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 */
65int
66ufs_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