xref: /freebsd/sys/geom/gate/g_gate.c (revision 1e413cf93298b5b97441a21d9a50fdcd0ee9945e)
1 /*-
2  * Copyright (c) 2004-2006 Pawel Jakub Dawidek <pjd@FreeBSD.org>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  */
26 
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29 
30 #include <sys/param.h>
31 #include <sys/systm.h>
32 #include <sys/bio.h>
33 #include <sys/conf.h>
34 #include <sys/kernel.h>
35 #include <sys/kthread.h>
36 #include <sys/fcntl.h>
37 #include <sys/linker.h>
38 #include <sys/lock.h>
39 #include <sys/malloc.h>
40 #include <sys/mutex.h>
41 #include <sys/proc.h>
42 #include <sys/limits.h>
43 #include <sys/queue.h>
44 #include <sys/sysctl.h>
45 #include <sys/signalvar.h>
46 #include <sys/time.h>
47 #include <machine/atomic.h>
48 
49 #include <geom/geom.h>
50 #include <geom/gate/g_gate.h>
51 
52 static MALLOC_DEFINE(M_GATE, "gg_data", "GEOM Gate Data");
53 
54 SYSCTL_DECL(_kern_geom);
55 SYSCTL_NODE(_kern_geom, OID_AUTO, gate, CTLFLAG_RW, 0, "GEOM_GATE stuff");
56 static u_int g_gate_debug = 0;
57 SYSCTL_UINT(_kern_geom_gate, OID_AUTO, debug, CTLFLAG_RW, &g_gate_debug, 0,
58     "Debug level");
59 
60 struct g_class g_gate_class = {
61 	.name = G_GATE_CLASS_NAME,
62 	.version = G_VERSION,
63 };
64 
65 static struct cdev *status_dev;
66 static d_ioctl_t g_gate_ioctl;
67 static struct cdevsw g_gate_cdevsw = {
68 	.d_version =	D_VERSION,
69 	.d_ioctl =	g_gate_ioctl,
70 	.d_name =	G_GATE_CTL_NAME
71 };
72 
73 
74 static LIST_HEAD(, g_gate_softc) g_gate_list =
75     LIST_HEAD_INITIALIZER(&g_gate_list);
76 static struct mtx g_gate_list_mtx;
77 
78 
79 static int
80 g_gate_destroy(struct g_gate_softc *sc, boolean_t force)
81 {
82 	struct g_provider *pp;
83 	struct g_geom *gp;
84 	struct bio *bp;
85 
86 	g_topology_assert();
87 	mtx_assert(&g_gate_list_mtx, MA_OWNED);
88 	pp = sc->sc_provider;
89 	if (!force && (pp->acr != 0 || pp->acw != 0 || pp->ace != 0)) {
90 		mtx_unlock(&g_gate_list_mtx);
91 		return (EBUSY);
92 	}
93 	mtx_unlock(&g_gate_list_mtx);
94 	mtx_lock(&sc->sc_queue_mtx);
95 	if ((sc->sc_flags & G_GATE_FLAG_DESTROY) == 0)
96 		sc->sc_flags |= G_GATE_FLAG_DESTROY;
97 	wakeup(sc);
98 	mtx_unlock(&sc->sc_queue_mtx);
99 	gp = pp->geom;
100 	pp->flags |= G_PF_WITHER;
101 	g_orphan_provider(pp, ENXIO);
102 	callout_drain(&sc->sc_callout);
103 	mtx_lock(&sc->sc_queue_mtx);
104 	for (;;) {
105 		bp = bioq_first(&sc->sc_inqueue);
106 		if (bp != NULL) {
107 			bioq_remove(&sc->sc_inqueue, bp);
108 			sc->sc_queue_count--;
109 			G_GATE_LOGREQ(1, bp, "Request canceled.");
110 			g_io_deliver(bp, ENXIO);
111 		} else {
112 			break;
113 		}
114 	}
115 	for (;;) {
116 		bp = bioq_first(&sc->sc_outqueue);
117 		if (bp != NULL) {
118 			bioq_remove(&sc->sc_outqueue, bp);
119 			sc->sc_queue_count--;
120 			G_GATE_LOGREQ(1, bp, "Request canceled.");
121 			g_io_deliver(bp, ENXIO);
122 		} else {
123 			break;
124 		}
125 	}
126 	mtx_unlock(&sc->sc_queue_mtx);
127 	g_topology_unlock();
128 	mtx_lock(&g_gate_list_mtx);
