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ufs_bmap.c revision 1.1.1.1 
      1 /*	$NetBSD: ufs_bmap.c,v 1.1.1.1 2001/10/26 06:22:21 lukem Exp $	*/
      2 /* From: NetBSD: ufs_bmap.c,v 1.10 2000/11/27 08:39:57 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. All advertising materials mentioning features or use of this software
     22  *    must display the following acknowledgement:
     23  *	This product includes software developed by the University of
     24  *	California, Berkeley and its contributors.
     25  * 4. Neither the name of the University nor the names of its contributors
     26  *    may be used to endorse or promote products derived from this software
     27  *    without specific prior written permission.
     28  *
     29  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     30  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     31  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     32  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     33  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     34  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     35  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     37  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     38  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     39  * SUCH DAMAGE.
     40  *
     41  *	@(#)ufs_bmap.c	8.8 (Berkeley) 8/11/95
     42  */
     43 
     44 #include <sys/param.h>
     45 #include <sys/time.h>
     46 
     47 #include <errno.h>
     48 
     49 #include <ufs/ufs/ufs_bswap.h>
     50 #include <ufs/ufs/inode.h>
     51 #include <ufs/ffs/fs.h>
     52 
     53 #include "ffs/buf.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
     66 ufs_getlbns(struct inode *ip, ufs_daddr_t bn, struct indir *ap, int *nump)
     67 {
     68 	long 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 	/* The first NDADDR blocks are direct blocks. */
     83 	if (bn < NDADDR)
     84 		return (0);
     85 
     86 	/*
     87 	 * Determine the number of levels of indirection.  After this loop
     88 	 * is done, blockcnt indicates the number of data blocks possible
     89 	 * at the given level of indirection, and NIADDR - i is the number
     90 	 * of levels of indirection needed to locate the requested block.
     91 	 */
     92 
     93 	bn -= NDADDR;
     94 	for (lbc = 0, i = NIADDR;; i--, bn -= blockcnt) {
     95 		if (i == 0)
     96 			return (EFBIG);
     97 
     98 		lbc += lognindir;
     99 		blockcnt = (int64_t)1 << lbc;
    100 
    101 		if (bn < blockcnt)
    102 			break;
    103 	}
    104 
    105 	/* Calculate the address of the first meta-block. */
    106 	if (realbn >= 0)
    107 		metalbn = -(realbn - bn + NIADDR - i);
    108 	else
    109 		metalbn = -(-realbn - bn + NIADDR - i);
    110 
    111 	/*
    112 	 * At each iteration, off is the offset into the bap array which is
    113 	 * an array of disk addresses at the current level of indirection.
    114 	 * The logical block number and the offset in that block are stored
    115 	 * into the argument array.
    116 	 */
    117 	ap->in_lbn = metalbn;
    118 	ap->in_off = off = NIADDR - i;
    119 	ap->in_exists = 0;
    120 	ap++;
    121 	for (++numlevels; i <= NIADDR; i++) {
    122 		/* If searching for a meta-data block, quit when found. */
    123 		if (metalbn == realbn)
    124 			break;
    125 
    126 		lbc -= lognindir;
    127 		blockcnt = (int64_t)1 << lbc;
    128 		off = (bn >> lbc) & (NINDIR(ip->i_fs) - 1);
    129 
    130 		++numlevels;
    131 		ap->in_lbn = metalbn;
    132 		ap->in_off = off;
    133 		ap->in_exists = 0;
    134 		++ap;
    135 
    136 		metalbn -= -1 + off * blockcnt;
    137 	}
    138 	if (nump)
    139 		*nump = numlevels;
    140 	return (0);
    141 }
    142