1/* $NetBSD: null_vfsops.c,v 1.90 2014/11/09 18:08:07 maxv 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, 1995
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_vfsops.c,v 1.9 1992/05/30 10:26:24 jsp Exp
68 * from: @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92
69 * @(#)null_vfsops.c 8.7 (Berkeley) 5/14/95
70 */
71
72/*
73 * Null file-system: VFS operations.
74 *
75 * See null_vnops.c for a description.
76 */
77
78#include <sys/cdefs.h>
79__KERNEL_RCSID(0, "$NetBSD: null_vfsops.c,v 1.90 2014/11/09 18:08:07 maxv Exp $");
80
81#include <sys/param.h>
82#include <sys/systm.h>
83#include <sys/sysctl.h>
84#include <sys/vnode.h>
85#include <sys/mount.h>
86#include <sys/namei.h>
87#include <sys/module.h>
88
89#include <miscfs/nullfs/null.h>
90#include <miscfs/genfs/layer_extern.h>
91
92MODULE(MODULE_CLASS_VFS, null, "layerfs");
93
94VFS_PROTOS(nullfs);
95
96static struct sysctllog *nullfs_sysctl_log;
97
98int
99nullfs_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
100{
101 struct vnode *lowerrootvp, *vp;
102 struct null_args *args = data;
103 struct null_mount *nmp;
104 struct layer_mount *lmp;
105 struct pathbuf *pb;
106 struct nameidata nd;
107 int error;
108
109 if (args == NULL)
110 return EINVAL;
111 if (*data_len < sizeof(*args))
112 return EINVAL;
113
114 if (mp->mnt_flag & MNT_GETARGS) {
115 lmp = MOUNTTOLAYERMOUNT(mp);
116 if (lmp == NULL)
117 return EIO;
118 args->la.target = NULL;
119 *data_len = sizeof(*args);
120 return 0;
121 }
122
123 /* Update is not supported. */
124 if (mp->mnt_flag & MNT_UPDATE)
125 return EOPNOTSUPP;
126
127 /* Find the lower vnode and lock it. */
128 error = pathbuf_copyin(args->la.target, &pb);
129 if (error) {
130 return error;
131 }
132 NDINIT(&nd, LOOKUP, FOLLOW|LOCKLEAF, pb);
133 if ((error = namei(&nd)) != 0) {
134 pathbuf_destroy(pb);
135 return error;
136 }
137 lowerrootvp = nd.ni_vp;
138 pathbuf_destroy(pb);
139
140 /* Create the mount point. */
141 nmp = kmem_zalloc(sizeof(struct null_mount), KM_SLEEP);
142 mp->mnt_data = nmp;
143 nmp->nullm_vfs = lowerrootvp->v_mount;
144 if (nmp->nullm_vfs->mnt_flag & MNT_LOCAL)
145 mp->mnt_flag |= MNT_LOCAL;
146
147 /*
148 * Make sure that the mount point is sufficiently initialized
149 * that the node create call will work.
150 */
151 vfs_getnewfsid(mp);
152
153 nmp->nullm_size = sizeof(struct null_node);
154 nmp->nullm_tag = VT_NULL;
155 nmp->nullm_bypass = layer_bypass;
156 nmp->nullm_vnodeop_p = null_vnodeop_p;
157
158 /* Setup a null node for root vnode. */
159 VOP_UNLOCK(lowerrootvp);
160 error = layer_node_create(mp, lowerrootvp, &vp);
161 if (error) {
162 vrele(lowerrootvp);
163 kmem_free(nmp, sizeof(struct null_mount));
164 return error;
165 }
166 /*
167 * Keep a held reference to the root vnode. It will be released on
168 * umount. Note: nullfs is MP-safe.
169 */
170 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
171 vp->v_vflag |= VV_ROOT;
172 nmp->nullm_rootvp = vp;
173 mp->mnt_iflag |= IMNT_MPSAFE;
174 VOP_UNLOCK(vp);
175
176 error = set_statvfs_info(path, UIO_USERSPACE, args->la.target,
177 UIO_USERSPACE, mp->mnt_op->vfs_name, mp, curlwp);
178 return error;
179}
180
181int
182nullfs_unmount(struct mount *mp, int mntflags)
183{
184 struct null_mount *nmp = MOUNTTONULLMOUNT(mp);
185 struct vnode *null_rootvp = nmp->nullm_rootvp;
186 int error, flags = 0;
187
188 if (mntflags & MNT_FORCE)
189 flags |= FORCECLOSE;
190
191 if (null_rootvp->v_usecount > 1 && (mntflags & MNT_FORCE) == 0)
192 return EBUSY;
193
194 if ((error = vflush(mp, null_rootvp, flags)) != 0)
195 return error;
196
197 /* Eliminate all activity and release the vnode. */
198 vgone(null_rootvp);
199
200 /* Finally, destroy the mount point structures. */
201 kmem_free(mp->mnt_data, sizeof(struct null_mount));
202 mp->mnt_data = NULL;
203 return 0;
204}
205
206extern const struct vnodeopv_desc null_vnodeop_opv_desc;
207
208const struct vnodeopv_desc * const nullfs_vnodeopv_descs[] = {
209 &null_vnodeop_opv_desc,
210 NULL,
211};
212
213struct vfsops nullfs_vfsops = {
214 .vfs_name = MOUNT_NULL,
215 .vfs_min_mount_data = sizeof (struct null_args),
216 .vfs_mount = nullfs_mount,
217 .vfs_start = layerfs_start,
218 .vfs_unmount = nullfs_unmount,
219 .vfs_root = layerfs_root,
220 .vfs_quotactl = layerfs_quotactl,
221 .vfs_statvfs = layerfs_statvfs,
222 .vfs_sync = layerfs_sync,
223 .vfs_loadvnode = layerfs_loadvnode,
224 .vfs_vget = layerfs_vget,
225 .vfs_fhtovp = layerfs_fhtovp,
226 .vfs_vptofh = layerfs_vptofh,
227 .vfs_init = layerfs_init,
228 .vfs_done = layerfs_done,
229 .vfs_snapshot = layerfs_snapshot,
230 .vfs_extattrctl = vfs_stdextattrctl,
231 .vfs_suspendctl = (void *)eopnotsupp,
232 .vfs_renamelock_enter = layerfs_renamelock_enter,
233 .vfs_renamelock_exit = layerfs_renamelock_exit,
234 .vfs_fsync = (void *)eopnotsupp,
235 .vfs_opv_descs = nullfs_vnodeopv_descs
236};
237
238static int
239null_modcmd(modcmd_t cmd, void *arg)
240{
241 int error;
242
243 switch (cmd) {
244 case MODULE_CMD_INIT:
245 error = vfs_attach(&nullfs_vfsops);
246 if (error != 0)
247 break;
248 sysctl_createv(&nullfs_sysctl_log, 0, NULL, NULL,
249 CTLFLAG_PERMANENT,
250 CTLTYPE_NODE, "null",
251 SYSCTL_DESCR("Loopback file system"),
252 NULL, 0, NULL, 0,
253 CTL_VFS, 9, CTL_EOL);
254 /*
255 * XXX the "9" above could be dynamic, thereby eliminating
256 * one more instance of the "number to vfs" mapping problem,
257 * but "9" is the order as taken from sys/mount.h
258 */
259 break;
260 case MODULE_CMD_FINI:
261 error = vfs_detach(&nullfs_vfsops);
262 if (error != 0)
263 break;
264 sysctl_teardown(&nullfs_sysctl_log);
265 break;
266 default:
267 error = ENOTTY;
268 break;
269 }
270 return error;
271}
272