129 	/* One reference is ours. */
130 	sc->sc_ref--;
131 	while (sc->sc_ref > 0) {
132 		msleep(&sc->sc_ref, &g_gate_list_mtx, 0, "gg:destroy", 0);
133 	}
134 	LIST_REMOVE(sc, sc_next);
135 	mtx_unlock(&g_gate_list_mtx);
136 	mtx_destroy(&sc->sc_queue_mtx);
137 	g_topology_lock();
138 	G_GATE_DEBUG(0, "Device %s destroyed.", gp->name);
139 	gp->softc = NULL;
140 	g_wither_geom(gp, ENXIO);
141 	sc->sc_provider = NULL;
142 	free(sc, M_GATE);
143 	return (0);
144 }
145 
146 static int
147 g_gate_access(struct g_provider *pp, int dr, int dw, int de)
148 {
149 	struct g_gate_softc *sc;
150 
151 	if (dr <= 0 && dw <= 0 && de <= 0)
152 		return (0);
153 	sc = pp->geom->softc;
154 	if (sc == NULL || (sc->sc_flags & G_GATE_FLAG_DESTROY) != 0)
155 		return (ENXIO);
156 	/* XXX: Hack to allow read-only mounts. */
157 #if 0
158 	if ((sc->sc_flags & G_GATE_FLAG_READONLY) != 0 && dw > 0)
159 		return (EPERM);
160 #endif
161 	if ((sc->sc_flags & G_GATE_FLAG_WRITEONLY) != 0 && dr > 0)
162 		return (EPERM);
163 	return (0);
164 }
165 
166 static void
167 g_gate_start(struct bio *bp)
168 {
169 	struct g_gate_softc *sc;
170 
171 	sc = bp->bio_to->geom->softc;
172 	if (sc == NULL || (sc->sc_flags & G_GATE_FLAG_DESTROY) != 0) {
173 		g_io_deliver(bp, ENXIO);
174 		return;
175 	}
176 	G_GATE_LOGREQ(2, bp, "Request received.");
177 	switch (bp->bio_cmd) {
178 	case BIO_READ:
179 		break;
180 	case BIO_DELETE:
181 	case BIO_WRITE:
182 		/* XXX: Hack to allow read-only mounts. */
183 		if ((sc->sc_flags & G_GATE_FLAG_READONLY) != 0) {
184 			g_io_deliver(bp, EPERM);
185 			return;
186 		}
187 		break;
188 	case BIO_GETATTR:
189 	default:
190 		G_GATE_LOGREQ(2, bp, "Ignoring request.");
191 		g_io_deliver(bp, EOPNOTSUPP);
192 		return;
193 	}
194 
195 	mtx_lock(&sc->sc_queue_mtx);
196 	if (sc->sc_queue_count > sc->sc_queue_size) {
197 		mtx_unlock(&sc->sc_queue_mtx);
198 		G_GATE_LOGREQ(1, bp, "Queue full, request canceled.");
199 		g_io_deliver(bp, EIO);
200 		return;
201 	}
202 
203 	bp->bio_driver1 = (void *)sc->sc_seq;
204 	sc->sc_seq++;
205 	sc->sc_queue_count++;
206 
207 	bioq_insert_tail(&sc->sc_inqueue, bp);
208 	wakeup(sc);
209 
210 	mtx_unlock(&sc->sc_queue_mtx);
211 }
212 
213 static struct g_gate_softc *
214 g_gate_hold(u_int unit)
215 {
216 	struct g_gate_softc *sc;
217 
218 	mtx_lock(&g_gate_list_mtx);
219 	LIST_FOREACH(sc, &g_gate_list, sc_next) {
220 		if (sc->sc_unit == unit)
221 			break;
222 	}
223 	if (sc != NULL)
224 		sc->sc_ref++;
225 	mtx_unlock(&g_gate_list_mtx);
226 	return (sc);
227 }
228 
229 static void
230 g_gate_release(struct g_gate_softc *sc)
231 {
232 
233 	g_topology_assert_not();
234 	mtx_lock(&g_gate_list_mtx);
235 	sc->sc_ref--;
236 	KASSERT(sc->sc_ref >= 0, ("Negative sc_ref for %s.", sc->sc_name));
237 	if (sc->sc_ref == 0 && (sc->sc_flags & G_GATE_FLAG_DESTROY) != 0) {
238 		wakeup(&sc->sc_ref);
239 		mtx_unlock(&g_gate_list_mtx);
240 	} else {
241 		mtx_unlock(&g_gate_list_mtx);
242 	}
243 }
244 
