xref: /freebsd/sys/geom/gate/g_gate.c (revision 884a2a699669ec61e2366e3e358342dbc94be24a)
1 /*-
2  * Copyright (c) 2004-2006 Pawel Jakub Dawidek <pjd@FreeBSD.org>
3  * Copyright (c) 2009-2010 The FreeBSD Foundation
4  * All rights reserved.
5  *
6  * Portions of this software were developed by Pawel Jakub Dawidek
7  * under sponsorship from the FreeBSD Foundation.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28  * SUCH DAMAGE.
29  */
30 
31 #include <sys/cdefs.h>
32 __FBSDID("$FreeBSD$");
33 
34 #include <sys/param.h>
35 #include <sys/systm.h>
36 #include <sys/bio.h>
37 #include <sys/conf.h>
38 #include <sys/kernel.h>
39 #include <sys/kthread.h>
40 #include <sys/fcntl.h>
41 #include <sys/linker.h>
42 #include <sys/lock.h>
43 #include <sys/malloc.h>
44 #include <sys/mutex.h>
45 #include <sys/proc.h>
46 #include <sys/limits.h>
47 #include <sys/queue.h>
48 #include <sys/sysctl.h>
49 #include <sys/signalvar.h>
50 #include <sys/time.h>
51 #include <machine/atomic.h>
52 
53 #include <geom/geom.h>
54 #include <geom/gate/g_gate.h>
55 
56 FEATURE(geom_gate, "GEOM Gate module");
57 
58 static MALLOC_DEFINE(M_GATE, "gg_data", "GEOM Gate Data");
59 
60 SYSCTL_DECL(_kern_geom);
61 SYSCTL_NODE(_kern_geom, OID_AUTO, gate, CTLFLAG_RW, 0, "GEOM_GATE stuff");
62 static int g_gate_debug = 0;
63 TUNABLE_INT("kern.geom.gate.debug", &g_gate_debug);
64 SYSCTL_INT(_kern_geom_gate, OID_AUTO, debug, CTLFLAG_RW, &g_gate_debug, 0,
65     "Debug level");
66 static u_int g_gate_maxunits = 256;
67 TUNABLE_INT("kern.geom.gate.maxunits", &g_gate_maxunits);
68 SYSCTL_UINT(_kern_geom_gate, OID_AUTO, maxunits, CTLFLAG_RDTUN,
69     &g_gate_maxunits, 0, "Maximum number of ggate devices");
70 
71 struct g_class g_gate_class = {
72 	.name = G_GATE_CLASS_NAME,
73 	.version = G_VERSION,
74 };
75 
76 static struct cdev *status_dev;
77 static d_ioctl_t g_gate_ioctl;
78 static struct cdevsw g_gate_cdevsw = {
79 	.d_version =	D_VERSION,
80 	.d_ioctl =	g_gate_ioctl,
81 	.d_name =	G_GATE_CTL_NAME
82 };
83 
84 
85 static struct g_gate_softc **g_gate_units;
86 static u_int g_gate_nunits;
87 static struct mtx g_gate_units_lock;
88 
89 static int
90 g_gate_destroy(struct g_gate_softc *sc, boolean_t force)
91 {
92 	struct g_provider *pp;
93 	struct g_geom *gp;
94 	struct bio *bp;
95 
96 	g_topology_assert();
97 	mtx_assert(&g_gate_units_lock, MA_OWNED);
98 	pp = sc->sc_provider;
99 	if (!force && (pp->acr != 0 || pp->acw != 0 || pp->ace != 0)) {
100 		mtx_unlock(&g_gate_units_lock);
101 		return (EBUSY);
102 	}
103 	mtx_unlock(&g_gate_units_lock);
104 	mtx_lock(&sc->sc_queue_mtx);
105 	if ((sc->sc_flags & G_GATE_FLAG_DESTROY) == 0)
106 		sc->sc_flags |= G_GATE_FLAG_DESTROY;
107 	wakeup(sc);
108 	mtx_unlock(&sc->sc_queue_mtx);
109 	gp = pp->geom;
110 	pp->flags |= G_PF_WITHER;
111 	g_orphan_provider(pp, ENXIO);
