xref: /freebsd/sbin/umount/umount.c (revision 780fb4a2)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1980, 1989, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #ifndef lint
33 static const char copyright[] =
34 "@(#) Copyright (c) 1980, 1989, 1993\n\
35 	The Regents of the University of California.  All rights reserved.\n";
36 #endif /* not lint */
37 
38 #ifndef lint
39 #if 0
40 static char sccsid[] = "@(#)umount.c	8.8 (Berkeley) 5/8/95";
41 #endif
42 static const char rcsid[] =
43   "$FreeBSD$";
44 #endif /* not lint */
45 
46 #include <sys/param.h>
47 #include <sys/mount.h>
48 #include <sys/socket.h>
49 #include <sys/stat.h>
50 
51 #include <netdb.h>
52 #include <rpc/rpc.h>
53 #include <rpcsvc/mount.h>
54 #include <nfs/nfssvc.h>
55 
56 #include <ctype.h>
57 #include <err.h>
58 #include <errno.h>
59 #include <fstab.h>
60 #include <stdio.h>
61 #include <stdlib.h>
62 #include <string.h>
63 #include <unistd.h>
64 
65 #include "mounttab.h"
66 
67 typedef enum { FIND, REMOVE, CHECKUNIQUE } dowhat;
68 
69 static struct addrinfo *nfshost_ai = NULL;
70 static int	fflag, vflag;
71 static char	*nfshost;
72 
73 struct statfs *checkmntlist(char *);
74 int	 checkvfsname (const char *, char **);
75 struct statfs *getmntentry(const char *fromname, const char *onname,
76 	     fsid_t *fsid, dowhat what);
77 char   **makevfslist (const char *);
78 size_t	 mntinfo (struct statfs **);
79 int	 namematch (struct addrinfo *);
80 int	 parsehexfsid(const char *hex, fsid_t *fsid);
81 int	 sacmp (void *, void *);
82 int	 umountall (char **);
83 int	 checkname (char *, char **);
84 int	 umountfs(struct statfs *sfs);
85 void	 usage (void);
86 int	 xdr_dir (XDR *, char *);
87 
88 int
89 main(int argc, char *argv[])
90 {
91 	int all, errs, ch, mntsize, error, nfsforce, ret;
92 	char **typelist = NULL;
93 	struct statfs *mntbuf, *sfs;
94 	struct addrinfo hints;
95 
96 	nfsforce = all = errs = 0;
97 	while ((ch = getopt(argc, argv, "AaF:fh:Nnt:v")) != -1)
98 		switch (ch) {
99 		case 'A':
100 			all = 2;
101 			break;
102 		case 'a':
103 			all = 1;
104 			break;
105 		case 'F':
106 			setfstab(optarg);
107 			break;
108 		case 'f':
109 			fflag |= MNT_FORCE;
110 			break;
111 		case 'h':	/* -h implies -A. */
112 			all = 2;
113 			nfshost = optarg;
114 			break;
115 		case 'N':
116 			nfsforce = 1;
117 			break;
118 		case 'n':
119 			fflag |= MNT_NONBUSY;
120 			break;
121 		case 't':
122 			if (typelist != NULL)
123 				err(1, "only one -t option may be specified");
124 			typelist = makevfslist(optarg);
125 			break;
126 		case 'v':
127 			vflag = 1;
128 			break;
129 		default:
130 			usage();
131 			/* NOTREACHED */
132 		}
133 	argc -= optind;
134 	argv += optind;
135 
136 	if ((fflag & MNT_FORCE) != 0 && (fflag & MNT_NONBUSY) != 0)
137 		err(1, "-f and -n are mutually exclusive");
138 
139 	/* Start disks transferring immediately. */
140 	if ((fflag & (MNT_FORCE | MNT_NONBUSY)) == 0 && nfsforce == 0)
141 		sync();
142 
143 	if ((argc == 0 && !all) || (argc != 0 && all))
144 		usage();
145 
146 	if (nfsforce != 0 && (argc == 0 || nfshost != NULL || typelist != NULL))
147 		usage();
148 
149 	/* -h implies "-t nfs" if no -t flag. */
150 	if ((nfshost != NULL) && (typelist == NULL))
151 		typelist = makevfslist("nfs");
152 
153 	if (nfshost != NULL) {
154 		memset(&hints, 0, sizeof hints);
155 		error = getaddrinfo(nfshost, NULL, &hints, &nfshost_ai);
156 		if (error)
157 			errx(1, "%s: %s", nfshost, gai_strerror(error));
158 	}
159 
160 	switch (all) {
161 	case 2:
162 		if ((mntsize = mntinfo(&mntbuf)) <= 0)
163 			break;
164 		/*
165 		 * We unmount the nfs-mounts in the reverse order
166 		 * that they were mounted.
