1 /* 2 * Copyright (c) 2005 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Matthew Dillon <dillon@backplane.com> 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 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * 3. Neither the name of The DragonFly Project nor the names of its 18 * contributors may be used to endorse or promote products derived 19 * from this software without specific, prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * $FreeBSD: src/sbin/dump/cache.c,v 1.1.2.1 2003/01/25 18:54:59 dillon Exp $ 35 */ 36 /* 37 * Block cache for dump 38 */ 39 40 #include <sys/param.h> 41 #include <sys/stat.h> 42 #include <sys/mman.h> 43 44 #include <vfs/ufs/dir.h> 45 #include <vfs/ufs/dinode.h> 46 #include <vfs/ufs/fs.h> 47 48 #include <protocols/dumprestore.h> 49 50 #include <ctype.h> 51 #include <stdio.h> 52 #include <errno.h> 53 #include <string.h> 54 #include <stdlib.h> 55 #include <unistd.h> 56 57 #include "dump.h" 58 59 typedef struct Block { 60 struct Block *b_HNext; /* must be first field */ 61 off_t b_Offset; 62 char *b_Data; 63 } Block; 64 65 #define HFACTOR 4 66 #define BLKFACTOR 4 67 68 static char *DataBase; 69 static Block **BlockHash; 70 static int BlockSize; 71 static int HSize; 72 static int NBlocks; 73 74 static void 75 cinit(void) 76 { 77 int i; 78 int hi; 79 Block *base; 80 81 if ((BlockSize = sblock->fs_bsize * BLKFACTOR) > MAXBSIZE) 82 BlockSize = MAXBSIZE; 83 NBlocks = cachesize / BlockSize; 84 HSize = NBlocks / HFACTOR; 85 86 msg("Cache %d MB, blocksize = %d\n", 87 NBlocks * BlockSize / (1024 * 1024), BlockSize); 88 89 base = calloc(sizeof(Block), NBlocks); 90 BlockHash = calloc(sizeof(Block *), HSize); 91 DataBase = mmap(NULL, NBlocks * BlockSize, 92 PROT_READ|PROT_WRITE, MAP_ANON, -1, 0); 93 for (i = 0; i < NBlocks; ++i) { 94 base[i].b_Data = DataBase + i * BlockSize; 95 base[i].b_Offset = (off_t)-1; 96 hi = i / HFACTOR; 97 base[i].b_HNext = BlockHash[hi]; 98 BlockHash[hi] = &base[i]; 99 } 100 } 101 102 ssize_t 103 cread(int fd, void *buf, size_t nbytes, off_t offset) 104 { 105 Block *blk; 106 Block **pblk; 107 Block **ppblk; 108 int hi; 109 int n; 110 off_t mask; 111 112 /* 113 * If the cache is disabled, or we do not yet know the filesystem 114 * block size, then revert to pread. Otherwise initialize the 115 * cache as necessary and continue. 116 */ 117 if (cachesize <= 0 || sblock->fs_bsize == 0) 118 return(pread(fd, buf, nbytes, offset)); 119 if (DataBase == NULL) 120 cinit(); 121 122 /* 123 * If the request crosses a cache block boundary, or the 124 * request is larger or equal to the cache block size, 125 * revert to pread(). Full-block-reads are typically 126 * one-time calls and caching would be detrimental. 127 */ 128 mask = ~(off_t)(BlockSize - 1); 129 if (nbytes >= (unsigned)BlockSize || 130 ((offset ^ (offset + nbytes - 1)) & mask) != 0) { 131 return(pread(fd, buf, nbytes, offset)); 132 } 133 134 /* 135 * Obtain and access the cache block. Cache a successful 136 * result. If an error occurs, revert to pread() (this might 137 * occur near the end of the media). 138 */ 139 hi = (offset / BlockSize) % HSize; 140 pblk = &BlockHash[hi]; 141 ppblk = NULL; 142 while ((blk = *pblk) != NULL) { 143 if (((blk->b_Offset ^ offset) & mask) == 0) 144 break; 145 ppblk = pblk; 146 pblk = &blk->b_HNext; 147 } 148 if (blk == NULL) { 149 blk = *ppblk; 150 pblk = ppblk; 151 blk->b_Offset = offset & mask; 152 n = pread(fd, blk->b_Data, BlockSize, blk->b_Offset); 153 if (n != BlockSize) { 154 blk->b_Offset = (off_t)-1; 155 blk = NULL; 156 } 157 } 158 if (blk) { 159 bcopy(blk->b_Data + (offset - blk->b_Offset), buf, nbytes); 160 *pblk = blk->b_HNext; 161 blk->b_HNext = BlockHash[hi]; 162 BlockHash[hi] = blk; 163 return(nbytes); 164 } else { 165 return(pread(fd, buf, nbytes, offset)); 166 } 167 } 168 169