1 /* $NetBSD: overlay_vfsops.c,v 1.73 2022/11/04 11:20:39 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, 1995
37 * The Regents of the University of California. All rights reserved.
38 *
39 * This code is derived from software donated to Berkeley by
40 * Jan-Simon Pendry.
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 * from: Id: lofs_vfsops.c,v 1.9 1992/05/30 10:26:24 jsp Exp
67 * from: @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92
68 * @(#)null_vfsops.c 8.7 (Berkeley) 5/14/95
69 */
70
71 /*
72 * Overlay Layer
73 * (See overlay_vnops.c for a description of what this does.)
74 */
75
76 #include <sys/cdefs.h>
77 __KERNEL_RCSID(0, "$NetBSD: overlay_vfsops.c,v 1.73 2022/11/04 11:20:39 hannken Exp $");
78
79 #include <sys/param.h>
80 #include <sys/systm.h>
81 #include <sys/sysctl.h>
82 #include <sys/time.h>
83 #include <sys/proc.h>
84 #include <sys/vnode.h>
85 #include <sys/mount.h>
86 #include <sys/namei.h>
87 #include <sys/module.h>
88 #include <miscfs/overlay/overlay.h>
89 #include <miscfs/genfs/layer_extern.h>
90
91 MODULE(MODULE_CLASS_VFS, overlay, "layerfs");
92
93 VFS_PROTOS(ov);
94
95 #define NOVERLAYNODECACHE 16
96
97 /*
98 * Mount overlay layer
99 */
100 int
ov_mount(struct mount * mp,const char * path,void * data,size_t * data_len)101 ov_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
102 {
103 struct lwp *l = curlwp;
104 int error = 0;
105 struct overlay_args *args = data;
106 struct vnode *lowerrootvp, *vp;
107 struct overlay_mount *nmp;
108 struct layer_mount *lmp;
109
110 #ifdef OVERLAYFS_DIAGNOSTIC
111 printf("ov_mount(mp = %p)\n", mp);
112 #endif
113
114 if (args == NULL)
115 return EINVAL;
116 if (*data_len < sizeof *args)
117 return EINVAL;
118
119 if (mp->mnt_flag & MNT_GETARGS) {
120 lmp = MOUNTTOLAYERMOUNT(mp);
121 if (lmp == NULL)
122 return EIO;
123 args->la.target = NULL;
124 *data_len = sizeof *args;
125 return 0;
126 }
127
128 /*
129 * Update is not supported
130 */
131 if (mp->mnt_flag & MNT_UPDATE)
132 return EOPNOTSUPP;
133
134 /*
135 * Find lower node
136 */
137 lowerrootvp = mp->mnt_vnodecovered;
138 vref(lowerrootvp);
139 if ((error = vn_lock(lowerrootvp, LK_EXCLUSIVE))) {
140 vrele(lowerrootvp);
141 return (error);
142 }
143
144 /*
145 * First cut at fixing up upper mount point
146 */
147 nmp = kmem_zalloc(sizeof(struct overlay_mount), KM_SLEEP);
148
149 mp->mnt_data = nmp;
150
151 /*
152 * Make sure that the mount point is sufficiently initialized
153 * that the node create call will work.
154 */
155 vfs_getnewfsid(mp);
156 error = vfs_set_lowermount(mp, lowerrootvp->v_mount);
157 if (error) {
158 vput(lowerrootvp);
159 kmem_free(nmp, sizeof(struct overlay_mount));
160 return error;
161 }
162
163 nmp->ovm_size = sizeof (struct overlay_node);
164 nmp->ovm_tag = VT_OVERLAY;
165 nmp->ovm_bypass = layer_bypass;
166 nmp->ovm_vnodeop_p = overlay_vnodeop_p;
167
168 /*
169 * Fix up overlay node for root vnode
170 */
171 VOP_UNLOCK(lowerrootvp);
172 error = layer_node_create(mp, lowerrootvp, &vp);
173 /*
174 * Make sure the fixup worked
175 */
176 if (error) {
177 vrele(lowerrootvp);
178 kmem_free(nmp, sizeof(struct overlay_mount));
179 return error;
180 }
181
182 /*
183 * Keep a held reference to the root vnode.
184 * It is vrele'd in ov_unmount.
