xref: /freebsd/sys/fs/autofs/autofs.c (revision eda14cbc264d6969b02f2b1994cef11148e914f1)
1 /*-
2  * Copyright (c) 2014 The FreeBSD Foundation
3  * All rights reserved.
4  *
5  * This software was developed by Edward Tomasz Napierala under sponsorship
6  * from the FreeBSD Foundation.
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  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  */
30 /*-
31  * Copyright (c) 1989, 1991, 1993, 1995
32  *	The Regents of the University of California.  All rights reserved.
33  *
34  * This code is derived from software contributed to Berkeley by
35  * Rick Macklem at The University of Guelph.
36  *
37  * Redistribution and use in source and binary forms, with or without
38  * modification, are permitted provided that the following conditions
39  * are met:
40  * 1. Redistributions of source code must retain the above copyright
41  *    notice, this list of conditions and the following disclaimer.
42  * 2. Redistributions in binary form must reproduce the above copyright
43  *    notice, this list of conditions and the following disclaimer in the
44  *    documentation and/or other materials provided with the distribution.
45  * 3. Neither the name of the University nor the names of its contributors
46  *    may be used to endorse or promote products derived from this software
47  *    without specific prior written permission.
48  *
49  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
50  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
51  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
52  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
53  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
54  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
55  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
56  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
57  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
58  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
59  * SUCH DAMAGE.
60  *
61  */
62 
63 #include <sys/cdefs.h>
64 __FBSDID("$FreeBSD$");
65 
66 #include <sys/param.h>
67 #include <sys/systm.h>
68 #include <sys/buf.h>
69 #include <sys/conf.h>
70 #include <sys/dirent.h>
71 #include <sys/ioccom.h>
72 #include <sys/kernel.h>
73 #include <sys/module.h>
74 #include <sys/mount.h>
75 #include <sys/refcount.h>
76 #include <sys/sx.h>
77 #include <sys/sysctl.h>
78 #include <sys/syscallsubr.h>
79 #include <sys/taskqueue.h>
80 #include <sys/tree.h>
81 #include <sys/vnode.h>
82 #include <machine/atomic.h>
83 #include <vm/uma.h>
84 
85 #include <fs/autofs/autofs.h>
86 #include <fs/autofs/autofs_ioctl.h>
87 
88 MALLOC_DEFINE(M_AUTOFS, "autofs", "Automounter filesystem");
89 
90 uma_zone_t autofs_request_zone;
91 uma_zone_t autofs_node_zone;
92 
93 static int	autofs_open(struct cdev *dev, int flags, int fmt,
94 		    struct thread *td);
95 static int	autofs_close(struct cdev *dev, int flag, int fmt,
96 		    struct thread *td);
97 static int	autofs_ioctl(struct cdev *dev, u_long cmd, caddr_t arg,
98 		    int mode, struct thread *td);
99 
100 static struct cdevsw autofs_cdevsw = {
101      .d_version = D_VERSION,
102      .d_open   = autofs_open,
103      .d_close   = autofs_close,
104      .d_ioctl   = autofs_ioctl,
105      .d_name    = "autofs",
106 };
107 
108 /*
109  * List of signals that can interrupt an autofs trigger.  Might be a good
110  * idea to keep it synchronised with list in sys/fs/nfs/nfs_commonkrpc.c.
