cd9660_bmap.c

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    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  * 4. 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  */
   36 
   37 #include <sys/cdefs.h>
   38 __FBSDID("$FreeBSD$");
   39 
   40 #include <sys/param.h>
   41 #include <sys/systm.h>
   42 #include <sys/vnode.h>
   43 #include <sys/mount.h>
   44 
   45 #include <fs/cd9660/iso.h>
   46 #include <fs/cd9660/cd9660_node.h>
   47 
   48 /*
   49  * Bmap converts a the logical block number of a file to its physical block
   50  * number on the disk. The conversion is done by using the logical block
   51  * number to index into the data block (extent) for the file.
   52  */
   53 int
   54 cd9660_bmap(ap)
   55         struct vop_bmap_args /* {
   56                 struct vnode *a_vp;
   57                 daddr_t  a_bn;
   58                 struct bufobj **a_bop;
   59                 daddr_t *a_bnp;
   60                 int *a_runp;
   61                 int *a_runb;
   62         } */ *ap;
   63 {
   64         struct iso_node *ip = VTOI(ap->a_vp);
   65         daddr_t lblkno = ap->a_bn;
   66         int bshift;
   67 
   68         /*
   69          * Check for underlying vnode requests and ensure that logical
   70          * to physical mapping is requested.
   71          */
   72         if (ap->a_bop != NULL)
   73                 *ap->a_bop = &ip->i_mnt->im_devvp->v_bufobj;
   74         if (ap->a_bnp == NULL)
   75                 return (0);
   76 
   77         /*
   78          * Compute the requested block number
   79          */
   80         bshift = ip->i_mnt->im_bshift;
   81         *ap->a_bnp = (ip->iso_start + lblkno) << (bshift - DEV_BSHIFT);
   82 
   83         /*
   84          * Determine maximum number of readahead blocks following the
   85          * requested block.
   86          */
   87         if (ap->a_runp) {
   88                 int nblk;
   89 
   90                 nblk = (ip->i_size >> bshift) - (lblkno + 1);
   91                 if (nblk <= 0)
   92                         *ap->a_runp = 0;
   93                 else if (nblk >= (MAXBSIZE >> bshift))
   94                         *ap->a_runp = (MAXBSIZE >> bshift) - 1;
   95                 else
   96                         *ap->a_runp = nblk;
   97         }
   98 
   99         if (ap->a_runb) {
  100                 *ap->a_runb = 0;
  101         }
  102 
  103         return 0;
  104 }

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FreeBSD/Linux Kernel Cross Reference sys/fs/cd9660/cd9660_bmap.c

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sys/fs/cd9660/cd9660_bmap.c