xref: /netbsd-src/sys/miscfs/overlay/overlay_vfsops.c (revision cfe3f2c3990b612b14ff11f121a05ffbcc46939c)
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