1/*-
2 * Copyright (c) 1992, 1993, 1995
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software donated to Berkeley by
6 * Jan-Simon Pendry.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * @(#)null_vfsops.c 8.2 (Berkeley) 1/21/94
33 *
34 * @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92
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36 */
37
38/*
39 * Null Layer
40 * (See null_vnops.c for a description of what this does.)
41 */
42
43#include <sys/param.h>
44#include <sys/systm.h>
45#include <sys/fcntl.h>
46#include <sys/kernel.h>
47#include <sys/lock.h>
48#include <sys/malloc.h>
49#include <sys/mount.h>
50#include <sys/namei.h>
51#include <sys/proc.h>
52#include <sys/vnode.h>
53
54#include <fs/nullfs/null.h>
55
56static MALLOC_DEFINE(M_NULLFSMNT, "nullfs_mount", "NULLFS mount structure");
57
58static vfs_fhtovp_t nullfs_fhtovp;
59static vfs_mount_t nullfs_mount;
60static vfs_quotactl_t nullfs_quotactl;
61static vfs_root_t nullfs_root;
62static vfs_sync_t nullfs_sync;
63static vfs_statfs_t nullfs_statfs;
64static vfs_unmount_t nullfs_unmount;
65static vfs_vget_t nullfs_vget;
66static vfs_extattrctl_t nullfs_extattrctl;
67
68/*
69 * Mount null layer
70 */
71static int
72nullfs_mount(struct mount *mp)
73{
74 int error = 0;
75 struct vnode *lowerrootvp, *vp;
76 struct vnode *nullm_rootvp;
77 struct null_mount *xmp;
78 char *target;
79 int isvnunlocked = 0, len;
80 struct nameidata nd, *ndp = &nd;
81
82 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp);
83
84 if (mp->mnt_flag & MNT_ROOTFS)
85 return (EOPNOTSUPP);
86 /*
87 * Update is a no-op
88 */
89 if (mp->mnt_flag & MNT_UPDATE) {
90 /*
91 * Only support update mounts for NFS export.
92 */
93 if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0))
94 return (0);
95 else
96 return (EOPNOTSUPP);
97 }
98
99 /*
100 * Get argument
101 */
102 error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len);
103 if (error || target[len - 1] != '\0')
104 return (EINVAL);
105
106 /*
107 * Unlock lower node to avoid possible deadlock.
108 */
109 if ((mp->mnt_vnodecovered->v_op == &null_vnodeops) &&
110 VOP_ISLOCKED(mp->mnt_vnodecovered) == LK_EXCLUSIVE) {
111 VOP_UNLOCK(mp->mnt_vnodecovered, 0);
112 isvnunlocked = 1;
113 }
114 /*
115 * Find lower node
116 */
117 NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, UIO_SYSSPACE, target, curthread);
118 error = namei(ndp);
119 /*
120 * Re-lock vnode.
121 */
122 if (isvnunlocked)
123 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY);
124
125 if (error)
126 return (error);
127 NDFREE(ndp, NDF_ONLY_PNBUF);
128
129 /*
130 * Sanity check on lower vnode
131 */
132 lowerrootvp = ndp->ni_vp;
133
134 /*
135 * Check multi null mount to avoid `lock against myself' panic.
136 */
137 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) {
138 NULLFSDEBUG("nullfs_mount: multi null mount?\n");
139 vput(lowerrootvp);
140 return (EDEADLK);
141 }
142
143 xmp = (struct null_mount *) malloc(sizeof(struct null_mount),
144 M_NULLFSMNT, M_WAITOK); /* XXX */
145
146 /*
147 * Save reference to underlying FS
148 */
149 xmp->nullm_vfs = lowerrootvp->v_mount;
150
151 /*
152 * Save reference. Each mount also holds
153 * a reference on the root vnode.
154 */
155 error = null_nodeget(mp, lowerrootvp, &vp);
156 /*
157 * Make sure the node alias worked
158 */
159 if (error) {
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161 return (error);
162 }
163
164 /*
165 * Keep a held reference to the root vnode.
166 * It is vrele'd in nullfs_unmount.
