1 /* $OpenBSD: ufs_bmap.c,v 1.7 2021/10/06 00:40:41 deraadt Exp $ */
2 /* $NetBSD: ufs_bmap.c,v 1.18 2013/06/19 17:51:27 dholland Exp $ */
3 /* From: NetBSD: ufs_bmap.c,v 1.14 2001/11/08 05:00:51 chs Exp */
4
5 /*
6 * Copyright (c) 1989, 1991, 1993
7 * The Regents of the University of California. All rights reserved.
8 * (c) UNIX System Laboratories, Inc.
9 * All or some portions of this file are derived from material licensed
10 * to the University of California by American Telephone and Telegraph
11 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
12 * the permission of UNIX System Laboratories, Inc.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 * notice, this list of conditions and the following disclaimer in the
21 * documentation and/or other materials provided with the distribution.
22 * 3. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 * @(#)ufs_bmap.c 8.8 (Berkeley) 8/11/95
39 */
40
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_inode.h"
53 #include "ffs/ffs_extern.h"
54
55 /*
56 * Create an array of logical block number/offset pairs which represent the
57 * path of indirect blocks required to access a data block. The first "pair"
58 * contains the logical block number of the appropriate single, double or
59 * triple indirect block and the offset into the inode indirect block array.
60 * Note, the logical block number of the inode single/double/triple indirect
61 * block appears twice in the array, once with the offset into the i_ffs_ib and
62 * once with the offset into the page itself.
63 */
64 int
ufs_getlbns(struct inode * ip,daddr_t bn,struct indir * ap,int * nump)65 ufs_getlbns(struct inode *ip, daddr_t bn, struct indir *ap, int *nump)
66 {
67 daddr_t metalbn, realbn;
68 int64_t blockcnt;
69 int lbc;
70 int i, numlevels, off;
71 u_long lognindir;
72
73 lognindir = ffs(NINDIR(ip->i_fs)) - 1;
74 if (nump)
75 *nump = 0;
76 numlevels = 0;
77 realbn = bn;
78 if ((long)bn < 0)
79 bn = -(long)bn;
80
81 assert (bn >= NDADDR);
82
83 /*
84 * Determine the number of levels of indirection. After this loop
85 * is done, blockcnt indicates the number of data blocks possible
86 * at the given level of indirection, and NIADDR - i is the number
87 * of levels of indirection needed to locate the requested block.
88 */
89
90 bn -= NDADDR;
91 for (lbc = 0, i = NIADDR;; i--, bn -= blockcnt) {
92 if (i == 0)
93 return (EFBIG);
94
95 lbc += lognindir;
96 blockcnt = (int64_t)1 << lbc;
97
98 if (bn < blockcnt)
99 break;
100 }
101
102 /* Calculate the address of the first meta-block. */
103 metalbn = -((realbn >= 0 ? realbn : -realbn) - bn + NIADDR - i);
104
105 /*
106 * At each iteration, off is the offset into the bap array which is
107 * an array of disk addresses at the current level of indirection.
108 * The logical block number and the offset in that block are stored
109 * into the argument array.
110 */
111 ap->in_lbn = metalbn;
112 ap->in_off = off = NIADDR - i;
113 ap->in_exists = 0;
114 ap++;
115 for (++numlevels; i <= NIADDR; i++) {
116 /* If searching for a meta-data block, quit when found. */
117 if (metalbn == realbn)
118 break;
119
120 lbc -= lognindir;
121 blockcnt = (int64_t)1 << lbc;
122 off = (bn >> lbc) & (NINDIR(ip->i_fs) - 1);
123
124 ++numlevels;
125 ap->in_lbn = metalbn;
126 ap->in_off = off;
127 ap->in_exists = 0;
128 ++ap;
129
130 metalbn -= -1 + (off << lbc);
131 }
132 if (nump)
133 *nump = numlevels;
134 return (0);
135 }
136