null.h revision 1541 
1/*
2 * Copyright (c) 1992, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software donated to Berkeley by
6 * Jan-Simon Pendry.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *	This product includes software developed by the University of
19 *	California, Berkeley and its contributors.
20 * 4. 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 *	@(#)null.h	8.2 (Berkeley) 1/21/94
37 *
38 * $Id: lofs.h,v 1.8 1992/05/30 10:05:43 jsp Exp jsp $
39 */
40
41struct null_args {
42	char		*target;	/* Target of loopback  */
43};
44
45struct null_mount {
46	struct mount	*nullm_vfs;
47	struct vnode	*nullm_rootvp;	/* Reference to root null_node */
48};
49
50#ifdef KERNEL
51/*
52 * A cache of vnode references
53 */
54struct null_node {
55	struct null_node	*null_forw;	/* Hash chain */
56	struct null_node	*null_back;
57	struct vnode	        *null_lowervp;	/* VREFed once */
58	struct vnode		*null_vnode;	/* Back pointer */
59};
60
61extern int null_node_create __P((struct mount *mp, struct vnode *target, struct vnode **vpp));
62
63#define	MOUNTTONULLMOUNT(mp) ((struct null_mount *)((mp)->mnt_data))
64#define	VTONULL(vp) ((struct null_node *)(vp)->v_data)
65#define	NULLTOV(xp) ((xp)->null_vnode)
66#ifdef NULLFS_DIAGNOSTIC
67extern struct vnode *null_checkvp __P((struct vnode *vp, char *fil, int lno));
68#define	NULLVPTOLOWERVP(vp) null_checkvp((vp), __FILE__, __LINE__)
69#else
70#define	NULLVPTOLOWERVP(vp) (VTONULL(vp)->null_lowervp)
71#endif
72
73extern int (**null_vnodeop_p)();
74extern struct vfsops null_vfsops;
75#endif /* KERNEL */
76