167 */
168 nullm_rootvp = vp;
169 nullm_rootvp->v_vflag |= VV_ROOT;
170 xmp->nullm_rootvp = nullm_rootvp;
171
172 /*
173 * Unlock the node (either the lower or the alias)
174 */
175 VOP_UNLOCK(vp, 0);
176
177 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) {
178 MNT_ILOCK(mp);
179 mp->mnt_flag |= MNT_LOCAL;
180 MNT_IUNLOCK(mp);
181 }
182 MNT_ILOCK(mp);
183 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & MNTK_MPSAFE;
184 MNT_IUNLOCK(mp);
185 mp->mnt_data = xmp;
186 vfs_getnewfsid(mp);
187
188 vfs_mountedfrom(mp, target);
189
190 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n",
191 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
192 return (0);
193}
194
195/*
196 * Free reference to null layer
197 */
198static int
199nullfs_unmount(mp, mntflags)
200 struct mount *mp;
201 int mntflags;
202{
203 void *mntdata;
204 int error;
205 int flags = 0;
206
207 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp);
208
209 if (mntflags & MNT_FORCE)
210 flags |= FORCECLOSE;
211
212 /* There is 1 extra root vnode reference (nullm_rootvp). */
213 error = vflush(mp, 1, flags, curthread);
214 if (error)
215 return (error);
216
217 /*
218 * Finally, throw away the null_mount structure
219 */
220 mntdata = mp->mnt_data;
221 mp->mnt_data = 0;
222 free(mntdata, M_NULLFSMNT);
223 return 0;
224}
225
226static int
227nullfs_root(mp, flags, vpp)
228 struct mount *mp;
229 int flags;
230 struct vnode **vpp;
231{
232 struct vnode *vp;
233
234 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp,
235 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
236 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
237
238 /*
239 * Return locked reference to root.
240 */
241 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp;
242 VREF(vp);
243
244 ASSERT_VOP_UNLOCKED(vp, "root vnode is locked");
245 vn_lock(vp, flags | LK_RETRY);
246 *vpp = vp;
247 return 0;
248}
249
250static int
251nullfs_quotactl(mp, cmd, uid, arg)
252 struct mount *mp;
253 int cmd;
254 uid_t uid;
255 void *arg;
256{
257 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg);
258}
259
260static int
261nullfs_statfs(mp, sbp)
262 struct mount *mp;
263 struct statfs *sbp;
264{
265 int error;
266 struct statfs mstat;
267
268 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp,
269 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
270 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
271
272 bzero(&mstat, sizeof(mstat));
273
274 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat);
275 if (error)
276 return (error);
277
278 /* now copy across the "interesting" information and fake the rest */
279 sbp->f_type = mstat.f_type;
280 sbp->f_flags = mstat.f_flags;
281 sbp->f_bsize = mstat.f_bsize;
282 sbp->f_iosize = mstat.f_iosize;
283 sbp->f_blocks = mstat.f_blocks;
284 sbp->f_bfree = mstat.f_bfree;
285 sbp->f_bavail = mstat.f_bavail;
286 sbp->f_files = mstat.f_files;
287 sbp->f_ffree = mstat.f_ffree;
288 return (0);
289}
290
291static int
292nullfs_sync(mp, waitfor)
293 struct mount *mp;
294 int waitfor;
295{
296 /*
297 * XXX - Assumes no data cached at null layer.
298 */
299 return (0);
300}
301
302static int
303nullfs_vget(mp, ino, flags, vpp)
304 struct mount *mp;
305 ino_t ino;
306 int flags;
307 struct vnode **vpp;
308{
309 int error;
310 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp);
311 if (error)
312 return (error);
313
314 return (null_nodeget(mp, *vpp, vpp));
315}
316
317static int
318nullfs_fhtovp(mp, fidp, flags, vpp)
319 struct mount *mp;
320 struct fid *fidp;
321 int flags;
322 struct vnode **vpp;
323{
324 int error;
325 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, LK_EXCLUSIVE,
326 vpp);
327 if (error)
328 return (error);
329
330 return (null_nodeget(mp, *vpp, vpp));
331}
332
333static int
334nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname)
335 struct mount *mp;
336 int cmd;
337 struct vnode *filename_vp;
338 int namespace;
339 const char *attrname;
340{
341 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, filename_vp,
342 namespace, attrname);
343}
344
345
346static struct vfsops null_vfsops = {
347 .vfs_extattrctl = nullfs_extattrctl,
348 .vfs_fhtovp = nullfs_fhtovp,
349 .vfs_init = nullfs_init,
350 .vfs_mount = nullfs_mount,
351 .vfs_quotactl = nullfs_quotactl,
352 .vfs_root = nullfs_root,
353 .vfs_statfs = nullfs_statfs,
354 .vfs_sync = nullfs_sync,
355 .vfs_uninit = nullfs_uninit,
356 .vfs_unmount = nullfs_unmount,
357 .vfs_vget = nullfs_vget,
358};
359
360VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK);
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