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Annotation of sys/isofs/cd9660/cd9660_bmap.c, Revision 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: }