xref: /freebsd/sys/geom/gate/g_gate.c (revision 10b59a9b4add0320d52c15ce057dd697261e7dfc)
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/sbuf.h>
49 #include <sys/sysctl.h>
50 #include <sys/signalvar.h>
51 #include <sys/time.h>
52 #include <machine/atomic.h>
53 
54 #include <geom/geom.h>
55 #include <geom/gate/g_gate.h>
56 
57 FEATURE(geom_gate, "GEOM Gate module");
58 
59 static MALLOC_DEFINE(M_GATE, "gg_data", "GEOM Gate Data");
60 
61 SYSCTL_DECL(_kern_geom);
62 static SYSCTL_NODE(_kern_geom, OID_AUTO, gate, CTLFLAG_RW, 0,
63     "GEOM_GATE stuff");
64 static int g_gate_debug = 0;
65 TUNABLE_INT("kern.geom.gate.debug", &g_gate_debug);
66 SYSCTL_INT(_kern_geom_gate, OID_AUTO, debug, CTLFLAG_RW, &g_gate_debug, 0,
67     "Debug level");
68 static u_int g_gate_maxunits = 256;
69 TUNABLE_INT("kern.geom.gate.maxunits", &g_gate_maxunits);
70 SYSCTL_UINT(_kern_geom_gate, OID_AUTO, maxunits, CTLFLAG_RDTUN,
71     &g_gate_maxunits, 0, "Maximum number of ggate devices");
72 
73 struct g_class g_gate_class = {
74 	.name = G_GATE_CLASS_NAME,
75 	.version = G_VERSION,
76 };
77 
78 static struct cdev *status_dev;
79 static d_ioctl_t g_gate_ioctl;
80 static struct cdevsw g_gate_cdevsw = {
81 	.d_version =	D_VERSION,
82 	.d_ioctl =	g_gate_ioctl,
83 	.d_name =	G_GATE_CTL_NAME
84 };
85 
86 
87 static struct g_gate_softc **g_gate_units;
88 static u_int g_gate_nunits;
89 static struct mtx g_gate_units_lock;
90 
91 static int
92 g_gate_destroy(struct g_gate_softc *sc, boolean_t force)
93 {
94 	struct g_provider *pp;
95 	struct g_geom *gp;
96 	struct bio *bp;
97 
98 	g_topology_assert();
99 	mtx_assert(&g_gate_units_lock, MA_OWNED);
100 	pp = sc->sc_provider;
101 	if (!force && (pp->acr != 0 || pp->acw != 0 || pp->ace != 0)) {
102 		mtx_unlock(&g_gate_units_lock);
103 		return (EBUSY);
104 	}
105 	mtx_unlock(&g_gate_units_lock);
106 	mtx_lock(&sc->sc_queue_mtx);
107 	if ((sc->sc_flags & G_GATE_FLAG_DESTROY) == 0)
108 		sc->sc_flags |= G_GATE_FLAG_DESTROY;
109 	wakeup(sc);
110 	mtx_unlock(&sc->sc_queue_mtx);
111 	gp = pp->geom;
112 	pp->flags |= G_PF_WITHER;
113 	g_orphan_provider(pp, ENXIO);
114 	callout_drain(&sc->sc_callout);
115 	mtx_lock(&sc->sc_queue_mtx);
116 	while ((bp = bioq_first(&sc->sc_inqueue)) != NULL) {
117 		bioq_remove(&sc->sc_inqueue, bp);
118 		sc->sc_queue_count--;
119 		G_GATE_LOGREQ(1, bp, "Request canceled.");
120 		g_io_deliver(bp, ENXIO);
121 	}
122 	while ((bp = bioq_first(&sc->sc_outqueue)) != NULL) {
123 		bioq_remove(&sc->sc_outqueue, bp);
124 		sc->sc_queue_count--;
125 		G_GATE_LOGREQ(1, bp, "Request canceled.");
126 		g_io_deliver(bp, ENXIO);
127 	}
128 	mtx_unlock(&sc->sc_queue_mtx);
129 	g_topology_unlock();
130 	mtx_lock(&g_gate_units_lock);
131 	/* One reference is ours. */
132 	sc->sc_ref--;
133 	while (sc->sc_ref > 0)
134 		msleep(&sc->sc_ref, &g_gate_units_lock, 0, "gg:destroy", 0);
135 	g_gate_units[sc->sc_unit] = NULL;
