text: /*	$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. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *	This product includes software developed by the University of
   *	California, Berkeley and its contributors.
   * 4. 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);
  }
  