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 #include <sys/jail.h>
54
55 #include <fs/nullfs/null.h>
56
57 static MALLOC_DEFINE(M_NULLFSMNT, "nullfs_mount", "NULLFS mount structure");
58
59 static vfs_fhtovp_t nullfs_fhtovp;
60 static vfs_mount_t nullfs_mount;
61 static vfs_quotactl_t nullfs_quotactl;
62 static vfs_root_t nullfs_root;
63 static vfs_sync_t nullfs_sync;
64 static vfs_statfs_t nullfs_statfs;
65 static vfs_unmount_t nullfs_unmount;
66 static vfs_vget_t nullfs_vget;
67 static vfs_extattrctl_t nullfs_extattrctl;
68
69 /*
70 * Mount null layer
71 */
72 static int
73 nullfs_mount(struct mount *mp)
74 {
75 int error = 0;
76 struct vnode *lowerrootvp, *vp;
77 struct vnode *nullm_rootvp;
78 struct null_mount *xmp;
79 struct thread *td = curthread;
80 char *target;
81 int isvnunlocked = 0, len;
82 struct nameidata nd, *ndp = &nd;
83
84 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp);
85
86 if (!prison_allow(td->td_ucred, PR_ALLOW_MOUNT_NULLFS))
87 return (EPERM);
88 if (mp->mnt_flag & MNT_ROOTFS)
89 return (EOPNOTSUPP);
90
91 /*
92 * Update is a no-op
93 */
94 if (mp->mnt_flag & MNT_UPDATE) {
95 /*
96 * Only support update mounts for NFS export.
97 */
98 if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0))
99 return (0);
100 else
101 return (EOPNOTSUPP);
102 }
103
104 /*
105 * Get argument
106 */
107 error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len);
108 if (error || target[len - 1] != '\0')
109 return (EINVAL);
110
111 /*
112 * Unlock lower node to avoid possible deadlock.
113 */
114 if ((mp->mnt_vnodecovered->v_op == &null_vnodeops) &&
115 VOP_ISLOCKED(mp->mnt_vnodecovered) == LK_EXCLUSIVE) {
116 VOP_UNLOCK(mp->mnt_vnodecovered, 0);
117 isvnunlocked = 1;
118 }
119 /*
120 * Find lower node
121 */
122 NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, UIO_SYSSPACE, target, curthread);
123 error = namei(ndp);
124
125 /*
126 * Re-lock vnode.
127 * XXXKIB This is deadlock-prone as well.
128 */
129 if (isvnunlocked)
130 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY);
131
132 if (error)
133 return (error);
134 NDFREE(ndp, NDF_ONLY_PNBUF);
135
136 /*
137 * Sanity check on lower vnode
138 */
139 lowerrootvp = ndp->ni_vp;
140
141 /*
142 * Check multi null mount to avoid `lock against myself' panic.
143 */
144 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) {
145 NULLFSDEBUG("nullfs_mount: multi null mount?\n");
146 vput(lowerrootvp);
147 return (EDEADLK);
148 }
149
150 xmp = (struct null_mount *) malloc(sizeof(struct null_mount),
151 M_NULLFSMNT, M_WAITOK | M_ZERO);
152
153 /*
154 * Save reference to underlying FS
155 */
156 xmp->nullm_vfs = lowerrootvp->v_mount;
157
158 /*
159 * Save reference. Each mount also holds
160 * a reference on the root vnode.
161 */
162 error = null_nodeget(mp, lowerrootvp, &vp);
163 /*
164 * Make sure the node alias worked
165 */
166 if (error) {
167 free(xmp, M_NULLFSMNT);
168 return (error);
169 }
170
171 /*
172 * Keep a held reference to the root vnode.
173 * It is vrele'd in nullfs_unmount.
