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Annotation of sys/isofs/cd9660/cd9660_bmap.c, Revision 1.1.1.1

1.1       nbrk        1: /*     $OpenBSD: cd9660_bmap.c,v 1.6 2007/06/06 17:15:13 deraadt Exp $ */
                      2: /*     $NetBSD: cd9660_bmap.c,v 1.7 1997/01/24 00:27:29 cgd Exp $      */
                      3:
                      4: /*-
                      5:  * Copyright (c) 1994
                      6:  *     The Regents of the University of California.  All rights reserved.
                      7:  *
                      8:  * This code is derived from software contributed to Berkeley
                      9:  * by Pace Willisson (pace@blitz.com).  The Rock Ridge Extension
                     10:  * Support code is derived from software contributed to Berkeley
                     11:  * by Atsushi Murai (amurai@spec.co.jp).
                     12:  *
                     13:  * Redistribution and use in source and binary forms, with or without
                     14:  * modification, are permitted provided that the following conditions
                     15:  * are met:
                     16:  * 1. Redistributions of source code must retain the above copyright
                     17:  *    notice, this list of conditions and the following disclaimer.
                     18:  * 2. Redistributions in binary form must reproduce the above copyright
                     19:  *    notice, this list of conditions and the following disclaimer in the
                     20:  *    documentation and/or other materials provided with the distribution.
                     21:  * 3. Neither the name of the University nor the names of its contributors
                     22:  *    may be used to endorse or promote products derived from this software
                     23:  *    without specific prior written permission.
                     24:  *
                     25:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
                     26:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     27:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     28:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
                     29:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     30:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     31:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     32:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     33:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     34:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     35:  * SUCH DAMAGE.
                     36:  *
                     37:  *     @(#)cd9660_bmap.c       8.4 (Berkeley) 12/5/94
                     38:  */
                     39:
                     40: #include <sys/param.h>
                     41: #include <sys/namei.h>
                     42: #include <sys/buf.h>
                     43: #include <sys/file.h>
                     44: #include <sys/vnode.h>
                     45: #include <sys/mount.h>
                     46:
                     47: #include <isofs/cd9660/iso.h>
                     48: #include <isofs/cd9660/cd9660_extern.h>
                     49: #include <isofs/cd9660/cd9660_node.h>
                     50:
                     51: /*
                     52:  * Bmap converts a the logical block number of a file to its physical block
                     53:  * number on the disk. The conversion is done by using the logical block
                     54:  * number to index into the data block (extent) for the file.
                     55:  */
                     56: int
                     57: cd9660_bmap(v)
                     58:        void *v;
                     59: {
                     60:        struct vop_bmap_args *ap = v;
                     61:        struct iso_node *ip = VTOI(ap->a_vp);
                     62:        daddr64_t lblkno = ap->a_bn;
                     63:        int bshift;
                     64:
                     65:        /*
                     66:         * Check for underlying vnode requests and ensure that logical
                     67:         * to physical mapping is requested.
                     68:         */
                     69:        if (ap->a_vpp != NULL)
                     70:                *ap->a_vpp = ip->i_devvp;
                     71:        if (ap->a_bnp == NULL)
                     72:                return (0);
                     73:
                     74:        /*
                     75:         * Compute the requested block number
                     76:         */
                     77:        bshift = ip->i_mnt->im_bshift;
                     78:        *ap->a_bnp = (ip->iso_start + lblkno) << (bshift - DEV_BSHIFT);
                     79:
                     80:        /*
                     81:         * Determine maximum number of readahead blocks following the
                     82:         * requested block.
                     83:         */
                     84:        if (ap->a_runp) {
                     85:                int nblk;
                     86:
                     87:                nblk = (ip->i_size >> bshift) - (lblkno + 1);
                     88:                if (nblk <= 0)
                     89:                        *ap->a_runp = 0;
                     90:                else if (nblk >= (MAXBSIZE >> bshift))
                     91:                        *ap->a_runp = (MAXBSIZE >> bshift) - 1;
                     92:                else
                     93:                        *ap->a_runp = nblk;
                     94:        }
                     95:
                     96:        return (0);
                     97: }