245 static int
246 g_gate_getunit(int unit)
247 {
248 	struct g_gate_softc *sc;
249 
250 	mtx_assert(&g_gate_list_mtx, MA_OWNED);
251 	if (unit >= 0) {
252 		LIST_FOREACH(sc, &g_gate_list, sc_next) {
253 			if (sc->sc_unit == unit)
254 				return (-1);
255 		}
256 	} else {
257 		unit = 0;
258 once_again:
259 		LIST_FOREACH(sc, &g_gate_list, sc_next) {
260 			if (sc->sc_unit == unit) {
261 				if (++unit > 666)
262 					return (-1);
263 				goto once_again;
264 			}
265 		}
266 	}
267 	return (unit);
268 }
269 
270 static void
271 g_gate_guard(void *arg)
272 {
273 	struct g_gate_softc *sc;
274 	struct bintime curtime;
275 	struct bio *bp, *bp2;
276 
277 	sc = arg;
278 	binuptime(&curtime);
279 	g_gate_hold(sc->sc_unit);
280 	mtx_lock(&sc->sc_queue_mtx);
281 	TAILQ_FOREACH_SAFE(bp, &sc->sc_inqueue.queue, bio_queue, bp2) {
282 		if (curtime.sec - bp->bio_t0.sec < 5)
283 			continue;
284 		bioq_remove(&sc->sc_inqueue, bp);
285 		sc->sc_queue_count--;
286 		G_GATE_LOGREQ(1, bp, "Request timeout.");
287 		g_io_deliver(bp, EIO);
288 	}
289 	TAILQ_FOREACH_SAFE(bp, &sc->sc_outqueue.queue, bio_queue, bp2) {
290 		if (curtime.sec - bp->bio_t0.sec < 5)
291 			continue;
292 		bioq_remove(&sc->sc_outqueue, bp);
293 		sc->sc_queue_count--;
294 		G_GATE_LOGREQ(1, bp, "Request timeout.");
295 		g_io_deliver(bp, EIO);
296 	}
297 	mtx_unlock(&sc->sc_queue_mtx);
298 	if ((sc->sc_flags & G_GATE_FLAG_DESTROY) == 0) {
299 		callout_reset(&sc->sc_callout, sc->sc_timeout * hz,
300 		    g_gate_guard, sc);
301 	}
302 	g_gate_release(sc);
303 }
304 
305 static void
306 g_gate_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp,
307     struct g_consumer *cp, struct g_provider *pp)
308 {
309 	struct g_gate_softc *sc;
310 
311 	sc = gp->softc;
312 	if (sc == NULL || pp != NULL || cp != NULL)
313 		return;
314 	g_gate_hold(sc->sc_unit);
315 	if ((sc->sc_flags & G_GATE_FLAG_READONLY) != 0) {
316 		sbuf_printf(sb, "%s<access>%s</access>\n", indent, "read-only");
317 	} else if ((sc->sc_flags & G_GATE_FLAG_WRITEONLY) != 0) {
318 		sbuf_printf(sb, "%s<access>%s</access>\n", indent,
319 		    "write-only");
320 	} else {
321 		sbuf_printf(sb, "%s<access>%s</access>\n", indent,
322 		    "read-write");
323 	}
324 	sbuf_printf(sb, "%s<timeout>%u</timeout>\n", indent, sc->sc_timeout);
325 	sbuf_printf(sb, "%s<info>%s</info>\n", indent, sc->sc_info);
326 	sbuf_printf(sb, "%s<queue_count>%u</queue_count>\n", indent,
327 	    sc->sc_queue_count);
328 	sbuf_printf(sb, "%s<queue_size>%u</queue_size>\n", indent,
329 	    sc->sc_queue_size);
330 	sbuf_printf(sb, "%s<ref>%u</ref>\n", indent, sc->sc_ref);
331 	g_topology_unlock();
332 	g_gate_release(sc);
333 	g_topology_lock();
334 }
335 
336 static int
337 g_gate_create(struct g_gate_ctl_create *ggio)
338 {
339 	struct g_gate_softc *sc;
340 	struct g_geom *gp;
341 	struct g_provider *pp;
342 
343 	if (ggio->gctl_mediasize == 0) {
344 		G_GATE_DEBUG(1, "Invalid media size.");
345 		return (EINVAL);
346 	}
