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 *	@(#)ufs_bmap.c	8.8 (Berkeley) 8/11/95
40 */
41
42#include <sys/cdefs.h>
43__FBSDID("$FreeBSD$");
44
45#include <sys/param.h>
46#include <sys/time.h>
47
48#include <assert.h>
49#include <errno.h>
50#include <strings.h>
51
52#include "makefs.h"
53
54#include <ufs/ufs/dinode.h>
55#include <ufs/ffs/fs.h>
56
57#include "ffs/ufs_bswap.h"
58#include "ffs/ufs_inode.h"
59#include "ffs/ffs_extern.h"
60
61/*
62 * Create an array of logical block number/offset pairs which represent the
63 * path of indirect blocks required to access a data block.  The first "pair"
64 * contains the logical block number of the appropriate single, double or
65 * triple indirect block and the offset into the inode indirect block array.
66 * Note, the logical block number of the inode single/double/triple indirect
67 * block appears twice in the array, once with the offset into the i_ffs_ib and
68 * once with the offset into the page itself.
69 */
70int
71ufs_getlbns(struct inode *ip, daddr_t bn, struct indir *ap, int *nump)
72{
73	daddr_t metalbn, realbn;
74	int64_t blockcnt;
75	int lbc;
76	int i, numlevels, off;
77	u_long lognindir;
78
79	lognindir = ffs(NINDIR(ip->i_fs)) - 1;
80	if (nump)
81		*nump = 0;
82	numlevels = 0;
83	realbn = bn;
84	if ((long)bn < 0)
85		bn = -(long)bn;
86
87	assert (bn >= UFS_NDADDR);
88
89	/*
90	 * Determine the number of levels of indirection.  After this loop
91	 * is done, blockcnt indicates the number of data blocks possible
92	 * at the given level of indirection, and UFS_NIADDR - i is the number
93	 * of levels of indirection needed to locate the requested block.
94	 */
95
96	bn -= UFS_NDADDR;
97	for (lbc = 0, i = UFS_NIADDR;; i--, bn -= blockcnt) {
98		if (i == 0)
99			return (EFBIG);
100
101		lbc += lognindir;
102		blockcnt = (int64_t)1 << lbc;
103
104		if (bn < blockcnt)
105			break;
106	}
107
108	/* Calculate the address of the first meta-block. */
109	if (realbn >= 0)
110		metalbn = -(realbn - bn + UFS_NIADDR - i);
111	else
112		metalbn = -(-realbn - bn + UFS_NIADDR - i);
113
114	/*
115	 * At each iteration, off is the offset into the bap array which is
116	 * an array of disk addresses at the current level of indirection.
117	 * The logical block number and the offset in that block are stored
118	 * into the argument array.
119	 */
120	ap->in_lbn = metalbn;
121	ap->in_off = off = UFS_NIADDR - i;
122	ap++;
123	for (++numlevels; i <= UFS_NIADDR; i++) {
124		/* If searching for a meta-data block, quit when found. */
125		if (metalbn == realbn)
126			break;
127
128		lbc -= lognindir;
129		blockcnt = (int64_t)1 << lbc;
130		off = (bn >> lbc) & (NINDIR(ip->i_fs) - 1);
131
132		++numlevels;
133		ap->in_lbn = metalbn;
134		ap->in_off = off;
135		++ap;
136
137		metalbn -= -1 + (off << lbc);
138	}
139	if (nump)
140		*nump = numlevels;
141	return (0);
142}
143