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ufs_bmap.c revision 1.16 
      1 /*	$NetBSD: ufs_bmap.c,v 1.16 2005/10/08 03:21:17 chs Exp $	*/
      2 /* From: NetBSD: ufs_bmap.c,v 1.14 2001/11/08 05:00:51 chs Exp */
      3 
      4 /*
      5  * Copyright (c) 1989, 1991, 1993
      6  *	The Regents of the University of California.  All rights reserved.
      7  * (c) UNIX System Laboratories, Inc.
      8  * All or some portions of this file are derived from material licensed
      9  * to the University of California by American Telephone and Telegraph
     10  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
     11  * the permission of UNIX System Laboratories, Inc.
     12  *
     13  * Redistribution and use in source and binary forms, with or without
     14  * modification, are permitted provided that the following conditions
     15  * are met:
     16  * 1. Redistributions of source code must retain the above copyright
     17  *    notice, this list of conditions and the following disclaimer.
     18  * 2. Redistributions in binary form must reproduce the above copyright
     19  *    notice, this list of conditions and the following disclaimer in the
     20  *    documentation and/or other materials provided with the distribution.
     21  * 3. Neither the name of the University nor the names of its contributors
     22  *    may be used to endorse or promote products derived from this software
     23  *    without specific prior written permission.
     24  *
     25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     35  * SUCH DAMAGE.
     36  *
     37  *	@(#)ufs_bmap.c	8.8 (Berkeley) 8/11/95
     38  */
     39 
     40 #if HAVE_NBTOOL_CONFIG_H
     41 #include "nbtool_config.h"
     42 #endif
     43 
     44 #include <sys/cdefs.h>
     45 #if defined(__RCSID) && !defined(__lint)
     46 __RCSID("$NetBSD: ufs_bmap.c,v 1.16 2005/10/08 03:21:17 chs Exp $");
     47 #endif	/* !__lint */
     48 
     49 #include <sys/param.h>
     50 #include <sys/time.h>
     51 
     52 #include <assert.h>
     53 #include <errno.h>
     54 #include <strings.h>
     55 
     56 #include "makefs.h"
     57 
     58 #include <ufs/ufs/dinode.h>
     59 #include <ufs/ufs/ufs_bswap.h>
     60 #include <ufs/ffs/fs.h>
     61 
     62 #include "ffs/ufs_inode.h"
     63 #include "ffs/ffs_extern.h"
     64 
     65 /*
     66  * Create an array of logical block number/offset pairs which represent the
     67  * path of indirect blocks required to access a data block.  The first "pair"
     68  * contains the logical block number of the appropriate single, double or
     69  * triple indirect block and the offset into the inode indirect block array.
     70  * Note, the logical block number of the inode single/double/triple indirect
     71  * block appears twice in the array, once with the offset into the i_ffs_ib and
     72  * once with the offset into the page itself.
     73  */
     74 int
     75 ufs_getlbns(struct inode *ip, daddr_t bn, struct indir *ap, int *nump)
     76 {
     77 	daddr_t metalbn, realbn;
     78 	int64_t blockcnt;
     79 	int lbc;
     80 	int i, numlevels, off;
     81 	u_long lognindir;
     82 
     83 	lognindir = ffs(NINDIR(ip->i_fs)) - 1;
     84 	if (nump)
     85 		*nump = 0;
     86 	numlevels = 0;
     87 	realbn = bn;
     88 	if ((long)bn < 0)
     89 		bn = -(long)bn;
     90 
     91 	assert (bn >= NDADDR);
     92 
     93 	/*
     94 	 * Determine the number of levels of indirection.  After this loop
     95 	 * is done, blockcnt indicates the number of data blocks possible
     96 	 * at the given level of indirection, and NIADDR - i is the number
     97 	 * of levels of indirection needed to locate the requested block.
     98 	 */
     99 
    100 	bn -= NDADDR;
    101 	for (lbc = 0, i = NIADDR;; i--, bn -= blockcnt) {
    102 		if (i == 0)
    103 			return (EFBIG);
    104 
    105 		lbc += lognindir;
    106 		blockcnt = (int64_t)1 << lbc;
    107 
    108 		if (bn < blockcnt)
    109 			break;
    110 	}
    111 
    112 	/* Calculate the address of the first meta-block. */
    113 	metalbn = -((realbn >= 0 ? realbn : -realbn) - bn + NIADDR - i);
    114 
    115 	/*
    116 	 * At each iteration, off is the offset into the bap array which is
    117 	 * an array of disk addresses at the current level of indirection.
    118 	 * The logical block number and the offset in that block are stored
    119 	 * into the argument array.
    120 	 */
    121 	ap->in_lbn = metalbn;
    122 	ap->in_off = off = NIADDR - i;
    123 	ap->in_exists = 0;
    124 	ap++;
    125 	for (++numlevels; i <= NIADDR; i++) {
    126 		/* If searching for a meta-data block, quit when found. */
    127 		if (metalbn == realbn)
    128 			break;
    129 
    130 		lbc -= lognindir;
    131 		blockcnt = (int64_t)1 << lbc;
    132 		off = (bn >> lbc) & (NINDIR(ip->i_fs) - 1);
    133 
    134 		++numlevels;
    135 		ap->in_lbn = metalbn;
    136 		ap->in_off = off;
    137 		ap->in_exists = 0;
    138 		++ap;
    139 
    140 		metalbn -= -1 + (off << lbc);
    141 	}
    142 	if (nump)
    143 		*nump = numlevels;
    144 	return (0);
    145 }
    146