xref: /freebsd/sys/geom/gate/g_gate.c (revision 4f29da19bd44f0e99f021510460a81bf754c21d2)
1 /*-
2  * Copyright (c) 2004-2005 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  * $FreeBSD$
27  */
28 
29 #include <sys/param.h>
30 #include <sys/systm.h>
31 #include <sys/bio.h>
32 #include <sys/conf.h>
33 #include <sys/kernel.h>
34 #include <sys/kthread.h>
35 #include <sys/fcntl.h>
36 #include <sys/linker.h>
37 #include <sys/lock.h>
38 #include <sys/malloc.h>
39 #include <sys/mutex.h>
40 #include <sys/proc.h>
41 #include <sys/limits.h>
42 #include <sys/queue.h>
43 #include <sys/sysctl.h>
44 #include <sys/signalvar.h>
45 #include <sys/time.h>
46 #include <machine/atomic.h>
47 
48 #include <geom/geom.h>
49 #include <geom/gate/g_gate.h>
50 
51 static MALLOC_DEFINE(M_GATE, "gg_data", "GEOM Gate Data");
52 
53 SYSCTL_DECL(_kern_geom);
54 SYSCTL_NODE(_kern_geom, OID_AUTO, gate, CTLFLAG_RW, 0, "GEOM_GATE stuff");
55 static u_int g_gate_debug = 0;
56 SYSCTL_UINT(_kern_geom_gate, OID_AUTO, debug, CTLFLAG_RW, &g_gate_debug, 0,
57     "Debug level");
58 
59 static int g_gate_destroy_geom(struct gctl_req *, struct g_class *,
60     struct g_geom *);
61 struct g_class g_gate_class = {
62 	.name = G_GATE_CLASS_NAME,
63 	.version = G_VERSION,
64 	.destroy_geom = g_gate_destroy_geom
65 };
66 
67 static struct cdev *status_dev;
68 static d_ioctl_t g_gate_ioctl;
69 static struct cdevsw g_gate_cdevsw = {
70 	.d_version =	D_VERSION,
71 	.d_ioctl =	g_gate_ioctl,
72 	.d_name =	G_GATE_CTL_NAME
73 };
74 
75 
76 static LIST_HEAD(, g_gate_softc) g_gate_list =
77     LIST_HEAD_INITIALIZER(&g_gate_list);
78 static struct mtx g_gate_list_mtx;
79 
80 
81 static void
82 g_gate_wither(struct g_gate_softc *sc)
83 {
84 
85 	atomic_set_32(&sc->sc_flags, G_GATE_FLAG_DESTROY);
86 }
87 
88 static int
89 g_gate_destroy(struct g_gate_softc *sc, boolean_t force)
90 {
91 	struct g_provider *pp;
92 	struct bio *bp;
93 
94 	g_topology_assert();
95 	mtx_assert(&g_gate_list_mtx, MA_OWNED);
96 	pp = sc->sc_provider;
97 	if (!force && (pp->acr != 0 || pp->acw != 0 || pp->ace != 0)) {
98 		mtx_unlock(&g_gate_list_mtx);
99 		return (EBUSY);
100 	}
101 	if ((sc->sc_flags & G_GATE_FLAG_DESTROY) == 0) {
102 		g_gate_wither(sc);
103 		LIST_REMOVE(sc, sc_next);
104 	}
105 	mtx_unlock(&g_gate_list_mtx);
106 	mtx_lock(&sc->sc_queue_mtx);
107 	wakeup(sc);
108 	mtx_unlock(&sc->sc_queue_mtx);
109 	if (sc->sc_ref > 0) {
110 		G_GATE_DEBUG(1, "Cannot destroy %s yet.", sc->sc_name);
111 		return (0);
112 	}
113 	callout_drain(&sc->sc_callout);