111  */
112 int autofs_sig_set[] = {
113 	SIGINT,
114 	SIGTERM,
115 	SIGHUP,
116 	SIGKILL,
117 	SIGQUIT
118 };
119 
120 struct autofs_softc	*autofs_softc;
121 
122 SYSCTL_NODE(_vfs, OID_AUTO, autofs, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
123     "Automounter filesystem");
124 int autofs_debug = 1;
125 TUNABLE_INT("vfs.autofs.debug", &autofs_debug);
126 SYSCTL_INT(_vfs_autofs, OID_AUTO, debug, CTLFLAG_RWTUN,
127     &autofs_debug, 1, "Enable debug messages");
128 int autofs_mount_on_stat = 0;
129 TUNABLE_INT("vfs.autofs.mount_on_stat", &autofs_mount_on_stat);
130 SYSCTL_INT(_vfs_autofs, OID_AUTO, mount_on_stat, CTLFLAG_RWTUN,
131     &autofs_mount_on_stat, 0, "Trigger mount on stat(2) on mountpoint");
132 int autofs_timeout = 30;
133 TUNABLE_INT("vfs.autofs.timeout", &autofs_timeout);
134 SYSCTL_INT(_vfs_autofs, OID_AUTO, timeout, CTLFLAG_RWTUN,
135     &autofs_timeout, 30, "Number of seconds to wait for automountd(8)");
136 int autofs_cache = 600;
137 TUNABLE_INT("vfs.autofs.cache", &autofs_cache);
138 SYSCTL_INT(_vfs_autofs, OID_AUTO, cache, CTLFLAG_RWTUN,
139     &autofs_cache, 600, "Number of seconds to wait before reinvoking "
140     "automountd(8) for any given file or directory");
141 int autofs_retry_attempts = 3;
142 TUNABLE_INT("vfs.autofs.retry_attempts", &autofs_retry_attempts);
143 SYSCTL_INT(_vfs_autofs, OID_AUTO, retry_attempts, CTLFLAG_RWTUN,
144     &autofs_retry_attempts, 3, "Number of attempts before failing mount");
145 int autofs_retry_delay = 1;
146 TUNABLE_INT("vfs.autofs.retry_delay", &autofs_retry_delay);
147 SYSCTL_INT(_vfs_autofs, OID_AUTO, retry_delay, CTLFLAG_RWTUN,
148     &autofs_retry_delay, 1, "Number of seconds before retrying");
149 int autofs_interruptible = 1;
150 TUNABLE_INT("vfs.autofs.interruptible", &autofs_interruptible);
151 SYSCTL_INT(_vfs_autofs, OID_AUTO, interruptible, CTLFLAG_RWTUN,
152     &autofs_interruptible, 1, "Allow requests to be interrupted by signal");
153 
154 static int
155 autofs_node_cmp(const struct autofs_node *a, const struct autofs_node *b)
156 {
157 
158 	return (strcmp(a->an_name, b->an_name));
159 }
160 
161 RB_GENERATE(autofs_node_tree, autofs_node, an_link, autofs_node_cmp);
162 
163 int
164 autofs_init(struct vfsconf *vfsp)
165 {
166 	int error;
167 
168 	KASSERT(autofs_softc == NULL,
169 	    ("softc %p, should be NULL", autofs_softc));
170 
171 	autofs_softc = malloc(sizeof(*autofs_softc), M_AUTOFS,
172 	    M_WAITOK | M_ZERO);
173 
174 	autofs_request_zone = uma_zcreate("autofs_request",
175 	    sizeof(struct autofs_request), NULL, NULL, NULL, NULL,
176 	    UMA_ALIGN_PTR, 0);
177 	autofs_node_zone = uma_zcreate("autofs_node",
178 	    sizeof(struct autofs_node), NULL, NULL, NULL, NULL,
179 	    UMA_ALIGN_PTR, 0);
180 
181 	TAILQ_INIT(&autofs_softc->sc_requests);
182 	cv_init(&autofs_softc->sc_cv, "autofscv");
183 	sx_init(&autofs_softc->sc_lock, "autofslk");
184 
185 	error = make_dev_p(MAKEDEV_CHECKNAME, &autofs_softc->sc_cdev,
186 	    &autofs_cdevsw, NULL, UID_ROOT, GID_WHEEL, 0600, "autofs");
187 	if (error != 0) {
188 		AUTOFS_WARN("failed to create device node, error %d", error);
189 		uma_zdestroy(autofs_request_zone);
190 		uma_zdestroy(autofs_node_zone);
191 		free(autofs_softc, M_AUTOFS);
192 
193 		return (error);
194 	}
195 	autofs_softc->sc_cdev->si_drv1 = autofs_softc;
196 
197 	return (0);
198 }
199 
200 int
201 autofs_uninit(struct vfsconf *vfsp)
202 {
203 
204 	sx_xlock(&autofs_softc->sc_lock);
205 	if (autofs_softc->sc_dev_opened) {
206 		sx_xunlock(&autofs_softc->sc_lock);
207 		return (EBUSY);
208 	}
209 	if (autofs_softc->sc_cdev != NULL)
210 		destroy_dev(autofs_softc->sc_cdev);
211 
212 	uma_zdestroy(autofs_request_zone);
213 	uma_zdestroy(autofs_node_zone);
214 
215 	sx_xunlock(&autofs_softc->sc_lock);
216 	/*
217 	 * XXX: Race with open?
