cd9660_bmap.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-3-Clause
    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       8.3 (Berkeley) 1/23/94
   37  */
   38 
   39 #include <sys/cdefs.h>
   40 __FBSDID("$FreeBSD$");
   41 
   42 #include <sys/param.h>
   43 #include <sys/systm.h>
   44 #include <sys/vnode.h>
   45 #include <sys/mount.h>
   46 
   47 #include <fs/cd9660/iso.h>
   48 #include <fs/cd9660/cd9660_node.h>
   49 
   50 /*
   51  * Bmap converts the logical block number of a file to its physical
   52  * block number on the disk. The conversion is done by using the
   53  * logical block number to index into the data block (extent) for the
   54  * file.
   55  */
   56 int
   57 cd9660_bmap(ap)
   58         struct vop_bmap_args /* {
   59                 struct vnode *a_vp;
   60                 daddr_t  a_bn;
   61                 struct bufobj **a_bop;
   62                 daddr_t *a_bnp;
   63                 int *a_runp;
   64                 int *a_runb;
   65         } */ *ap;
   66 {
   67         struct iso_node *ip = VTOI(ap->a_vp);
   68         daddr_t lblkno = ap->a_bn;
   69         int bshift;
   70 
   71         /*
   72          * Check for underlying vnode requests and ensure that logical
   73          * to physical mapping is requested.
   74          */
   75         if (ap->a_bop != NULL)
   76                 *ap->a_bop = &ip->i_mnt->im_devvp->v_bufobj;
   77         if (ap->a_bnp == NULL)
   78                 return (0);
   79 
   80         /*
   81          * Compute the requested block number
   82          */
   83         bshift = ip->i_mnt->im_bshift;
   84         *ap->a_bnp = (ip->iso_start + lblkno) << (bshift - DEV_BSHIFT);
   85 
   86         /*
   87          * Determine maximum number of readahead blocks following the
   88          * requested block.
   89          */
   90         if (ap->a_runp) {
   91                 int nblk;
   92 
   93                 nblk = (ip->i_size >> bshift) - (lblkno + 1);
   94                 if (nblk <= 0)
   95                         *ap->a_runp = 0;
   96                 else if (nblk >= (MAXBSIZE >> bshift))
   97                         *ap->a_runp = (MAXBSIZE >> bshift) - 1;
   98                 else
   99                         *ap->a_runp = nblk;
  100         }
  101 
  102         if (ap->a_runb) {
  103                 *ap->a_runb = 0;
  104         }
  105 
  106         return 0;
  107 }

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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