136 	KASSERT(g_gate_nunits > 0, ("negative g_gate_nunits?"));
137 	g_gate_nunits--;
138 	mtx_unlock(&g_gate_units_lock);
139 	mtx_destroy(&sc->sc_queue_mtx);
140 	g_topology_lock();
141 	G_GATE_DEBUG(1, "Device %s destroyed.", gp->name);
142 	gp->softc = NULL;
143 	g_wither_geom(gp, ENXIO);
144 	sc->sc_provider = NULL;
145 	free(sc, M_GATE);
146 	return (0);
147 }
148 
149 static int
150 g_gate_access(struct g_provider *pp, int dr, int dw, int de)
151 {
152 	struct g_gate_softc *sc;
153 
154 	if (dr <= 0 && dw <= 0 && de <= 0)
155 		return (0);
156 	sc = pp->geom->softc;
157 	if (sc == NULL || (sc->sc_flags & G_GATE_FLAG_DESTROY) != 0)
158 		return (ENXIO);
159 	/* XXX: Hack to allow read-only mounts. */
160 #if 0
161 	if ((sc->sc_flags & G_GATE_FLAG_READONLY) != 0 && dw > 0)
162 		return (EPERM);
163 #endif
164 	if ((sc->sc_flags & G_GATE_FLAG_WRITEONLY) != 0 && dr > 0)
165 		return (EPERM);
166 	return (0);
167 }
168 
169 static void
170 g_gate_start(struct bio *bp)
171 {
172 	struct g_gate_softc *sc;
173 
174 	sc = bp->bio_to->geom->softc;
175 	if (sc == NULL || (sc->sc_flags & G_GATE_FLAG_DESTROY) != 0) {
176 		g_io_deliver(bp, ENXIO);
177 		return;
178 	}
179 	G_GATE_LOGREQ(2, bp, "Request received.");
180 	switch (bp->bio_cmd) {
181 	case BIO_READ:
182 		break;
183 	case BIO_DELETE:
184 	case BIO_WRITE:
185 	case BIO_FLUSH:
186 		/* XXX: Hack to allow read-only mounts. */
187 		if ((sc->sc_flags & G_GATE_FLAG_READONLY) != 0) {
188 			g_io_deliver(bp, EPERM);
189 			return;
190 		}
191 		break;
192 	case BIO_GETATTR:
193 	default:
194 		G_GATE_LOGREQ(2, bp, "Ignoring request.");
195 		g_io_deliver(bp, EOPNOTSUPP);
196 		return;
197 	}
198 
199 	mtx_lock(&sc->sc_queue_mtx);
200 	if (sc->sc_queue_size > 0 && sc->sc_queue_count > sc->sc_queue_size) {
201 		mtx_unlock(&sc->sc_queue_mtx);
202 		G_GATE_LOGREQ(1, bp, "Queue full, request canceled.");
203 		g_io_deliver(bp, ENOMEM);
204 		return;
205 	}
206 
207 	bp->bio_driver1 = (void *)sc->sc_seq;
208 	sc->sc_seq++;
209 	sc->sc_queue_count++;
210 
211 	bioq_insert_tail(&sc->sc_inqueue, bp);
212 	wakeup(sc);
213 
214 	mtx_unlock(&sc->sc_queue_mtx);
215 }
216 
217 static struct g_gate_softc *
218 g_gate_hold(int unit, const char *name)
219 {
220 	struct g_gate_softc *sc = NULL;
221 
222 	mtx_lock(&g_gate_units_lock);
223 	if (unit >= 0 && unit < g_gate_maxunits)
224 		sc = g_gate_units[unit];
225 	else if (unit == G_GATE_NAME_GIVEN) {
226 		KASSERT(name != NULL, ("name is NULL"));
227 		for (unit = 0; unit < g_gate_maxunits; unit++) {
228 			if (g_gate_units[unit] == NULL)
229 				continue;
230 			if (strcmp(name,
231 			    g_gate_units[unit]->sc_provider->name) != 0) {
232 				continue;
233 			}
234 			sc = g_gate_units[unit];
235 			break;
236 		}
237 	}
238 	if (sc != NULL)
239 		sc->sc_ref++;
240 	mtx_unlock(&g_gate_units_lock);
241 	return (sc);
242 }
243 
244 static void
245 g_gate_release(struct g_gate_softc *sc)
246 {