218 	 */
219 	free(autofs_softc, M_AUTOFS);
220 
221 	return (0);
222 }
223 
224 bool
225 autofs_ignore_thread(const struct thread *td)
226 {
227 	struct proc *p;
228 
229 	p = td->td_proc;
230 
231 	if (autofs_softc->sc_dev_opened == false)
232 		return (false);
233 
234 	PROC_LOCK(p);
235 	if (p->p_session->s_sid == autofs_softc->sc_dev_sid) {
236 		PROC_UNLOCK(p);
237 		return (true);
238 	}
239 	PROC_UNLOCK(p);
240 
241 	return (false);
242 }
243 
244 static char *
245 autofs_path(struct autofs_node *anp)
246 {
247 	struct autofs_mount *amp;
248 	char *path, *tmp;
249 
250 	amp = anp->an_mount;
251 
252 	path = strdup("", M_AUTOFS);
253 	for (; anp->an_parent != NULL; anp = anp->an_parent) {
254 		tmp = malloc(strlen(anp->an_name) + strlen(path) + 2,
255 		    M_AUTOFS, M_WAITOK);
256 		strcpy(tmp, anp->an_name);
257 		strcat(tmp, "/");
258 		strcat(tmp, path);
259 		free(path, M_AUTOFS);
260 		path = tmp;
261 	}
262 
263 	tmp = malloc(strlen(amp->am_mountpoint) + strlen(path) + 2,
264 	    M_AUTOFS, M_WAITOK);
265 	strcpy(tmp, amp->am_mountpoint);
266 	strcat(tmp, "/");
267 	strcat(tmp, path);
268 	free(path, M_AUTOFS);
269 	path = tmp;
270 
271 	return (path);
272 }
273 
274 static void
275 autofs_task(void *context, int pending)
276 {
277 	struct autofs_request *ar;
278 
279 	ar = context;
280 
281 	sx_xlock(&autofs_softc->sc_lock);
282 	AUTOFS_WARN("request %d for %s timed out after %d seconds",
283 	    ar->ar_id, ar->ar_path, autofs_timeout);
284 	/*
285 	 * XXX: EIO perhaps?
286 	 */
287 	ar->ar_error = ETIMEDOUT;
288 	ar->ar_wildcards = true;
289 	ar->ar_done = true;
290 	ar->ar_in_progress = false;
291 	cv_broadcast(&autofs_softc->sc_cv);
292 	sx_xunlock(&autofs_softc->sc_lock);
293 }
294 
295 bool
296 autofs_cached(struct autofs_node *anp, const char *component, int componentlen)
297 {
298 	int error;
299 	struct autofs_mount *amp;
300 
301 	amp = anp->an_mount;
302 
303 	AUTOFS_ASSERT_UNLOCKED(amp);
304 
305 	/*
306 	 * For root node we need to request automountd(8) assistance even
307 	 * if the node is marked as cached, but the requested top-level
308 	 * directory does not exist.  This is necessary for wildcard indirect
309 	 * map keys to work.  We don't do this if we know that there are
310 	 * no wildcards.