174 */
175 nullm_rootvp = vp;
176 nullm_rootvp->v_vflag |= VV_ROOT;
177 xmp->nullm_rootvp = nullm_rootvp;
178
179 /*
180 * Unlock the node (either the lower or the alias)
181 */
182 VOP_UNLOCK(vp, 0);
183
184 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) {
185 MNT_ILOCK(mp);
186 mp->mnt_flag |= MNT_LOCAL;
187 MNT_IUNLOCK(mp);
188 }
189
190 xmp->nullm_flags |= NULLM_CACHE;
191 if (vfs_getopt(mp->mnt_optnew, "nocache", NULL, NULL) == 0 ||
192 (xmp->nullm_vfs->mnt_kern_flag & MNTK_NULL_NOCACHE) != 0)
193 xmp->nullm_flags &= ~NULLM_CACHE;
194
195 MNT_ILOCK(mp);
196 if ((xmp->nullm_flags & NULLM_CACHE) != 0) {
197 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag &
198 (MNTK_SHARED_WRITES | MNTK_LOOKUP_SHARED |
199 MNTK_EXTENDED_SHARED);
200 }
201 mp->mnt_kern_flag |= MNTK_LOOKUP_EXCL_DOTDOT;
202 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag &
203 (MNTK_USES_BCACHE | MNTK_NO_IOPF | MNTK_UNMAPPED_BUFS);
204 MNT_IUNLOCK(mp);
205 mp->mnt_data = xmp;
206 vfs_getnewfsid(mp);
207 if ((xmp->nullm_flags & NULLM_CACHE) != 0) {
208 MNT_ILOCK(xmp->nullm_vfs);
209 TAILQ_INSERT_TAIL(&xmp->nullm_vfs->mnt_uppers, mp,
210 mnt_upper_link);
211 MNT_IUNLOCK(xmp->nullm_vfs);
212 }
213
214 vfs_mountedfrom(mp, target);
215
216 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n",
217 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
218 return (0);
219 }
220
221 /*
222 * Free reference to null layer
223 */
224 static int
225 nullfs_unmount(mp, mntflags)
226 struct mount *mp;
227 int mntflags;
228 {
229 struct null_mount *mntdata;
230 struct mount *ump;
231 int error, flags;
232
233 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp);
234
235 if (mntflags & MNT_FORCE)
236 flags = FORCECLOSE;
237 else
238 flags = 0;
239
240 /* There is 1 extra root vnode reference (nullm_rootvp). */
241 error = vflush(mp, 1, flags, curthread);
242 if (error)
243 return (error);
244
245 /*
246 * Finally, throw away the null_mount structure
247 */
248 mntdata = mp->mnt_data;
249 ump = mntdata->nullm_vfs;
250 if ((mntdata->nullm_flags & NULLM_CACHE) != 0) {
251 MNT_ILOCK(ump);
252 while ((ump->mnt_kern_flag & MNTK_VGONE_UPPER) != 0) {
253 ump->mnt_kern_flag |= MNTK_VGONE_WAITER;
254 msleep(&ump->mnt_uppers, &ump->mnt_mtx, 0, "vgnupw", 0);
255 }
256 TAILQ_REMOVE(&ump->mnt_uppers, mp, mnt_upper_link);
257 MNT_IUNLOCK(ump);
258 }
259 mp->mnt_data = NULL;
260 free(mntdata, M_NULLFSMNT);
261 return (0);
262 }
263
264 static int
265 nullfs_root(mp, flags, vpp)
266 struct mount *mp;
267 int flags;
268 struct vnode **vpp;
269 {
270 struct vnode *vp;
271
272 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp,
273 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
274 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
275
276 /*
277 * Return locked reference to root.
278 */
279 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp;
280 VREF(vp);
281
282 ASSERT_VOP_UNLOCKED(vp, "root vnode is locked");
283 vn_lock(vp, flags | LK_RETRY);
284 *vpp = vp;
285 return 0;
286 }
287
288 static int
289 nullfs_quotactl(mp, cmd, uid, arg)
290 struct mount *mp;
291 int cmd;
292 uid_t uid;
293 void *arg;
294 {
295 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg);
296 }
297
298 static int
299 nullfs_statfs(mp, sbp)
300 struct mount *mp;
301 struct statfs *sbp;
302 {
303 int error;
304 struct statfs mstat;
305
306 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp,
307 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
308 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
309
310 bzero(&mstat, sizeof(mstat));
311
312 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat);
313 if (error)
314 return (error);
315
316 /* now copy across the "interesting" information and fake the rest */
317 sbp->f_type = mstat.f_type;
318 sbp->f_flags = (sbp->f_flags & (MNT_RDONLY | MNT_NOEXEC | MNT_NOSUID |
319 MNT_UNION | MNT_NOSYMFOLLOW)) | (mstat.f_flags & ~MNT_ROOTFS);
320 sbp->f_bsize = mstat.f_bsize;
321 sbp->f_iosize = mstat.f_iosize;
322 sbp->f_blocks = mstat.f_blocks;
323 sbp->f_bfree = mstat.f_bfree;
324 sbp->f_bavail = mstat.f_bavail;
325 sbp->f_files = mstat.f_files;
326 sbp->f_ffree = mstat.f_ffree;
327 return (0);
328 }
329
330 static int
331 nullfs_sync(mp, waitfor)
332 struct mount *mp;
333 int waitfor;
334 {
335 /*
336 * XXX - Assumes no data cached at null layer.