247 
248 	g_topology_assert_not();
249 	mtx_lock(&g_gate_units_lock);
250 	sc->sc_ref--;
251 	KASSERT(sc->sc_ref >= 0, ("Negative sc_ref for %s.", sc->sc_name));
252 	if (sc->sc_ref == 0 && (sc->sc_flags & G_GATE_FLAG_DESTROY) != 0)
253 		wakeup(&sc->sc_ref);
254 	mtx_unlock(&g_gate_units_lock);
255 }
256 
257 static int
258 g_gate_getunit(int unit, int *errorp)
259 {
260 
261 	mtx_assert(&g_gate_units_lock, MA_OWNED);
262 	if (unit >= 0) {
263 		if (unit >= g_gate_maxunits)
264 			*errorp = EINVAL;
265 		else if (g_gate_units[unit] == NULL)
266 			return (unit);
267 		else
268 			*errorp = EEXIST;
269 	} else {
270 		for (unit = 0; unit < g_gate_maxunits; unit++) {
271 			if (g_gate_units[unit] == NULL)
272 				return (unit);
273 		}
274 		*errorp = ENFILE;
275 	}
276 	return (-1);
277 }
278 
279 static void
280 g_gate_guard(void *arg)
281 {
282 	struct g_gate_softc *sc;
283 	struct bintime curtime;
284 	struct bio *bp, *bp2;
285 
286 	sc = arg;
287 	binuptime(&curtime);
288 	g_gate_hold(sc->sc_unit, NULL);
289 	mtx_lock(&sc->sc_queue_mtx);
290 	TAILQ_FOREACH_SAFE(bp, &sc->sc_inqueue.queue, bio_queue, bp2) {
291 		if (curtime.sec - bp->bio_t0.sec < 5)
292 			continue;
293 		bioq_remove(&sc->sc_inqueue, bp);
294 		sc->sc_queue_count--;
295 		G_GATE_LOGREQ(1, bp, "Request timeout.");
296 		g_io_deliver(bp, EIO);
297 	}
298 	TAILQ_FOREACH_SAFE(bp, &sc->sc_outqueue.queue, bio_queue, bp2) {
299 		if (curtime.sec - bp->bio_t0.sec < 5)
300 			continue;
301 		bioq_remove(&sc->sc_outqueue, bp);
302 		sc->sc_queue_count--;
303 		G_GATE_LOGREQ(1, bp, "Request timeout.");
304 		g_io_deliver(bp, EIO);
305 	}
306 	mtx_unlock(&sc->sc_queue_mtx);
307 	if ((sc->sc_flags & G_GATE_FLAG_DESTROY) == 0) {
308 		callout_reset(&sc->sc_callout, sc->sc_timeout * hz,
309 		    g_gate_guard, sc);
310 	}
311 	g_gate_release(sc);
312 }
313 
314 static void
315 g_gate_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp,
316     struct g_consumer *cp, struct g_provider *pp)
317 {
318 	struct g_gate_softc *sc;
319 
320 	sc = gp->softc;
321 	if (sc == NULL || pp != NULL || cp != NULL)
322 		return;
323 	g_gate_hold(sc->sc_unit, NULL);
324 	if ((sc->sc_flags & G_GATE_FLAG_READONLY) != 0) {
325 		sbuf_printf(sb, "%s<access>%s</access>\n", indent, "read-only");
326 	} else if ((sc->sc_flags & G_GATE_FLAG_WRITEONLY) != 0) {
327 		sbuf_printf(sb, "%s<access>%s</access>\n", indent,
328 		    "write-only");
329 	} else {
330 		sbuf_printf(sb, "%s<access>%s</access>\n", indent,
331 		    "read-write");
332 	}
333 	sbuf_printf(sb, "%s<timeout>%u</timeout>\n", indent, sc->sc_timeout);
334 	sbuf_printf(sb, "%s<info>%s</info>\n", indent, sc->sc_info);
335 	sbuf_printf(sb, "%s<queue_count>%u</queue_count>\n", indent,
336 	    sc->sc_queue_count);
337 	sbuf_printf(sb, "%s<queue_size>%u</queue_size>\n", indent,
338 	    sc->sc_queue_size);
339 	sbuf_printf(sb, "%s<ref>%u</ref>\n", indent, sc->sc_ref);