167 		 */
168 		for (errs = 0, mntsize--; mntsize > 0; mntsize--) {
169 			sfs = &mntbuf[mntsize];
170 			if (checkvfsname(sfs->f_fstypename, typelist))
171 				continue;
172 			if (strcmp(sfs->f_mntonname, "/dev") == 0)
173 				continue;
174 			if (umountfs(sfs) != 0)
175 				errs = 1;
176 		}
177 		free(mntbuf);
178 		break;
179 	case 1:
180 		if (setfsent() == 0)
181 			err(1, "%s", getfstab());
182 		errs = umountall(typelist);
183 		break;
184 	case 0:
185 		for (errs = 0; *argv != NULL; ++argv)
186 			if (nfsforce != 0) {
187 				/*
188 				 * First do the nfssvc() syscall to shut down
189 				 * the mount point and then do the forced
190 				 * dismount.
191 				 */
192 				ret = nfssvc(NFSSVC_FORCEDISM, *argv);
193 				if (ret >= 0)
194 					ret = unmount(*argv, MNT_FORCE);
195 				if (ret < 0) {
196 					warn("%s", *argv);
197 					errs = 1;
198 				}
199 			} else if (checkname(*argv, typelist) != 0)
200 				errs = 1;
201 		break;
202 	}
203 	exit(errs);
204 }
205 
206 int
207 umountall(char **typelist)
208 {
209 	struct xvfsconf vfc;
210 	struct fstab *fs;
211 	int rval;
212 	char *cp;
213 	static int firstcall = 1;
214 
215 	if ((fs = getfsent()) != NULL)
216 		firstcall = 0;
217 	else if (firstcall)
218 		errx(1, "fstab reading failure");
219 	else
220 		return (0);
221 	do {
222 		/* Ignore the root. */
223 		if (strcmp(fs->fs_file, "/") == 0)
224 			continue;
225 		/*
226 		 * !!!
227 		 * Historic practice: ignore unknown FSTAB_* fields.
228 		 */
229 		if (strcmp(fs->fs_type, FSTAB_RW) &&
230 		    strcmp(fs->fs_type, FSTAB_RO) &&
231 		    strcmp(fs->fs_type, FSTAB_RQ))
232 			continue;
233 		/* Ignore unknown file system types. */
234 		if (getvfsbyname(fs->fs_vfstype, &vfc) == -1)
235 			continue;
236 		if (checkvfsname(fs->fs_vfstype, typelist))
237 			continue;
238 
239 		/*
240 		 * We want to unmount the file systems in the reverse order
241 		 * that they were mounted.  So, we save off the file name
242 		 * in some allocated memory, and then call recursively.
243 		 */
244 		if ((cp = malloc((size_t)strlen(fs->fs_file) + 1)) == NULL)
245 			err(1, "malloc failed");
246 		(void)strcpy(cp, fs->fs_file);
247 		rval = umountall(typelist);
248 		rval = checkname(cp, typelist) || rval;
249 		free(cp);
250 		return (rval);
251 	} while ((fs = getfsent()) != NULL);
252 	return (0);
253 }
254 
255 /*
256  * Do magic checks on mountpoint/device/fsid, and then call unmount(2).