112 	callout_drain(&sc->sc_callout);
113 	mtx_lock(&sc->sc_queue_mtx);
114 	while ((bp = bioq_first(&sc->sc_inqueue)) != NULL) {
115 		bioq_remove(&sc->sc_inqueue, bp);
116 		sc->sc_queue_count--;
117 		G_GATE_LOGREQ(1, bp, "Request canceled.");
118 		g_io_deliver(bp, ENXIO);
119 	}
120 	while ((bp = bioq_first(&sc->sc_outqueue)) != NULL) {
121 		bioq_remove(&sc->sc_outqueue, bp);
122 		sc->sc_queue_count--;
123 		G_GATE_LOGREQ(1, bp, "Request canceled.");
124 		g_io_deliver(bp, ENXIO);
125 	}
126 	mtx_unlock(&sc->sc_queue_mtx);
127 	g_topology_unlock();
128 	mtx_lock(&g_gate_units_lock);
129 	/* One reference is ours. */
130 	sc->sc_ref--;
131 	while (sc->sc_ref > 0)
132 		msleep(&sc->sc_ref, &g_gate_units_lock, 0, "gg:destroy", 0);
133 	g_gate_units[sc->sc_unit] = NULL;
134 	KASSERT(g_gate_nunits > 0, ("negative g_gate_nunits?"));
135 	g_gate_nunits--;
136 	mtx_unlock(&g_gate_units_lock);
137 	mtx_destroy(&sc->sc_queue_mtx);
138 	g_topology_lock();
139 	G_GATE_DEBUG(1, "Device %s destroyed.", gp->name);
140 	gp->softc = NULL;
141 	g_wither_geom(gp, ENXIO);
142 	sc->sc_provider = NULL;
143 	free(sc, M_GATE);
144 	return (0);
145 }
146 
147 static int
148 g_gate_access(struct g_provider *pp, int dr, int dw, int de)
149 {
150 	struct g_gate_softc *sc;
151 
152 	if (dr <= 0 && dw <= 0 && de <= 0)
153 		return (0);
154 	sc = pp->geom->softc;
155 	if (sc == NULL || (sc->sc_flags & G_GATE_FLAG_DESTROY) != 0)
156 		return (ENXIO);
157 	/* XXX: Hack to allow read-only mounts. */
158 #if 0
159 	if ((sc->sc_flags & G_GATE_FLAG_READONLY) != 0 && dw > 0)
160 		return (EPERM);
161 #endif
162 	if ((sc->sc_flags & G_GATE_FLAG_WRITEONLY) != 0 && dr > 0)
163 		return (EPERM);
164 	return (0);
165 }
166 
167 static void
168 g_gate_start(struct bio *bp)
169 {
170 	struct g_gate_softc *sc;
171 
172 	sc = bp->bio_to->geom->softc;
173 	if (sc == NULL || (sc->sc_flags & G_GATE_FLAG_DESTROY) != 0) {
174 		g_io_deliver(bp, ENXIO);
175 		return;
176 	}
177 	G_GATE_LOGREQ(2, bp, "Request received.");
178 	switch (bp->bio_cmd) {
179 	case BIO_READ:
180 		break;
181 	case BIO_DELETE:
182 	case BIO_WRITE:
183 	case BIO_FLUSH:
184 		/* XXX: Hack to allow read-only mounts. */
185 		if ((sc->sc_flags & G_GATE_FLAG_READONLY) != 0) {
186 			g_io_deliver(bp, EPERM);
187 			return;
188 		}
189 		break;
190 	case BIO_GETATTR:
191 	default:
192 		G_GATE_LOGREQ(2, bp, "Ignoring request.");
193 		g_io_deliver(bp, EOPNOTSUPP);
194 		return;
195 	}
196 
197 	mtx_lock(&sc->sc_queue_mtx);
198 	if (sc->sc_queue_size > 0 && sc->sc_queue_count > sc->sc_queue_size) {
199 		mtx_unlock(&sc->sc_queue_mtx);
200 		G_GATE_LOGREQ(1, bp, "Queue full, request canceled.");
201 		g_io_deliver(bp, ENOMEM);
202 		return;
203 	}
204 
205 	bp->bio_driver1 = (void *)sc->sc_seq;
206 	sc->sc_seq++;
207 	sc->sc_queue_count++;