114 	mtx_lock(&sc->sc_queue_mtx);
115 	for (;;) {
116 		bp = bioq_first(&sc->sc_inqueue);
117 		if (bp != NULL) {
118 			bioq_remove(&sc->sc_inqueue, 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 	for (;;) {
127 		bp = bioq_first(&sc->sc_outqueue);
128 		if (bp != NULL) {
129 			bioq_remove(&sc->sc_outqueue, bp);
130 			sc->sc_queue_count--;
131 			G_GATE_LOGREQ(1, bp, "Request canceled.");
132 			g_io_deliver(bp, ENXIO);
133 		} else {
134 			break;
135 		}
136 	}
137 	mtx_destroy(&sc->sc_queue_mtx);
138 	G_GATE_DEBUG(0, "Device %s destroyed.", sc->sc_name);
139 	pp->geom->softc = NULL;
140 	g_wither_geom(pp->geom, ENXIO);
141 	sc->sc_provider = NULL;
142 	free(sc, M_GATE);
143 	return (0);
144 }
145 
146 static void
147 g_gate_destroy_it(void *arg, int flag __unused)
148 {
149 	struct g_gate_softc *sc;
150 
151 	g_topology_assert();
152 	sc = arg;
153 	mtx_lock(&g_gate_list_mtx);
154 	g_gate_destroy(sc, 1);
155 }
156 
157 static int
158 g_gate_destroy_geom(struct gctl_req *req, struct g_class *mp, struct g_geom *gp)
159 {
160 
161 	g_topology_assert();
162 	mtx_lock(&g_gate_list_mtx);
163 	return (g_gate_destroy(gp->softc, 0));
164 }
165 
166 static int
167 g_gate_access(struct g_provider *pp, int dr, int dw, int de)
168 {
169 	struct g_gate_softc *sc;
170 
171 	if (dr <= 0 && dw <= 0 && de <= 0)
172 		return (0);
173 	sc = pp->geom->softc;
174 	if (sc == NULL || (sc->sc_flags & G_GATE_FLAG_DESTROY) != 0)
175 		return (ENXIO);
176 	/* XXX: Hack to allow read-only mounts. */
177 #if 0
178 	if ((sc->sc_flags & G_GATE_FLAG_READONLY) != 0 && dw > 0)
179 		return (EPERM);
180 #endif
181 	if ((sc->sc_flags & G_GATE_FLAG_WRITEONLY) != 0 && dr > 0)
182 		return (EPERM);
183 	return (0);
184 }
185 
186 static void
187 g_gate_start(struct bio *bp)
188 {
189 	struct g_gate_softc *sc;
190 
191 	sc = bp->bio_to->geom->softc;
192 	if (sc == NULL || (sc->sc_flags & G_GATE_FLAG_DESTROY) != 0) {
193 		g_io_deliver(bp, ENXIO);
194 		return;
195 	}
196 	G_GATE_LOGREQ(2, bp, "Request received.");
197 	switch (bp->bio_cmd) {
198 	case BIO_READ:
199 		break;
200 	case BIO_DELETE:
201 	case BIO_WRITE:
202 		/* XXX: Hack to allow read-only mounts. */
203 		if ((sc->sc_flags & G_GATE_FLAG_READONLY) != 0) {
204 			g_io_deliver(bp, EPERM);
205 			return;
206 		}
207 		break;
208 	case BIO_GETATTR:
209 	default:
210 		G_GATE_LOGREQ(2, bp, "Ignoring request.");
211 		g_io_deliver(bp, EOPNOTSUPP);
212 		return;
213 	}
214 
215 	mtx_lock(&sc->sc_queue_mtx);
216 	if (sc->sc_queue_count > sc->sc_queue_size) {
