[444] | 1 | /*- |
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| 2 | * Copyright (c) 1990, 1993, 1994 |
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| 3 | * The Regents of the University of California. All rights reserved. |
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| 4 | * |
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| 5 | * This code is derived from software contributed to Berkeley by |
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| 6 | * Margo Seltzer. |
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| 7 | * |
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| 8 | * Redistribution and use in source and binary forms, with or without |
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| 9 | * modification, are permitted provided that the following conditions |
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| 10 | * are met: |
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| 11 | * 1. Redistributions of source code must retain the above copyright |
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| 12 | * notice, this list of conditions and the following disclaimer. |
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| 13 | * 2. Redistributions in binary form must reproduce the above copyright |
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| 14 | * notice, this list of conditions and the following disclaimer in the |
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| 15 | * documentation and/or other materials provided with the distribution. |
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| 16 | * 3. All advertising materials mentioning features or use of this software |
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| 17 | * must display the following acknowledgement: |
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| 18 | * This product includes software developed by the University of |
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| 19 | * California, Berkeley and its contributors. |
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| 20 | * 4. Neither the name of the University nor the names of its contributors |
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| 21 | * may be used to endorse or promote products derived from this software |
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| 22 | * without specific prior written permission. |
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| 23 | * |
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| 24 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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| 25 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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| 26 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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| 27 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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| 28 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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| 29 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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| 30 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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| 31 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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| 32 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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| 33 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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| 34 | * SUCH DAMAGE. |
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| 35 | */ |
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| 36 | |
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| 37 | #include <sys/param.h> |
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| 38 | #if defined(LIBC_SCCS) && !defined(lint) |
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| 39 | static char sccsid[] = "@(#)hash_buf.c 8.5 (Berkeley) 7/15/94"; |
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| 40 | #endif /* LIBC_SCCS and not lint */ |
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| 41 | #include <sys/cdefs.h> |
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| 42 | |
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| 43 | /* |
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| 44 | * PACKAGE: hash |
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| 45 | * |
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| 46 | * DESCRIPTION: |
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| 47 | * Contains buffer management |
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| 48 | * |
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| 49 | * ROUTINES: |
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| 50 | * External |
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| 51 | * __buf_init |
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| 52 | * __get_buf |
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| 53 | * __buf_free |
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| 54 | * __reclaim_buf |
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| 55 | * Internal |
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| 56 | * newbuf |
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| 57 | */ |
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| 58 | |
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| 59 | #include <sys/param.h> |
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| 60 | |
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| 61 | #include <stddef.h> |
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| 62 | #include <stdio.h> |
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| 63 | #include <stdlib.h> |
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| 64 | |
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| 65 | #ifdef DEBUG |
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| 66 | #include <assert.h> |
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| 67 | #endif |
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| 68 | |
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| 69 | #include "db_local.h" |
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| 70 | #include "hash.h" |
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| 71 | #include "page.h" |
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| 72 | #include "extern.h" |
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| 73 | |
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| 74 | static BUFHEAD *newbuf(HTAB *, __uint32_t, BUFHEAD *); |
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| 75 | |
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| 76 | /* Unlink B from its place in the lru */ |
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| 77 | #define BUF_REMOVE(B) { \ |
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| 78 | (B)->prev->next = (B)->next; \ |
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| 79 | (B)->next->prev = (B)->prev; \ |
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| 80 | } |
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| 81 | |
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| 82 | /* Insert B after P */ |
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| 83 | #define BUF_INSERT(B, P) { \ |
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| 84 | (B)->next = (P)->next; \ |
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| 85 | (B)->prev = (P); \ |
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| 86 | (P)->next = (B); \ |
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| 87 | (B)->next->prev = (B); \ |
