1/*	$NetBSD: overlay_vnops.c,v 1.18 2011/01/10 11:11:03 hannken Exp $	*/
2
3/*
4 * Copyright (c) 1999, 2000 National Aeronautics & Space Administration
5 * All rights reserved.
6 *
7 * This software was written by William Studenmund of the
8 * Numerical Aerospace Simulation Facility, NASA Ames Research Center.
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 National Aeronautics & Space Administration
19 *    nor the names of its contributors may be used to endorse or promote
20 *    products derived from this software without specific prior written
21 *    permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE NATIONAL AERONAUTICS & SPACE ADMINISTRATION
24 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
25 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
26 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE ADMINISTRATION OR CONTRIB-
27 * UTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
28 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
29 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
30 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
31 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
32 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
33 * POSSIBILITY OF SUCH DAMAGE.
34 */
35/*
36 * Copyright (c) 1992, 1993
37 *	The Regents of the University of California.  All rights reserved.
38 *
39 * This code is derived from software contributed to Berkeley by
40 * John Heidemann of the UCLA Ficus project.
41 *
42 * Redistribution and use in source and binary forms, with or without
43 * modification, are permitted provided that the following conditions
44 * are met:
45 * 1. Redistributions of source code must retain the above copyright
46 *    notice, this list of conditions and the following disclaimer.
47 * 2. Redistributions in binary form must reproduce the above copyright
48 *    notice, this list of conditions and the following disclaimer in the
49 *    documentation and/or other materials provided with the distribution.
50 * 3. Neither the name of the University nor the names of its contributors
51 *    may be used to endorse or promote products derived from this software
52 *    without specific prior written permission.
53 *
54 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
55 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
56 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
57 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
58 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
59 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
60 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
61 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
62 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
63 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
64 * SUCH DAMAGE.
65 *
66 *	@(#)null_vnops.c	8.6 (Berkeley) 5/27/95
67 *
68 * Ancestors:
69 *	@(#)lofs_vnops.c	1.2 (Berkeley) 6/18/92
70 *	$Id: overlay_vnops.c,v 1.19 2011/07/11 08:27:39 hannken Exp $
71 *	...and...
72 *	@(#)null_vnodeops.c 1.20 92/07/07 UCLA Ficus project
73 */
74
75/*
76 * Overlay Layer
77 *
78 * (See mount_overlay(8) for more information.)
79 *
80 * The overlay layer has two purposes.  First, it serves as a demonstration
81 * of layering by providing a layer which really does nothing (the null
82 * layer makes the underlying files appear elsewhere in the file hierarchy).
83 * Second, the overlay layer can serve as a prototype layer. Since it
84 * provides all necessary layer framework, new file system layers can be
85 * created very easily by starting with an overlay layer.
86 *
87 * The remainder of this comment examines the overlay layer as a basis
88 * for constructing new layers.
89 *
90 *
91 * INSTANTIATING NEW OVERLAY LAYERS
92 *
93 * New overlay layers are created with mount_overlay(8).
94 * mount_overlay(8) takes two arguments, an ignored string
95 * and the pathname which the overlay will mount over. After
96 * the overlay layer is put into place, all access to the mount
97 * point path will proceed through the overlay layer.
98 *
99 *
100 * OPERATION OF AN OVERLAY LAYER
101 *
102 * The operation of an overlay layer is identical to that of a null
103 * layer. See the null layer (and layerfs) documentation for more info.
104 *
105 *
106 * CREATING OTHER FILE SYSTEM LAYERS
107 *
108 * One of the easiest ways to construct new file system layers is to make
109 * a copy of either the null layer or the overlay layer, rename all files
110 * and variables, and then begin modifying the copy.  sed(1) can be used to
111 * easily rename all variables.
112 *
113 * The choice between using a null and an overlay layer depends on
114 * the desirability of retaining access to the underlying filestore.
115 * For instance, the umap filesystem presents both a uid-translated and an
116 * untranslated view of the underlying files, and so it is based off of
117 * the null layer. However a layer implementing Access Control Lists
118 * might prefer to block access to the underlying filestore, for which
119 * the overlay layer is a better basis.
120 *
121 *
122 * INVOKING OPERATIONS ON LOWER LAYERS
123 *
124 * See the null layer documentation.
125 *
126 */
127
128#include <sys/cdefs.h>
129__KERNEL_RCSID(0, "$NetBSD: overlay_vnops.c,v 1.18 2011/01/10 11:11:03 hannken Exp $");
130
131#include <sys/param.h>
132#include <sys/systm.h>
133#include <sys/proc.h>
134#include <sys/time.h>
135#include <sys/vnode.h>
136#include <sys/mount.h>
137#include <sys/namei.h>
138#include <sys/malloc.h>
139#include <sys/buf.h>
140#include <miscfs/genfs/genfs.h>
141#include <miscfs/overlay/overlay.h>
142#include <miscfs/genfs/layer_extern.h>
143
144/*
145 * Global vfs data structures
146 */
147int (**overlay_vnodeop_p)(void *);
148const struct vnodeopv_entry_desc overlay_vnodeop_entries[] = {
149	{ &vop_default_desc,  layer_bypass },
150
151	{ &vop_lookup_desc,   layer_lookup },
152	{ &vop_setattr_desc,  layer_setattr },
153	{ &vop_getattr_desc,  layer_getattr },
154	{ &vop_access_desc,   layer_access },
155	{ &vop_fsync_desc,    layer_fsync },
156	{ &vop_inactive_desc, layer_inactive },
157	{ &vop_reclaim_desc,  layer_reclaim },
158	{ &vop_print_desc,    layer_print },
159	{ &vop_remove_desc,   layer_remove },
160	{ &vop_rename_desc,   layer_rename },
161	{ &vop_revoke_desc,   layer_revoke },
162	{ &vop_rmdir_desc,    layer_rmdir },
163
164	{ &vop_open_desc,     layer_open },	/* mount option handling */
165
166	{ &vop_bmap_desc,     layer_bmap },
167	{ &vop_getpages_desc, layer_getpages },
168	{ &vop_putpages_desc, layer_putpages },
169
170	{ NULL, NULL }
171};
172const struct vnodeopv_desc overlay_vnodeop_opv_desc =
173	{ &overlay_vnodeop_p, overlay_vnodeop_entries };
174