1 /* $NetBSD: ufs_bmap.c,v 1.14 2004/06/20 22:20:18 jmc Exp $ */ 2 /* From: NetBSD: ufs_bmap.c,v 1.14 2001/11/08 05:00:51 chs Exp */ 3 4 /* 5 * Copyright (c) 1989, 1991, 1993 6 * The Regents of the University of California. All rights reserved. 7 * (c) UNIX System Laboratories, Inc. 8 * All or some portions of this file are derived from material licensed 9 * to the University of California by American Telephone and Telegraph 10 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 11 * the permission of UNIX System Laboratories, Inc. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * @(#)ufs_bmap.c 8.8 (Berkeley) 8/11/95 38 */ 39 40 #include <sys/cdefs.h> 41 __FBSDID("$FreeBSD$"); 42 43 #include <sys/param.h> 44 #include <sys/time.h> 45 46 #include <assert.h> 47 #include <errno.h> 48 #include <strings.h> 49 50 #include "makefs.h" 51 52 #include <ufs/ufs/dinode.h> 53 #include <ufs/ffs/fs.h> 54 55 #include "ffs/ufs_bswap.h" 56 #include "ffs/ufs_inode.h" 57 #include "ffs/ffs_extern.h" 58 59 /* 60 * Create an array of logical block number/offset pairs which represent the 61 * path of indirect blocks required to access a data block. The first "pair" 62 * contains the logical block number of the appropriate single, double or 63 * triple indirect block and the offset into the inode indirect block array. 64 * Note, the logical block number of the inode single/double/triple indirect 65 * block appears twice in the array, once with the offset into the i_ffs_ib and 66 * once with the offset into the page itself. 67 */ 68 int 69 ufs_getlbns(struct inode *ip, daddr_t bn, struct indir *ap, int *nump) 70 { 71 daddr_t metalbn, realbn; 72 int64_t blockcnt; 73 int lbc; 74 int i, numlevels, off; 75 u_long lognindir; 76 77 lognindir = ffs(NINDIR(ip->i_fs)) - 1; 78 if (nump) 79 *nump = 0; 80 numlevels = 0; 81 realbn = bn; 82 if ((long)bn < 0) 83 bn = -(long)bn; 84 85 assert (bn >= NDADDR); 86 87 /* 88 * Determine the number of levels of indirection. After this loop 89 * is done, blockcnt indicates the number of data blocks possible 90 * at the given level of indirection, and NIADDR - i is the number 91 * of levels of indirection needed to locate the requested block. 92 */ 93 94 bn -= NDADDR; 95 for (lbc = 0, i = NIADDR;; i--, bn -= blockcnt) { 96 if (i == 0) 97 return (EFBIG); 98 99 lbc += lognindir; 100 blockcnt = (int64_t)1 << lbc; 101 102 if (bn < blockcnt) 103 break; 104 } 105 106 /* Calculate the address of the first meta-block. */ 107 if (realbn >= 0) 108 metalbn = -(realbn - bn + NIADDR - i); 109 else 110 metalbn = -(-realbn - bn + NIADDR - i); 111 112 /* 113 * At each iteration, off is the offset into the bap array which is 114 * an array of disk addresses at the current level of indirection. 115 * The logical block number and the offset in that block are stored 116 * into the argument array. 117 */ 118 ap->in_lbn = metalbn; 119 ap->in_off = off = NIADDR - i; 120 ap++; 121 for (++numlevels; i <= NIADDR; i++) { 122 /* If searching for a meta-data block, quit when found. */ 123 if (metalbn == realbn) 124 break; 125 126 lbc -= lognindir; 127 blockcnt = (int64_t)1 << lbc; 128 off = (bn >> lbc) & (NINDIR(ip->i_fs) - 1); 129 130 ++numlevels; 131 ap->in_lbn = metalbn; 132 ap->in_off = off; 133 ++ap; 134 135 metalbn -= -1 + (off << lbc); 136 } 137 if (nump) 138 *nump = numlevels; 139 return (0); 140 } 141