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 * $FreeBSD$
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
56 static MALLOC_DEFINE(M_NULLFSMNT, "nullfs_mount", "NULLFS mount structure");
57
58 static vfs_fhtovp_t nullfs_fhtovp;
59 static vfs_mount_t nullfs_mount;
60 static vfs_quotactl_t nullfs_quotactl;
61 static vfs_root_t nullfs_root;
62 static vfs_sync_t nullfs_sync;
63 static vfs_statfs_t nullfs_statfs;
64 static vfs_unmount_t nullfs_unmount;
65 static vfs_vget_t nullfs_vget;
66 static vfs_extattrctl_t nullfs_extattrctl;
67
68 /*
69 * Mount null layer
70 */
71 static int
72 nullfs_mount(struct mount *mp, struct thread *td)
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 deadlock.
108 * (XXX) VOP_ISLOCKED is needed?
109 */
110 if ((mp->mnt_vnodecovered->v_op == &null_vnodeops) &&
111 VOP_ISLOCKED(mp->mnt_vnodecovered, NULL)) {
112 VOP_UNLOCK(mp->mnt_vnodecovered, 0, td);
113 isvnunlocked = 1;
114 }
115 /*
116 * Find lower node
117 */
118 NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF,
119 UIO_SYSSPACE, target, td);
120 error = namei(ndp);
121 /*
122 * Re-lock vnode.
123 */
124 if (isvnunlocked && !VOP_ISLOCKED(mp->mnt_vnodecovered, NULL))
125 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY, td);
126
127 if (error)
128 return (error);
129 NDFREE(ndp, NDF_ONLY_PNBUF);
130
131 /*
132 * Sanity check on lower vnode
133 */
134 lowerrootvp = ndp->ni_vp;
135
136 /*
137 * Check multi null mount to avoid `lock against myself' panic.
138 */
139 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) {
140 NULLFSDEBUG("nullfs_mount: multi null mount?\n");
141 vput(lowerrootvp);
142 return (EDEADLK);
143 }
144
145 xmp = (struct null_mount *) malloc(sizeof(struct null_mount),
146 M_NULLFSMNT, M_WAITOK); /* XXX */
147
148 /*
149 * Save reference to underlying FS
150 */
151 xmp->nullm_vfs = lowerrootvp->v_mount;
152
153 /*
154 * Save reference. Each mount also holds
155 * a reference on the root vnode.
156 */
157 error = null_nodeget(mp, lowerrootvp, &vp);
158 /*
159 * Make sure the node alias worked
160 */
161 if (error) {
162 VOP_UNLOCK(vp, 0, td);
163 vrele(lowerrootvp);
164 free(xmp, M_NULLFSMNT); /* XXX */
165 return (error);
166 }
167
168 /*
169 * Keep a held reference to the root vnode.
170 * It is vrele'd in nullfs_unmount.
171 */
172 nullm_rootvp = vp;
173 nullm_rootvp->v_vflag |= VV_ROOT;
174 xmp->nullm_rootvp = nullm_rootvp;
175
176 /*
177 * Unlock the node (either the lower or the alias)
178 */
179 VOP_UNLOCK(vp, 0, td);
180
181 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) {
182 MNT_ILOCK(mp);
183 mp->mnt_flag |= MNT_LOCAL;
184 MNT_IUNLOCK(mp);
185 }
186 MNT_ILOCK(mp);
187 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & MNTK_MPSAFE;
188 MNT_IUNLOCK(mp);
189 mp->mnt_data = (qaddr_t) xmp;
190 vfs_getnewfsid(mp);
191
192 vfs_mountedfrom(mp, target);
193
194 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n",
195 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
196 return (0);
197 }
198
199 /*
200 * Free reference to null layer
201 */
202 static int
203 nullfs_unmount(mp, mntflags, td)
204 struct mount *mp;
205 int mntflags;
206 struct thread *td;
207 {
208 void *mntdata;
209 int error;
210 int flags = 0;
211
212 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp);
213
214 if (mntflags & MNT_FORCE)
215 flags |= FORCECLOSE;
216
217 /* There is 1 extra root vnode reference (nullm_rootvp). */
218 error = vflush(mp, 1, flags, td);
219 if (error)
220 return (error);
221
222 /*
223 * Finally, throw away the null_mount structure
224 */
225 mntdata = mp->mnt_data;
226 mp->mnt_data = 0;
227 free(mntdata, M_NULLFSMNT);
228 return 0;
229 }
230
231 static int
232 nullfs_root(mp, flags, vpp, td)
233 struct mount *mp;
234 int flags;
235 struct vnode **vpp;
236 struct thread *td;
237 {
238 struct vnode *vp;
239
240 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp,
241 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
242 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
243
244 /*
245 * Return locked reference to root.