337 */
338 return (0);
339 }
340
341 static int
342 nullfs_vget(mp, ino, flags, vpp)
343 struct mount *mp;
344 ino_t ino;
345 int flags;
346 struct vnode **vpp;
347 {
348 int error;
349
350 KASSERT((flags & LK_TYPE_MASK) != 0,
351 ("nullfs_vget: no lock requested"));
352
353 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp);
354 if (error != 0)
355 return (error);
356 return (null_nodeget(mp, *vpp, vpp));
357 }
358
359 static int
360 nullfs_fhtovp(mp, fidp, flags, vpp)
361 struct mount *mp;
362 struct fid *fidp;
363 int flags;
364 struct vnode **vpp;
365 {
366 int error;
367
368 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, flags,
369 vpp);
370 if (error != 0)
371 return (error);
372 return (null_nodeget(mp, *vpp, vpp));
373 }
374
375 static int
376 nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname)
377 struct mount *mp;
378 int cmd;
379 struct vnode *filename_vp;
380 int namespace;
381 const char *attrname;
382 {
383
384 return (VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd,
385 filename_vp, namespace, attrname));
386 }
387
388 static void
389 nullfs_reclaim_lowervp(struct mount *mp, struct vnode *lowervp)
390 {
391 struct vnode *vp;
392
393 vp = null_hashget(mp, lowervp);
394 if (vp == NULL)
395 return;
396 VTONULL(vp)->null_flags |= NULLV_NOUNLOCK;
397 vgone(vp);
398 vput(vp);
399 }
400
401 static void
402 nullfs_unlink_lowervp(struct mount *mp, struct vnode *lowervp)
403 {
404 struct vnode *vp;
405 struct null_node *xp;
406
407 vp = null_hashget(mp, lowervp);
408 if (vp == NULL)
409 return;
410 xp = VTONULL(vp);
411 xp->null_flags |= NULLV_DROP | NULLV_NOUNLOCK;
412 vhold(vp);
413 vunref(vp);
414
415 if (vp->v_usecount == 0) {
416 /*
417 * If vunref() dropped the last use reference on the
418 * nullfs vnode, it must be reclaimed, and its lock
419 * was split from the lower vnode lock. Need to do
420 * extra unlock before allowing the final vdrop() to
421 * free the vnode.
422 */
423 KASSERT((vp->v_iflag & VI_DOOMED) != 0,
424 ("not reclaimed nullfs vnode %p", vp));
425 VOP_UNLOCK(vp, 0);
426 } else {
427 /*
428 * Otherwise, the nullfs vnode still shares the lock
429 * with the lower vnode, and must not be unlocked.
430 * Also clear the NULLV_NOUNLOCK, the flag is not
431 * relevant for future reclamations.
432 */
433 ASSERT_VOP_ELOCKED(vp, "unlink_lowervp");
434 KASSERT((vp->v_iflag & VI_DOOMED) == 0,
435 ("reclaimed nullfs vnode %p", vp));
436 xp->null_flags &= ~NULLV_NOUNLOCK;
437 }
438 vdrop(vp);
439 }
440
441 static struct vfsops null_vfsops = {
442 .vfs_extattrctl = nullfs_extattrctl,
443 .vfs_fhtovp = nullfs_fhtovp,
444 .vfs_init = nullfs_init,
445 .vfs_mount = nullfs_mount,
446 .vfs_quotactl = nullfs_quotactl,
447 .vfs_root = nullfs_root,
448 .vfs_statfs = nullfs_statfs,
449 .vfs_sync = nullfs_sync,
450 .vfs_uninit = nullfs_uninit,
451 .vfs_unmount = nullfs_unmount,
452 .vfs_vget = nullfs_vget,
453 .vfs_reclaim_lowervp = nullfs_reclaim_lowervp,
454 .vfs_unlink_lowervp = nullfs_unlink_lowervp,
455 };
456
457 VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK | VFCF_JAIL);
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