1 /* $NetBSD: layer_subr.c,v 1.39 2022/04/10 09:50:46 andvar Exp $ */
2
3 /*
4 * Copyright (c) 1999 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 /*
37 * Copyright (c) 1992, 1993
38 * The Regents of the University of California. All rights reserved.
39 *
40 * This code is derived from software donated to Berkeley by
41 * Jan-Simon Pendry.
42 *
43 * Redistribution and use in source and binary forms, with or without
44 * modification, are permitted provided that the following conditions
45 * are met:
46 * 1. Redistributions of source code must retain the above copyright
47 * notice, this list of conditions and the following disclaimer.
48 * 2. Redistributions in binary form must reproduce the above copyright
49 * notice, this list of conditions and the following disclaimer in the
50 * documentation and/or other materials provided with the distribution.
51 * 3. Neither the name of the University nor the names of its contributors
52 * may be used to endorse or promote products derived from this software
53 * without specific prior written permission.
54 *
55 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
56 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
57 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
58 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
59 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
60 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
61 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
62 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
63 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
64 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
65 * SUCH DAMAGE.
66 *
67 * from: Id: lofs_subr.c,v 1.11 1992/05/30 10:05:43 jsp Exp
68 * @(#)null_subr.c 8.7 (Berkeley) 5/14/95
69 */
70
71 #include <sys/cdefs.h>
72 __KERNEL_RCSID(0, "$NetBSD: layer_subr.c,v 1.39 2022/04/10 09:50:46 andvar Exp $");
73
74 #include <sys/param.h>
75 #include <sys/systm.h>
76 #include <sys/proc.h>
77 #include <sys/time.h>
78 #include <sys/vnode.h>
79 #include <sys/mount.h>
80 #include <sys/namei.h>
81 #include <sys/kmem.h>
82
83 #include <miscfs/genfs/layer.h>
84 #include <miscfs/genfs/layer_extern.h>
85
86 #ifdef LAYERFS_DIAGNOSTIC
87 int layerfs_debug = 1;
88 #endif
89
90 /*
91 * layer cache:
92 * Each cache entry holds a reference to the lower vnode
93 * along with a pointer to the alias vnode. When an
94 * entry is added the lower vnode is VREF'd. When the
95 * alias is removed the lower vnode is vrele'd.
96 */
97
98 void
layerfs_init(void)99 layerfs_init(void)
100 {
101 /* Nothing. */
102 }
103
104 void
layerfs_done(void)105 layerfs_done(void)
106 {
107 /* Nothing. */
108 }
109
110 /*
111 * layer_node_create: try to find an existing layerfs vnode referring to it,
112 * otherwise make a new vnode which contains a reference to the lower vnode.
113 */
114 int
layer_node_create(struct mount * mp,struct vnode * lowervp,struct vnode ** nvpp)115 layer_node_create(struct mount *mp, struct vnode *lowervp, struct vnode **nvpp)
116 {
117 int error;
118 struct vnode *aliasvp;
119
120 error = vcache_get(mp, &lowervp, sizeof(lowervp), &aliasvp);
121 if (error)
122 return error;
123
124 /*
125 * Now that we acquired a reference on the upper vnode, release one
126 * on the lower node. The existence of the layer_node retains one
127 * reference to the lower node.
128 */
129 vrele(lowervp);
130 KASSERT(vrefcnt(lowervp) > 0);
131
132 #ifdef LAYERFS_DIAGNOSTIC
133 if (layerfs_debug)
134 vprint("layer_node_create: alias", aliasvp);
135 #endif
136 *nvpp = aliasvp;
137 return 0;
138 }
139
140 #ifdef LAYERFS_DIAGNOSTIC
141 struct vnode *
layer_checkvp(struct vnode * vp,const char * fil,int lno)142 layer_checkvp(struct vnode *vp, const char *fil, int lno)
143 {
144 struct layer_node *a = VTOLAYER(vp);
145 #ifdef notyet
146 /*
147 * Can't do this check because vop_reclaim runs
148 * with a funny vop vector.
149 *
150 * WRS - no it doesnt...
151 */
152 if (vp->v_op != layer_vnodeop_p) {
153 printf ("layer_checkvp: on non-layer-node\n");
154 #ifdef notyet
155 while (layer_checkvp_barrier) /*WAIT*/ ;
156 #endif
157 panic("layer_checkvp");
158 };
159 #endif
160 if (a->layer_lowervp == NULL) {
161 /* Should never happen */
162 int i; u_long *p;
163 printf("vp = %p, ZERO ptr\n", vp);
164 for (p = (u_long *) a, i = 0; i < 8; i++)
165 printf(" %lx", p[i]);
166 printf("\n");
167 /* wait for debugger */
168 panic("layer_checkvp");
169 }
170 if (vrefcnt(a->layer_lowervp) < 1) {
171 int i; u_long *p;
172 printf("vp = %p, unref'ed lowervp\n", vp);
173 for (p = (u_long *) a, i = 0; i < 8; i++)
174 printf(" %lx", p[i]);
175 printf("\n");
176 /* wait for debugger */
177 panic ("layer with unref'ed lowervp");
178 };
179 #ifdef notnow
180 printf("layer %p/%d -> %p/%d [%s, %d]\n",
181 LAYERTOV(a), vrefcnt(LAYERTOV(a)),
182 a->layer_lowervp, vrefcnt(a->layer_lowervp),
183 fil, lno);
184 #endif
185 return a->layer_lowervp;
186 }
187 #endif
188