257  */
258 int
259 checkname(char *mntname, char **typelist)
260 {
261 	char buf[MAXPATHLEN];
262 	struct statfs sfsbuf;
263 	struct stat sb;
264 	struct statfs *sfs;
265 	char *delimp;
266 	dev_t dev;
267 	int len;
268 
269 	/*
270 	 * 1. Check if the name exists in the mounttable.
271 	 */
272 	sfs = checkmntlist(mntname);
273 	/*
274 	 * 2. Remove trailing slashes if there are any. After that
275 	 * we look up the name in the mounttable again.
276 	 */
277 	if (sfs == NULL) {
278 		len = strlen(mntname);
279 		while (len > 1 && mntname[len - 1] == '/')
280 			mntname[--len] = '\0';
281 		sfs = checkmntlist(mntname);
282 	}
283 	/*
284 	 * 3. Check if the deprecated NFS syntax with an '@' has been used
285 	 * and translate it to the ':' syntax. Look up the name in the
286 	 * mount table again.
287 	 */
288 	if (sfs == NULL && (delimp = strrchr(mntname, '@')) != NULL) {
289 		snprintf(buf, sizeof(buf), "%s:%.*s", delimp + 1,
290 		    (int)(delimp - mntname), mntname);
291 		len = strlen(buf);
292 		while (len > 1 && buf[len - 1] == '/')
293 			buf[--len] = '\0';
294 		sfs = checkmntlist(buf);
295 	}
296 	/*
297 	 * 4. Resort to a statfs(2) call. This is the last check so that
298 	 * hung NFS filesystems for example can be unmounted without
299 	 * potentially blocking forever in statfs() as long as the
300 	 * filesystem is specified unambiguously. This covers all the
301 	 * hard cases such as symlinks and mismatches between the
302 	 * mount list and reality.
303 	 * We also do this if an ambiguous mount point was specified.
304 	 */
305 	if (sfs == NULL || (getmntentry(NULL, mntname, NULL, FIND) != NULL &&
306 	    getmntentry(NULL, mntname, NULL, CHECKUNIQUE) == NULL)) {
307 		if (statfs(mntname, &sfsbuf) != 0) {
308 			warn("%s: statfs", mntname);
309 		} else if (stat(mntname, &sb) != 0) {
310 			warn("%s: stat", mntname);
311 		} else if (S_ISDIR(sb.st_mode)) {
312 			/* Check that `mntname' is the root directory. */
313 			dev = sb.st_dev;
314 			snprintf(buf, sizeof(buf), "%s/..", mntname);
315 			if (stat(buf, &sb) != 0) {
316 				warn("%s: stat", buf);
317 			} else if (sb.st_dev == dev) {
318 				warnx("%s: not a file system root directory",
319 				    mntname);
320 				return (1);
321 			} else
322 				sfs = &sfsbuf;
323 		}
324 	}
325 	if (sfs == NULL) {
326 		warnx("%s: unknown file system", mntname);
327 		return (1);
328 	}
329 	if (checkvfsname(sfs->f_fstypename, typelist))
330 		return (1);
331 	return (umountfs(sfs));
332 }
333 
334 /*
335  * NFS stuff and unmount(2) call
336  */
337 int
338 umountfs(struct statfs *sfs)
339 {
340 	char fsidbuf[64];
341 	enum clnt_stat clnt_stat;
342 	struct timeval try;
343 	struct addrinfo *ai, hints;
344 	int do_rpc;
345 	CLIENT *clp;
346 	char *nfsdirname, *orignfsdirname;
347 	char *hostp, *delimp;
348 	char buf[1024];
349 	struct nfscl_dumpmntopts dumpmntopts;
350 	const char *proto_ptr = NULL;
351 
352 	ai = NULL;
353 	do_rpc = 0;
354 	hostp = NULL;
355 	nfsdirname = delimp = orignfsdirname = NULL;
356 	memset(&hints, 0, sizeof hints);
357 
358 	if (strcmp(sfs->f_fstypename, "nfs") == 0) {
359 		if ((nfsdirname = strdup(sfs->f_mntfromname)) == NULL)
360 			err(1, "strdup");
361 		orignfsdirname = nfsdirname;
362 		if (*nfsdirname == '[' &&
363 		    (delimp = strchr(nfsdirname + 1, ']')) != NULL &&
364 		    *(delimp + 1) == ':') {
365 			hostp = nfsdirname + 1;
366 			nfsdirname = delimp + 2;
367 		} else if ((delimp = strrchr(nfsdirname, ':')) != NULL) {
368 			hostp = nfsdirname;
369 			nfsdirname = delimp + 1;
370 		}
371 		if (hostp != NULL) {
372 			*delimp = '\0';
373 			getaddrinfo(hostp, NULL, &hints, &ai);
374 			if (ai == NULL) {
375 				warnx("can't get net id for host");
376 			}
377 		}
378 
379 		/*
380 		 * Check if we have to start the rpc-call later.