208 
209 	bioq_insert_tail(&sc->sc_inqueue, bp);
210 	wakeup(sc);
211 
212 	mtx_unlock(&sc->sc_queue_mtx);
213 }
214 
215 static struct g_gate_softc *
216 g_gate_hold(int unit, const char *name)
217 {
218 	struct g_gate_softc *sc = NULL;
219 
220 	mtx_lock(&g_gate_units_lock);
221 	if (unit >= 0 && unit < g_gate_maxunits)
222 		sc = g_gate_units[unit];
223 	else if (unit == G_GATE_NAME_GIVEN) {
224 		KASSERT(name != NULL, ("name is NULL"));
225 		for (unit = 0; unit < g_gate_maxunits; unit++) {
226 			if (g_gate_units[unit] == NULL)
227 				continue;
228 			if (strcmp(name,
229 			    g_gate_units[unit]->sc_provider->name) != 0) {
230 				continue;
231 			}
232 			sc = g_gate_units[unit];
233 			break;
234 		}
235 	}
236 	if (sc != NULL)
237 		sc->sc_ref++;
238 	mtx_unlock(&g_gate_units_lock);
239 	return (sc);
240 }
241 
242 static void
243 g_gate_release(struct g_gate_softc *sc)
244 {
245 
246 	g_topology_assert_not();
247 	mtx_lock(&g_gate_units_lock);
248 	sc->sc_ref--;
249 	KASSERT(sc->sc_ref >= 0, ("Negative sc_ref for %s.", sc->sc_name));
250 	if (sc->sc_ref == 0 && (sc->sc_flags & G_GATE_FLAG_DESTROY) != 0)
251 		wakeup(&sc->sc_ref);
252 	mtx_unlock(&g_gate_units_lock);
253 }
254 
255 static int
256 g_gate_getunit(int unit, int *errorp)
257 {
258 
259 	mtx_assert(&g_gate_units_lock, MA_OWNED);
260 	if (unit >= 0) {
261 		if (unit >= g_gate_maxunits)
262 			*errorp = EINVAL;
263 		else if (g_gate_units[unit] == NULL)
264 			return (unit);
265 		else
266 			*errorp = EEXIST;
267 	} else {
268 		for (unit = 0; unit < g_gate_maxunits; unit++) {
269 			if (g_gate_units[unit] == NULL)
270 				return (unit);
271 		}
272 		*errorp = ENFILE;
273 	}
274 	return (-1);
275 }
276 
277 static void
278 g_gate_guard(void *arg)
279 {
280 	struct g_gate_softc *sc;
281 	struct bintime curtime;
282 	struct bio *bp, *bp2;
283 
284 	sc = arg;
285 	binuptime(&curtime);
286 	g_gate_hold(sc->sc_unit, NULL);
287 	mtx_lock(&sc->sc_queue_mtx);
288 	TAILQ_FOREACH_SAFE(bp, &sc->sc_inqueue.queue, bio_queue, bp2) {
289 		if (curtime.sec - bp->bio_t0.sec < 5)
290 			continue;
291 		bioq_remove(&sc->sc_inqueue, bp);
292 		sc->sc_queue_count--;
293 		G_GATE_LOGREQ(1, bp, "Request timeout.");
294 		g_io_deliver(bp, EIO);
295 	}
296 	TAILQ_FOREACH_SAFE(bp, &sc->sc_outqueue.queue, bio_queue, bp2) {
297 		if (curtime.sec - bp->bio_t0.sec < 5)
298 			continue;
299 		bioq_remove(&sc->sc_outqueue, bp);
300 		sc->sc_queue_count--;
301 		G_GATE_LOGREQ(1, bp, "Request timeout.");
302 		g_io_deliver(bp, EIO);
303 	}
304 	mtx_unlock(&sc->sc_queue_mtx);
305 	if ((sc->sc_flags & G_GATE_FLAG_DESTROY) == 0) {
306 		callout_reset(&sc->sc_callout, sc->sc_timeout * hz,
307 		    g_gate_guard, sc);
308 	}
309 	g_gate_release(sc);
310 }
311 
312 static void
313 g_gate_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp,
314     struct g_consumer *cp, struct g_provider *pp)
315 {
316 	struct g_gate_softc *sc;
317 
318 	sc = gp->softc;
319 	if (sc == NULL || pp != NULL || cp != NULL)
320 		return;
321 	g_gate_hold(sc->sc_unit, NULL);
322 	if ((sc->sc_flags & G_GATE_FLAG_READONLY) != 0) {
323 		sbuf_printf(sb, "%s<access>%s</access>\n", indent, "read-only");
324 	} else if ((sc->sc_flags & G_GATE_FLAG_WRITEONLY) != 0) {
325 		sbuf_printf(sb, "%s<access>%s</access>\n", indent,
326 		    "write-only");
327 	} else {
328 		sbuf_printf(sb, "%s<access>%s</access>\n", indent,
329 		    "read-write");
330 	}
331 	sbuf_printf(sb, "%s<timeout>%u</timeout>\n", indent, sc->sc_timeout);
332 	sbuf_printf(sb, "%s<info>%s</info>\n", indent, sc->sc_info);
333 	sbuf_printf(sb, "%s<queue_count>%u</queue_count>\n", indent,
334 	    sc->sc_queue_count);
335 	sbuf_printf(sb, "%s<queue_size>%u</queue_size>\n", indent,
336 	    sc->sc_queue_size);
337 	sbuf_printf(sb, "%s<ref>%u</ref>\n", indent, sc->sc_ref);
338 	sbuf_printf(sb, "%s<unit>%d</unit>\n", indent, sc->sc_unit);
339 	g_topology_unlock();
340 	g_gate_release(sc);
341 	g_topology_lock();
342 }
343 
344 static int
345 g_gate_create(struct g_gate_ctl_create *ggio)
346 {
347 	struct g_gate_softc *sc;
348 	struct g_geom *gp;
349 	struct g_provider *pp;
350 	char name[NAME_MAX];
351 	int error = 0, unit;
352 
353 	if (ggio->gctl_mediasize == 0) {
354 		G_GATE_DEBUG(1, "Invalid media size.");
355 		return (EINVAL);
356 	}
357 	if (ggio->gctl_sectorsize > 0 && !powerof2(ggio->gctl_sectorsize)) {
358 		G_GATE_DEBUG(1, "Invalid sector size.");
359 		return (EINVAL);
360 	}
361 	if ((ggio->gctl_mediasize % ggio->gctl_sectorsize) != 0) {
362 		G_GATE_DEBUG(1, "Invalid media size.");
363 		return (EINVAL);
364 	}
365 	if ((ggio->gctl_flags & G_GATE_FLAG_READONLY) != 0 &&
366 	    (ggio->gctl_flags & G_GATE_FLAG_WRITEONLY) != 0) {
367 		G_GATE_DEBUG(1, "Invalid flags.");
368 		return (EINVAL);
369 	}
370 	if (ggio->gctl_unit != G_GATE_UNIT_AUTO &&
371 	    ggio->gctl_unit != G_GATE_NAME_GIVEN &&
372 	    ggio->gctl_unit < 0) {
373 		G_GATE_DEBUG(1, "Invalid unit number.");
374 		return (EINVAL);
375 	}
376 	if (ggio->gctl_unit == G_GATE_NAME_GIVEN &&
377 	    ggio->gctl_name[0] == '\0') {
378 		G_GATE_DEBUG(1, "No device name.");
379 		return (EINVAL);
380 	}
381 
382 	sc = malloc(sizeof(*sc), M_GATE, M_WAITOK | M_ZERO);
383 	sc->sc_flags = (ggio->gctl_flags & G_GATE_USERFLAGS);
384 	strlcpy(sc->sc_info, ggio->gctl_info, sizeof(sc->sc_info));
385 	sc->sc_seq = 1;
386 	bioq_init(&sc->sc_inqueue);
387 	bioq_init(&sc->sc_outqueue);
388 	mtx_init(&sc->sc_queue_mtx, "gg:queue", NULL, MTX_DEF);
389 	sc->sc_queue_count = 0;
390 	sc->sc_queue_size = ggio->gctl_maxcount;
391 	if (sc->sc_queue_size > G_GATE_MAX_QUEUE_SIZE)
