1/* $NetBSD: overlay_vfsops.c,v 1.63 2014/11/10 18:46:33 maxv 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 1.63 2014/11/10 18:46:33 maxv 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
91MODULE(MODULE_CLASS_VFS, overlay, "layerfs");
92
93VFS_PROTOS(ov);
94
95static struct sysctllog *overlay_sysctl_log;
96
97#define NOVERLAYNODECACHE 16
98
99/*
100 * Mount overlay layer
101 */
102int
103ov_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
104{
105 struct lwp *l = curlwp;
106 int error = 0;
107 struct overlay_args *args = data;
108 struct vnode *lowerrootvp, *vp;
109 struct overlay_mount *nmp;
110 struct layer_mount *lmp;
111
112#ifdef OVERLAYFS_DIAGNOSTIC
113 printf("ov_mount(mp = %p)\n", mp);
114#endif
115
116 if (args == NULL)
117 return EINVAL;
118 if (*data_len < sizeof *args)
119 return EINVAL;
120
121 if (mp->mnt_flag & MNT_GETARGS) {
122 lmp = MOUNTTOLAYERMOUNT(mp);
123 if (lmp == NULL)
124 return EIO;
125 args->la.target = NULL;
126 *data_len = sizeof *args;
127 return 0;
128 }
129
130 /*
131 * Update is not supported
132 */
133 if (mp->mnt_flag & MNT_UPDATE)
134 return EOPNOTSUPP;
135
136 /*
137 * Find lower node
138 */
139 lowerrootvp = mp->mnt_vnodecovered;
140 vref(lowerrootvp);
141 if ((error = vn_lock(lowerrootvp, LK_EXCLUSIVE | LK_RETRY))) {
142 vrele(lowerrootvp);
143 return (error);
144 }
145
146 /*
147 * First cut at fixing up upper mount point
148 */
149 nmp = kmem_zalloc(sizeof(struct overlay_mount), KM_SLEEP);
150
151 mp->mnt_data = nmp;
152 nmp->ovm_vfs = lowerrootvp->v_mount;
153 if (nmp->ovm_vfs->mnt_flag & MNT_LOCAL)
154 mp->mnt_flag |= MNT_LOCAL;
155
156 /*
157 * Make sure that the mount point is sufficiently initialized
158 * that the node create call will work.
159 */
160 vfs_getnewfsid(mp);
161
162 nmp->ovm_size = sizeof (struct overlay_node);
163 nmp->ovm_tag = VT_OVERLAY;
164 nmp->ovm_bypass = layer_bypass;
165 nmp->ovm_vnodeop_p = overlay_vnodeop_p;
166
167 /*
168 * Fix up overlay node for root vnode
169 */
170 VOP_UNLOCK(lowerrootvp);
171 error = layer_node_create(mp, lowerrootvp, &vp);
172 /*
173 * Make sure the fixup worked
174 */
175 if (error) {
176 vrele(lowerrootvp);
177 kmem_free(nmp, sizeof(struct overlay_mount));
178 return error;
179 }
180
181 /*
182 * Keep a held reference to the root vnode.
183 * It is vrele'd in ov_unmount.
184 */
185 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
186 vp->v_vflag |= VV_ROOT;
187 nmp->ovm_rootvp = vp;
188 VOP_UNLOCK(vp);
189
190 error = set_statvfs_info(path, UIO_USERSPACE, args->la.target,
191 UIO_USERSPACE, mp->mnt_op->vfs_name, mp, l);
192#ifdef OVERLAYFS_DIAGNOSTIC
193 printf("ov_mount: lower %s, alias at %s\n",
194 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
195#endif
196 return error;
197}
198
199/*
200 * Free reference to overlay layer
201 */
202int
203ov_unmount(struct mount *mp, int mntflags)
204{
205 struct vnode *overlay_rootvp = MOUNTTOOVERLAYMOUNT(mp)->ovm_rootvp;
206 struct overlay_mount *omp;
207 int error;
208 int flags = 0;
209
210#ifdef OVERLAYFS_DIAGNOSTIC
211 printf("ov_unmount(mp = %p)\n", mp);
212#endif
213
214 if (mntflags & MNT_FORCE)
215 flags |= FORCECLOSE;
216
217 if (overlay_rootvp->v_usecount > 1 && (mntflags & MNT_FORCE) == 0)
218 return (EBUSY);
219 if ((error = vflush(mp, overlay_rootvp, flags)) != 0)
220 return (error);
221
222#ifdef OVERLAYFS_DIAGNOSTIC
223 vprint("alias root of lower", overlay_rootvp);
224#endif
225 /*
226 * Blow it away for future re-use
227 */
228 vgone(overlay_rootvp);
229 /*
230 * Finally, throw away the overlay_mount structure
231 */
232 omp = mp->mnt_data;
233 kmem_free(omp, sizeof(struct overlay_mount));
234 mp->mnt_data = NULL;
235 return 0;
236}
237
238extern const struct vnodeopv_desc overlay_vnodeop_opv_desc;
239
240const struct vnodeopv_desc * const ov_vnodeopv_descs[] = {
241 &overlay_vnodeop_opv_desc,
242 NULL,
243};
244
245struct vfsops overlay_vfsops = {
246 .vfs_name = MOUNT_OVERLAY,
247 .vfs_min_mount_data = sizeof (struct overlay_args),
248 .vfs_mount = ov_mount,
249 .vfs_start = layerfs_start,
250 .vfs_unmount = ov_unmount,
251 .vfs_root = layerfs_root,
252 .vfs_quotactl = layerfs_quotactl,
253 .vfs_statvfs = layerfs_statvfs,
254 .vfs_sync = layerfs_sync,
255 .vfs_loadvnode = layerfs_loadvnode,
256 .vfs_vget = layerfs_vget,
257 .vfs_fhtovp = layerfs_fhtovp,
258 .vfs_vptofh = layerfs_vptofh,
259 .vfs_init = layerfs_init,
260 .vfs_done = layerfs_done,
261 .vfs_snapshot = layerfs_snapshot,
262 .vfs_extattrctl = vfs_stdextattrctl,
263 .vfs_suspendctl = (void *)eopnotsupp,
264 .vfs_renamelock_enter = layerfs_renamelock_enter,
265 .vfs_renamelock_exit = layerfs_renamelock_exit,
266 .vfs_fsync = (void *)eopnotsupp,
267 .vfs_opv_descs = ov_vnodeopv_descs
268};
269
270static int
271overlay_modcmd(modcmd_t cmd, void *arg)
272{
273 int error;
274
275 switch (cmd) {
276 case MODULE_CMD_INIT:
277 error = vfs_attach(&overlay_vfsops);
278 if (error != 0)
279 break;
280 sysctl_createv(&overlay_sysctl_log, 0, NULL, NULL,
281 CTLFLAG_PERMANENT, CTLTYPE_NODE, "overlay",
282 SYSCTL_DESCR("Overlay file system"),
283 NULL, 0, NULL, 0,
284 CTL_VFS, CTL_CREATE, CTL_EOL);
285 break;
286 case MODULE_CMD_FINI:
287 error = vfs_detach(&overlay_vfsops);
288 if (error != 0)
289 break;
290 sysctl_teardown(&overlay_sysctl_log);
291 break;
292 default:
293 error = ENOTTY;
294 break;
295 }
296
297 return (error);
298}
299