sbin/dump/cache.c

   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  * $DragonFly: src/sbin/dump/cache.c,v 1.5 2006/10/21 04:10:02 pavalos Exp $
  36  */
  37 /*
  38  * Block cache for dump
  39  */
  40
  41 #include <sys/param.h>
  42 #include <sys/stat.h>
  43 #include <sys/mman.h>
  44
  45 #ifdef sunos
  46 #include <sys/vnode.h>
  47
  48 #include <ufs/fs.h>
  49 #include <ufs/fsdir.h>
  50 #include <ufs/inode.h>
  51 #else
  52 #include <vfs/ufs/dir.h>
  53 #include <vfs/ufs/dinode.h>
  54 #include <vfs/ufs/fs.h>
  55 #endif
  56
  57 #include <protocols/dumprestore.h>
  58
  59 #include <ctype.h>
  60 #include <stdio.h>
  61 #ifdef __STDC__
  62 #include <errno.h>
  63 #include <string.h>
  64 #include <stdlib.h>
  65 #include <unistd.h>
  66 #endif
  67 #include "dump.h"
  68
  69 typedef struct Block {
  70         struct Block    *b_HNext;       /* must be first field */
  71         off_t           b_Offset;
  72         char            *b_Data;
  73 } Block;
  74
  75 #define HFACTOR         4
  76 #define BLKFACTOR       4
  77
  78 static char  *DataBase;
  79 static Block **BlockHash;
  80 static int   BlockSize;
  81 static int   HSize;
  82 static int   NBlocks;
  83
  84 static void
  85 cinit(void)
  86 {
  87         int i;
  88         int hi;
  89         Block *base;
  90
  91         if ((BlockSize = sblock->fs_bsize * BLKFACTOR) > MAXBSIZE)
  92                 BlockSize = MAXBSIZE;
  93         NBlocks = cachesize / BlockSize;
  94         HSize = NBlocks / HFACTOR;
  95
  96         msg("Cache %d MB, blocksize = %d\n",
  97             NBlocks * BlockSize / (1024 * 1024), BlockSize);
  98
  99         base = calloc(sizeof(Block), NBlocks);
 100         BlockHash = calloc(sizeof(Block *), HSize);
 101         DataBase = mmap(NULL, NBlocks * BlockSize,
 102                         PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
 103         for (i = 0; i < NBlocks; ++i) {
 104                 base[i].b_Data = DataBase + i * BlockSize;
 105                 base[i].b_Offset = (off_t)-1;
 106                 hi = i / HFACTOR;
 107                 base[i].b_HNext = BlockHash[hi];
 108                 BlockHash[hi] = &base[i];
 109         }
 110 }
 111
 112 ssize_t
 113 cread(int fd, void *buf, size_t nbytes, off_t offset)
 114 {
 115         Block *blk;
 116         Block **pblk;
 117         Block **ppblk;
 118         int hi;
 119         int n;
 120         off_t mask;
 121
 122         /*
 123          * If the cache is disabled, or we do not yet know the filesystem
 124          * block size, then revert to pread.  Otherwise initialize the
 125          * cache as necessary and continue.
 126          */
 127         if (cachesize <= 0 || sblock->fs_bsize == 0)
 128                 return(pread(fd, buf, nbytes, offset));
 129         if (DataBase == NULL)
 130                 cinit();
 131
 132         /*
 133          * If the request crosses a cache block boundary, or the
 134          * request is larger or equal to the cache block size,
 135          * revert to pread().  Full-block-reads are typically
 136          * one-time calls and caching would be detrimental.
 137          */
 138         mask = ~(off_t)(BlockSize - 1);
 139         if (nbytes >= (unsigned)BlockSize ||
 140             ((offset ^ (offset + nbytes - 1)) & mask) != 0) {
 141                 return(pread(fd, buf, nbytes, offset));
 142         }
 143
 144         /*
 145          * Obtain and access the cache block.  Cache a successful
 146          * result.  If an error occurs, revert to pread() (this might
 147          * occur near the end of the media).
 148          */
 149         hi = (offset / BlockSize) % HSize;
 150         pblk = &BlockHash[hi];
 151         ppblk = NULL;
 152         while ((blk = *pblk) != NULL) {
 153                 if (((blk->b_Offset ^ offset) & mask) == 0)
 154                         break;
 155                 ppblk = pblk;
 156                 pblk = &blk->b_HNext;
 157         }
 158         if (blk == NULL) {
 159                 blk = *ppblk;
 160                 pblk = ppblk;
 161                 blk->b_Offset = offset & mask;
 162                 n = pread(fd, blk->b_Data, BlockSize, blk->b_Offset);
 163                 if (n != BlockSize) {
 164                         blk->b_Offset = (off_t)-1;
 165                         blk = NULL;
 166                 }
 167         }
 168         if (blk) {
 169                 bcopy(blk->b_Data + (offset - blk->b_Offset), buf, nbytes);
 170                 *pblk = blk->b_HNext;
 171                 blk->b_HNext = BlockHash[hi];
 172                 BlockHash[hi] = blk;
 173                 return(nbytes);
 174         } else {
 175                 return(pread(fd, buf, nbytes, offset));
 176         }
 177 }
 178