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cd9660_bmap.c revision 1.2 
      1 /*	$NetBSD: cd9660_bmap.c,v 1.2 2003/08/07 16:31:34 agc Exp $	*/
      2 
      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 (at) blitz.com).  The Rock Ridge Extension
      9  * Support code is derived from software contributed to Berkeley
     10  * by Atsushi Murai (amurai (at) 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	8.4 (Berkeley) 12/5/94
     37  */
     38 
     39 #include <sys/cdefs.h>
     40 __KERNEL_RCSID(0, "$NetBSD: cd9660_bmap.c,v 1.2 2003/08/07 16:31:34 agc Exp $");
     41 
     42 #include <sys/param.h>
     43 #include <sys/namei.h>
     44 #include <sys/buf.h>
     45 #include <sys/file.h>
     46 #include <sys/vnode.h>
     47 #include <sys/mount.h>
     48 
     49 #include <fs/cd9660/iso.h>
     50 #include <fs/cd9660/cd9660_extern.h>
     51 #include <fs/cd9660/cd9660_node.h>
     52 
     53 /*
     54  * Bmap converts a the logical block number of a file to its physical block
     55  * number on the disk. The conversion is done by using the logical block
     56  * number to index into the data block (extent) for the file.
     57  */
     58 int
     59 cd9660_bmap(v)
     60 	void *v;
     61 {
     62 	struct vop_bmap_args /* {
     63 		struct vnode *a_vp;
     64 		daddr_t  a_bn;
     65 		struct vnode **a_vpp;
     66 		daddr_t *a_bnp;
     67 		int *a_runp;
     68 	} */ *ap = v;
     69 	struct iso_node *ip = VTOI(ap->a_vp);
     70 	daddr_t lblkno = ap->a_bn;
     71 	int bshift;
     72 
     73 	/*
     74 	 * Check for underlying vnode requests and ensure that logical
     75 	 * to physical mapping is requested.
     76 	 */
     77 	if (ap->a_vpp != NULL)
     78 		*ap->a_vpp = ip->i_devvp;
     79 	if (ap->a_bnp == NULL)
     80 		return (0);
     81 
     82 	/*
     83 	 * Compute the requested block number
     84 	 */
     85 	bshift = ip->i_mnt->im_bshift;
     86 	*ap->a_bnp = (ip->iso_start + lblkno) << (bshift - DEV_BSHIFT);
     87 
     88 	/*
     89 	 * Determine maximum number of readahead blocks following the
     90 	 * requested block.
     91 	 */
     92 	if (ap->a_runp) {
     93 		int nblk;
     94 
     95 		nblk = (ip->i_size >> bshift) - (lblkno + 1);
     96 		if (nblk <= 0)
     97 			*ap->a_runp = 0;
     98 		else if (nblk >= (MAXBSIZE >> bshift))
     99 			*ap->a_runp = (MAXBSIZE >> bshift) - 1;
    100 		else
    101 			*ap->a_runp = nblk;
    102 	}
    103 
    104 	return (0);
    105 }
    106