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Annotation of kernel/bsd/isofs/cd9660/cd9660_bmap.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
        !             7:  * Reserved.  This file contains Original Code and/or Modifications of
        !             8:  * Original Code as defined in and that are subject to the Apple Public
        !             9:  * Source License Version 1.1 (the "License").  You may not use this file
        !            10:  * except in compliance with the License.  Please obtain a copy of the
        !            11:  * License at http://www.apple.com/publicsource and read it before using
        !            12:  * this file.
        !            13:  * 
        !            14:  * The Original Code and all software distributed under the License are
        !            15:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            16:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            17:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            18:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            19:  * License for the specific language governing rights and limitations
        !            20:  * under the License.
        !            21:  * 
        !            22:  * @APPLE_LICENSE_HEADER_END@
        !            23:  */
        !            24: 
        !            25: /*     $NetBSD: cd9660_bmap.c,v 1.5 1994/12/13 22:33:12 mycroft Exp $  */
        !            26: 
        !            27: /*-
        !            28:  * Copyright (c) 1994
        !            29:  *     The Regents of the University of California.  All rights reserved.
        !            30:  *
        !            31:  * This code is derived from software contributed to Berkeley
        !            32:  * by Pace Willisson ([email protected]).  The Rock Ridge Extension
        !            33:  * Support code is derived from software contributed to Berkeley
        !            34:  * by Atsushi Murai ([email protected]).
        !            35:  *
        !            36:  * Redistribution and use in source and binary forms, with or without
        !            37:  * modification, are permitted provided that the following conditions
        !            38:  * are met:
        !            39:  * 1. Redistributions of source code must retain the above copyright
        !            40:  *    notice, this list of conditions and the following disclaimer.
        !            41:  * 2. Redistributions in binary form must reproduce the above copyright
        !            42:  *    notice, this list of conditions and the following disclaimer in the
        !            43:  *    documentation and/or other materials provided with the distribution.
        !            44:  * 3. All advertising materials mentioning features or use of this software
        !            45:  *    must display the following acknowledgement:
        !            46:  *     This product includes software developed by the University of
        !            47:  *     California, Berkeley and its contributors.
        !            48:  * 4. Neither the name of the University nor the names of its contributors
        !            49:  *    may be used to endorse or promote products derived from this software
        !            50:  *    without specific prior written permission.
        !            51:  *
        !            52:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            53:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            54:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            55:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            56:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            57:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            58:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            59:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            60:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            61:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            62:  * SUCH DAMAGE.
        !            63:  *
        !            64:  *     @(#)cd9660_bmap.c       8.4 (Berkeley) 12/5/94
        !            65:  */
        !            66: 
        !            67: #include <sys/param.h>
        !            68: #include <sys/namei.h>
        !            69: #include <sys/buf.h>
        !            70: #include <sys/file.h>
        !            71: #include <sys/vnode.h>
        !            72: #include <sys/mount.h>
        !            73: 
        !            74: #include <isofs/cd9660/iso.h>
        !            75: #include <isofs/cd9660/cd9660_node.h>
        !            76: 
        !            77: /*
        !            78:  * Bmap converts a the logical block number of a file to its physical block
        !            79:  * number on the disk. The conversion is done by using the logical block
        !            80:  * number to index into the data block (extent) for the file.
        !            81:  */
        !            82: int
        !            83: cd9660_bmap(ap)
        !            84:        struct vop_bmap_args /* {
        !            85:                struct vnode *a_vp;
        !            86:                daddr_t  a_bn;
        !            87:                struct vnode **a_vpp;
        !            88:                daddr_t *a_bnp;
        !            89:                int *a_runp;
        !            90:        } */ *ap;
        !            91: {
        !            92:        struct iso_node *ip = VTOI(ap->a_vp);
        !            93:        daddr_t lblkno = ap->a_bn;
        !            94:        int bshift;
        !            95: 
        !            96:        /*
        !            97:         * Check for underlying vnode requests and ensure that logical
        !            98:         * to physical mapping is requested.
        !            99:         */
        !           100:        if (ap->a_vpp != NULL)
        !           101:                *ap->a_vpp = ip->i_devvp;
        !           102:        if (ap->a_bnp == NULL)
        !           103:                return (0);
        !           104: 
        !           105:        /*
        !           106:         * Compute the requested block number
        !           107:         */
        !           108:        bshift = ip->i_mnt->im_bshift;
        !           109: #if 1 
        !           110:        *ap->a_bnp = (ip->iso_start + lblkno);
        !           111: #else
        !           112:        *ap->a_bnp = (ip->iso_start + lblkno) << (bshift - DEV_BSHIFT);
        !           113: #endif
        !           114: 
        !           115:        /*
        !           116:         * Determine maximum number of readahead blocks following the
        !           117:         * requested block.
        !           118:         */
        !           119:        if (ap->a_runp) {
        !           120:                int nblk;
        !           121: 
        !           122:                nblk = (ip->i_size >> bshift) - (lblkno + 1);
        !           123:                if (nblk <= 0)
        !           124:                        *ap->a_runp = 0;
        !           125:                else if (nblk >= (MAXBSIZE >> bshift))
        !           126:                        *ap->a_runp = (MAXBSIZE >> bshift) - 1;
        !           127:                else
        !           128:                        *ap->a_runp = nblk;
        !           129:        }
        !           130: 
        !           131:        return (0);
        !           132: }

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