347 	if (ggio->gctl_sectorsize > 0 && !powerof2(ggio->gctl_sectorsize)) {
348 		G_GATE_DEBUG(1, "Invalid sector size.");
349 		return (EINVAL);
350 	}
351 	if ((ggio->gctl_mediasize % ggio->gctl_sectorsize) != 0) {
352 		G_GATE_DEBUG(1, "Invalid media size.");
353 		return (EINVAL);
354 	}
355 	if ((ggio->gctl_flags & G_GATE_FLAG_READONLY) != 0 &&
356 	    (ggio->gctl_flags & G_GATE_FLAG_WRITEONLY) != 0) {
357 		G_GATE_DEBUG(1, "Invalid flags.");
358 		return (EINVAL);
359 	}
360 	if (ggio->gctl_unit < -1) {
361 		G_GATE_DEBUG(1, "Invalid unit number.");
362 		return (EINVAL);
363 	}
364 
365 	sc = malloc(sizeof(*sc), M_GATE, M_WAITOK | M_ZERO);
366 	sc->sc_flags = (ggio->gctl_flags & G_GATE_USERFLAGS);
367 	strlcpy(sc->sc_info, ggio->gctl_info, sizeof(sc->sc_info));
368 	sc->sc_seq = 0;
369 	bioq_init(&sc->sc_inqueue);
370 	bioq_init(&sc->sc_outqueue);
371 	mtx_init(&sc->sc_queue_mtx, "gg:queue", NULL, MTX_DEF);
372 	sc->sc_queue_count = 0;
373 	sc->sc_queue_size = ggio->gctl_maxcount;
374 	if (sc->sc_queue_size > G_GATE_MAX_QUEUE_SIZE)
375 		sc->sc_queue_size = G_GATE_MAX_QUEUE_SIZE;
376 	sc->sc_timeout = ggio->gctl_timeout;
377 	callout_init(&sc->sc_callout, CALLOUT_MPSAFE);
378 	mtx_lock(&g_gate_list_mtx);
379 	ggio->gctl_unit = g_gate_getunit(ggio->gctl_unit);
380 	if (ggio->gctl_unit == -1) {
381 		mtx_unlock(&g_gate_list_mtx);
382 		mtx_destroy(&sc->sc_queue_mtx);
383 		free(sc, M_GATE);
384 		return (EBUSY);
385 	}
386 	sc->sc_unit = ggio->gctl_unit;
387 	LIST_INSERT_HEAD(&g_gate_list, sc, sc_next);
388 	mtx_unlock(&g_gate_list_mtx);
389 
390 	g_topology_lock();
391 	gp = g_new_geomf(&g_gate_class, "%s%d", G_GATE_PROVIDER_NAME,
392 	    sc->sc_unit);
393 	gp->start = g_gate_start;
394 	gp->access = g_gate_access;
395 	gp->dumpconf = g_gate_dumpconf;
396 	gp->softc = sc;
397 	pp = g_new_providerf(gp, "%s%d", G_GATE_PROVIDER_NAME, sc->sc_unit);
398 	pp->mediasize = ggio->gctl_mediasize;
399 	pp->sectorsize = ggio->gctl_sectorsize;
400 	sc->sc_provider = pp;
401 	g_error_provider(pp, 0);
402 	g_topology_unlock();
403 
404 	if (sc->sc_timeout > 0) {
405 		callout_reset(&sc->sc_callout, sc->sc_timeout * hz,
406 		    g_gate_guard, sc);
407 	}
408 	return (0);
409 }
410 
411 #define	G_GATE_CHECK_VERSION(ggio)	do {				\
412 	if ((ggio)->gctl_version != G_GATE_VERSION) {			\
413 		printf("Version mismatch %d != %d.\n",			\
414 		    ggio->gctl_version, G_GATE_VERSION);		\
415 		return (EINVAL);					\
416 	}								\
417 } while (0)
418 static int
419 g_gate_ioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags, struct thread *td)
420 {
421 	struct g_gate_softc *sc;
422 	struct bio *bp;
423 	int error = 0;
424 
425 	G_GATE_DEBUG(4, "ioctl(%s, %lx, %p, %x, %p)", devtoname(dev), cmd, addr,
426 	    flags, td);
427 
428 	switch (cmd) {
429 	case G_GATE_CMD_CREATE:
430 	    {
431 		struct g_gate_ctl_create *ggio = (void *)addr;
432 
433 		G_GATE_CHECK_VERSION(ggio);
434 		error = g_gate_create(ggio);
435 		/*
436 		 * Reset TDP_GEOM flag.