217 		mtx_unlock(&sc->sc_queue_mtx);
218 		G_GATE_LOGREQ(1, bp, "Queue full, request canceled.");
219 		g_io_deliver(bp, EIO);
220 		return;
221 	}
222 
223 	bp->bio_driver1 = (void *)sc->sc_seq;
224 	sc->sc_seq++;
225 	sc->sc_queue_count++;
226 
227 	bioq_insert_tail(&sc->sc_inqueue, bp);
228 	wakeup(sc);
229 
230 	mtx_unlock(&sc->sc_queue_mtx);
231 }
232 
233 static struct g_gate_softc *
234 g_gate_find(u_int unit)
235 {
236 	struct g_gate_softc *sc;
237 
238 	LIST_FOREACH(sc, &g_gate_list, sc_next) {
239 		if (sc->sc_unit == unit)
240 			break;
241 	}
242 	return (sc);
243 }
244 
245 static struct g_gate_softc *
246 g_gate_hold(u_int unit)
247 {
248 	struct g_gate_softc *sc;
249 
250 	mtx_lock(&g_gate_list_mtx);
251 	sc = g_gate_find(unit);
252 	if (sc != NULL) {
253 		if ((sc->sc_flags & G_GATE_FLAG_DESTROY) != 0)
254 			sc = NULL;
255 		else
256 			sc->sc_ref++;
257 	}
258 	mtx_unlock(&g_gate_list_mtx);
259 	return (sc);
260 }
261 
262 static void
263 g_gate_release(struct g_gate_softc *sc)
264 {
265 
266 	g_topology_assert_not();
267 	mtx_lock(&g_gate_list_mtx);
268 	sc->sc_ref--;
269 	KASSERT(sc->sc_ref >= 0, ("Negative sc_ref for %s.", sc->sc_name));
270 	if (sc->sc_ref == 0 && (sc->sc_flags & G_GATE_FLAG_DESTROY) != 0) {
271 		mtx_unlock(&g_gate_list_mtx);
272 		g_waitfor_event(g_gate_destroy_it, sc, M_WAITOK, NULL);
273 	} else {
274 		mtx_unlock(&g_gate_list_mtx);
275 	}
276 }
277 
278 static int
279 g_gate_getunit(int unit)
280 {
281 	struct g_gate_softc *sc;
282 
283 	mtx_assert(&g_gate_list_mtx, MA_OWNED);
284 	if (unit >= 0) {
285 		LIST_FOREACH(sc, &g_gate_list, sc_next) {
286 			if (sc->sc_unit == unit)
287 				return (-1);
288 		}
289 	} else {
290 		unit = 0;
291 once_again:
292 		LIST_FOREACH(sc, &g_gate_list, sc_next) {
293 			if (sc->sc_unit == unit) {
294 				if (++unit > 666)
295 					return (-1);
296 				goto once_again;
297 			}
298 		}
299 	}
300 	return (unit);
301 }
302 
303 static void
304 g_gate_guard(void *arg)
305 {
306 	struct g_gate_softc *sc;
307 	struct bintime curtime;
308 	struct bio *bp, *bp2;
309 
310 	sc = arg;
311 	binuptime(&curtime);
312 	g_gate_hold(sc->sc_unit);
313 	mtx_lock(&sc->sc_queue_mtx);
314 	TAILQ_FOREACH_SAFE(bp, &sc->sc_inqueue.queue, bio_queue, bp2) {
315 		if (curtime.sec - bp->bio_t0.sec < 5)
316 			continue;
317 		bioq_remove(&sc->sc_inqueue, bp);
318 		sc->sc_queue_count--;
319 		G_GATE_LOGREQ(1, bp, "Request timeout.");
320 		g_io_deliver(bp, EIO);
321 	}
322 	TAILQ_FOREACH_SAFE(bp, &sc->sc_outqueue.queue, bio_queue, bp2) {