381 		 * If there are still identical nfs-names mounted,
382 		 * we skip the rpc-call. Obviously this has to
383 		 * happen before unmount(2), but it should happen
384 		 * after the previous namecheck.
385 		 * A non-NULL return means that this is the last
386 		 * mount from mntfromname that is still mounted.
387 		 */
388 		if (getmntentry(sfs->f_mntfromname, NULL, NULL,
389 		    CHECKUNIQUE) != NULL) {
390 			do_rpc = 1;
391 			proto_ptr = "udp";
392 			/*
393 			 * Try and find out whether this NFS mount is NFSv4 and
394 			 * what protocol is being used. If this fails, the
395 			 * default is NFSv2,3 and use UDP for the Unmount RPC.
396 			 */
397 			dumpmntopts.ndmnt_fname = sfs->f_mntonname;
398 			dumpmntopts.ndmnt_buf = buf;
399 			dumpmntopts.ndmnt_blen = sizeof(buf);
400 			if (nfssvc(NFSSVC_DUMPMNTOPTS, &dumpmntopts) >= 0) {
401 				if (strstr(buf, "nfsv4,") != NULL)
402 					do_rpc = 0;
403 				else if (strstr(buf, ",tcp,") != NULL)
404 					proto_ptr = "tcp";
405 			}
406 		}
407 	}
408 
409 	if (!namematch(ai)) {
410 		free(orignfsdirname);
411 		return (1);
412 	}
413 	/* First try to unmount using the file system ID. */
414 	snprintf(fsidbuf, sizeof(fsidbuf), "FSID:%d:%d", sfs->f_fsid.val[0],
415 	    sfs->f_fsid.val[1]);
416 	if (unmount(fsidbuf, fflag | MNT_BYFSID) != 0) {
417 		/* XXX, non-root users get a zero fsid, so don't warn. */
418 		if (errno != ENOENT || sfs->f_fsid.val[0] != 0 ||
419 		    sfs->f_fsid.val[1] != 0)
420 			warn("unmount of %s failed", sfs->f_mntonname);
421 		if (errno != ENOENT) {
422 			free(orignfsdirname);
423 			return (1);
424 		}
425 		/* Compatibility for old kernels. */
426 		if (sfs->f_fsid.val[0] != 0 || sfs->f_fsid.val[1] != 0)
427 			warnx("retrying using path instead of file system ID");
428 		if (unmount(sfs->f_mntonname, fflag) != 0) {
429 			warn("unmount of %s failed", sfs->f_mntonname);
430 			free(orignfsdirname);
431 			return (1);
432 		}
433 	}
434 	/* Mark this this file system as unmounted. */
435 	getmntentry(NULL, NULL, &sfs->f_fsid, REMOVE);
436 	if (vflag)
437 		(void)printf("%s: unmount from %s\n", sfs->f_mntfromname,
438 		    sfs->f_mntonname);
439 	/*
440 	 * Report to mountd-server which nfsname
441 	 * has been unmounted.
