1 | /* $NetBSD: overlay_vnops.c,v 1.21 2014/11/10 18:46:33 maxv 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 1.21 2014/11/10 18:46:33 maxv 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 1.21 2014/11/10 18:46:33 maxv 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/buf.h> |
139 | #include <miscfs/genfs/genfs.h> |
140 | #include <miscfs/overlay/overlay.h> |
141 | #include <miscfs/genfs/layer_extern.h> |
142 | |
143 | /* |
144 | * Global vfs data structures |
145 | */ |
146 | int (**overlay_vnodeop_p)(void *); |
147 | const struct vnodeopv_entry_desc overlay_vnodeop_entries[] = { |
148 | { &vop_default_desc, layer_bypass }, |
149 | |
150 | { &vop_lookup_desc, layer_lookup }, |
151 | { &vop_setattr_desc, layer_setattr }, |
152 | { &vop_getattr_desc, layer_getattr }, |
153 | { &vop_access_desc, layer_access }, |
154 | { &vop_fsync_desc, layer_fsync }, |
155 | { &vop_inactive_desc, layer_inactive }, |
156 | { &vop_reclaim_desc, layer_reclaim }, |
157 | { &vop_lock_desc, layer_lock }, |
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 | }; |
172 | const struct vnodeopv_desc overlay_vnodeop_opv_desc = |
173 | { &overlay_vnodeop_p, overlay_vnodeop_entries }; |
174 | |