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| 88 | } |
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| 89 | |
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| 90 | #define MRU hashp->bufhead.next |
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| 91 | #define LRU hashp->bufhead.prev |
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| 92 | |
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| 93 | #define MRU_INSERT(B) BUF_INSERT((B), &hashp->bufhead) |
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| 94 | #define LRU_INSERT(B) BUF_INSERT((B), LRU) |
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| 95 | |
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| 96 | /* Macros for min/max. */ |
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| 97 | #ifndef MIN |
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| 98 | #define MIN(a,b) (((a)<(b))?(a):(b)) |
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| 99 | #endif |
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| 100 | #ifndef MAX |
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| 101 | #define MAX(a,b) (((a)>(b))?(a):(b)) |
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| 102 | #endif |
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| 103 | |
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| 104 | /* |
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| 105 | * We are looking for a buffer with address "addr". If prev_bp is NULL, then |
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| 106 | * address is a bucket index. If prev_bp is not NULL, then it points to the |
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| 107 | * page previous to an overflow page that we are trying to find. |
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| 108 | * |
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| 109 | * CAVEAT: The buffer header accessed via prev_bp's ovfl field may no longer |
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| 110 | * be valid. Therefore, you must always verify that its address matches the |
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| 111 | * address you are seeking. |
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| 112 | */ |
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| 113 | extern BUFHEAD * |
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| 114 | __get_buf(hashp, addr, prev_bp, newpage) |
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| 115 | HTAB *hashp; |
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| 116 | __uint32_t addr; |
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| 117 | BUFHEAD *prev_bp; |
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| 118 | int newpage; /* If prev_bp set, indicates a new overflow page. */ |
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| 119 | { |
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| 120 | BUFHEAD *bp; |
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| 121 | __uint32_t is_disk_mask; |
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| 122 | int is_disk, segment_ndx = 0; |
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| 123 | SEGMENT segp = NULL; |
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| 124 | |
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| 125 | is_disk = 0; |
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| 126 | is_disk_mask = 0; |
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| 127 | if (prev_bp) { |
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| 128 | bp = prev_bp->ovfl; |
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| 129 | if (!bp || (bp->addr != addr)) |
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| 130 | bp = NULL; |
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| 131 | if (!newpage) |
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| 132 | is_disk = BUF_DISK; |
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| 133 | } else { |
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| 134 | /* Grab buffer out of directory */ |
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| 135 | segment_ndx = addr & (hashp->SGSIZE - 1); |
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| 136 | |
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| 137 | /* valid segment ensured by __call_hash() */ |
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| 138 | segp = hashp->dir[addr >> hashp->SSHIFT]; |
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| 139 | #ifdef DEBUG |
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| 140 | assert(segp != NULL); |
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| 141 | #endif |
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| 142 | bp = PTROF(segp[segment_ndx]); |
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| 143 | is_disk_mask = ISDISK(segp[segment_ndx]); |
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| 144 | is_disk = is_disk_mask || !hashp->new_file; |
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| 145 | } |
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| 146 | |
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| 147 | if (!bp) { |
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| 148 | bp = newbuf(hashp, addr, prev_bp); |
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| 149 | if (!bp || |
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| 150 | __get_page(hashp, bp->page, addr, !prev_bp, is_disk, 0)) |
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| 151 | return (NULL); |
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| 152 | if (!prev_bp) |
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| 153 | segp[segment_ndx] = |
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| 154 | (BUFHEAD *)((ptrdiff_t)bp | is_disk_mask); |
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| 155 | } else { |
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| 156 | BUF_REMOVE(bp); |
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| 157 | MRU_INSERT(bp); |
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| 158 | } |
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| 159 | return (bp); |
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| 160 | } |
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| 161 | |
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| 162 | /* |
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| 163 | * We need a buffer for this page. Either allocate one, or evict a resident |
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| 164 | * one (if we have as many buffers as we're allowed) and put this one in. |
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| 165 | * |
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| 166 | * If newbuf finds an error (returning NULL), it also sets errno. |
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| 167 | */ |
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| 168 | static BUFHEAD * |
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| 169 | newbuf(hashp, addr, prev_bp) |
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| 170 | HTAB *hashp; |
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| 171 | __uint32_t addr; |
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| 172 | BUFHEAD *prev_bp; |
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| 173 | { |
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| 174 | BUFHEAD *bp; /* The buffer we're going to use */ |
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| 175 | BUFHEAD *xbp; /* Temp pointer */ |
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| 176 | BUFHEAD *next_xbp; |
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| 177 | SEGMENT segp; |