340 	sbuf_printf(sb, "%s<unit>%d</unit>\n", indent, sc->sc_unit);
341 	g_topology_unlock();
342 	g_gate_release(sc);
343 	g_topology_lock();
344 }
345 
346 static int
347 g_gate_create(struct g_gate_ctl_create *ggio)
348 {
349 	struct g_gate_softc *sc;
350 	struct g_geom *gp;
351 	struct g_provider *pp;
352 	char name[NAME_MAX];
353 	int error = 0, unit;
354 
355 	if (ggio->gctl_mediasize == 0) {
356 		G_GATE_DEBUG(1, "Invalid media size.");
357 		return (EINVAL);
358 	}
359 	if (ggio->gctl_sectorsize > 0 && !powerof2(ggio->gctl_sectorsize)) {
360 		G_GATE_DEBUG(1, "Invalid sector size.");
361 		return (EINVAL);
362 	}
363 	if ((ggio->gctl_mediasize % ggio->gctl_sectorsize) != 0) {
364 		G_GATE_DEBUG(1, "Invalid media size.");
365 		return (EINVAL);
366 	}
367 	if ((ggio->gctl_flags & G_GATE_FLAG_READONLY) != 0 &&
368 	    (ggio->gctl_flags & G_GATE_FLAG_WRITEONLY) != 0) {
369 		G_GATE_DEBUG(1, "Invalid flags.");
370 		return (EINVAL);
371 	}
372 	if (ggio->gctl_unit != G_GATE_UNIT_AUTO &&
373 	    ggio->gctl_unit != G_GATE_NAME_GIVEN &&
374 	    ggio->gctl_unit < 0) {
375 		G_GATE_DEBUG(1, "Invalid unit number.");
376 		return (EINVAL);
377 	}
378 	if (ggio->gctl_unit == G_GATE_NAME_GIVEN &&
379 	    ggio->gctl_name[0] == '\0') {
380 		G_GATE_DEBUG(1, "No device name.");
381 		return (EINVAL);
382 	}
383 
384 	sc = malloc(sizeof(*sc), M_GATE, M_WAITOK | M_ZERO);
385 	sc->sc_flags = (ggio->gctl_flags & G_GATE_USERFLAGS);
386 	strlcpy(sc->sc_info, ggio->gctl_info, sizeof(sc->sc_info));
387 	sc->sc_seq = 1;
388 	bioq_init(&sc->sc_inqueue);
389 	bioq_init(&sc->sc_outqueue);
390 	mtx_init(&sc->sc_queue_mtx, "gg:queue", NULL, MTX_DEF);
391 	sc->sc_queue_count = 0;
392 	sc->sc_queue_size = ggio->gctl_maxcount;
393 	if (sc->sc_queue_size > G_GATE_MAX_QUEUE_SIZE)
394 		sc->sc_queue_size = G_GATE_MAX_QUEUE_SIZE;
395 	sc->sc_timeout = ggio->gctl_timeout;
396 	callout_init(&sc->sc_callout, CALLOUT_MPSAFE);
397 	mtx_lock(&g_gate_units_lock);
398 	sc->sc_unit = g_gate_getunit(ggio->gctl_unit, &error);
399 	if (sc->sc_unit < 0) {
400 		mtx_unlock(&g_gate_units_lock);
401 		mtx_destroy(&sc->sc_queue_mtx);
402 		free(sc, M_GATE);
403 		return (error);
404 	}
405 	if (ggio->gctl_unit == G_GATE_NAME_GIVEN)
406 		snprintf(name, sizeof(name), "%s", ggio->gctl_name);
407 	else {
408 		snprintf(name, sizeof(name), "%s%d", G_GATE_PROVIDER_NAME,
409 		    sc->sc_unit);
410 	}
411 	/* Check for name collision. */
412 	for (unit = 0; unit < g_gate_maxunits; unit++) {
413 		if (g_gate_units[unit] == NULL)
414 			continue;
415 		if (strcmp(name, g_gate_units[unit]->sc_name) != 0)
416 			continue;
417 		mtx_unlock(&g_gate_units_lock);
418 		mtx_destroy(&sc->sc_queue_mtx);
419 		free(sc, M_GATE);
420 		return (EEXIST);
421 	}
422 	sc->sc_name = name;
423 	g_gate_units[sc->sc_unit] = sc;
424 	g_gate_nunits++;
425 	mtx_unlock(&g_gate_units_lock);
426 
427 	ggio->gctl_unit = sc->sc_unit;
428 