311 	 */
312 	if (anp->an_parent == NULL && componentlen != 0 && anp->an_wildcards) {
313 		AUTOFS_SLOCK(amp);
314 		error = autofs_node_find(anp, component, componentlen, NULL);
315 		AUTOFS_SUNLOCK(amp);
316 		if (error != 0)
317 			return (false);
318 	}
319 
320 	return (anp->an_cached);
321 }
322 
323 static void
324 autofs_cache_callout(void *context)
325 {
326 	struct autofs_node *anp;
327 
328 	anp = context;
329 	anp->an_cached = false;
330 }
331 
332 void
333 autofs_flush(struct autofs_mount *amp)
334 {
335 
336 	/*
337 	 * XXX: This will do for now, but ideally we should iterate
338 	 * 	over all the nodes.
339 	 */
340 	amp->am_root->an_cached = false;
341 	AUTOFS_DEBUG("%s flushed", amp->am_mountpoint);
342 }
343 
344 /*
345  * The set/restore sigmask functions are used to (temporarily) overwrite
346  * the thread td_sigmask during triggering.
347  */
348 static void
349 autofs_set_sigmask(sigset_t *oldset)
350 {
351 	sigset_t newset;
352 	int i;
353 
354 	SIGFILLSET(newset);
355 	/* Remove the autofs set of signals from newset */
356 	PROC_LOCK(curproc);
357 	mtx_lock(&curproc->p_sigacts->ps_mtx);
358 	for (i = 0 ; i < nitems(autofs_sig_set); i++) {
359 		/*
360 		 * But make sure we leave the ones already masked
361 		 * by the process, i.e. remove the signal from the
362 		 * temporary signalmask only if it wasn't already
363 		 * in p_sigmask.
364 		 */
365 		if (!SIGISMEMBER(curthread->td_sigmask, autofs_sig_set[i]) &&
366 		    !SIGISMEMBER(curproc->p_sigacts->ps_sigignore,
367 		    autofs_sig_set[i])) {
368 			SIGDELSET(newset, autofs_sig_set[i]);
369 		}
370 	}
371 	mtx_unlock(&curproc->p_sigacts->ps_mtx);
372 	kern_sigprocmask(curthread, SIG_SETMASK, &newset, oldset,
373 	    SIGPROCMASK_PROC_LOCKED);
374 	PROC_UNLOCK(curproc);
375 }
376 
377 static void
378 autofs_restore_sigmask(sigset_t *set)
379 {
380 
381 	kern_sigprocmask(curthread, SIG_SETMASK, set, NULL, 0);
382 }
383 
384 static int
385 autofs_trigger_one(struct autofs_node *anp,
386     const char *component, int componentlen)
387 {
388 	sigset_t oldset;
389 	struct autofs_mount *amp;
390 	struct autofs_node *firstanp;
391 	struct autofs_request *ar;
392 	char *key, *path;
393 	int error = 0, request_error, last;
394 	bool wildcards;
395 
396 	amp = anp->an_mount;
397 
398 	sx_assert(&autofs_softc->sc_lock, SA_XLOCKED);
399 
400 	if (anp->an_parent == NULL) {
401 		key = strndup(component, componentlen, M_AUTOFS);
402 	} else {
403 		for (firstanp = anp; firstanp->an_parent->an_parent != NULL;
404 		    firstanp = firstanp->an_parent)
405 			continue;
406 		key = strdup(firstanp->an_name, M_AUTOFS);
407 	}
408 
409 	path = autofs_path(anp);
410 
411 	TAILQ_FOREACH(ar, &autofs_softc->sc_requests, ar_next) {
412 		if (strcmp(ar->ar_path, path) != 0)
413 			continue;
414 		if (strcmp(ar->ar_key, key) != 0)