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| 178 | int segment_ndx; |
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| 179 | __uint16_t oaddr, *shortp; |
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| 180 | |
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| 181 | oaddr = 0; |
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| 182 | bp = LRU; |
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| 183 | /* |
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| 184 | * If LRU buffer is pinned, the buffer pool is too small. We need to |
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| 185 | * allocate more buffers. |
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| 186 | */ |
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| 187 | if (hashp->nbufs || (bp->flags & BUF_PIN)) { |
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| 188 | /* Allocate a new one */ |
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| 189 | if ((bp = (BUFHEAD *)malloc(sizeof(BUFHEAD))) == NULL) |
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| 190 | return (NULL); |
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| 191 | #ifdef PURIFY |
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| 192 | memset(bp, 0xff, sizeof(BUFHEAD)); |
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| 193 | #endif |
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| 194 | if ((bp->page = (char *)malloc(hashp->BSIZE)) == NULL) { |
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| 195 | free(bp); |
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| 196 | return (NULL); |
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| 197 | } |
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| 198 | #ifdef PURIFY |
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| 199 | memset(bp->page, 0xff, hashp->BSIZE); |
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| 200 | #endif |
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| 201 | if (hashp->nbufs) |
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| 202 | hashp->nbufs--; |
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| 203 | } else { |
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| 204 | /* Kick someone out */ |
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| 205 | BUF_REMOVE(bp); |
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| 206 | /* |
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| 207 | * If this is an overflow page with addr 0, it's already been |
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| 208 | * flushed back in an overflow chain and initialized. |
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| 209 | */ |
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| 210 | if ((bp->addr != 0) || (bp->flags & BUF_BUCKET)) { |
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| 211 | /* |
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| 212 | * Set oaddr before __put_page so that you get it |
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| 213 | * before bytes are swapped. |
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| 214 | */ |
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| 215 | shortp = (__uint16_t *)bp->page; |
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| 216 | if (shortp[0]) |
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| 217 | oaddr = shortp[shortp[0] - 1]; |
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| 218 | if ((bp->flags & BUF_MOD) && __put_page(hashp, bp->page, |
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| 219 | bp->addr, (int)IS_BUCKET(bp->flags), 0)) |
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| 220 | return (NULL); |
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| 221 | /* |
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| 222 | * Update the pointer to this page (i.e. invalidate it). |
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| 223 | * |
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| 224 | * If this is a new file (i.e. we created it at open |
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| 225 | * time), make sure that we mark pages which have been |
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| 226 | * written to disk so we retrieve them from disk later, |
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| 227 | * rather than allocating new pages. |
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| 228 | */ |
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| 229 | if (IS_BUCKET(bp->flags)) { |
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| 230 | segment_ndx = bp->addr & (hashp->SGSIZE - 1); |
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| 231 | segp = hashp->dir[bp->addr >> hashp->SSHIFT]; |
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| 232 | #ifdef DEBUG |
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| 233 | assert(segp != NULL); |
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| 234 | #endif |
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| 235 | |
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| 236 | if (hashp->new_file && |
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| 237 | ((bp->flags & BUF_MOD) || |
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| 238 | ISDISK(segp[segment_ndx]))) |
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| 239 | segp[segment_ndx] = (BUFHEAD *)BUF_DISK; |
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| 240 | else |
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| 241 | segp[segment_ndx] = NULL; |
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| 242 | } |
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| 243 | /* |
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| 244 | * Since overflow pages can only be access by means of |
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| 245 | * their bucket, free overflow pages associated with |
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| 246 | * this bucket. |
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| 247 | */ |
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| 248 | for (xbp = bp; xbp->ovfl;) { |
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| 249 | next_xbp = xbp->ovfl; |
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| 250 | xbp->ovfl = 0; |
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| 251 | xbp = next_xbp; |
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| 252 | |
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| 253 | /* Check that ovfl pointer is up date. */ |
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| 254 | if (IS_BUCKET(xbp->flags) || |
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| 255 | (oaddr != xbp->addr)) |
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| 256 | break; |
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| 257 | |
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| 258 | shortp = (__uint16_t *)xbp->page; |
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| 259 | if (shortp[0]) |
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| 260 | /* set before __put_page */ |
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| 261 | oaddr = shortp[shortp[0] - 1]; |
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| 262 | if ((xbp->flags & BUF_MOD) && __put_page(hashp, |
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| 263 | xbp->page, xbp->addr, 0, 0)) |
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| 264 | return (NULL); |
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| 265 | xbp->addr = 0; |
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| 266 | xbp->flags = 0; |
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| 267 | BUF_REMOVE(xbp); |
