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