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cd9660_bmap.c

/*    $OpenBSD: cd9660_bmap.c,v 1.4 2003/06/02 23:28:05 millert Exp $   */
/*    $NetBSD: cd9660_bmap.c,v 1.7 1997/01/24 00:27:29 cgd Exp $  */

/*-
 * Copyright (c) 1994
 *    The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley
 * by Pace Willisson (pace@blitz.com).  The Rock Ridge Extension
 * Support code is derived from software contributed to Berkeley
 * by Atsushi Murai (amurai@spec.co.jp).
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *    @(#)cd9660_bmap.c 8.4 (Berkeley) 12/5/94
 */

#include <sys/param.h>
#include <sys/namei.h>
#include <sys/buf.h>
#include <sys/file.h>
#include <sys/vnode.h>
#include <sys/mount.h>

#include <isofs/cd9660/iso.h>
#include <isofs/cd9660/cd9660_extern.h>
#include <isofs/cd9660/cd9660_node.h>

/*
 * Bmap converts a the logical block number of a file to its physical block
 * number on the disk. The conversion is done by using the logical block
 * number to index into the data block (extent) for the file.
 */
int
cd9660_bmap(v)
      void *v;
{
      struct vop_bmap_args /* {
            struct vnode *a_vp;
            daddr_t  a_bn;
            struct vnode **a_vpp;
            daddr_t *a_bnp;
            int *a_runp;
      } */ *ap = v;
      struct iso_node *ip = VTOI(ap->a_vp);
      daddr_t lblkno = ap->a_bn;
      int bshift;

      /*
       * Check for underlying vnode requests and ensure that logical
       * to physical mapping is requested.
       */
      if (ap->a_vpp != NULL)
            *ap->a_vpp = ip->i_devvp;
      if (ap->a_bnp == NULL)
            return (0);

      /*
       * Compute the requested block number
       */
      bshift = ip->i_mnt->im_bshift;
      *ap->a_bnp = (ip->iso_start + lblkno) << (bshift - DEV_BSHIFT);

      /*
       * Determine maximum number of readahead blocks following the
       * requested block.
       */
      if (ap->a_runp) {
            int nblk;

            nblk = (ip->i_size >> bshift) - (lblkno + 1);
            if (nblk <= 0)
                  *ap->a_runp = 0;
            else if (nblk >= (MAXBSIZE >> bshift))
                  *ap->a_runp = (MAXBSIZE >> bshift) - 1;
            else
                  *ap->a_runp = nblk;
      }

      return (0);
}

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