1 /* $NetBSD: null_vfsops.c,v 1.101 2023/02/06 10:32:58 hannken 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 1.101 2023/02/06 10:32:58 hannken 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
92 MODULE(MODULE_CLASS_VFS, null, "layerfs");
93
94 VFS_PROTOS(nullfs);
95
96 int
nullfs_mount(struct mount * mp,const char * path,void * data,size_t * data_len)97 nullfs_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
98 {
99 struct vnode *lowerrootvp, *vp;
100 struct null_args *args = data;
101 struct null_mount *nmp;
102 struct layer_mount *lmp;
103 struct pathbuf *pb;
104 struct nameidata nd;
105 int error;
106
107 if (args == NULL)
108 return EINVAL;
109 if (*data_len < sizeof(*args))
110 return EINVAL;
111
112 if (mp->mnt_flag & MNT_GETARGS) {
113 lmp = MOUNTTOLAYERMOUNT(mp);
114 if (lmp == NULL)
115 return EIO;
116 args->la.target = NULL;
117 *data_len = sizeof(*args);
118 return 0;
119 }
120
121 /* Update is not supported. */
122 if (mp->mnt_flag & MNT_UPDATE)
123 return EOPNOTSUPP;
124
125 /* Find the lower vnode and lock it. */
126 error = pathbuf_copyin(args->la.target, &pb);
127 if (error) {
128 return error;
129 }
130 NDINIT(&nd, LOOKUP, FOLLOW|LOCKLEAF, pb);
131 if ((error = namei(&nd)) != 0) {
132 pathbuf_destroy(pb);
133 return error;
134 }
135 lowerrootvp = nd.ni_vp;
136 pathbuf_destroy(pb);
137
138 /* Create the mount point. */
139 nmp = kmem_zalloc(sizeof(struct null_mount), KM_SLEEP);
140 mp->mnt_data = nmp;
141 mp->mnt_iflag |= lowerrootvp->v_mount->mnt_iflag & IMNT_MPSAFE;
142 mp->mnt_iflag |= lowerrootvp->v_mount->mnt_iflag & IMNT_SHRLOOKUP;
143
144 /*
145 * Make sure that the mount point is sufficiently initialized
146 * that the node create call will work.
147 */
148 vfs_getnewfsid(mp);
149 error = vfs_set_lowermount(mp, lowerrootvp->v_mount);
150 if (error) {
151 vput(lowerrootvp);
152 kmem_free(nmp, sizeof(struct null_mount));
153 return error;
154 }
155
156 nmp->nullm_size = sizeof(struct null_node);
157 nmp->nullm_tag = VT_NULL;
158 nmp->nullm_bypass = layer_bypass;
159 nmp->nullm_vnodeop_p = null_vnodeop_p;
160
161 /* Setup a null node for root vnode. */
162 VOP_UNLOCK(lowerrootvp);
163 error = layer_node_create(mp, lowerrootvp, &vp);
164 if (error) {
165 vrele(lowerrootvp);
166 kmem_free(nmp, sizeof(struct null_mount));
167 return error;
168 }
169 /*
170 * Keep a held reference to the root vnode. It will be released on
171 * umount. Note: nullfs is MP-safe.
172 */
173 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
174 vp->v_vflag |= VV_ROOT;
175 nmp->nullm_rootvp = vp;
176 VOP_UNLOCK(vp);
177
178 error = set_statvfs_info(path, UIO_USERSPACE, args->la.target,
179 UIO_USERSPACE, mp->mnt_op->vfs_name, mp, curlwp);
180 if (error)
181 return error;
182
183 if (mp->mnt_lower->mnt_flag & MNT_LOCAL)
184 mp->mnt_flag |= MNT_LOCAL;
185 return 0;
186 }
187
188 int
nullfs_unmount(struct mount * mp,int mntflags)189 nullfs_unmount(struct mount *mp, int mntflags)
190 {
191 struct null_mount *nmp = MOUNTTONULLMOUNT(mp);
192 struct vnode *null_rootvp = nmp->nullm_rootvp;
193 int error, flags = 0;
194
195 if (mntflags & MNT_FORCE)
196 flags |= FORCECLOSE;
197
198 if (vrefcnt(null_rootvp) > 1 && (mntflags & MNT_FORCE) == 0)
199 return EBUSY;
200
201 if ((error = vflush(mp, null_rootvp, flags)) != 0)
202 return error;
203
204 /* Eliminate all activity and release the vnode. */
205 vgone(null_rootvp);
206
207 /* Finally, destroy the mount point structures. */
208 kmem_free(mp->mnt_data, sizeof(struct null_mount));
209 mp->mnt_data = NULL;
210 return 0;
211 }
212
213 extern const struct vnodeopv_desc null_vnodeop_opv_desc;
214
215 const struct vnodeopv_desc * const nullfs_vnodeopv_descs[] = {
216 &null_vnodeop_opv_desc,
217 NULL,
218 };
219
220 struct vfsops nullfs_vfsops = {
221 .vfs_name = MOUNT_NULL,
222 .vfs_min_mount_data = sizeof (struct null_args),
223 .vfs_mount = nullfs_mount,
224 .vfs_start = layerfs_start,
225 .vfs_unmount = nullfs_unmount,
226 .vfs_root = layerfs_root,
227 .vfs_quotactl = layerfs_quotactl,
228 .vfs_statvfs = layerfs_statvfs,
229 .vfs_sync = layerfs_sync,
230 .vfs_loadvnode = layerfs_loadvnode,
231 .vfs_vget = layerfs_vget,
232 .vfs_fhtovp = layerfs_fhtovp,
233 .vfs_vptofh = layerfs_vptofh,
234 .vfs_init = layerfs_init,
235 .vfs_done = layerfs_done,
236 .vfs_snapshot = layerfs_snapshot,
237 .vfs_extattrctl = vfs_stdextattrctl,
238 .vfs_suspendctl = layerfs_suspendctl,
239 .vfs_renamelock_enter = layerfs_renamelock_enter,
240 .vfs_renamelock_exit = layerfs_renamelock_exit,
241 .vfs_fsync = (void *)eopnotsupp,
242 .vfs_opv_descs = nullfs_vnodeopv_descs
243 };
244
245 SYSCTL_SETUP(nullfs_sysctl_setup, "nullfs sysctl")
246 {
247
248 sysctl_createv(clog, 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 }
260
261 static int
null_modcmd(modcmd_t cmd,void * arg)262 null_modcmd(modcmd_t cmd, void *arg)
263 {
264 int error;
265
266 switch (cmd) {
267 case MODULE_CMD_INIT:
268 error = vfs_attach(&nullfs_vfsops);
269 if (error != 0)
270 break;
271 break;
272 case MODULE_CMD_FINI:
273 error = vfs_detach(&nullfs_vfsops);
274 if (error != 0)
275 break;
276 break;
277 default:
278 error = ENOTTY;
279 break;
280 }
281 return error;
282 }
283