437 		 * There are pending events for sure, because we just created
438 		 * new provider and other classes want to taste it, but we
439 		 * cannot answer on I/O requests until we're here.
440 		 */
441 		td->td_pflags &= ~TDP_GEOM;
442 		return (error);
443 	    }
444 	case G_GATE_CMD_DESTROY:
445 	    {
446 		struct g_gate_ctl_destroy *ggio = (void *)addr;
447 
448 		G_GATE_CHECK_VERSION(ggio);
449 		sc = g_gate_hold(ggio->gctl_unit);
450 		if (sc == NULL)
451 			return (ENXIO);
452 		g_topology_lock();
453 		mtx_lock(&g_gate_list_mtx);
454 		error = g_gate_destroy(sc, ggio->gctl_force);
455 		g_topology_unlock();
456 		if (error != 0)
457 			g_gate_release(sc);
458 		return (error);
459 	    }
460 	case G_GATE_CMD_CANCEL:
461 	    {
462 		struct g_gate_ctl_cancel *ggio = (void *)addr;
463 		struct bio *tbp, *lbp;
464 
465 		G_GATE_CHECK_VERSION(ggio);
466 		sc = g_gate_hold(ggio->gctl_unit);
467 		if (sc == NULL)
468 			return (ENXIO);
469 		lbp = NULL;
470 		mtx_lock(&sc->sc_queue_mtx);
471 		TAILQ_FOREACH_SAFE(bp, &sc->sc_outqueue.queue, bio_queue, tbp) {
472 			if (ggio->gctl_seq == 0 ||
473 			    ggio->gctl_seq == (uintptr_t)bp->bio_driver1) {
474 				G_GATE_LOGREQ(1, bp, "Request canceled.");
475 				bioq_remove(&sc->sc_outqueue, bp);
476 				/*
477 				 * Be sure to put requests back onto incoming
478 				 * queue in the proper order.
479 				 */
480 				if (lbp == NULL)
481 					bioq_insert_head(&sc->sc_inqueue, bp);
482 				else {
483 					TAILQ_INSERT_AFTER(&sc->sc_inqueue.queue,
484 					    lbp, bp, bio_queue);
485 				}
486 				lbp = bp;
487 				/*
488 				 * If only one request was canceled, leave now.
489 				 */
490 				if (ggio->gctl_seq != 0)
491 					break;
492 			}
493 		}
494 		mtx_unlock(&sc->sc_queue_mtx);
495 		g_gate_release(sc);
496 		return (error);
497 	    }
498 	case G_GATE_CMD_START:
499 	    {
500 		struct g_gate_ctl_io *ggio = (void *)addr;
501 
502 		G_GATE_CHECK_VERSION(ggio);
503 		sc = g_gate_hold(ggio->gctl_unit);
504 		if (sc == NULL)
505 			return (ENXIO);
506 		error = 0;
507 		for (;;) {
508 			mtx_lock(&sc->sc_queue_mtx);
509 			bp = bioq_first(&sc->sc_inqueue);
510 			if (bp != NULL)
511 				break;
512 			if ((sc->sc_flags & G_GATE_FLAG_DESTROY) != 0) {
513 				ggio->gctl_error = ECANCELED;
514 				mtx_unlock(&sc->sc_queue_mtx);
515 				goto start_end;
516 			}
517 			if (msleep(sc, &sc->sc_queue_mtx,
518 			    PPAUSE | PDROP | PCATCH, "ggwait", 0) != 0) {
519 				ggio->gctl_error = ECANCELED;
520 				goto start_end;
521 			}
522 		}
523 		ggio->gctl_cmd = bp->bio_cmd;
524 		if ((bp->bio_cmd == BIO_DELETE || bp->bio_cmd == BIO_WRITE) &&
525 		    bp->bio_length > ggio->gctl_length) {
526 			mtx_unlock(&sc->sc_queue_mtx);
527 			ggio->gctl_length = bp->bio_length;
528 			ggio->gctl_error = ENOMEM;
529 			goto start_end;
530 		}
531 		bioq_remove(&sc->sc_inqueue, bp);
532 		bioq_insert_tail(&sc->sc_outqueue, bp);
533 		mtx_unlock(&sc->sc_queue_mtx);
534 
535 		ggio->gctl_seq = (uintptr_t)bp->bio_driver1;
536 		ggio->gctl_offset = bp->bio_offset;
537 		ggio->gctl_length = bp->bio_length;
538 
539 		switch (bp->bio_cmd) {