415 			continue;
416 
417 		KASSERT(strcmp(ar->ar_from, amp->am_from) == 0,
418 		    ("from changed; %s != %s", ar->ar_from, amp->am_from));
419 		KASSERT(strcmp(ar->ar_prefix, amp->am_prefix) == 0,
420 		    ("prefix changed; %s != %s",
421 		     ar->ar_prefix, amp->am_prefix));
422 		KASSERT(strcmp(ar->ar_options, amp->am_options) == 0,
423 		    ("options changed; %s != %s",
424 		     ar->ar_options, amp->am_options));
425 
426 		break;
427 	}
428 
429 	if (ar != NULL) {
430 		refcount_acquire(&ar->ar_refcount);
431 	} else {
432 		ar = uma_zalloc(autofs_request_zone, M_WAITOK | M_ZERO);
433 		ar->ar_mount = amp;
434 
435 		ar->ar_id =
436 		    atomic_fetchadd_int(&autofs_softc->sc_last_request_id, 1);
437 		strlcpy(ar->ar_from, amp->am_from, sizeof(ar->ar_from));
438 		strlcpy(ar->ar_path, path, sizeof(ar->ar_path));
439 		strlcpy(ar->ar_prefix, amp->am_prefix, sizeof(ar->ar_prefix));
440 		strlcpy(ar->ar_key, key, sizeof(ar->ar_key));
441 		strlcpy(ar->ar_options,
442 		    amp->am_options, sizeof(ar->ar_options));
443 
444 		TIMEOUT_TASK_INIT(taskqueue_thread, &ar->ar_task, 0,
445 		    autofs_task, ar);
446 		taskqueue_enqueue_timeout(taskqueue_thread, &ar->ar_task,
447 		    autofs_timeout * hz);
448 		refcount_init(&ar->ar_refcount, 1);
449 		TAILQ_INSERT_TAIL(&autofs_softc->sc_requests, ar, ar_next);
450 	}
451 
452 	cv_broadcast(&autofs_softc->sc_cv);
453 	while (ar->ar_done == false) {
454 		if (autofs_interruptible != 0) {
455 			autofs_set_sigmask(&oldset);
456 			error = cv_wait_sig(&autofs_softc->sc_cv,
457 			    &autofs_softc->sc_lock);
458 			autofs_restore_sigmask(&oldset);
459 			if (error != 0) {
460 				AUTOFS_WARN("cv_wait_sig for %s failed "
461 				    "with error %d", ar->ar_path, error);
462 				break;
463 			}
464 		} else {
465 			cv_wait(&autofs_softc->sc_cv, &autofs_softc->sc_lock);
466 		}
467 	}
468 
469 	request_error = ar->ar_error;
470 	if (request_error != 0) {
471 		AUTOFS_WARN("request for %s completed with error %d, "
472 		    "pid %d (%s)", ar->ar_path, request_error,
473 		    curproc->p_pid, curproc->p_comm);
474 	}
475 
476 	wildcards = ar->ar_wildcards;
477 
478 	last = refcount_release(&ar->ar_refcount);
479 	if (last) {
480 		TAILQ_REMOVE(&autofs_softc->sc_requests, ar, ar_next);
481 		/*
482 		 * Unlock the sc_lock, so that autofs_task() can complete.
483 		 */
484 		sx_xunlock(&autofs_softc->sc_lock);
485 		taskqueue_cancel_timeout(taskqueue_thread, &ar->ar_task, NULL);
486 		taskqueue_drain_timeout(taskqueue_thread, &ar->ar_task);
487 		uma_zfree(autofs_request_zone, ar);
488 		sx_xlock(&autofs_softc->sc_lock);
489 	}
490 
491 	/*
492 	 * Note that we do not do negative caching on purpose.  This
493 	 * way the user can retry access at any time, e.g. after fixing
494 	 * the failure reason, without waiting for cache timer to expire.