323 		if (curtime.sec - bp->bio_t0.sec < 5)
324 			continue;
325 		bioq_remove(&sc->sc_outqueue, bp);
326 		sc->sc_queue_count--;
327 		G_GATE_LOGREQ(1, bp, "Request timeout.");
328 		g_io_deliver(bp, EIO);
329 	}
330 	mtx_unlock(&sc->sc_queue_mtx);
331 	if ((sc->sc_flags & G_GATE_FLAG_DESTROY) == 0) {
332 		callout_reset(&sc->sc_callout, sc->sc_timeout * hz,
333 		    g_gate_guard, sc);
334 	}
335 	g_gate_release(sc);
336 }
337 
338 static void
339 g_gate_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp,
340     struct g_consumer *cp, struct g_provider *pp)
341 {
342 	struct g_gate_softc *sc;
343 
344 	sc = gp->softc;
345 	if (sc == NULL || pp != NULL || cp != NULL)
346 		return;
347 	g_gate_hold(sc->sc_unit);
348 	if ((sc->sc_flags & G_GATE_FLAG_READONLY) != 0) {
349 		sbuf_printf(sb, "%s<access>%s</access>\n", indent, "read-only");
350 	} else if ((sc->sc_flags & G_GATE_FLAG_WRITEONLY) != 0) {
351 		sbuf_printf(sb, "%s<access>%s</access>\n", indent,
352 		    "write-only");
353 	} else {
354 		sbuf_printf(sb, "%s<access>%s</access>\n", indent,
355 		    "read-write");
356 	}
357 	sbuf_printf(sb, "%s<timeout>%u</timeout>\n", indent, sc->sc_timeout);
358 	sbuf_printf(sb, "%s<info>%s</info>\n", indent, sc->sc_info);
359 	sbuf_printf(sb, "%s<queue_count>%u</queue_count>\n", indent,
360 	    sc->sc_queue_count);
361 	sbuf_printf(sb, "%s<queue_size>%u</queue_size>\n", indent,
362 	    sc->sc_queue_size);
363 	sbuf_printf(sb, "%s<ref>%u</ref>\n", indent, sc->sc_ref);
364 	g_topology_unlock();
365 	g_gate_release(sc);
366 	g_topology_lock();
367 }
368 
369 static int
370 g_gate_create(struct g_gate_ctl_create *ggio)
371 {
372 	struct g_gate_softc *sc;
373 	struct g_geom *gp;
374 	struct g_provider *pp;
375 
376 	if (ggio->gctl_mediasize == 0) {
377 		G_GATE_DEBUG(1, "Invalid media size.");
378 		return (EINVAL);
379 	}
380 	if (ggio->gctl_sectorsize > 0 && !powerof2(ggio->gctl_sectorsize)) {
381 		G_GATE_DEBUG(1, "Invalid sector size.");
382 		return (EINVAL);
383 	}
384 	if ((ggio->gctl_mediasize % ggio->gctl_sectorsize) != 0) {
385 		G_GATE_DEBUG(1, "Invalid media size.");
386 		return (EINVAL);
387 	}
388 	if ((ggio->gctl_flags & G_GATE_FLAG_READONLY) != 0 &&
389 	    (ggio->gctl_flags & G_GATE_FLAG_WRITEONLY) != 0) {
390 		G_GATE_DEBUG(1, "Invalid flags.");
391 		return (EINVAL);
392 	}
393 	if (ggio->gctl_unit < -1) {
394 		G_GATE_DEBUG(1, "Invalid unit number.");
395 		return (EINVAL);
396 	}
397 
398 	sc = malloc(sizeof(*sc), M_GATE, M_WAITOK | M_ZERO);
