cd9660_bmap.c revision 75856 
1/*-
2 * Copyright (c) 1994
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley
6 * by Pace Willisson (pace@blitz.com).  The Rock Ridge Extension
7 * Support code is derived from software contributed to Berkeley
8 * by Atsushi Murai (amurai@spec.co.jp).
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 *    must display the following acknowledgement:
20 *	This product includes software developed by the University of
21 *	California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 *    may be used to endorse or promote products derived from this software
24 *    without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 *	@(#)cd9660_bmap.c	8.3 (Berkeley) 1/23/94
39 * $FreeBSD: head/sys/fs/cd9660/cd9660_bmap.c 75856 2001-04-23 08:28:44Z grog $
40 */
41
42#include <sys/param.h>
43#include <sys/vnode.h>
44#include <net/radix.h>
45#include <sys/socket.h>
46#include <sys/mount.h>
47
48#include <isofs/cd9660/iso.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 */
56int
57cd9660_bmap(ap)
58	struct vop_bmap_args /* {
59		struct vnode *a_vp;
60		daddr_t  a_bn;
61		struct vnode **a_vpp;
62		daddr_t *a_bnp;
63		int *a_runp;
64		int *a_runb;
65	} */ *ap;
66{
67	struct iso_node *ip = VTOI(ap->a_vp);
68	daddr_t lblkno = ap->a_bn;
69	int bshift;
70
71	/*
72	 * Check for underlying vnode requests and ensure that logical
73	 * to physical mapping is requested.
74	 */
75	if (ap->a_vpp != NULL)
76		*ap->a_vpp = ip->i_devvp;
77	if (ap->a_bnp == NULL)
78		return (0);
79
80	/*
81	 * Compute the requested block number
82	 */
83	bshift = ip->i_mnt->im_bshift;
84	*ap->a_bnp = (ip->iso_start + lblkno) << (bshift - DEV_BSHIFT);
85
86	/*
87	 * Determine maximum number of readahead blocks following the
88	 * requested block.
89	 */
90	if (ap->a_runp) {
91		int nblk;
92
93		nblk = (ip->i_size >> bshift) - (lblkno + 1);
94		if (nblk <= 0)
95			*ap->a_runp = 0;
96		else if (nblk >= (MAXBSIZE >> bshift))
97			*ap->a_runp = (MAXBSIZE >> bshift) - 1;
98		else
99			*ap->a_runp = nblk;
100	}
101
102	if (ap->a_runb) {
103		*ap->a_runb = 0;
104	}
105
106	return 0;
107}
108