185 */
186 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
187 vp->v_vflag |= VV_ROOT;
188 nmp->ovm_rootvp = vp;
189 VOP_UNLOCK(vp);
190
191 error = set_statvfs_info(path, UIO_USERSPACE, args->la.target,
192 UIO_USERSPACE, mp->mnt_op->vfs_name, mp, l);
193 if (error)
194 return error;
195
196 if (mp->mnt_lower->mnt_flag & MNT_LOCAL)
197 mp->mnt_flag |= MNT_LOCAL;
198 #ifdef OVERLAYFS_DIAGNOSTIC
199 printf("ov_mount: lower %s, alias at %s\n",
200 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
201 #endif
202 return 0;
203 }
204
205 /*
206 * Free reference to overlay layer
207 */
208 int
ov_unmount(struct mount * mp,int mntflags)209 ov_unmount(struct mount *mp, int mntflags)
210 {
211 struct vnode *overlay_rootvp = MOUNTTOOVERLAYMOUNT(mp)->ovm_rootvp;
212 struct overlay_mount *omp;
213 int error;
214 int flags = 0;
215
216 #ifdef OVERLAYFS_DIAGNOSTIC
217 printf("ov_unmount(mp = %p)\n", mp);
218 #endif
219
220 if (mntflags & MNT_FORCE)
221 flags |= FORCECLOSE;
222
223 if (vrefcnt(overlay_rootvp) > 1 && (mntflags & MNT_FORCE) == 0)
224 return (EBUSY);
225 if ((error = vflush(mp, overlay_rootvp, flags)) != 0)
226 return (error);
227
228 #ifdef OVERLAYFS_DIAGNOSTIC
229 vprint("alias root of lower", overlay_rootvp);
230 #endif
231 /*
232 * Blow it away for future re-use
233 */
234 vgone(overlay_rootvp);
235 /*
236 * Finally, throw away the overlay_mount structure
237 */
238 omp = mp->mnt_data;
239 kmem_free(omp, sizeof(struct overlay_mount));
240 mp->mnt_data = NULL;
241 return 0;
242 }
243
244 extern const struct vnodeopv_desc overlay_vnodeop_opv_desc;
245
246 const struct vnodeopv_desc * const ov_vnodeopv_descs[] = {
247 &overlay_vnodeop_opv_desc,
248 NULL,
249 };
250
251 struct vfsops overlay_vfsops = {
252 .vfs_name = MOUNT_OVERLAY,
253 .vfs_min_mount_data = sizeof (struct overlay_args),
254 .vfs_mount = ov_mount,
255 .vfs_start = layerfs_start,
256 .vfs_unmount = ov_unmount,
257 .vfs_root = layerfs_root,
258 .vfs_quotactl = layerfs_quotactl,
259 .vfs_statvfs = layerfs_statvfs,
260 .vfs_sync = layerfs_sync,
261 .vfs_loadvnode = layerfs_loadvnode,
262 .vfs_vget = layerfs_vget,
263 .vfs_fhtovp = layerfs_fhtovp,
264 .vfs_vptofh = layerfs_vptofh,
265 .vfs_init = layerfs_init,
266 .vfs_done = layerfs_done,
267 .vfs_snapshot = layerfs_snapshot,
268 .vfs_extattrctl = vfs_stdextattrctl,
269 .vfs_suspendctl = layerfs_suspendctl,
270 .vfs_renamelock_enter = layerfs_renamelock_enter,
271 .vfs_renamelock_exit = layerfs_renamelock_exit,
272 .vfs_fsync = (void *)eopnotsupp,
273 .vfs_opv_descs = ov_vnodeopv_descs
274 };
275
276 SYSCTL_SETUP(overlay_sysctl_setup, "overlay fs sysctl")
277 {
278
279 sysctl_createv(clog, 0, NULL, NULL,
280 CTLFLAG_PERMANENT, CTLTYPE_NODE, "overlay",
281 SYSCTL_DESCR("Overlay file system"),
282 NULL, 0, NULL, 0,
283 CTL_VFS, CTL_CREATE, CTL_EOL);
284 }
285
286 static int
overlay_modcmd(modcmd_t cmd,void * arg)287 overlay_modcmd(modcmd_t cmd, void *arg)
288 {
289 int error;
290
291 switch (cmd) {
292 case MODULE_CMD_INIT:
293 error = vfs_attach(&overlay_vfsops);
294 if (error != 0)
295 break;
296 break;
297 case MODULE_CMD_FINI:
298 error = vfs_detach(&overlay_vfsops);
299 if (error != 0)
300 break;
301 break;
302 default:
303 error = ENOTTY;
304 break;
305 }
306
307 return (error);
308 }
309