399 	sc->sc_flags = (ggio->gctl_flags & G_GATE_USERFLAGS);
400 	strlcpy(sc->sc_info, ggio->gctl_info, sizeof(sc->sc_info));
401 	sc->sc_seq = 0;
402 	bioq_init(&sc->sc_inqueue);
403 	bioq_init(&sc->sc_outqueue);
404 	mtx_init(&sc->sc_queue_mtx, "gg:queue", NULL, MTX_DEF);
405 	sc->sc_queue_count = 0;
406 	sc->sc_queue_size = ggio->gctl_maxcount;
407 	if (sc->sc_queue_size > G_GATE_MAX_QUEUE_SIZE)
408 		sc->sc_queue_size = G_GATE_MAX_QUEUE_SIZE;
409 	sc->sc_timeout = ggio->gctl_timeout;
410 	callout_init(&sc->sc_callout, CALLOUT_MPSAFE);
411 	mtx_lock(&g_gate_list_mtx);
412 	ggio->gctl_unit = g_gate_getunit(ggio->gctl_unit);
413 	if (ggio->gctl_unit == -1) {
414 		mtx_unlock(&g_gate_list_mtx);
415 		mtx_destroy(&sc->sc_queue_mtx);
416 		free(sc, M_GATE);
417 		return (EBUSY);
418 	}
419 	sc->sc_unit = ggio->gctl_unit;
420 	LIST_INSERT_HEAD(&g_gate_list, sc, sc_next);
421 	mtx_unlock(&g_gate_list_mtx);
422 
423 	g_topology_lock();
424 	gp = g_new_geomf(&g_gate_class, "%s%d", G_GATE_PROVIDER_NAME,
425 	    sc->sc_unit);
426 	gp->start = g_gate_start;
427 	gp->access = g_gate_access;
428 	gp->dumpconf = g_gate_dumpconf;
429 	gp->softc = sc;
430 	pp = g_new_providerf(gp, "%s%d", G_GATE_PROVIDER_NAME, sc->sc_unit);
431 	pp->mediasize = ggio->gctl_mediasize;
432 	pp->sectorsize = ggio->gctl_sectorsize;
433 	sc->sc_provider = pp;
434 	g_error_provider(pp, 0);
435 	g_topology_unlock();
436 
437 	if (sc->sc_timeout > 0) {
438 		callout_reset(&sc->sc_callout, sc->sc_timeout * hz,
439 		    g_gate_guard, sc);
440 	}
441 	return (0);
442 }
443 
444 #define	G_GATE_CHECK_VERSION(ggio)	do {				\
445 	if ((ggio)->gctl_version != G_GATE_VERSION) {			\
446 		printf("Version mismatch %d != %d.\n",			\
447 		    ggio->gctl_version, G_GATE_VERSION);		\
448 		return (EINVAL);					\
449 	}								\
450 } while (0)
451 static int
452 g_gate_ioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags, struct thread *td)
453 {
454 	struct g_gate_softc *sc;
455 	struct bio *bp;
456 	int error = 0;
457 
458 	G_GATE_DEBUG(4, "ioctl(%s, %lx, %p, %x, %p)", devtoname(dev), cmd, addr,
459 	    flags, td);
460 
461 	switch (cmd) {
462 	case G_GATE_CMD_CREATE:
463 	    {
464 		struct g_gate_ctl_create *ggio = (void *)addr;
465 
466 		G_GATE_CHECK_VERSION(ggio);
467 		error = g_gate_create(ggio);
468 		/*
469 		 * Reset TDP_GEOM flag.
470 		 * There are pending events for sure, because we just created
471 		 * new provider and other classes want to taste it, but we
472 		 * cannot answer on I/O requests until we're here.