429 	g_topology_lock();
430 	gp = g_new_geomf(&g_gate_class, "%s", name);
431 	gp->start = g_gate_start;
432 	gp->access = g_gate_access;
433 	gp->dumpconf = g_gate_dumpconf;
434 	gp->softc = sc;
435 	pp = g_new_providerf(gp, "%s", name);
436 	pp->mediasize = ggio->gctl_mediasize;
437 	pp->sectorsize = ggio->gctl_sectorsize;
438 	sc->sc_provider = pp;
439 	g_error_provider(pp, 0);
440 	g_topology_unlock();
441 	mtx_lock(&g_gate_units_lock);
442 	sc->sc_name = sc->sc_provider->name;
443 	mtx_unlock(&g_gate_units_lock);
444 	G_GATE_DEBUG(1, "Device %s created.", gp->name);
445 
446 	if (sc->sc_timeout > 0) {
447 		callout_reset(&sc->sc_callout, sc->sc_timeout * hz,
448 		    g_gate_guard, sc);
449 	}
450 	return (0);
451 }
452 
453 #define	G_GATE_CHECK_VERSION(ggio)	do {				\
454 	if ((ggio)->gctl_version != G_GATE_VERSION) {			\
455 		printf("Version mismatch %d != %d.\n",			\
456 		    ggio->gctl_version, G_GATE_VERSION);		\
457 		return (EINVAL);					\
458 	}								\
459 } while (0)
460 static int
461 g_gate_ioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags, struct thread *td)
462 {
463 	struct g_gate_softc *sc;
464 	struct bio *bp;
465 	int error = 0;
466 
467 	G_GATE_DEBUG(4, "ioctl(%s, %lx, %p, %x, %p)", devtoname(dev), cmd, addr,
468 	    flags, td);
469 
470 	switch (cmd) {
471 	case G_GATE_CMD_CREATE:
472 	    {
473 		struct g_gate_ctl_create *ggio = (void *)addr;
474 
475 		G_GATE_CHECK_VERSION(ggio);
476 		error = g_gate_create(ggio);
477 		/*
478 		 * Reset TDP_GEOM flag.
479 		 * There are pending events for sure, because we just created
480 		 * new provider and other classes want to taste it, but we
481 		 * cannot answer on I/O requests until we're here.
482 		 */
483 		td->td_pflags &= ~TDP_GEOM;
484 		return (error);
485 	    }
486 	case G_GATE_CMD_DESTROY:
487 	    {
488 		struct g_gate_ctl_destroy *ggio = (void *)addr;
489 
490 		G_GATE_CHECK_VERSION(ggio);
491 		sc = g_gate_hold(ggio->gctl_unit, ggio->gctl_name);
492 		if (sc == NULL)
493 			return (ENXIO);
494 		g_topology_lock();
495 		mtx_lock(&g_gate_units_lock);
496 		error = g_gate_destroy(sc, ggio->gctl_force);
497 		g_topology_unlock();
498 		if (error != 0)
499 			g_gate_release(sc);
500 		return (error);
501 	    }
502 	case G_GATE_CMD_CANCEL:
503 	    {
504 		struct g_gate_ctl_cancel *ggio = (void *)addr;
505 		struct bio *tbp, *lbp;
506 
507 		G_GATE_CHECK_VERSION(ggio);
508 		sc = g_gate_hold(ggio->gctl_unit, ggio->gctl_name);
509 		if (sc == NULL)
510 			return (ENXIO);
511 		lbp = NULL;
512 		mtx_lock(&sc->sc_queue_mtx);
513 		TAILQ_FOREACH_SAFE(bp, &sc->sc_outqueue.queue, bio_queue, tbp) {
514 			if (ggio->gctl_seq == 0 ||
515 			    ggio->gctl_seq == (uintptr_t)bp->bio_driver1) {
516 				G_GATE_LOGREQ(1, bp, "Request canceled.");
517 				bioq_remove(&sc->sc_outqueue, bp);
518 				/*
519 				 * Be sure to put requests back onto incoming
520 				 * queue in the proper order.
