1/*-
 2 * SPDX-License-Identifier: BSD-3-Clause
 3 *
 4 * Copyright (c) 1992, 1993
 5 *	The Regents of the University of California.  All rights reserved.
 6 *
 7 * This code is derived from software donated to Berkeley by
 8 * Jan-Simon Pendry.
 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. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 *	@(#)null.h	8.3 (Berkeley) 8/20/94
35 */
36
37#ifndef	FS_NULL_H
38#define	FS_NULL_H
39
40#define	NULLM_CACHE	0x0001
41
42struct null_mount {
43	struct mount	*nullm_vfs;
44	struct vnode	*nullm_lowerrootvp;	/* Ref to lower root vnode */
45	uint64_t	nullm_flags;
46	struct mount_upper_node upper_node;
47	struct mount_upper_node notify_node;
48};
49
50#ifdef _KERNEL
51/*
52 * A cache of vnode references
53 */
54struct null_node {
55	LIST_ENTRY(null_node)	null_hash;	/* Hash list */
56	struct vnode	        *null_lowervp;	/* VREFed once */
57	struct vnode		*null_vnode;	/* Back pointer */
58	u_int			null_flags;
59};
60
61#define	NULLV_NOUNLOCK	0x0001
62#define	NULLV_DROP	0x0002
63
64#define	MOUNTTONULLMOUNT(mp) ((struct null_mount *)((mp)->mnt_data))
65#define	VTONULL(vp) ((struct null_node *)(vp)->v_data)
66#define	NULLTOV(xp) ((xp)->null_vnode)
67
68int nullfs_init(struct vfsconf *vfsp);
69int nullfs_uninit(struct vfsconf *vfsp);
70int null_nodeget(struct mount *mp, struct vnode *target, struct vnode **vpp);
71struct vnode *null_hashget(struct mount *mp, struct vnode *lowervp);
72void null_hashrem(struct null_node *xp);
73int null_bypass(struct vop_generic_args *ap);
74
75#ifdef DIAGNOSTIC
76struct vnode *null_checkvp(struct vnode *vp, char *fil, int lno);
77#define	NULLVPTOLOWERVP(vp) null_checkvp((vp), __FILE__, __LINE__)
78#else
79#define	NULLVPTOLOWERVP(vp) (VTONULL(vp)->null_lowervp)
80#endif
81
82extern struct vop_vector null_vnodeops;
83
84#ifdef MALLOC_DECLARE
85MALLOC_DECLARE(M_NULLFSNODE);
86#endif
87
88#ifdef NULLFS_DEBUG
89#define NULLFSDEBUG(format, args...) printf(format ,## args)
90#else
91#define NULLFSDEBUG(format, args...)
92#endif /* NULLFS_DEBUG */
93
94#endif /* _KERNEL */
95
96#endif