392 		sc->sc_queue_size = G_GATE_MAX_QUEUE_SIZE;
393 	sc->sc_timeout = ggio->gctl_timeout;
394 	callout_init(&sc->sc_callout, CALLOUT_MPSAFE);
395 	mtx_lock(&g_gate_units_lock);
396 	sc->sc_unit = g_gate_getunit(ggio->gctl_unit, &error);
397 	if (sc->sc_unit < 0) {
398 		mtx_unlock(&g_gate_units_lock);
399 		mtx_destroy(&sc->sc_queue_mtx);
400 		free(sc, M_GATE);
401 		return (error);
402 	}
403 	if (ggio->gctl_unit == G_GATE_NAME_GIVEN)
404 		snprintf(name, sizeof(name), "%s", ggio->gctl_name);
405 	else {
406 		snprintf(name, sizeof(name), "%s%d", G_GATE_PROVIDER_NAME,
407 		    sc->sc_unit);
408 	}
409 	/* Check for name collision. */
410 	for (unit = 0; unit < g_gate_maxunits; unit++) {
411 		if (g_gate_units[unit] == NULL)
412 			continue;
413 		if (strcmp(name, g_gate_units[unit]->sc_name) != 0)
414 			continue;
415 		mtx_unlock(&g_gate_units_lock);
416 		mtx_destroy(&sc->sc_queue_mtx);
417 		free(sc, M_GATE);
418 		return (EEXIST);
419 	}
420 	sc->sc_name = name;
421 	g_gate_units[sc->sc_unit] = sc;
422 	g_gate_nunits++;
423 	mtx_unlock(&g_gate_units_lock);
424 
425 	ggio->gctl_unit = sc->sc_unit;
426 
427 	g_topology_lock();
428 	gp = g_new_geomf(&g_gate_class, "%s", name);
429 	gp->start = g_gate_start;
430 	gp->access = g_gate_access;
431 	gp->dumpconf = g_gate_dumpconf;
432 	gp->softc = sc;
433 	pp = g_new_providerf(gp, "%s", name);
434 	pp->mediasize = ggio->gctl_mediasize;
435 	pp->sectorsize = ggio->gctl_sectorsize;
436 	sc->sc_provider = pp;
437 	g_error_provider(pp, 0);
438 	g_topology_unlock();
439 	mtx_lock(&g_gate_units_lock);
440 	sc->sc_name = sc->sc_provider->name;
441 	mtx_unlock(&g_gate_units_lock);
442 	G_GATE_DEBUG(1, "Device %s created.", gp->name);
443 
444 	if (sc->sc_timeout > 0) {
445 		callout_reset(&sc->sc_callout, sc->sc_timeout * hz,
446 		    g_gate_guard, sc);
447 	}
448 	return (0);
449 }
450 
451 #define	G_GATE_CHECK_VERSION(ggio)	do {				\
452 	if ((ggio)->gctl_version != G_GATE_VERSION) {			\
453 		printf("Version mismatch %d != %d.\n",			\
454 		    ggio->gctl_version, G_GATE_VERSION);		\
455 		return (EINVAL);					\
456 	}								\
457 } while (0)
458 static int
459 g_gate_ioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags, struct thread *td)
460 {
461 	struct g_gate_softc *sc;
462 	struct bio *bp;
463 	int error = 0;
464 
465 	G_GATE_DEBUG(4, "ioctl(%s, %lx, %p, %x, %p)", devtoname(dev), cmd, addr,
466 	    flags, td);
467 
468 	switch (cmd) {
469 	case G_GATE_CMD_CREATE:
470 	    {
471 		struct g_gate_ctl_create *ggio = (void *)addr;
472 
473 		G_GATE_CHECK_VERSION(ggio);
474 		error = g_gate_create(ggio);
475 		/*
476 		 * Reset TDP_GEOM flag.
477 		 * There are pending events for sure, because we just created
478 		 * new provider and other classes want to taste it, but we
479 		 * cannot answer on I/O requests until we're here.