473 		 */
474 		td->td_pflags &= ~TDP_GEOM;
475 		return (error);
476 	    }
477 	case G_GATE_CMD_DESTROY:
478 	    {
479 		struct g_gate_ctl_destroy *ggio = (void *)addr;
480 
481 		G_GATE_CHECK_VERSION(ggio);
482 		sc = g_gate_hold(ggio->gctl_unit);
483 		if (sc == NULL)
484 			return (ENXIO);
485 		g_topology_lock();
486 		mtx_lock(&g_gate_list_mtx);
487 		error = g_gate_destroy(sc, ggio->gctl_force);
488 		if (error == 0)
489 			g_gate_wither(sc);
490 		g_topology_unlock();
491 		g_gate_release(sc);
492 		return (error);
493 	    }
494 	case G_GATE_CMD_CANCEL:
495 	    {
496 		struct g_gate_ctl_cancel *ggio = (void *)addr;
497 		struct bio *tbp, *lbp;
498 
499 		G_GATE_CHECK_VERSION(ggio);
500 		sc = g_gate_hold(ggio->gctl_unit);
501 		if (sc == NULL)
502 			return (ENXIO);
503 		lbp = NULL;
504 		mtx_lock(&sc->sc_queue_mtx);
505 		TAILQ_FOREACH_SAFE(bp, &sc->sc_outqueue.queue, bio_queue, tbp) {
506 			if (ggio->gctl_seq == 0 ||
507 			    ggio->gctl_seq == (uintptr_t)bp->bio_driver1) {
508 				G_GATE_LOGREQ(1, bp, "Request canceled.");
509 				bioq_remove(&sc->sc_outqueue, bp);
510 				/*
511 				 * Be sure to put requests back onto incoming
512 				 * queue in the proper order.
513 				 */
514 				if (lbp == NULL)
515 					bioq_insert_head(&sc->sc_inqueue, bp);
516 				else {
517 					TAILQ_INSERT_AFTER(&sc->sc_inqueue.queue,
518 					    lbp, bp, bio_queue);
519 				}
520 				lbp = bp;
521 				/*
522 				 * If only one request was canceled, leave now.
523 				 */
524 				if (ggio->gctl_seq != 0)
525 					break;
526 			}
527 		}
528 		mtx_unlock(&sc->sc_queue_mtx);
529 		g_gate_release(sc);
530 		return (error);
531 	    }
532 	case G_GATE_CMD_START:
533 	    {
534 		struct g_gate_ctl_io *ggio = (void *)addr;
535 
536 		G_GATE_CHECK_VERSION(ggio);
537 		sc = g_gate_find(ggio->gctl_unit);
538 		if (sc == NULL)
539 			return (ENXIO);
540 		for (;;) {
541 			mtx_lock(&sc->sc_queue_mtx);
542 			bp = bioq_first(&sc->sc_inqueue);
543 			if (bp != NULL)
544 				break;
545 			if (msleep(sc, &sc->sc_queue_mtx,
546 			    PPAUSE | PDROP | PCATCH, "ggwait", 0) != 0) {
547 				ggio->gctl_error = ECANCELED;
548 				return (0);
549 			}
550 			if ((sc->sc_flags & G_GATE_FLAG_DESTROY) != 0) {
551 				ggio->gctl_error = ECANCELED;
552 				return (0);
553 			}
554 		}
555 		ggio->gctl_cmd = bp->bio_cmd;
556 		if ((bp->bio_cmd == BIO_DELETE || bp->bio_cmd == BIO_WRITE) &&
557 		    bp->bio_length > ggio->gctl_length) {
558 			mtx_unlock(&sc->sc_queue_mtx);
559 			ggio->gctl_length = bp->bio_length;
560 			ggio->gctl_error = ENOMEM;
561 			return (0);
562 		}
563 		bioq_remove(&sc->sc_inqueue, bp);
564 		bioq_insert_tail(&sc->sc_outqueue, bp);
565 		mtx_unlock(&sc->sc_queue_mtx);
566 
567 		ggio->gctl_seq = (uintptr_t)bp->bio_driver1;
568 		ggio->gctl_offset = bp->bio_offset;
569 		ggio->gctl_length = bp->bio_length;
570 
571 		switch (bp->bio_cmd) {
572 		case BIO_READ:
573 			break;
574 		case BIO_DELETE:
575 		case BIO_WRITE:
576 			error = copyout(bp->bio_data, ggio->gctl_data,
577 			    bp->bio_length);
578 			if (error != 0) {
579 				mtx_lock(&sc->sc_queue_mtx);
580 				bioq_remove(&sc->sc_outqueue, bp);
581 				bioq_insert_head(&sc->sc_inqueue, bp);
582 				mtx_unlock(&sc->sc_queue_mtx);
583 				return (error);
584 			}
585 			break;
586 		}
587 		return (0);
588 	    }
589 	case G_GATE_CMD_DONE:
590 	    {
591 		struct g_gate_ctl_io *ggio = (void *)addr;
592 
593 		G_GATE_CHECK_VERSION(ggio);
594 		sc = g_gate_find(ggio->gctl_unit);
595 		if (sc == NULL)
596 			return (ENOENT);
597 		mtx_lock(&sc->sc_queue_mtx);
598 		TAILQ_FOREACH(bp, &sc->sc_outqueue.queue, bio_queue) {
599 			if (ggio->gctl_seq == (uintptr_t)bp->bio_driver1)
600 				break;
601 		}
602 		if (bp != NULL) {
603 			bioq_remove(&sc->sc_outqueue, bp);
604 			sc->sc_queue_count--;
605 		}
606 		mtx_unlock(&sc->sc_queue_mtx);
607 		if (bp == NULL) {
608 			/*
609 			 * Request was probably canceled.