495 	 */
496 	if (error == 0 && request_error == 0 && autofs_cache > 0) {
497 		anp->an_cached = true;
498 		anp->an_wildcards = wildcards;
499 		callout_reset(&anp->an_callout, autofs_cache * hz,
500 		    autofs_cache_callout, anp);
501 	}
502 
503 	free(key, M_AUTOFS);
504 	free(path, M_AUTOFS);
505 
506 	if (error != 0)
507 		return (error);
508 	return (request_error);
509 }
510 
511 /*
512  * Send request to automountd(8) and wait for completion.
513  */
514 int
515 autofs_trigger(struct autofs_node *anp,
516     const char *component, int componentlen)
517 {
518 	int error;
519 
520 	for (;;) {
521 		error = autofs_trigger_one(anp, component, componentlen);
522 		if (error == 0) {
523 			anp->an_retries = 0;
524 			return (0);
525 		}
526 		if (error == EINTR || error == ERESTART) {
527 			AUTOFS_DEBUG("trigger interrupted by signal, "
528 			    "not retrying");
529 			anp->an_retries = 0;
530 			return (error);
531 		}
532 		anp->an_retries++;
533 		if (anp->an_retries >= autofs_retry_attempts) {
534 			AUTOFS_DEBUG("trigger failed %d times; returning "
535 			    "error %d", anp->an_retries, error);
536 			anp->an_retries = 0;
537 			return (error);
538 
539 		}
540 		AUTOFS_DEBUG("trigger failed with error %d; will retry in "
541 		    "%d seconds, %d attempts left", error, autofs_retry_delay,
542 		    autofs_retry_attempts - anp->an_retries);
543 		sx_xunlock(&autofs_softc->sc_lock);
544 		pause("autofs_retry", autofs_retry_delay * hz);
545 		sx_xlock(&autofs_softc->sc_lock);
546 	}
547 }
548 
549 static int
550 autofs_ioctl_request(struct autofs_daemon_request *adr)
551 {
552 	struct autofs_request *ar;
553 	int error;
554 
555 	sx_xlock(&autofs_softc->sc_lock);
556 	for (;;) {
557 		TAILQ_FOREACH(ar, &autofs_softc->sc_requests, ar_next) {
558 			if (ar->ar_done)
559 				continue;
560 			if (ar->ar_in_progress)
561 				continue;
562 
563 			break;
564 		}
565 
566 		if (ar != NULL)
567 			break;
568 
569 		error = cv_wait_sig(&autofs_softc->sc_cv,
570 		    &autofs_softc->sc_lock);
571 		if (error != 0) {
572 			sx_xunlock(&autofs_softc->sc_lock);
573 			return (error);
574 		}
575 	}
576 
577 	ar->ar_in_progress = true;
578 	sx_xunlock(&autofs_softc->sc_lock);
579 
580 	adr->adr_id = ar->ar_id;
581 	strlcpy(adr->adr_from, ar->ar_from, sizeof(adr->adr_from));
582 	strlcpy(adr->adr_path, ar->ar_path, sizeof(adr->adr_path));
583 	strlcpy(adr->adr_prefix, ar->ar_prefix, sizeof(adr->adr_prefix));
584 	strlcpy(adr->adr_key, ar->ar_key, sizeof(adr->adr_key));
585 	strlcpy(adr->adr_options, ar->ar_options, sizeof(adr->adr_options));
586 
587 	PROC_LOCK(curproc);
588 	autofs_softc->sc_dev_sid = curproc->p_session->s_sid;
589 	PROC_UNLOCK(curproc);
590 
591 	return (0);
592 }
593 
594 static int
595 autofs_ioctl_done_101(struct autofs_daemon_done_101 *add)
596 {
597 	struct autofs_request *ar;
598 
599 	sx_xlock(&autofs_softc->sc_lock);
