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
35 * $FreeBSD: head/sys/fs/nullfs/null_vfsops.c 226688 2011-10-24 13:56:31Z kib $
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) {
160 vrele(lowerrootvp);
161 free(xmp, M_NULLFSMNT); /* XXX */
162 return (error);
163 }
164
165 /*
166 * Keep a held reference to the root vnode.
167 * It is vrele'd in nullfs_unmount.
168 */
169 nullm_rootvp = vp;
170 nullm_rootvp->v_vflag |= VV_ROOT;
171 xmp->nullm_rootvp = nullm_rootvp;
172
173 /*
174 * Unlock the node (either the lower or the alias)
175 */
176 VOP_UNLOCK(vp, 0);
177
178 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) {
179 MNT_ILOCK(mp);
180 mp->mnt_flag |= MNT_LOCAL;
181 MNT_IUNLOCK(mp);
182 }
183 MNT_ILOCK(mp);
184 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & MNTK_MPSAFE;
185 MNT_IUNLOCK(mp);
186 mp->mnt_data = xmp;
187 vfs_getnewfsid(mp);
188
189 vfs_mountedfrom(mp, target);
190
191 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n",
192 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
193 return (0);
194}
195
196/*
197 * Free reference to null layer
198 */
199static int
200nullfs_unmount(mp, mntflags)
201 struct mount *mp;
202 int mntflags;
203{
204 void *mntdata;
205 int error;
206 int flags = 0;
207
208 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp);
209
210 if (mntflags & MNT_FORCE)
211 flags |= FORCECLOSE;
212
213 /* There is 1 extra root vnode reference (nullm_rootvp). */
214 error = vflush(mp, 1, flags, curthread);
215 if (error)
216 return (error);
217
218 /*
219 * Finally, throw away the null_mount structure
220 */
221 mntdata = mp->mnt_data;
222 mp->mnt_data = 0;
223 free(mntdata, M_NULLFSMNT);
224 return 0;
225}
226
227static int
228nullfs_root(mp, flags, vpp)
229 struct mount *mp;
230 int flags;
231 struct vnode **vpp;
232{
233 struct vnode *vp;
234
235 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp,
236 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
237 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
238
239 /*
240 * Return locked reference to root.
241 */
242 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp;
243 VREF(vp);
244
245 ASSERT_VOP_UNLOCKED(vp, "root vnode is locked");
246 vn_lock(vp, flags | LK_RETRY);
247 *vpp = vp;
248 return 0;
249}
250
251static int
252nullfs_quotactl(mp, cmd, uid, arg)
253 struct mount *mp;
254 int cmd;
255 uid_t uid;
256 void *arg;
257{
258 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg);
259}
260
261static int
262nullfs_statfs(mp, sbp)
263 struct mount *mp;
264 struct statfs *sbp;
265{
266 int error;
267 struct statfs mstat;
268
269 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp,
270 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
271 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
272
273 bzero(&mstat, sizeof(mstat));
274
275 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat);
276 if (error)
277 return (error);
278
279 /* now copy across the "interesting" information and fake the rest */
280 sbp->f_type = mstat.f_type;
281 sbp->f_flags = mstat.f_flags;
282 sbp->f_bsize = mstat.f_bsize;
283 sbp->f_iosize = mstat.f_iosize;
284 sbp->f_blocks = mstat.f_blocks;
285 sbp->f_bfree = mstat.f_bfree;
286 sbp->f_bavail = mstat.f_bavail;
287 sbp->f_files = mstat.f_files;
288 sbp->f_ffree = mstat.f_ffree;
289 return (0);
290}
291
292static int
293nullfs_sync(mp, waitfor)
294 struct mount *mp;
295 int waitfor;
296{
297 /*
298 * XXX - Assumes no data cached at null layer.
299 */
300 return (0);
301}
302
303static int
304nullfs_vget(mp, ino, flags, vpp)
305 struct mount *mp;
306 ino_t ino;
307 int flags;
308 struct vnode **vpp;
309{
310 int error;
311 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp);
312 if (error)
313 return (error);
314
315 return (null_nodeget(mp, *vpp, vpp));
316}
317
318static int
319nullfs_fhtovp(mp, fidp, flags, vpp)
320 struct mount *mp;
321 struct fid *fidp;
322 int flags;
323 struct vnode **vpp;
324{
325 int error;
326 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, LK_EXCLUSIVE,
327 vpp);
328 if (error)
329 return (error);
330
331 return (null_nodeget(mp, *vpp, vpp));
332}
333
334static int
335nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname)
336 struct mount *mp;
337 int cmd;
338 struct vnode *filename_vp;
339 int namespace;
340 const char *attrname;
341{
342 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, filename_vp,
343 namespace, attrname);
344}
345
346
347static struct vfsops null_vfsops = {
348 .vfs_extattrctl = nullfs_extattrctl,
349 .vfs_fhtovp = nullfs_fhtovp,
350 .vfs_init = nullfs_init,
351 .vfs_mount = nullfs_mount,
352 .vfs_quotactl = nullfs_quotactl,
353 .vfs_root = nullfs_root,
354 .vfs_statfs = nullfs_statfs,
355 .vfs_sync = nullfs_sync,
356 .vfs_uninit = nullfs_uninit,
357 .vfs_unmount = nullfs_unmount,
358 .vfs_vget = nullfs_vget,
359};
360
361VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK);