xref: /freebsd/sys/geom/mirror/g_mirror.c (revision c9c67103c371140fa440f0be08eaa8f308b23239)
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/kernel.h>
33 #include <sys/module.h>
34 #include <sys/limits.h>
35 #include <sys/lock.h>
36 #include <sys/mutex.h>
37 #include <sys/bio.h>
38 #include <sys/sbuf.h>
39 #include <sys/sysctl.h>
40 #include <sys/malloc.h>
41 #include <sys/eventhandler.h>
42 #include <vm/uma.h>
43 #include <geom/geom.h>
44 #include <sys/proc.h>
45 #include <sys/kthread.h>
46 #include <sys/sched.h>
47 #include <geom/mirror/g_mirror.h>
48 
49 FEATURE(geom_mirror, "GEOM mirroring support");
50 
51 static MALLOC_DEFINE(M_MIRROR, "mirror_data", "GEOM_MIRROR Data");
52 
53 SYSCTL_DECL(_kern_geom);
54 static SYSCTL_NODE(_kern_geom, OID_AUTO, mirror, CTLFLAG_RW, 0,
55     "GEOM_MIRROR stuff");
56 u_int g_mirror_debug = 0;
57 TUNABLE_INT("kern.geom.mirror.debug", &g_mirror_debug);
58 SYSCTL_UINT(_kern_geom_mirror, OID_AUTO, debug, CTLFLAG_RW, &g_mirror_debug, 0,
59     "Debug level");
60 static u_int g_mirror_timeout = 4;
61 TUNABLE_INT("kern.geom.mirror.timeout", &g_mirror_timeout);
62 SYSCTL_UINT(_kern_geom_mirror, OID_AUTO, timeout, CTLFLAG_RW, &g_mirror_timeout,
63     0, "Time to wait on all mirror components");
64 static u_int g_mirror_idletime = 5;
65 TUNABLE_INT("kern.geom.mirror.idletime", &g_mirror_idletime);
66 SYSCTL_UINT(_kern_geom_mirror, OID_AUTO, idletime, CTLFLAG_RW,
67     &g_mirror_idletime, 0, "Mark components as clean when idling");
68 static u_int g_mirror_disconnect_on_failure = 1;
69 TUNABLE_INT("kern.geom.mirror.disconnect_on_failure",
70     &g_mirror_disconnect_on_failure);
71 SYSCTL_UINT(_kern_geom_mirror, OID_AUTO, disconnect_on_failure, CTLFLAG_RW,
72     &g_mirror_disconnect_on_failure, 0, "Disconnect component on I/O failure.");
73 static u_int g_mirror_syncreqs = 2;
74 TUNABLE_INT("kern.geom.mirror.sync_requests", &g_mirror_syncreqs);
75 SYSCTL_UINT(_kern_geom_mirror, OID_AUTO, sync_requests, CTLFLAG_RDTUN,
76     &g_mirror_syncreqs, 0, "Parallel synchronization I/O requests.");
77 
78 #define	MSLEEP(ident, mtx, priority, wmesg, timeout)	do {		\
79 	G_MIRROR_DEBUG(4, "%s: Sleeping %p.", __func__, (ident));	\
80 	msleep((ident), (mtx), (priority), (wmesg), (timeout));		\
81 	G_MIRROR_DEBUG(4, "%s: Woken up %p.", __func__, (ident));	\
82 } while (0)
83 
84 static eventhandler_tag g_mirror_post_sync = NULL;
85 static int g_mirror_shutdown = 0;
86 
87 static int g_mirror_destroy_geom(struct gctl_req *req, struct g_class *mp,
88     struct g_geom *gp);
89 static g_taste_t g_mirror_taste;
90 static void g_mirror_init(struct g_class *mp);
91 static void g_mirror_fini(struct g_class *mp);
92 
93 struct g_class g_mirror_class = {
94 	.name = G_MIRROR_CLASS_NAME,
95 	.version = G_VERSION,
96 	.ctlreq = g_mirror_config,
97 	.taste = g_mirror_taste,
98 	.destroy_geom = g_mirror_destroy_geom,
99 	.init = g_mirror_init,
100 	.fini = g_mirror_fini
101 };
102 
103 
104 static void g_mirror_destroy_provider(struct g_mirror_softc *sc);
105 static int g_mirror_update_disk(struct g_mirror_disk *disk, u_int state);
106 static void g_mirror_update_device(struct g_mirror_softc *sc, boolean_t force);
107 static void g_mirror_dumpconf(struct sbuf *sb, const char *indent,
108     struct g_geom *gp, struct g_consumer *cp, struct g_provider *pp);
109 static void g_mirror_sync_stop(struct g_mirror_disk *disk, int type);
110 static void g_mirror_register_request(struct bio *bp);
111 static void g_mirror_sync_release(struct g_mirror_softc *sc);
112 
113 
114 static const char *
115 g_mirror_disk_state2str(int state)
116 {
117 
118 	switch (state) {
119 	case G_MIRROR_DISK_STATE_NONE:
120 		return ("NONE");
121 	case G_MIRROR_DISK_STATE_NEW:
122 		return ("NEW");
123 	case G_MIRROR_DISK_STATE_ACTIVE:
124 		return ("ACTIVE");
125 	case G_MIRROR_DISK_STATE_STALE:
126 		return ("STALE");
127 	case G_MIRROR_DISK_STATE_SYNCHRONIZING:
128 		return ("SYNCHRONIZING");
129 	case G_MIRROR_DISK_STATE_DISCONNECTED:
130 		return ("DISCONNECTED");
131 	case G_MIRROR_DISK_STATE_DESTROY:
132 		return ("DESTROY");
133 	default:
134 		return ("INVALID");
135 	}
136 }
137 
138 static const char *
139 g_mirror_device_state2str(int state)
140 {
141 
142 	switch (state) {
143 	case G_MIRROR_DEVICE_STATE_STARTING:
144 		return ("STARTING");
145 	case G_MIRROR_DEVICE_STATE_RUNNING:
146 		return ("RUNNING");
147 	default:
148 		return ("INVALID");
149 	}
150 }
151 
152 static const char *
153 g_mirror_get_diskname(struct g_mirror_disk *disk)
154 {
155 
156 	if (disk->d_consumer == NULL || disk->d_consumer->provider == NULL)
157 		return ("[unknown]");
158 	return (disk->d_name);
159 }
160 
161 /*
162  * --- Events handling functions ---
163  * Events in geom_mirror are used to maintain disks and device status
164  * from one thread to simplify locking.
165  */
166 static void
167 g_mirror_event_free(struct g_mirror_event *ep)
168 {
169 
170 	free(ep, M_MIRROR);
171 }
172 
173 int
174 g_mirror_event_send(void *arg, int state, int flags)
175 {
176 	struct g_mirror_softc *sc;
177 	struct g_mirror_disk *disk;
178 	struct g_mirror_event *ep;
179 	int error;
180 
181 	ep = malloc(sizeof(*ep), M_MIRROR, M_WAITOK);
182 	G_MIRROR_DEBUG(4, "%s: Sending event %p.", __func__, ep);
183 	if ((flags & G_MIRROR_EVENT_DEVICE) != 0) {
184 		disk = NULL;
