb3d	192	u_int16_t oaddr, *shortp;
e9ce8d39 A	193
	194	oaddr = 0;
	195	bp = LRU;
	196	/*
	197	* If LRU buffer is pinned, the buffer pool is too small. We need to
	198	* allocate more buffers.
	199	*/
	200	if (hashp->nbufs \|\| (bp->flags & BUF_PIN)) {
	201	/* Allocate a new one */
	202	if ((bp = (BUFHEAD *)malloc(sizeof(BUFHEAD))) == NULL)
	203	return (NULL);
9385eb3d A	204	#ifdef PURIFY
	205	memset(bp, 0xff, sizeof(BUFHEAD));
	206	#endif
e9ce8d39 A	207	if ((bp->page = (char *)malloc(hashp->BSIZE)) == NULL) {
	208	free(bp);
	209	return (NULL);
	210	}
9385eb3d A	211	#ifdef PURIFY
	212	memset(bp->page, 0xff, hashp->BSIZE);
	213	#endif
e9ce8d39 A	214	if (hashp->nbufs)
	215	hashp->nbufs--;
	216	} else {
	217	/* Kick someone out */
	218	BUF_REMOVE(bp);
	219	/*
	220	* If this is an overflow page with addr 0, it's already been
	221	* flushed back in an overflow chain and initialized.
	222	*/
	223	if ((bp->addr != 0) \|\| (bp->flags & BUF_BUCKET)) {
	224	/*
	225	* Set oaddr before __put_page so that you get it
	226	* before bytes are swapped.
	227	*/
9385eb3d	228	shortp = (u_int16_t *)bp->page;
e9ce8d39 A	229	if (shortp[0])
	230	oaddr = shortp[shortp[0] - 1];
	231	if ((bp->flags & BUF_MOD) && __put_page(hashp, bp->page,
	232	bp->addr, (int)IS_BUCKET(bp->flags), 0))
	233	return (NULL);
	234	/*
	235	* Update the pointer to this page (i.e. invalidate it).
	236	*
	237	* If this is a new file (i.e. we created it at open
	238	* time), make sure that we mark pages which have been
	239	* written to disk so we retrieve them from disk later,
	240	* rather than allocating new pages.
	241	*/
	242	if (IS_BUCKET(bp->flags)) {
	243	segment_ndx = bp->addr & (hashp->SGSIZE - 1);
	244	segp = hashp->dir[bp->addr >> hashp->SSHIFT];
	245	#ifdef DEBUG
	246	assert(segp != NULL);
	247	#endif
	248
	249	if (hashp->new_file &&
	250	((bp->flags & BUF_MOD) \|\|
	251	ISDISK(segp[segment_ndx])))
	252	segp[segment_ndx] = (BUFHEAD *)BUF_DISK;
	253	else
	254	segp[segment_ndx] = NULL;
	255	}
	256	/*
	257	* Since overflow pages can only be access by means of
	258	* their bucket, free overflow pages associated with
	259	* this bucket.
	260	*/
	261	for (xbp = bp; xbp->ovfl;) {
	262	next_xbp = xbp->ovfl;
	263	xbp->ovfl = 0;
	264	xbp = next_xbp;
	265
	266	/* Check that ovfl pointer is up date. */
	267	if (IS_BUCKET(xbp->flags) \|\|
	268	(oaddr != xbp->addr))
	269	break;
	270
9385eb3d	271	shortp = (u_int16_t *)xbp->page;
e9ce8d39 A	272	if (shortp[0])
	273	/* set before __put_page */
	274	oaddr = shortp[shortp[0] - 1];
	275	if ((xbp->flags & BUF_MOD) && __put_page(hashp,
	276	xbp->page, xbp->addr, 0, 0))
	277	return (NULL);
	278	xbp->addr = 0;
	279	xbp->flags = 0;
	280	BUF_REMOVE(xbp);
	281	LRU_INSERT(xbp);
	282	}
	283	}
	284	}
	285
	286	/* Now assign this buffer */
	287	bp->addr = addr;
	288	#ifdef DEBUG1
	289	(void)fprintf(stderr, "NEWBUF1: %d->ovfl was %d is now %d\n",
	290	bp->addr, (bp->ovfl ? bp->ovfl->addr : 0), 0);
	291	#endif
	292	bp->ovfl = NULL;
	293	if (prev_bp) {
	294	/*
	295	* If prev_bp is set, this is an overflow page, hook it in to
	296	* the buffer overflow links.
	297	*/
	298	#ifdef DEBUG1
	299	(void)fprintf(stderr, "NEWBUF2: %d->ovfl was %d is now %d\n",
	300	prev_bp->addr, (prev_bp->ovfl ? bp->ovfl->addr : 0),
	301	(bp ? bp->addr : 0));
	302	#endif
	303	prev_bp->ovfl = bp;
	304	bp->flags = 0;
	305	} else
	306	bp->flags = BUF_BUCKET;
	307	MRU_INSERT(bp);
	308	return (bp);
	309	}
	310
	311	extern void
	312	__buf_init(hashp, nbytes)
	313	HTAB *hashp;
	314	int nbytes;
	315	{
	316	BUFHEAD *bfp;
	317	int npages;
	318
	319	bfp = &(hashp->bufhead);
	320	npages = (nbytes + hashp->BSIZE - 1) >> hashp->BSHIFT;
	321	npages = MAX(npages, MIN_BUFFERS);
	322
	323	hashp->nbufs = npages;
	324	bfp->next = bfp;
	325	bfp->prev = bfp;
	326	/*
	327	* This space is calloc'd so these are already null.
	328	*
	329	* bfp->ovfl = NULL;
	330	* bfp->flags = 0;
	331	* bfp->page = NULL;
	332	* bfp->addr = 0;
	333	*/
	334	}
	335
336	extern int
337	__buf_free(hashp, do_free, to_disk)
338	HTAB *hashp;
339	int do_free, to_disk;
340	{
341	BUFHEAD *bp;
342
343	/* Need to make sure that buffer manager has been initialized */
344	if (!LRU)
345	return (0);
346	for (bp = LRU; bp != &hashp->bufhead;) {
347	/* Check that the buffer is valid */
348	if (bp->addr \|\| IS_BUCKET(bp->flags)) {
349	if (to_disk && (bp->flags & BUF_MOD) &&
350	__put_page(hashp, bp->page,
351	bp->addr, IS_BUCKET(bp->flags), 0))
352	return (-1);
353	}
354	/* Check if we are freeing stuff */
355	if (do_free) {
356	if (bp->page)
357	free(bp->page);
358	BUF_REMOVE(bp);
359	free(bp);
360	bp = LRU;
361	} else
362	bp = bp->prev;
363	}
364	return (0);
365	}
366
367	extern void
368	__reclaim_buf(hashp, bp)
369	HTAB *hashp;
370	BUFHEAD *bp;
371	{
372	bp->ovfl = 0;
373	bp->addr = 0;
374	bp->flags = 0;
375	BUF_REMOVE(bp);
376	LRU_INSERT(bp);
377	}