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      1 /*	$NetBSD: bt_page.c,v 1.15 2016/09/24 21:31:25 christos Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1990, 1993, 1994
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #if HAVE_NBTOOL_CONFIG_H
     33 #include "nbtool_config.h"
     34 #endif
     35 
     36 #include <sys/cdefs.h>
     37 __RCSID("$NetBSD: bt_page.c,v 1.15 2016/09/24 21:31:25 christos Exp $");
     38 
     39 #include "namespace.h"
     40 #include <sys/types.h>
     41 
     42 #include <assert.h>
     43 #include <stdio.h>
     44 
     45 #include <db.h>
     46 #include "btree.h"
     47 
     48 /*
     49  * __bt_free --
     50  *	Put a page on the freelist.
     51  *
     52  * Parameters:
     53  *	t:	tree
     54  *	h:	page to free
     55  *
     56  * Returns:
     57  *	RET_ERROR, RET_SUCCESS
     58  *
     59  * Side-effect:
     60  *	mpool_put's the page.
     61  */
     62 int
     63 __bt_free(BTREE *t, PAGE *h)
     64 {
     65 	/* Insert the page at the head of the free list. */
     66 	h->prevpg = P_INVALID;
     67 	h->nextpg = t->bt_free;
     68 	t->bt_free = h->pgno;
     69 	F_SET(t, B_METADIRTY);
     70 
     71 	/* Make sure the page gets written back. */
     72 	return (mpool_put(t->bt_mp, h, MPOOL_DIRTY));
     73 }
     74 
     75 /*
     76  * __bt_new --
     77  *	Get a new page, preferably from the freelist.
     78  *
     79  * Parameters:
     80  *	t:	tree
     81  *	npg:	storage for page number.
     82  *
     83  * Returns:
     84  *	Pointer to a page, NULL on error.
     85  */
     86 PAGE *
     87 __bt_new(BTREE *t, pgno_t *npg)
     88 {
     89 	PAGE *h;
     90 
     91 	if (t->bt_free != P_INVALID &&
     92 	    (h = mpool_get(t->bt_mp, t->bt_free, 0)) != NULL) {
     93 		*npg = t->bt_free;
     94 		t->bt_free = h->nextpg;
     95 		F_SET(t, B_METADIRTY);
     96 		return (h);
     97 	}
     98 	return (mpool_new(t->bt_mp, npg));
     99 }
    100