185 		sc = arg;
186 	} else {
187 		disk = arg;
188 		sc = disk->d_softc;
189 	}
190 	ep->e_disk = disk;
191 	ep->e_state = state;
192 	ep->e_flags = flags;
193 	ep->e_error = 0;
194 	mtx_lock(&sc->sc_events_mtx);
195 	TAILQ_INSERT_TAIL(&sc->sc_events, ep, e_next);
196 	mtx_unlock(&sc->sc_events_mtx);
197 	G_MIRROR_DEBUG(4, "%s: Waking up %p.", __func__, sc);
198 	mtx_lock(&sc->sc_queue_mtx);
199 	wakeup(sc);
200 	mtx_unlock(&sc->sc_queue_mtx);
201 	if ((flags & G_MIRROR_EVENT_DONTWAIT) != 0)
202 		return (0);
203 	sx_assert(&sc->sc_lock, SX_XLOCKED);
204 	G_MIRROR_DEBUG(4, "%s: Sleeping %p.", __func__, ep);
205 	sx_xunlock(&sc->sc_lock);
206 	while ((ep->e_flags & G_MIRROR_EVENT_DONE) == 0) {
207 		mtx_lock(&sc->sc_events_mtx);
208 		MSLEEP(ep, &sc->sc_events_mtx, PRIBIO | PDROP, "m:event",
209 		    hz * 5);
210 	}
211 	error = ep->e_error;
212 	g_mirror_event_free(ep);
213 	sx_xlock(&sc->sc_lock);
214 	return (error);
215 }
216 
217 static struct g_mirror_event *
218 g_mirror_event_get(struct g_mirror_softc *sc)
219 {
220 	struct g_mirror_event *ep;
221 
222 	mtx_lock(&sc->sc_events_mtx);
223 	ep = TAILQ_FIRST(&sc->sc_events);
224 	mtx_unlock(&sc->sc_events_mtx);
225 	return (ep);
226 }
227 
228 static void
229 g_mirror_event_remove(struct g_mirror_softc *sc, struct g_mirror_event *ep)
230 {
231 
232 	mtx_lock(&sc->sc_events_mtx);
233 	TAILQ_REMOVE(&sc->sc_events, ep, e_next);
234 	mtx_unlock(&sc->sc_events_mtx);
235 }
236 
237 static void
238 g_mirror_event_cancel(struct g_mirror_disk *disk)
239 {
240 	struct g_mirror_softc *sc;
241 	struct g_mirror_event *ep, *tmpep;
242 
243 	sc = disk->d_softc;
244 	sx_assert(&sc->sc_lock, SX_XLOCKED);
245 
246 	mtx_lock(&sc->sc_events_mtx);
247 	TAILQ_FOREACH_SAFE(ep, &sc->sc_events, e_next, tmpep) {
248 		if ((ep->e_flags & G_MIRROR_EVENT_DEVICE) != 0)
249 			continue;
250 		if (ep->e_disk != disk)
251 			continue;
252 		TAILQ_REMOVE(&sc->sc_events, ep, e_next);
253 		if ((ep->e_flags & G_MIRROR_EVENT_DONTWAIT) != 0)
254 			g_mirror_event_free(ep);
255 		else {
256 			ep->e_error = ECANCELED;
257 			wakeup(ep);
258 		}
259 	}
260 	mtx_unlock(&sc->sc_events_mtx);
261 }
262 
263 /*
264  * Return the number of disks in given state.
265  * If state is equal to -1, count all connected disks.
266  */
267 u_int
268 g_mirror_ndisks(struct g_mirror_softc *sc, int state)
269 {
270 	struct g_mirror_disk *disk;
271 	u_int n = 0;
272 
273 	sx_assert(&sc->sc_lock, SX_LOCKED);
274 
275 	LIST_FOREACH(disk, &sc->sc_disks, d_next) {
276 		if (state == -1 || disk->d_state == state)
277 			n++;
278 	}
279 	return (n);
280 }
281 
282 /*
283  * Find a disk in mirror by its disk ID.
284  */
285 static struct g_mirror_disk *
286 g_mirror_id2disk(struct g_mirror_softc *sc, uint32_t id)
287 {
288 	struct g_mirror_disk *disk;
289 
290 	sx_assert(&sc->sc_lock, SX_XLOCKED);
291 
292 	LIST_FOREACH(disk, &sc->sc_disks, d_next) {
293 		if (disk->d_id == id)
294 			return (disk);
295 	}
296 	return (NULL);
297 }
298 
299 static u_int
300 g_mirror_nrequests(struct g_mirror_softc *sc, struct g_consumer *cp)
301 {
302 	struct bio *bp;
303 	u_int nreqs = 0;
304 
305 	mtx_lock(&sc->sc_queue_mtx);
306 	TAILQ_FOREACH(bp, &sc->sc_queue.queue, bio_queue) {
307 		if (bp->bio_from == cp)
308 			nreqs++;
309 	}
310 	mtx_unlock(&sc->sc_queue_mtx);
311 	return (nreqs);
312 }
313 
314 static int
315 g_mirror_is_busy(struct g_mirror_softc *sc, struct g_consumer *cp)
316 {
317 
318 	if (cp->index > 0) {
319 		G_MIRROR_DEBUG(2,
320 		    "I/O requests for %s exist, can't destroy it now.",
321 		    cp->provider->name);
322 		return (1);
323 	}
324 	if (g_mirror_nrequests(sc, cp) > 0) {
325 		G_MIRROR_DEBUG(2,
326 		    "I/O requests for %s in queue, can't destroy it now.",
327 		    cp->provider->name);
328 		return (1);
329 	}
330 	return (0);
331 }
332 
333 static void
334 g_mirror_destroy_consumer(void *arg, int flags __unused)
335 {
336 	struct g_consumer *cp;
337 
338 	g_topology_assert();
339 
340 	cp = arg;
341 	G_MIRROR_DEBUG(1, "Consumer %s destroyed.", cp->provider->name);
342 	g_detach(cp);
343 	g_destroy_consumer(cp);
344 }
345 
346 static void
347 g_mirror_kill_consumer(struct g_mirror_softc *sc, struct g_consumer *cp)
348 {
349 	struct g_provider *pp;
350 	int retaste_wait;
351 
352 	g_topology_assert();
353 
354 	cp->private = NULL;
355 	if (g_mirror_is_busy(sc, cp))
356 		return;
357 	pp = cp->provider;
358 	retaste_wait = 0;
359 	if (cp->acw == 1) {
360 		if ((pp->geom->flags & G_GEOM_WITHER) == 0)
361 			retaste_wait = 1;
362 	}
363 	G_MIRROR_DEBUG(2, "Access %s r%dw%de%d = %d", pp->name, -cp->acr,
364 	    -cp->acw, -cp->ace, 0);
365 	if (cp->acr > 0 || cp->acw > 0 || cp->ace > 0)
366 		g_access(cp, -cp->acr, -cp->acw, -cp->ace);
367 	if (retaste_wait) {
368 		/*
369 		 * After retaste event was send (inside g_access()), we can send
370 		 * event to detach and destroy consumer.
371 		 * A class, which has consumer to the given provider connected
372 		 * will not receive retaste event for the provider.
373 		 * This is the way how I ignore retaste events when I close
374 		 * consumers opened for write: I detach and destroy consumer
375 		 * after retaste event is sent.
376 		 */
377 		g_post_event(g_mirror_destroy_consumer, cp, M_WAITOK, NULL);
378 		return;
379 	}
380 	G_MIRROR_DEBUG(1, "Consumer %s destroyed.", pp->name);
381 	g_detach(cp);
382 	g_destroy_consumer(cp);
383 }
384 
385 static int
386 g_mirror_connect_disk(struct g_mirror_disk *disk, struct g_provider *pp)
387 {
388 	struct g_consumer *cp;
389 	int error;
390 
391 	g_topology_assert_not();
392 	KASSERT(disk->d_consumer == NULL,
393 	    ("Disk already connected (device %s).", disk->d_softc->sc_name));
394 
395 	g_topology_lock();
396 	cp = g_new_consumer(disk->d_softc->sc_geom);
397 	error = g_attach(cp, pp);
398 	if (error != 0) {
399 		g_destroy_consumer(cp);
400 		g_topology_unlock();
401 		return (error);
402 	}
403 	error = g_access(cp, 1, 1, 1);
404 	if (error != 0) {
405 		g_detach(cp);
406 		g_destroy_consumer(cp);
407 		g_topology_unlock();
408 		G_MIRROR_DEBUG(0, "Cannot open consumer %s (error=%d).",
409 		    pp->name, error);
410 		return (error);
411 	}
412 	g_topology_unlock();
413 	disk->d_consumer = cp;
414 	disk->d_consumer->private = disk;
415 	disk->d_consumer->index = 0;
416 
417 	G_MIRROR_DEBUG(2, "Disk %s connected.", g_mirror_get_diskname(disk));
418 	return (0);
419 }
420 
421 static void
422 g_mirror_disconnect_consumer(struct g_mirror_softc *sc, struct g_consumer *cp)
423 {
424 
425 	g_topology_assert();
426 
427 	if (cp == NULL)
428 		return;
429 	if (cp->provider != NULL)
430 		g_mirror_kill_consumer(sc, cp);
431 	else
432 		g_destroy_consumer(cp);
433 }
434 
435 /*
436  * Initialize disk. This means allocate memory, create consumer, attach it
437  * to the provider and open access (r1w1e1) to it.