600 	TAILQ_FOREACH(ar, &autofs_softc->sc_requests, ar_next) {
601 		if (ar->ar_id == add->add_id)
602 			break;
603 	}
604 
605 	if (ar == NULL) {
606 		sx_xunlock(&autofs_softc->sc_lock);
607 		AUTOFS_DEBUG("id %d not found", add->add_id);
608 		return (ESRCH);
609 	}
610 
611 	ar->ar_error = add->add_error;
612 	ar->ar_wildcards = true;
613 	ar->ar_done = true;
614 	ar->ar_in_progress = false;
615 	cv_broadcast(&autofs_softc->sc_cv);
616 
617 	sx_xunlock(&autofs_softc->sc_lock);
618 
619 	return (0);
620 }
621 
622 static int
623 autofs_ioctl_done(struct autofs_daemon_done *add)
624 {
625 	struct autofs_request *ar;
626 
627 	sx_xlock(&autofs_softc->sc_lock);
628 	TAILQ_FOREACH(ar, &autofs_softc->sc_requests, ar_next) {
629 		if (ar->ar_id == add->add_id)
630 			break;
631 	}
632 
633 	if (ar == NULL) {
634 		sx_xunlock(&autofs_softc->sc_lock);
635 		AUTOFS_DEBUG("id %d not found", add->add_id);
636 		return (ESRCH);
637 	}
638 
639 	ar->ar_error = add->add_error;
640 	ar->ar_wildcards = add->add_wildcards;
641 	ar->ar_done = true;
642 	ar->ar_in_progress = false;
643 	cv_broadcast(&autofs_softc->sc_cv);
644 
645 	sx_xunlock(&autofs_softc->sc_lock);
646 
647 	return (0);
648 }
649 
650 static int
651 autofs_open(struct cdev *dev, int flags, int fmt, struct thread *td)
652 {
653 
654 	sx_xlock(&autofs_softc->sc_lock);
655 	/*
656 	 * We must never block automountd(8) and its descendants, and we use
657 	 * session ID to determine that: we store session id of the process
658 	 * that opened the device, and then compare it with session ids
659 	 * of triggering processes.  This means running a second automountd(8)
660 	 * instance would break the previous one.  The check below prevents
661 	 * it from happening.
662 	 */
663 	if (autofs_softc->sc_dev_opened) {
664 		sx_xunlock(&autofs_softc->sc_lock);
665 		return (EBUSY);
666 	}
667 
668 	autofs_softc->sc_dev_opened = true;
669 	sx_xunlock(&autofs_softc->sc_lock);
670 
671 	return (0);
672 }
673 
674 static int
675 autofs_close(struct cdev *dev, int flag, int fmt, struct thread *td)
676 {
677 
678 	sx_xlock(&autofs_softc->sc_lock);
679 	KASSERT(autofs_softc->sc_dev_opened, ("not opened?"));
680 	autofs_softc->sc_dev_opened = false;
681 	sx_xunlock(&autofs_softc->sc_lock);
682 
683 	return (0);
684 }
685 
686 static int
687 autofs_ioctl(struct cdev *dev, u_long cmd, caddr_t arg, int mode,
688     struct thread *td)
689 {
690 
691 	KASSERT(autofs_softc->sc_dev_opened, ("not opened?"));
692 
693 	switch (cmd) {
694 	case AUTOFSREQUEST:
695 		return (autofs_ioctl_request(
696 		    (struct autofs_daemon_request *)arg));
697 	case AUTOFSDONE101:
698 		return (autofs_ioctl_done_101(
699 		    (struct autofs_daemon_done_101 *)arg));
700 	case AUTOFSDONE:
701 		return (autofs_ioctl_done(
702 		    (struct autofs_daemon_done *)arg));
703 	default:
704 		AUTOFS_DEBUG("invalid cmd %lx", cmd);
705 		return (EINVAL);
706 	}
707 }
708