540 		case BIO_READ:
541 			break;
542 		case BIO_DELETE:
543 		case BIO_WRITE:
544 			error = copyout(bp->bio_data, ggio->gctl_data,
545 			    bp->bio_length);
546 			if (error != 0) {
547 				mtx_lock(&sc->sc_queue_mtx);
548 				bioq_remove(&sc->sc_outqueue, bp);
549 				bioq_insert_head(&sc->sc_inqueue, bp);
550 				mtx_unlock(&sc->sc_queue_mtx);
551 				goto start_end;
552 			}
553 			break;
554 		}
555 start_end:
556 		g_gate_release(sc);
557 		return (error);
558 	    }
559 	case G_GATE_CMD_DONE:
560 	    {
561 		struct g_gate_ctl_io *ggio = (void *)addr;
562 
563 		G_GATE_CHECK_VERSION(ggio);
564 		sc = g_gate_hold(ggio->gctl_unit);
565 		if (sc == NULL)
566 			return (ENOENT);
567 		error = 0;
568 		mtx_lock(&sc->sc_queue_mtx);
569 		TAILQ_FOREACH(bp, &sc->sc_outqueue.queue, bio_queue) {
570 			if (ggio->gctl_seq == (uintptr_t)bp->bio_driver1)
571 				break;
572 		}
573 		if (bp != NULL) {
574 			bioq_remove(&sc->sc_outqueue, bp);
575 			sc->sc_queue_count--;
576 		}
577 		mtx_unlock(&sc->sc_queue_mtx);
578 		if (bp == NULL) {
579 			/*
580 			 * Request was probably canceled.
581 			 */
582 			goto done_end;
583 		}
584 		if (ggio->gctl_error == EAGAIN) {
585 			bp->bio_error = 0;
586 			G_GATE_LOGREQ(1, bp, "Request desisted.");
587 			mtx_lock(&sc->sc_queue_mtx);
588 			sc->sc_queue_count++;
589 			bioq_insert_head(&sc->sc_inqueue, bp);
590 			wakeup(sc);
591 			mtx_unlock(&sc->sc_queue_mtx);
592 		} else {
593 			bp->bio_error = ggio->gctl_error;
594 			if (bp->bio_error == 0) {
595 				bp->bio_completed = bp->bio_length;
596 				switch (bp->bio_cmd) {
597 				case BIO_READ:
598 					error = copyin(ggio->gctl_data,
599 					    bp->bio_data, bp->bio_length);
600 					if (error != 0)
601 						bp->bio_error = error;
602 					break;
603 				case BIO_DELETE:
604 				case BIO_WRITE:
605 					break;
606 				}
607 			}
608 			G_GATE_LOGREQ(2, bp, "Request done.");
609 			g_io_deliver(bp, bp->bio_error);
610 		}
611 done_end:
612 		g_gate_release(sc);
613 		return (error);
614 	    }
615 	}
616 	return (ENOIOCTL);
617 }
618 
619 static void
620 g_gate_device(void)
621 {
622 
623 	status_dev = make_dev(&g_gate_cdevsw, 0x0, UID_ROOT, GID_WHEEL, 0600,
624 	    G_GATE_CTL_NAME);
625 }
626 
627 static int
628 g_gate_modevent(module_t mod, int type, void *data)
629 {
630 	int error = 0;
631 
632 	switch (type) {
633 	case MOD_LOAD:
634 		mtx_init(&g_gate_list_mtx, "gg_list_lock", NULL, MTX_DEF);
635 		g_gate_device();
636 		break;
637 	case MOD_UNLOAD:
638 		mtx_lock(&g_gate_list_mtx);
639 		if (!LIST_EMPTY(&g_gate_list)) {
640 			mtx_unlock(&g_gate_list_mtx);
641 			error = EBUSY;
642 			break;
643 		}
644 		mtx_unlock(&g_gate_list_mtx);
645 		mtx_destroy(&g_gate_list_mtx);
646 		if (status_dev != 0)
647 			destroy_dev(status_dev);
648 		break;
649 	default:
650 		return (EOPNOTSUPP);
651 		break;
652 	}
653 
654 	return (error);
655 }
656 static moduledata_t g_gate_module = {
657 	G_GATE_MOD_NAME,
658 	g_gate_modevent,
659 	NULL
660 };
661 DECLARE_MODULE(geom_gate, g_gate_module, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
662 DECLARE_GEOM_CLASS(g_gate_class, g_gate);
663