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
ufs_getlbns(struct inode * ip,daddr_t bn,struct indir * ap,int * nump)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