480 		 */
481 		td->td_pflags &= ~TDP_GEOM;
482 		return (error);
483 	    }
484 	case G_GATE_CMD_DESTROY:
485 	    {
486 		struct g_gate_ctl_destroy *ggio = (void *)addr;
487 
488 		G_GATE_CHECK_VERSION(ggio);
489 		sc = g_gate_hold(ggio->gctl_unit, ggio->gctl_name);
490 		if (sc == NULL)
491 			return (ENXIO);
492 		g_topology_lock();
493 		mtx_lock(&g_gate_units_lock);
494 		error = g_gate_destroy(sc, ggio->gctl_force);
495 		g_topology_unlock();
496 		if (error != 0)
497 			g_gate_release(sc);
498 		return (error);
499 	    }
500 	case G_GATE_CMD_CANCEL:
501 	    {
502 		struct g_gate_ctl_cancel *ggio = (void *)addr;
503 		struct bio *tbp, *lbp;
504 
505 		G_GATE_CHECK_VERSION(ggio);
506 		sc = g_gate_hold(ggio->gctl_unit, ggio->gctl_name);
507 		if (sc == NULL)
508 			return (ENXIO);
509 		lbp = NULL;
510 		mtx_lock(&sc->sc_queue_mtx);
511 		TAILQ_FOREACH_SAFE(bp, &sc->sc_outqueue.queue, bio_queue, tbp) {
512 			if (ggio->gctl_seq == 0 ||
513 			    ggio->gctl_seq == (uintptr_t)bp->bio_driver1) {
514 				G_GATE_LOGREQ(1, bp, "Request canceled.");
515 				bioq_remove(&sc->sc_outqueue, bp);
516 				/*
517 				 * Be sure to put requests back onto incoming
518 				 * queue in the proper order.
519 				 */
520 				if (lbp == NULL)
521 					bioq_insert_head(&sc->sc_inqueue, bp);
522 				else {
523 					TAILQ_INSERT_AFTER(&sc->sc_inqueue.queue,
524 					    lbp, bp, bio_queue);
525 				}
526 				lbp = bp;
527 				/*
528 				 * If only one request was canceled, leave now.
529 				 */
530 				if (ggio->gctl_seq != 0)
531 					break;
532 			}
533 		}
534 		if (ggio->gctl_unit == G_GATE_NAME_GIVEN)
535 			ggio->gctl_unit = sc->sc_unit;
536 		mtx_unlock(&sc->sc_queue_mtx);
537 		g_gate_release(sc);
538 		return (error);
539 	    }
540 	case G_GATE_CMD_START:
541 	    {
542 		struct g_gate_ctl_io *ggio = (void *)addr;
543 
544 		G_GATE_CHECK_VERSION(ggio);
545 		sc = g_gate_hold(ggio->gctl_unit, NULL);
546 		if (sc == NULL)
547 			return (ENXIO);
548 		error = 0;
549 		for (;;) {
550 			mtx_lock(&sc->sc_queue_mtx);
551 			bp = bioq_first(&sc->sc_inqueue);
552 			if (bp != NULL)
553 				break;
554 			if ((sc->sc_flags & G_GATE_FLAG_DESTROY) != 0) {
555 				ggio->gctl_error = ECANCELED;
556 				mtx_unlock(&sc->sc_queue_mtx);
557 				goto start_end;
558 			}
559 			if (msleep(sc, &sc->sc_queue_mtx,
560 			    PPAUSE | PDROP | PCATCH, "ggwait", 0) != 0) {
561 				ggio->gctl_error = ECANCELED;
562 				goto start_end;
563 			}
564 		}
565 		ggio->gctl_cmd = bp->bio_cmd;
566 		if ((bp->bio_cmd == BIO_DELETE || bp->bio_cmd == BIO_WRITE) &&
567 		    bp->bio_length > ggio->gctl_length) {
568 			mtx_unlock(&sc->sc_queue_mtx);
569 			ggio->gctl_length = bp->bio_length;
570 			ggio->gctl_error = ENOMEM;
571 			goto start_end;
572 		}
573 		bioq_remove(&sc->sc_inqueue, bp);
574 		bioq_insert_tail(&sc->sc_outqueue, bp);
575 		mtx_unlock(&sc->sc_queue_mtx);
576 
577 		ggio->gctl_seq = (uintptr_t)bp->bio_driver1;
578 		ggio->gctl_offset = bp->bio_offset;
579 		ggio->gctl_length = bp->bio_length;
580 
581 		switch (bp->bio_cmd) {
582 		case BIO_READ:
583 		case BIO_DELETE:
584 		case BIO_FLUSH:
585 			break;
586 		case BIO_WRITE:
587 			error = copyout(bp->bio_data, ggio->gctl_data,
588 			    bp->bio_length);
589 			if (error != 0) {
590 				mtx_lock(&sc->sc_queue_mtx);
591 				bioq_remove(&sc->sc_outqueue, bp);
592 				bioq_insert_head(&sc->sc_inqueue, bp);
593 				mtx_unlock(&sc->sc_queue_mtx);
594 				goto start_end;
595 			}
596 			break;
597 		}
598 start_end:
599 		g_gate_release(sc);
600 		return (error);
601 	    }
602 	case G_GATE_CMD_DONE:
603 	    {
604 		struct g_gate_ctl_io *ggio = (void *)addr;
605 
606 		G_GATE_CHECK_VERSION(ggio);
607 		sc = g_gate_hold(ggio->gctl_unit, NULL);
608 		if (sc == NULL)
609 			return (ENOENT);
610 		error = 0;
611 		mtx_lock(&sc->sc_queue_mtx);
612 		TAILQ_FOREACH(bp, &sc->sc_outqueue.queue, bio_queue) {
613 			if (ggio->gctl_seq == (uintptr_t)bp->bio_driver1)
614 				break;
615 		}
616 		if (bp != NULL) {
617 			bioq_remove(&sc->sc_outqueue, bp);
618 			sc->sc_queue_count--;
619 		}
620 		mtx_unlock(&sc->sc_queue_mtx);
621 		if (bp == NULL) {
622 			/*
623 			 * Request was probably canceled.
