sys/fs/cd9660/cd9660_bmap.c

   1 /*      $NetBSD: cd9660_bmap.c,v 1.4 2008/02/27 19:43:36 matt Exp $     */
   2
   3 /*-
   4  * Copyright (c) 1994
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley
   8  * by Pace Willisson (pace@blitz.com).  The Rock Ridge Extension
   9  * Support code is derived from software contributed to Berkeley
  10  * by Atsushi Murai (amurai@spec.co.jp).
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  *      @(#)cd9660_bmap.c       8.4 (Berkeley) 12/5/94
  37  */
  38
  39 #include <sys/cdefs.h>
  40 __KERNEL_RCSID(0, "$NetBSD: cd9660_bmap.c,v 1.4 2008/02/27 19:43:36 matt Exp $");
  41
  42 #include <sys/param.h>
  43 #include <sys/namei.h>
  44 #include <sys/buf.h>
  45 #include <sys/file.h>
  46 #include <sys/vnode.h>
  47 #include <sys/mount.h>
  48
  49 #include <fs/cd9660/iso.h>
  50 #include <fs/cd9660/cd9660_extern.h>
  51 #include <fs/cd9660/cd9660_node.h>
  52
  53 /*
  54  * Bmap converts a the logical block number of a file to its physical block
  55  * number on the disk. The conversion is done by using the logical block
  56  * number to index into the data block (extent) for the file.
  57  */
  58 int
  59 cd9660_bmap(void *v)
  60 {
  61         struct vop_bmap_args /* {
  62                 struct vnode *a_vp;
  63                 daddr_t  a_bn;
  64                 struct vnode **a_vpp;
  65                 daddr_t *a_bnp;
  66                 int *a_runp;
  67         } */ *ap = v;
  68         struct iso_node *ip = VTOI(ap->a_vp);
  69         daddr_t lblkno = ap->a_bn;
  70         int bshift;
  71
  72         /*
  73          * Check for underlying vnode requests and ensure that logical
  74          * to physical mapping is requested.
  75          */
  76         if (ap->a_vpp != NULL)
  77                 *ap->a_vpp = ip->i_devvp;
  78         if (ap->a_bnp == NULL)
  79                 return (0);
  80
  81         /*
  82          * Compute the requested block number
  83          */
  84         bshift = ip->i_mnt->im_bshift;
  85         *ap->a_bnp = (ip->iso_start + lblkno) << (bshift - DEV_BSHIFT);
  86
  87         /*
  88          * Determine maximum number of readahead blocks following the
  89          * requested block.
  90          */
  91         if (ap->a_runp) {
  92                 int nblk;
  93
  94                 nblk = (ip->i_size >> bshift) - (lblkno + 1);
  95                 if (nblk <= 0)
  96                         *ap->a_runp = 0;
  97                 else if (nblk >= (MAXBSIZE >> bshift))
  98                         *ap->a_runp = (MAXBSIZE >> bshift) - 1;
  99                 else
 100                         *ap->a_runp = nblk;
 101         }
 102
 103         return (0);
 104 }