sys/vfs/isofs/cd9660/cd9660_bmap.c

   1 /*-
   2  * Copyright (c) 1994
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley
   6  * by Pace Willisson (pace@blitz.com).  The Rock Ridge Extension
   7  * Support code is derived from software contributed to Berkeley
   8  * by Atsushi Murai (amurai@spec.co.jp).
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  *      @(#)cd9660_bmap.c       8.3 (Berkeley) 1/23/94
  35  * $FreeBSD: src/sys/isofs/cd9660/cd9660_bmap.c,v 1.8 1999/08/28 00:46:06 peter Exp $
  36  */
  37
  38 #include <sys/param.h>
  39 #include <sys/systm.h>
  40 #include <sys/vnode.h>
  41 #include <sys/mount.h>
  42
  43 #include "iso.h"
  44 #include "cd9660_node.h"
  45
  46 /*
  47  * Bmap converts the logical block number of a file to its physical block
  48  * number on the disk. The conversion is done by using the logical block
  49  * number to index into the data block (extent) for the file.
  50  *
  51  * cd9660_bmap(struct vnode *a_vp, off_t a_loffset,
  52  *              off_t *a_doffsetp, int *a_runp, int *a_runb)
  53  */
  54 int
  55 cd9660_bmap(struct vop_bmap_args *ap)
  56 {
  57         struct iso_node *ip = VTOI(ap->a_vp);
  58         off_t loffset = ap->a_loffset;
  59         int bshift;
  60         int bsize;
  61
  62         /*
  63          * Check for underlying vnode requests and ensure that logical
  64          * to physical mapping is requested.
  65          */
  66         if (ap->a_doffsetp == NULL)
  67                 return (0);
  68
  69         /*
  70          * Compute the requested block number
  71          */
  72         bshift = ip->i_mnt->im_bshift;
  73         bsize = 1 << bshift;
  74         *ap->a_doffsetp = loffset + ((off_t)ip->iso_start << bshift);
  75
  76         KKASSERT((loffset & (bsize - 1)) == 0);
  77
  78         /*
  79          * Determine maximum number of readahead bytes following the
  80          * requested offset.  Align the result to the nearest block
  81          * boundary.  Do not count any non-full blocks(?)
  82          */
  83         if (ap->a_runp) {
  84                 off_t nbytes;
  85
  86                 nbytes = (off_t)ip->i_size - loffset;
  87                 if (nbytes < bsize)
  88                         *ap->a_runp = 0;
  89                 else if (nbytes > MAXBSIZE)
  90                         *ap->a_runp = MAXBSIZE;
  91                 else
  92                         *ap->a_runp = rounddown2((int)nbytes, bsize);
  93         }
  94
  95         if (ap->a_runb) {
  96                 *ap->a_runb = 0;
  97         }
  98
  99         return 0;
 100 }