442 	 */
443 	if (ai != NULL && !(fflag & MNT_FORCE) && do_rpc) {
444 		clp = clnt_create(hostp, MOUNTPROG, MOUNTVERS3, proto_ptr);
445 		if (clp  == NULL) {
446 			warnx("%s: %s", hostp,
447 			    clnt_spcreateerror("MOUNTPROG"));
448 			free(orignfsdirname);
449 			return (1);
450 		}
451 		clp->cl_auth = authsys_create_default();
452 		try.tv_sec = 20;
453 		try.tv_usec = 0;
454 		clnt_stat = clnt_call(clp, MOUNTPROC_UMNT, (xdrproc_t)xdr_dir,
455 		    nfsdirname, (xdrproc_t)xdr_void, (caddr_t)0, try);
456 		if (clnt_stat != RPC_SUCCESS) {
457 			warnx("%s: %s", hostp,
458 			    clnt_sperror(clp, "RPCMNT_UMOUNT"));
459 			free(orignfsdirname);
460 			return (1);
461 		}
462 		/*
463 		 * Remove the unmounted entry from /var/db/mounttab.
464 		 */
465 		if (read_mtab()) {
466 			clean_mtab(hostp, nfsdirname, vflag);
467 			if(!write_mtab(vflag))
468 				warnx("cannot remove mounttab entry %s:%s",
469 				    hostp, nfsdirname);
470 			free_mtab();
471 		}
472 		auth_destroy(clp->cl_auth);
473 		clnt_destroy(clp);
474 	}
475 	free(orignfsdirname);
476 	return (0);
477 }
478 
479 struct statfs *
480 getmntentry(const char *fromname, const char *onname, fsid_t *fsid, dowhat what)
481 {
482 	static struct statfs *mntbuf;
483 	static size_t mntsize = 0;
484 	static int *mntcheck = NULL;
485 	struct statfs *sfs, *foundsfs;
486 	int i, count;
487 
488 	if (mntsize <= 0) {
489 		if ((mntsize = mntinfo(&mntbuf)) <= 0)
490 			return (NULL);
491 	}
492 	if (mntcheck == NULL) {
493 		if ((mntcheck = calloc(mntsize + 1, sizeof(int))) == NULL)
494 			err(1, "calloc");
495 	}
496 	/*
497 	 * We want to get the file systems in the reverse order
498 	 * that they were mounted. Unmounted file systems are marked
499 	 * in a table called 'mntcheck'.
500 	 */
501 	count = 0;
502 	foundsfs = NULL;
503 	for (i = mntsize - 1; i >= 0; i--) {
504 		if (mntcheck[i])
505 			continue;
506 		sfs = &mntbuf[i];
507 		if (fromname != NULL && strcmp(sfs->f_mntfromname,
508 		    fromname) != 0)
509 			continue;
510 		if (onname != NULL && strcmp(sfs->f_mntonname, onname) != 0)
511 			continue;
512 		if (fsid != NULL && bcmp(&sfs->f_fsid, fsid,
513 		    sizeof(*fsid)) != 0)
514 			continue;
515 
516 		switch (what) {
517 		case CHECKUNIQUE:
518 			foundsfs = sfs;
519 			count++;
520 			continue;
521 		case REMOVE:
522 			mntcheck[i] = 1;
523 			break;
524 		default:
525 			break;
526 		}
527 		return (sfs);
528 	}
529 
530 	if (what == CHECKUNIQUE && count == 1)
531 		return (foundsfs);
532 	return (NULL);
533 }
534 
535 int
536 sacmp(void *sa1, void *sa2)
537 {
538 	void *p1, *p2;
539 	int len;
540 
541 	if (((struct sockaddr *)sa1)->sa_family !=
542 	    ((struct sockaddr *)sa2)->sa_family)
543 		return (1);
544 
545 	switch (((struct sockaddr *)sa1)->sa_family) {
