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/kernel.h>
46 #include <sys/lock.h>
47 #include <sys/malloc.h>
48 #include <sys/mount.h>
49 #include <sys/namei.h>
50 #include <sys/proc.h>
51 #include <sys/vnode.h>
52
53 #include <fs/nullfs/null.h>
54
55 static MALLOC_DEFINE(M_NULLFSMNT, "nullfs_mount", "NULLFS mount structure");
56
57 static vfs_fhtovp_t nullfs_fhtovp;
58 static vfs_mount_t nullfs_mount;
59 static vfs_quotactl_t nullfs_quotactl;
60 static vfs_root_t nullfs_root;
61 static vfs_sync_t nullfs_sync;
62 static vfs_statfs_t nullfs_statfs;
63 static vfs_unmount_t nullfs_unmount;
64 static vfs_vget_t nullfs_vget;
65 static vfs_extattrctl_t nullfs_extattrctl;
66
67 /*
68 * Mount null layer
69 */
70 static int
71 nullfs_mount(struct mount *mp, struct thread *td)
72 {
73 int error = 0;
74 struct vnode *lowerrootvp, *vp;
75 struct vnode *nullm_rootvp;
76 struct null_mount *xmp;
77 char *target;
78 int isvnunlocked = 0, len;
79 struct nameidata nd, *ndp = &nd;
80
81 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp);
82
83 if (mp->mnt_flag & MNT_ROOTFS)
84 return (EOPNOTSUPP);
85 /*
86 * Update is a no-op
87 */
88 if (mp->mnt_flag & MNT_UPDATE) {
89 /*
90 * Only support update mounts for NFS export.
91 */
92 if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0))
93 return (0);
94 else
95 return (EOPNOTSUPP);
96 }
97
98 /*
99 * Get argument
100 */
101 error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len);
102 if (error || target[len - 1] != '\0')
103 return (EINVAL);
104
105 /*
106 * Unlock lower node to avoid deadlock.
107 * (XXX) VOP_ISLOCKED is needed?
108 */
109 if ((mp->mnt_vnodecovered->v_op == &null_vnodeops) &&
110 VOP_ISLOCKED(mp->mnt_vnodecovered, NULL)) {
111 VOP_UNLOCK(mp->mnt_vnodecovered, 0, td);
112 isvnunlocked = 1;
113 }
114 /*
115 * Find lower node
116 */
117 NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF,
118 UIO_SYSSPACE, target, td);
119 error = namei(ndp);
120 /*
121 * Re-lock vnode.
122 */
123 if (isvnunlocked && !VOP_ISLOCKED(mp->mnt_vnodecovered, NULL))
124 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY, td);
125
126 if (error)
127 return (error);
128 NDFREE(ndp, NDF_ONLY_PNBUF);
129
130 /*
131 * Sanity check on lower vnode
132 */
133 lowerrootvp = ndp->ni_vp;
134
135 /*
136 * Check multi null mount to avoid `lock against myself' panic.
137 */
138 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) {
139 NULLFSDEBUG("nullfs_mount: multi null mount?\n");
140 vput(lowerrootvp);
141 return (EDEADLK);
142 }
143
144 xmp = (struct null_mount *) malloc(sizeof(struct null_mount),
145 M_NULLFSMNT, M_WAITOK); /* XXX */
146
147 /*
148 * Save reference to underlying FS
149 */
150 xmp->nullm_vfs = lowerrootvp->v_mount;
151
152 /*
153 * Save reference. Each mount also holds
154 * a reference on the root vnode.
155 */
156 error = null_nodeget(mp, lowerrootvp, &vp);
157 /*
158 * Make sure the node alias worked
159 */
160 if (error) {
161 VOP_UNLOCK(vp, 0, td);
162 vrele(lowerrootvp);
163 free(xmp, M_NULLFSMNT); /* XXX */
164 return (error);
165 }
166
167 /*
168 * Keep a held reference to the root vnode.
169 * It is vrele'd in nullfs_unmount.
