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(struct vop_bmap_args *ap)
   58 {
   59         struct iso_node *ip = VTOI(ap->a_vp);
   60         daddr_t lblkno = ap->a_bn;
   61         int bshift;
   62 
   63         /*
   64          * Check for underlying vnode requests and ensure that logical
   65          * to physical mapping is requested.
   66          */
   67         if (ap->a_bop != NULL)
   68                 *ap->a_bop = &ip->i_mnt->im_devvp->v_bufobj;
   69         if (ap->a_bnp == NULL)
   70                 return (0);
   71 
   72         /*
   73          * Compute the requested block number
   74          */
   75         bshift = ip->i_mnt->im_bshift;
   76         *ap->a_bnp = (ip->iso_start + lblkno) << (bshift - DEV_BSHIFT);
   77 
   78         /*
   79          * Determine maximum number of readahead blocks following the
   80          * requested block.
   81          */
   82         if (ap->a_runp) {
   83                 int nblk;
   84 
   85                 nblk = (ip->i_size >> bshift) - (lblkno + 1);
   86                 if (nblk <= 0)
   87                         *ap->a_runp = 0;
   88                 else if (nblk >= (MAXBSIZE >> bshift))
   89                         *ap->a_runp = (MAXBSIZE >> bshift) - 1;
   90                 else
   91                         *ap->a_runp = nblk;
   92         }
   93 
   94         if (ap->a_runb) {
   95                 *ap->a_runb = 0;
   96         }
   97 
   98         return 0;
   99 }

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sys/fs/cd9660/cd9660_bmap.c