438  */
439 static struct g_mirror_disk *
440 g_mirror_init_disk(struct g_mirror_softc *sc, struct g_provider *pp,
441     struct g_mirror_metadata *md, int *errorp)
442 {
443 	struct g_mirror_disk *disk;
444 	int i, error;
445 
446 	disk = malloc(sizeof(*disk), M_MIRROR, M_NOWAIT | M_ZERO);
447 	if (disk == NULL) {
448 		error = ENOMEM;
449 		goto fail;
450 	}
451 	disk->d_softc = sc;
452 	error = g_mirror_connect_disk(disk, pp);
453 	if (error != 0)
454 		goto fail;
455 	disk->d_id = md->md_did;
456 	disk->d_state = G_MIRROR_DISK_STATE_NONE;
457 	disk->d_priority = md->md_priority;
458 	disk->d_flags = md->md_dflags;
459 	error = g_getattr("GEOM::candelete", disk->d_consumer, &i);
460 	if (error == 0 && i != 0)
461 		disk->d_flags |= G_MIRROR_DISK_FLAG_CANDELETE;
462 	if (md->md_provider[0] != '\0')
463 		disk->d_flags |= G_MIRROR_DISK_FLAG_HARDCODED;
464 	disk->d_sync.ds_consumer = NULL;
465 	disk->d_sync.ds_offset = md->md_sync_offset;
466 	disk->d_sync.ds_offset_done = md->md_sync_offset;
467 	disk->d_genid = md->md_genid;
468 	disk->d_sync.ds_syncid = md->md_syncid;
469 	if (errorp != NULL)
470 		*errorp = 0;
471 	return (disk);
472 fail:
473 	if (errorp != NULL)
474 		*errorp = error;
475 	if (disk != NULL)
476 		free(disk, M_MIRROR);
477 	return (NULL);
478 }
479 
480 static void
481 g_mirror_destroy_disk(struct g_mirror_disk *disk)
482 {
483 	struct g_mirror_softc *sc;
484 
485 	g_topology_assert_not();
486 	sc = disk->d_softc;
487 	sx_assert(&sc->sc_lock, SX_XLOCKED);
488 
489 	LIST_REMOVE(disk, d_next);
490 	g_mirror_event_cancel(disk);
491 	if (sc->sc_hint == disk)
492 		sc->sc_hint = NULL;
493 	switch (disk->d_state) {
494 	case G_MIRROR_DISK_STATE_SYNCHRONIZING:
495 		g_mirror_sync_stop(disk, 1);
496 		/* FALLTHROUGH */
497 	case G_MIRROR_DISK_STATE_NEW:
498 	case G_MIRROR_DISK_STATE_STALE:
499 	case G_MIRROR_DISK_STATE_ACTIVE:
500 		g_topology_lock();
501 		g_mirror_disconnect_consumer(sc, disk->d_consumer);
502 		g_topology_unlock();
503 		free(disk, M_MIRROR);
504 		break;
505 	default:
506 		KASSERT(0 == 1, ("Wrong disk state (%s, %s).",
507 		    g_mirror_get_diskname(disk),
508 		    g_mirror_disk_state2str(disk->d_state)));
509 	}
510 }
511 
512 static void
513 g_mirror_destroy_device(struct g_mirror_softc *sc)
514 {
515 	struct g_mirror_disk *disk;
516 	struct g_mirror_event *ep;
517 	struct g_geom *gp;
518 	struct g_consumer *cp, *tmpcp;
519 
520 	g_topology_assert_not();
521 	sx_assert(&sc->sc_lock, SX_XLOCKED);
522 
523 	gp = sc->sc_geom;
