141 lines
4.5 KiB
C
141 lines
4.5 KiB
C
/* $NetBSD: ufs_bmap.c,v 1.14 2004/06/20 22:20:18 jmc Exp $ */
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/* From: NetBSD: ufs_bmap.c,v 1.14 2001/11/08 05:00:51 chs Exp */
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/*
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* Copyright (c) 1989, 1991, 1993
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* The Regents of the University of California. All rights reserved.
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* (c) UNIX System Laboratories, Inc.
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* All or some portions of this file are derived from material licensed
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* to the University of California by American Telephone and Telegraph
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* Co. or Unix System Laboratories, Inc. and are reproduced herein with
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* the permission of UNIX System Laboratories, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)ufs_bmap.c 8.8 (Berkeley) 8/11/95
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/time.h>
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#include <assert.h>
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#include <errno.h>
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#include <strings.h>
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#include "makefs.h"
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#include <ufs/ufs/dinode.h>
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#include <ufs/ffs/fs.h>
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#include "ffs/ufs_bswap.h"
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#include "ffs/ufs_inode.h"
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#include "ffs/ffs_extern.h"
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/*
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* Create an array of logical block number/offset pairs which represent the
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* path of indirect blocks required to access a data block. The first "pair"
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* contains the logical block number of the appropriate single, double or
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* triple indirect block and the offset into the inode indirect block array.
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* Note, the logical block number of the inode single/double/triple indirect
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* block appears twice in the array, once with the offset into the i_ffs_ib and
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* once with the offset into the page itself.
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*/
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int
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ufs_getlbns(struct inode *ip, daddr_t bn, struct indir *ap, int *nump)
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{
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daddr_t metalbn, realbn;
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int64_t blockcnt;
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int lbc;
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int i, numlevels, off;
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u_long lognindir;
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lognindir = ffs(NINDIR(ip->i_fs)) - 1;
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if (nump)
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*nump = 0;
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numlevels = 0;
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realbn = bn;
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if ((long)bn < 0)
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bn = -(long)bn;
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assert (bn >= NDADDR);
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/*
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* Determine the number of levels of indirection. After this loop
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* is done, blockcnt indicates the number of data blocks possible
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* at the given level of indirection, and NIADDR - i is the number
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* of levels of indirection needed to locate the requested block.
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*/
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bn -= NDADDR;
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for (lbc = 0, i = NIADDR;; i--, bn -= blockcnt) {
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if (i == 0)
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return (EFBIG);
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lbc += lognindir;
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blockcnt = (int64_t)1 << lbc;
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if (bn < blockcnt)
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break;
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}
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/* Calculate the address of the first meta-block. */
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if (realbn >= 0)
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metalbn = -(realbn - bn + NIADDR - i);
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else
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metalbn = -(-realbn - bn + NIADDR - i);
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/*
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* At each iteration, off is the offset into the bap array which is
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* an array of disk addresses at the current level of indirection.
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* The logical block number and the offset in that block are stored
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* into the argument array.
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*/
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ap->in_lbn = metalbn;
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ap->in_off = off = NIADDR - i;
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ap++;
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for (++numlevels; i <= NIADDR; i++) {
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/* If searching for a meta-data block, quit when found. */
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if (metalbn == realbn)
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break;
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lbc -= lognindir;
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blockcnt = (int64_t)1 << lbc;
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off = (bn >> lbc) & (NINDIR(ip->i_fs) - 1);
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++numlevels;
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ap->in_lbn = metalbn;
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ap->in_off = off;
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++ap;
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metalbn -= -1 + (off << lbc);
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}
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if (nump)
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*nump = numlevels;
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return (0);
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}
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