546 	case AF_INET:
547 		p1 = &((struct sockaddr_in *)sa1)->sin_addr;
548 		p2 = &((struct sockaddr_in *)sa2)->sin_addr;
549 		len = 4;
550 		break;
551 	case AF_INET6:
552 		p1 = &((struct sockaddr_in6 *)sa1)->sin6_addr;
553 		p2 = &((struct sockaddr_in6 *)sa2)->sin6_addr;
554 		len = 16;
555 		if (((struct sockaddr_in6 *)sa1)->sin6_scope_id !=
556 		    ((struct sockaddr_in6 *)sa2)->sin6_scope_id)
557 			return (1);
558 		break;
559 	default:
560 		return (1);
561 	}
562 
563 	return memcmp(p1, p2, len);
564 }
565 
566 int
567 namematch(struct addrinfo *ai)
568 {
569 	struct addrinfo *aip;
570 
571 	if (nfshost == NULL || nfshost_ai == NULL)
572 		return (1);
573 
574 	while (ai != NULL) {
575 		aip = nfshost_ai;
576 		while (aip != NULL) {
577 			if (sacmp(ai->ai_addr, aip->ai_addr) == 0)
578 				return (1);
579 			aip = aip->ai_next;
580 		}
581 		ai = ai->ai_next;
582 	}
583 
584 	return (0);
585 }
586 
587 struct statfs *
588 checkmntlist(char *mntname)
589 {
590 	struct statfs *sfs;
591 	fsid_t fsid;
592 
593 	sfs = NULL;
594 	if (parsehexfsid(mntname, &fsid) == 0)
595 		sfs = getmntentry(NULL, NULL, &fsid, FIND);
596 	if (sfs == NULL)
597 		sfs = getmntentry(NULL, mntname, NULL, FIND);
598 	if (sfs == NULL)
599 		sfs = getmntentry(mntname, NULL, NULL, FIND);
600 	return (sfs);
601 }
602 
603 size_t
604 mntinfo(struct statfs **mntbuf)
605 {
606 	static struct statfs *origbuf;
607 	size_t bufsize;
608 	int mntsize;
609 
610 	mntsize = getfsstat(NULL, 0, MNT_NOWAIT);
611 	if (mntsize <= 0)
612 		return (0);
613 	bufsize = (mntsize + 1) * sizeof(struct statfs);
614 	if ((origbuf = malloc(bufsize)) == NULL)
615 		err(1, "malloc");
616 	mntsize = getfsstat(origbuf, (long)bufsize, MNT_NOWAIT);
617 	*mntbuf = origbuf;
618 	return (mntsize);
619 }
620 
621 /*
622  * Convert a hexadecimal filesystem ID to an fsid_t.
623  * Returns 0 on success.
624  */
625 int
626 parsehexfsid(const char *hex, fsid_t *fsid)
627 {
628 	char hexbuf[3];
629 	int i;
630 
631 	if (strlen(hex) != sizeof(*fsid) * 2)
632 		return (-1);
633 	hexbuf[2] = '\0';
634 	for (i = 0; i < (int)sizeof(*fsid); i++) {
635 		hexbuf[0] = hex[i * 2];
636 		hexbuf[1] = hex[i * 2 + 1];
637 		if (!isxdigit(hexbuf[0]) || !isxdigit(hexbuf[1]))
638 			return (-1);
639 		((u_char *)fsid)[i] = strtol(hexbuf, NULL, 16);
640 	}
641 	return (0);
642 }
643 
644 /*
645  * xdr routines for mount rpc's
646  */
647 int
648 xdr_dir(XDR *xdrsp, char *dirp)
649 {
650 
651 	return (xdr_string(xdrsp, &dirp, MNTPATHLEN));
652 }
653 
654 void
655 usage(void)
656 {
657 
658 	(void)fprintf(stderr, "%s\n%s\n",
659 	    "usage: umount [-fNnv] special ... | node ... | fsid ...",
660 	    "       umount -a | -A [-F fstab] [-fnv] [-h host] [-t type]");
661 	exit(1);
662 }
663