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/cdefs.h> 41 #include <sys/param.h> 42 #include <sys/time.h> 43 44 #include <assert.h> 45 #include <errno.h> 46 #include <strings.h> 47 48 #include "makefs.h" 49 50 #include <ufs/ufs/dinode.h> 51 #include <ufs/ffs/fs.h> 52 53 #include "ffs/ufs_bswap.h" 54 #include "ffs/ufs_inode.h" 55 #include "ffs/ffs_extern.h" 56 57 /* 58 * Create an array of logical block number/offset pairs which represent the 59 * path of indirect blocks required to access a data block. The first "pair" 60 * contains the logical block number of the appropriate single, double or 61 * triple indirect block and the offset into the inode indirect block array. 62 * Note, the logical block number of the inode single/double/triple indirect 63 * block appears twice in the array, once with the offset into the i_ffs_ib and 64 * once with the offset into the page itself. 65 */ 66 int 67 ufs_getlbns(struct inode *ip, daddr_t bn, struct indir *ap, int *nump) 68 { 69 daddr_t metalbn, realbn; 70 int64_t blockcnt; 71 int lbc; 72 int i, numlevels, off; 73 u_long lognindir; 74 75 lognindir = ffs(NINDIR(ip->i_fs)) - 1; 76 if (nump) 77 *nump = 0; 78 numlevels = 0; 79 realbn = bn; 80 if ((long)bn < 0) 81 bn = -(long)bn; 82 83 assert (bn >= UFS_NDADDR); 84 85 /* 86 * Determine the number of levels of indirection. After this loop 87 * is done, blockcnt indicates the number of data blocks possible 88 * at the given level of indirection, and UFS_NIADDR - i is the number 89 * of levels of indirection needed to locate the requested block. 90 */ 91 92 bn -= UFS_NDADDR; 93 for (lbc = 0, i = UFS_NIADDR;; i--, bn -= blockcnt) { 94 if (i == 0) 95 return (EFBIG); 96 97 lbc += lognindir; 98 blockcnt = (int64_t)1 << lbc; 99 100 if (bn < blockcnt) 101 break; 102 } 103 104 /* Calculate the address of the first meta-block. */ 105 if (realbn >= 0) 106 metalbn = -(realbn - bn + UFS_NIADDR - i); 107 else 108 metalbn = -(-realbn - bn + UFS_NIADDR - i); 109 110 /* 111 * At each iteration, off is the offset into the bap array which is 112 * an array of disk addresses at the current level of indirection. 113 * The logical block number and the offset in that block are stored 114 * into the argument array. 115 */ 116 ap->in_lbn = metalbn; 117 ap->in_off = off = UFS_NIADDR - i; 118 ap++; 119 for (++numlevels; i <= UFS_NIADDR; i++) { 120 /* If searching for a meta-data block, quit when found. */ 121 if (metalbn == realbn) 122 break; 123 124 lbc -= lognindir; 125 blockcnt = (int64_t)1 << lbc; 126 off = (bn >> lbc) & (NINDIR(ip->i_fs) - 1); 127 128 ++numlevels; 129 ap->in_lbn = metalbn; 130 ap->in_off = off; 131 ++ap; 132 133 metalbn -= -1 + (off << lbc); 134 } 135 if (nump) 136 *nump = numlevels; 137 return (0); 138 } 139