610 			 */
611 			return (0);
612 		}
613 		if (ggio->gctl_error == EAGAIN) {
614 			bp->bio_error = 0;
615 			G_GATE_LOGREQ(1, bp, "Request desisted.");
616 			mtx_lock(&sc->sc_queue_mtx);
617 			sc->sc_queue_count++;
618 			bioq_insert_head(&sc->sc_inqueue, bp);
619 			wakeup(sc);
620 			mtx_unlock(&sc->sc_queue_mtx);
621 		} else {
622 			bp->bio_error = ggio->gctl_error;
623 			if (bp->bio_error == 0) {
624 				bp->bio_completed = bp->bio_length;
625 				switch (bp->bio_cmd) {
626 				case BIO_READ:
627 					error = copyin(ggio->gctl_data,
628 					    bp->bio_data, bp->bio_length);
629 					if (error != 0)
630 						bp->bio_error = error;
631 					break;
632 				case BIO_DELETE:
633 				case BIO_WRITE:
634 					break;
635 				}
636 			}
637 			G_GATE_LOGREQ(2, bp, "Request done.");
638 			g_io_deliver(bp, bp->bio_error);
639 		}
640 		return (error);
641 	    }
642 	}
643 	return (ENOIOCTL);
644 }
645 
646 static void
647 g_gate_device(void)
648 {
649 
650 	status_dev = make_dev(&g_gate_cdevsw, 0x0, UID_ROOT, GID_WHEEL, 0600,
651 	    G_GATE_CTL_NAME);
652 }
653 
654 static int
655 g_gate_modevent(module_t mod, int type, void *data)
656 {
657 	int error = 0;
658 
659 	switch (type) {
660 	case MOD_LOAD:
661 		mtx_init(&g_gate_list_mtx, "gg_list_lock", NULL, MTX_DEF);
662 		g_gate_device();
663 		break;
664 	case MOD_UNLOAD:
665 		mtx_lock(&g_gate_list_mtx);
666 		if (!LIST_EMPTY(&g_gate_list)) {
667 			mtx_unlock(&g_gate_list_mtx);
668 			error = EBUSY;
669 			break;
670 		}
671 		mtx_unlock(&g_gate_list_mtx);
672 		mtx_destroy(&g_gate_list_mtx);
673 		if (status_dev != 0)
674 			destroy_dev(status_dev);
675 		break;
676 	default:
677 		return (EOPNOTSUPP);
678 		break;
679 	}
680 
681 	return (error);
682 }
683 static moduledata_t g_gate_module = {
684 	G_GATE_MOD_NAME,
685 	g_gate_modevent,
686 	NULL
687 };
688 DECLARE_MODULE(geom_gate, g_gate_module, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
689 DECLARE_GEOM_CLASS(g_gate_class, g_gate);
690