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| 268 | LRU_INSERT(xbp); |
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| 269 | } |
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| 270 | } |
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| 271 | } |
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| 272 | |
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| 273 | /* Now assign this buffer */ |
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| 274 | bp->addr = addr; |
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| 275 | #ifdef DEBUG1 |
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| 276 | (void)fprintf(stderr, "NEWBUF1: %d->ovfl was %d is now %d\n", |
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| 277 | bp->addr, (bp->ovfl ? bp->ovfl->addr : 0), 0); |
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| 278 | #endif |
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| 279 | bp->ovfl = NULL; |
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| 280 | if (prev_bp) { |
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| 281 | /* |
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| 282 | * If prev_bp is set, this is an overflow page, hook it in to |
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| 283 | * the buffer overflow links. |
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| 284 | */ |
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| 285 | #ifdef DEBUG1 |
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| 286 | (void)fprintf(stderr, "NEWBUF2: %d->ovfl was %d is now %d\n", |
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| 287 | prev_bp->addr, (prev_bp->ovfl ? bp->ovfl->addr : 0), |
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| 288 | (bp ? bp->addr : 0)); |
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| 289 | #endif |
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| 290 | prev_bp->ovfl = bp; |
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| 291 | bp->flags = 0; |
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| 292 | } else |
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| 293 | bp->flags = BUF_BUCKET; |
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| 294 | MRU_INSERT(bp); |
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| 295 | return (bp); |
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| 296 | } |
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| 297 | |
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| 298 | extern void |
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| 299 | __buf_init(hashp, nbytes) |
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| 300 | HTAB *hashp; |
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| 301 | int nbytes; |
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| 302 | { |
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| 303 | BUFHEAD *bfp; |
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| 304 | int npages; |
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| 305 | |
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| 306 | bfp = &(hashp->bufhead); |
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| 307 | npages = (nbytes + hashp->BSIZE - 1) >> hashp->BSHIFT; |
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| 308 | npages = MAX(npages, MIN_BUFFERS); |
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| 309 | |
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| 310 | hashp->nbufs = npages; |
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| 311 | bfp->next = bfp; |
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| 312 | bfp->prev = bfp; |
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| 313 | /* |
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| 314 | * This space is calloc'd so these are already null. |
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| 315 | * |
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| 316 | * bfp->ovfl = NULL; |
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| 317 | * bfp->flags = 0; |
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| 318 | * bfp->page = NULL; |
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| 319 | * bfp->addr = 0; |
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| 320 | */ |
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| 321 | } |
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| 322 | |
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| 323 | extern int |
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| 324 | __buf_free(hashp, do_free, to_disk) |
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| 325 | HTAB *hashp; |
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| 326 | int do_free, to_disk; |
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| 327 | { |
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| 328 | BUFHEAD *bp; |
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| 329 | |
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| 330 | /* Need to make sure that buffer manager has been initialized */ |
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| 331 | if (!LRU) |
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| 332 | return (0); |
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| 333 | for (bp = LRU; bp != &hashp->bufhead;) { |
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| 334 | /* Check that the buffer is valid */ |
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| 335 | if (bp->addr || IS_BUCKET(bp->flags)) { |
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| 336 | if (to_disk && (bp->flags & BUF_MOD) && |
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| 337 | __put_page(hashp, bp->page, |
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| 338 | bp->addr, IS_BUCKET(bp->flags), 0)) |
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| 339 | return (-1); |
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| 340 | } |
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| 341 | /* Check if we are freeing stuff */ |
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| 342 | if (do_free) { |
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| 343 | if (bp->page) |
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| 344 | free(bp->page); |
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| 345 | BUF_REMOVE(bp); |
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| 346 | free(bp); |
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| 347 | bp = LRU; |
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| 348 | } else |
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| 349 | bp = bp->prev; |
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| 350 | } |
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| 351 | return (0); |
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| 352 | } |
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| 353 | |
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| 354 | extern void |
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| 355 | __reclaim_buf(hashp, bp) |
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| 356 | HTAB *hashp; |
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| 357 | BUFHEAD *bp; |
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| 358 | { |
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| 359 | bp->ovfl = 0; |
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| 360 | bp->addr = 0; |
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| 361 | bp->flags = 0; |
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| 362 | BUF_REMOVE(bp); |
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| 363 | LRU_INSERT(bp); |
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| 364 | } |
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