246 */
247 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp;
248 VREF(vp);
249
250 #ifdef NULLFS_DEBUG
251 if (VOP_ISLOCKED(vp, NULL))
252 panic("root vnode is locked.\n");
253 #endif
254 vn_lock(vp, flags | LK_RETRY, td);
255 *vpp = vp;
256 return 0;
257 }
258
259 static int
260 nullfs_quotactl(mp, cmd, uid, arg, td)
261 struct mount *mp;
262 int cmd;
263 uid_t uid;
264 void *arg;
265 struct thread *td;
266 {
267 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, td);
268 }
269
270 static int
271 nullfs_statfs(mp, sbp, td)
272 struct mount *mp;
273 struct statfs *sbp;
274 struct thread *td;
275 {
276 int error;
277 struct statfs mstat;
278
279 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp,
280 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
281 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
282
283 bzero(&mstat, sizeof(mstat));
284
285 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, td);
286 if (error)
287 return (error);
288
289 /* now copy across the "interesting" information and fake the rest */
290 sbp->f_type = mstat.f_type;
291 sbp->f_flags = mstat.f_flags;
292 sbp->f_bsize = mstat.f_bsize;
293 sbp->f_iosize = mstat.f_iosize;
294 sbp->f_blocks = mstat.f_blocks;
295 sbp->f_bfree = mstat.f_bfree;
296 sbp->f_bavail = mstat.f_bavail;
297 sbp->f_files = mstat.f_files;
298 sbp->f_ffree = mstat.f_ffree;
299 return (0);
300 }
301
302 static int
303 nullfs_sync(mp, waitfor, td)
304 struct mount *mp;
305 int waitfor;
306 struct thread *td;
307 {
308 /*
309 * XXX - Assumes no data cached at null layer.
310 */
311 return (0);
312 }
313
314 static int
315 nullfs_vget(mp, ino, flags, vpp)
316 struct mount *mp;
317 ino_t ino;
318 int flags;
319 struct vnode **vpp;
320 {
321 int error;
322 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp);
323 if (error)
324 return (error);
325
326 return (null_nodeget(mp, *vpp, vpp));
327 }
328
329 static int
330 nullfs_fhtovp(mp, fidp, vpp)
331 struct mount *mp;
332 struct fid *fidp;
333 struct vnode **vpp;
334 {
335 int error;
336 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, vpp);
337 if (error)
338 return (error);
339
340 return (null_nodeget(mp, *vpp, vpp));
341 }
342
343 static int
344 nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname, td)
345 struct mount *mp;
346 int cmd;
347 struct vnode *filename_vp;
348 int namespace;
349 const char *attrname;
350 struct thread *td;
351 {
352 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, filename_vp,
353 namespace, attrname, td);
354 }
355
356
357 static struct vfsops null_vfsops = {
358 .vfs_extattrctl = nullfs_extattrctl,
359 .vfs_fhtovp = nullfs_fhtovp,
360 .vfs_init = nullfs_init,
361 .vfs_mount = nullfs_mount,
362 .vfs_quotactl = nullfs_quotactl,
363 .vfs_root = nullfs_root,
364 .vfs_statfs = nullfs_statfs,
365 .vfs_sync = nullfs_sync,
366 .vfs_uninit = nullfs_uninit,
367 .vfs_unmount = nullfs_unmount,
368 .vfs_vget = nullfs_vget,
369 };
370
371 VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK);
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