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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