521 				 */
522 				if (lbp == NULL)
523 					bioq_insert_head(&sc->sc_inqueue, bp);
524 				else {
525 					TAILQ_INSERT_AFTER(&sc->sc_inqueue.queue,
526 					    lbp, bp, bio_queue);
527 				}
528 				lbp = bp;
529 				/*
530 				 * If only one request was canceled, leave now.
531 				 */
532 				if (ggio->gctl_seq != 0)
533 					break;
534 			}
535 		}
536 		if (ggio->gctl_unit == G_GATE_NAME_GIVEN)
537 			ggio->gctl_unit = sc->sc_unit;
538 		mtx_unlock(&sc->sc_queue_mtx);
539 		g_gate_release(sc);
540 		return (error);
541 	    }
542 	case G_GATE_CMD_START:
543 	    {
544 		struct g_gate_ctl_io *ggio = (void *)addr;
545 
546 		G_GATE_CHECK_VERSION(ggio);
547 		sc = g_gate_hold(ggio->gctl_unit, NULL);
548 		if (sc == NULL)
549 			return (ENXIO);
550 		error = 0;
551 		for (;;) {
552 			mtx_lock(&sc->sc_queue_mtx);
553 			bp = bioq_first(&sc->sc_inqueue);
554 			if (bp != NULL)
555 				break;
556 			if ((sc->sc_flags & G_GATE_FLAG_DESTROY) != 0) {
557 				ggio->gctl_error = ECANCELED;
558 				mtx_unlock(&sc->sc_queue_mtx);
559 				goto start_end;
560 			}
561 			if (msleep(sc, &sc->sc_queue_mtx,
562 			    PPAUSE | PDROP | PCATCH, "ggwait", 0) != 0) {
563 				ggio->gctl_error = ECANCELED;
564 				goto start_end;
565 			}
566 		}
567 		ggio->gctl_cmd = bp->bio_cmd;
568 		if ((bp->bio_cmd == BIO_DELETE || bp->bio_cmd == BIO_WRITE) &&
569 		    bp->bio_length > ggio->gctl_length) {
570 			mtx_unlock(&sc->sc_queue_mtx);
571 			ggio->gctl_length = bp->bio_length;
572 			ggio->gctl_error = ENOMEM;
573 			goto start_end;
574 		}
575 		bioq_remove(&sc->sc_inqueue, bp);
576 		bioq_insert_tail(&sc->sc_outqueue, bp);
577 		mtx_unlock(&sc->sc_queue_mtx);
578 
579 		ggio->gctl_seq = (uintptr_t)bp->bio_driver1;
580 		ggio->gctl_offset = bp->bio_offset;
581 		ggio->gctl_length = bp->bio_length;
582 
583 		switch (bp->bio_cmd) {
584 		case BIO_READ:
585 		case BIO_DELETE:
586 		case BIO_FLUSH:
587 			break;
588 		case BIO_WRITE:
589 			error = copyout(bp->bio_data, ggio->gctl_data,
590 			    bp->bio_length);
591 			if (error != 0) {
592 				mtx_lock(&sc->sc_queue_mtx);
593 				bioq_remove(&sc->sc_outqueue, bp);
594 				bioq_insert_head(&sc->sc_inqueue, bp);
595 				mtx_unlock(&sc->sc_queue_mtx);
596 				goto start_end;
597 			}
598 			break;
599 		}
600 start_end:
601 		g_gate_release(sc);
602 		return (error);
603 	    }
604 	case G_GATE_CMD_DONE:
605 	    {
606 		struct g_gate_ctl_io *ggio = (void *)addr;
607 
608 		G_GATE_CHECK_VERSION(ggio);
609 		sc = g_gate_hold(ggio->gctl_unit, NULL);
610 		if (sc == NULL)
611 			return (ENOENT);
612 		error = 0;
613 		mtx_lock(&sc->sc_queue_mtx);
614 		TAILQ_FOREACH(bp, &sc->sc_outqueue.queue, bio_queue) {
615 			if (ggio->gctl_seq == (uintptr_t)bp->bio_driver1)
616 				break;
617 		}
618 		if (bp != NULL) {
619 			bioq_remove(&sc->sc_outqueue, bp);
620 			sc->sc_queue_count--;
621 		}
622 		mtx_unlock(&sc->sc_queue_mtx);
623 		if (bp == NULL) {
624 			/*
625 			 * Request was probably canceled.