624 			 */
625 			goto done_end;
626 		}
627 		if (ggio->gctl_error == EAGAIN) {
628 			bp->bio_error = 0;
629 			G_GATE_LOGREQ(1, bp, "Request desisted.");
630 			mtx_lock(&sc->sc_queue_mtx);
631 			sc->sc_queue_count++;
632 			bioq_insert_head(&sc->sc_inqueue, bp);
633 			wakeup(sc);
634 			mtx_unlock(&sc->sc_queue_mtx);
635 		} else {
636 			bp->bio_error = ggio->gctl_error;
637 			if (bp->bio_error == 0) {
638 				bp->bio_completed = bp->bio_length;
639 				switch (bp->bio_cmd) {
640 				case BIO_READ:
641 					error = copyin(ggio->gctl_data,
642 					    bp->bio_data, bp->bio_length);
643 					if (error != 0)
644 						bp->bio_error = error;
645 					break;
646 				case BIO_DELETE:
647 				case BIO_WRITE:
648 				case BIO_FLUSH:
649 					break;
650 				}
651 			}
652 			G_GATE_LOGREQ(2, bp, "Request done.");
653 			g_io_deliver(bp, bp->bio_error);
654 		}
655 done_end:
656 		g_gate_release(sc);
657 		return (error);
658 	    }
659 	}
660 	return (ENOIOCTL);
661 }
662 
663 static void
664 g_gate_device(void)
665 {
666 
667 	status_dev = make_dev(&g_gate_cdevsw, 0x0, UID_ROOT, GID_WHEEL, 0600,
668 	    G_GATE_CTL_NAME);
669 }
670 
671 static int
672 g_gate_modevent(module_t mod, int type, void *data)
673 {
674 	int error = 0;
675 
676 	switch (type) {
677 	case MOD_LOAD:
678 		mtx_init(&g_gate_units_lock, "gg_units_lock", NULL, MTX_DEF);
679 		g_gate_units = malloc(g_gate_maxunits * sizeof(g_gate_units[0]),
680 		    M_GATE, M_WAITOK | M_ZERO);
681 		g_gate_nunits = 0;
682 		g_gate_device();
683 		break;
684 	case MOD_UNLOAD:
685 		mtx_lock(&g_gate_units_lock);
686 		if (g_gate_nunits > 0) {
687 			mtx_unlock(&g_gate_units_lock);
688 			error = EBUSY;
689 			break;
690 		}
691 		mtx_unlock(&g_gate_units_lock);
692 		mtx_destroy(&g_gate_units_lock);
693 		if (status_dev != 0)
694 			destroy_dev(status_dev);
695 		free(g_gate_units, M_GATE);
696 		break;
697 	default:
698 		return (EOPNOTSUPP);
699 		break;
700 	}
701 
702 	return (error);
703 }
704 static moduledata_t g_gate_module = {
705 	G_GATE_MOD_NAME,
706 	g_gate_modevent,
707 	NULL
708 };
709 DECLARE_MODULE(geom_gate, g_gate_module, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
710 DECLARE_GEOM_CLASS(g_gate_class, g_gate);
711