170 */
171 nullm_rootvp = vp;
172 nullm_rootvp->v_vflag |= VV_ROOT;
173 xmp->nullm_rootvp = nullm_rootvp;
174
175 /*
176 * Unlock the node (either the lower or the alias)
177 */
178 VOP_UNLOCK(vp, 0, td);
179
180 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) {
181 MNT_ILOCK(mp);
182 mp->mnt_flag |= MNT_LOCAL;
183 MNT_IUNLOCK(mp);
184 }
185 MNT_ILOCK(mp);
186 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & MNTK_MPSAFE;
187 MNT_IUNLOCK(mp);
188 mp->mnt_data = (qaddr_t) xmp;
189 vfs_getnewfsid(mp);
190
191 vfs_mountedfrom(mp, target);
192
193 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n",
194 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
195 return (0);
196 }
197
198 /*
199 * Free reference to null layer
200 */
201 static int
202 nullfs_unmount(mp, mntflags, td)
203 struct mount *mp;
204 int mntflags;
205 struct thread *td;
206 {
207 void *mntdata;
208 int error;
209 int flags = 0;
210
211 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp);
212
213 if (mntflags & MNT_FORCE)
214 flags |= FORCECLOSE;
215
216 /* There is 1 extra root vnode reference (nullm_rootvp). */
217 error = vflush(mp, 1, flags, td);
218 if (error)
219 return (error);
220
221 /*
222 * Finally, throw away the null_mount structure
223 */
224 mntdata = mp->mnt_data;
225 mp->mnt_data = 0;
226 free(mntdata, M_NULLFSMNT);
227 return 0;
228 }
229
230 static int
231 nullfs_root(mp, flags, vpp, td)
232 struct mount *mp;
233 int flags;
234 struct vnode **vpp;
235 struct thread *td;
236 {
237 struct vnode *vp;
238
239 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp,
240 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
241 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
242
243 /*
244 * Return locked reference to root.
245 */
246 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp;
247 VREF(vp);
248
249 #ifdef NULLFS_DEBUG
250 if (VOP_ISLOCKED(vp, NULL))
251 panic("root vnode is locked.\n");
252 #endif
253 vn_lock(vp, flags | LK_RETRY, td);
254 *vpp = vp;
255 return 0;
256 }
257
258 static int
259 nullfs_quotactl(mp, cmd, uid, arg, td)
260 struct mount *mp;
261 int cmd;
262 uid_t uid;
263 void *arg;
264 struct thread *td;
265 {
266 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, td);
267 }
268
269 static int
270 nullfs_statfs(mp, sbp, td)
271 struct mount *mp;
272 struct statfs *sbp;
273 struct thread *td;
274 {
275 int error;
276 struct statfs mstat;
277
278 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp,
279 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
280 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
281
282 bzero(&mstat, sizeof(mstat));
283
284 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, td);
285 if (error)
286 return (error);
287
288 /* now copy across the "interesting" information and fake the rest */
289 sbp->f_type = mstat.f_type;
290 sbp->f_flags = mstat.f_flags;
291 sbp->f_bsize = mstat.f_bsize;
292 sbp->f_iosize = mstat.f_iosize;
293 sbp->f_blocks = mstat.f_blocks;
294 sbp->f_bfree = mstat.f_bfree;
295 sbp->f_bavail = mstat.f_bavail;
296 sbp->f_files = mstat.f_files;
297 sbp->f_ffree = mstat.f_ffree;
298 return (0);
299 }
300
301 static int
302 nullfs_sync(mp, waitfor, td)
303 struct mount *mp;
304 int waitfor;
305 struct thread *td;
306 {
307 /*
308 * XXX - Assumes no data cached at null layer.
309 */
310 return (0);
311 }
312
313 static int
314 nullfs_vget(mp, ino, flags, vpp)
315 struct mount *mp;
316 ino_t ino;
317 int flags;
318 struct vnode **vpp;
319 {
320 int error;
321 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp);
322 if (error)
323 return (error);
324
325 return (null_nodeget(mp, *vpp, vpp));
326 }
327
328 static int
329 nullfs_fhtovp(mp, fidp, vpp)
330 struct mount *mp;
331 struct fid *fidp;
332 struct vnode **vpp;
333 {
334 int error;
335 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, vpp);
336 if (error)
337 return (error);
338
339 return (null_nodeget(mp, *vpp, vpp));
340 }
341
342 static int
343 nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname, td)
344 struct mount *mp;
345 int cmd;
346 struct vnode *filename_vp;
347 int namespace;
348 const char *attrname;
349 struct thread *td;
350 {
351 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, filename_vp,
352 namespace, attrname, td);
353 }
354
355
356 static struct vfsops null_vfsops = {
357 .vfs_extattrctl = nullfs_extattrctl,
358 .vfs_fhtovp = nullfs_fhtovp,
359 .vfs_init = nullfs_init,
360 .vfs_mount = nullfs_mount,
361 .vfs_quotactl = nullfs_quotactl,
362 .vfs_root = nullfs_root,
363 .vfs_statfs = nullfs_statfs,
364 .vfs_sync = nullfs_sync,
365 .vfs_uninit = nullfs_uninit,
366 .vfs_unmount = nullfs_unmount,
367 .vfs_vget = nullfs_vget,
368 };
369
370 VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK);
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