626 			 */
627 			goto done_end;
628 		}
629 		if (ggio->gctl_error == EAGAIN) {
630 			bp->bio_error = 0;
631 			G_GATE_LOGREQ(1, bp, "Request desisted.");
632 			mtx_lock(&sc->sc_queue_mtx);
633 			sc->sc_queue_count++;
634 			bioq_insert_head(&sc->sc_inqueue, bp);
635 			wakeup(sc);
636 			mtx_unlock(&sc->sc_queue_mtx);
637 		} else {
638 			bp->bio_error = ggio->gctl_error;
639 			if (bp->bio_error == 0) {
640 				bp->bio_completed = bp->bio_length;
641 				switch (bp->bio_cmd) {
642 				case BIO_READ:
643 					error = copyin(ggio->gctl_data,
644 					    bp->bio_data, bp->bio_length);
645 					if (error != 0)
646 						bp->bio_error = error;
647 					break;
648 				case BIO_DELETE:
649 				case BIO_WRITE:
650 				case BIO_FLUSH:
651 					break;
652 				}
653 			}
654 			G_GATE_LOGREQ(2, bp, "Request done.");
655 			g_io_deliver(bp, bp->bio_error);
656 		}
657 done_end:
658 		g_gate_release(sc);
659 		return (error);
660 	    }
661 	}
662 	return (ENOIOCTL);
663 }
664 
665 static void
666 g_gate_device(void)
667 {
668 
669 	status_dev = make_dev(&g_gate_cdevsw, 0x0, UID_ROOT, GID_WHEEL, 0600,
670 	    G_GATE_CTL_NAME);
671 }
672 
673 static int
674 g_gate_modevent(module_t mod, int type, void *data)
675 {
676 	int error = 0;
677 
678 	switch (type) {
679 	case MOD_LOAD:
680 		mtx_init(&g_gate_units_lock, "gg_units_lock", NULL, MTX_DEF);
681 		g_gate_units = malloc(g_gate_maxunits * sizeof(g_gate_units[0]),
682 		    M_GATE, M_WAITOK | M_ZERO);
683 		g_gate_nunits = 0;
684 		g_gate_device();
685 		break;
686 	case MOD_UNLOAD:
687 		mtx_lock(&g_gate_units_lock);
688 		if (g_gate_nunits > 0) {
689 			mtx_unlock(&g_gate_units_lock);
690 			error = EBUSY;
691 			break;
692 		}
693 		mtx_unlock(&g_gate_units_lock);
694 		mtx_destroy(&g_gate_units_lock);
695 		if (status_dev != 0)
696 			destroy_dev(status_dev);
697 		free(g_gate_units, M_GATE);
698 		break;
699 	default:
700 		return (EOPNOTSUPP);
701 		break;
702 	}
703 
704 	return (error);
705 }
706 static moduledata_t g_gate_module = {
707 	G_GATE_MOD_NAME,
708 	g_gate_modevent,
709 	NULL
710 };
711 DECLARE_MODULE(geom_gate, g_gate_module, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
712 DECLARE_GEOM_CLASS(g_gate_class, g_gate);
713