524 	if (sc->sc_provider != NULL)
525 		g_mirror_destroy_provider(sc);
526 	for (disk = LIST_FIRST(&sc->sc_disks); disk != NULL;
527 	    disk = LIST_FIRST(&sc->sc_disks)) {
528 		disk->d_flags &= ~G_MIRROR_DISK_FLAG_DIRTY;
529 		g_mirror_update_metadata(disk);
530 		g_mirror_destroy_disk(disk);
531 	}
532 	while ((ep = g_mirror_event_get(sc)) != NULL) {
533 		g_mirror_event_remove(sc, ep);
534 		if ((ep->e_flags & G_MIRROR_EVENT_DONTWAIT) != 0)
535 			g_mirror_event_free(ep);
536 		else {
537 			ep->e_error = ECANCELED;
538 			ep->e_flags |= G_MIRROR_EVENT_DONE;
539 			G_MIRROR_DEBUG(4, "%s: Waking up %p.", __func__, ep);
540 			mtx_lock(&sc->sc_events_mtx);
541 			wakeup(ep);
542 			mtx_unlock(&sc->sc_events_mtx);
543 		}
544 	}
545 	callout_drain(&sc->sc_callout);
546 
547 	g_topology_lock();
548 	LIST_FOREACH_SAFE(cp, &sc->sc_sync.ds_geom->consumer, consumer, tmpcp) {
549 		g_mirror_disconnect_consumer(sc, cp);
550 	}
551 	g_wither_geom(sc->sc_sync.ds_geom, ENXIO);
552 	G_MIRROR_DEBUG(0, "Device %s destroyed.", gp->name);
553 	g_wither_geom(gp, ENXIO);
554 	g_topology_unlock();
555 	mtx_destroy(&sc->sc_queue_mtx);
556 	mtx_destroy(&sc->sc_events_mtx);
557 	sx_xunlock(&sc->sc_lock);
558 	sx_destroy(&sc->sc_lock);
559 }
560 
561 static void
562 g_mirror_orphan(struct g_consumer *cp)
563 {
564 	struct g_mirror_disk *disk;
565 
566 	g_topology_assert();
567 
568 	disk = cp->private;
569 	if (disk == NULL)
570 		return;
571 	disk->d_softc->sc_bump_id |= G_MIRROR_BUMP_SYNCID;
572 	g_mirror_event_send(disk, G_MIRROR_DISK_STATE_DISCONNECTED,
573 	    G_MIRROR_EVENT_DONTWAIT);
574 }
575 
576 /*
577  * Function should return the next active disk on the list.
578  * It is possible that it will be the same disk as given.
579  * If there are no active disks on list, NULL is returned.
580  */
581 static __inline struct g_mirror_disk *
582 g_mirror_find_next(struct g_mirror_softc *sc, struct g_mirror_disk *disk)
583 {
584 	struct g_mirror_disk *dp;
585 
586 	for (dp = LIST_NEXT(disk, d_next); dp != disk;
587 	    dp = LIST_NEXT(dp, d_next)) {
588 		if (dp == NULL)
589 			dp = LIST_FIRST(&sc->sc_disks);
590 		if (dp->d_state == G_MIRROR_DISK_STATE_ACTIVE)
591 			break;
592 	}
593 	if (dp->d_state != G_MIRROR_DISK_STATE_ACTIVE)
594 		return (NULL);
595 	return (dp);
596 }
597 
598 static struct g_mirror_disk *
599 g_mirror_get_disk(struct g_mirror_softc *sc)
600 {
601 	struct g_mirror_disk *disk;
602 
603 	if (sc->sc_hint == NULL) {
604 		sc->sc_hint = LIST_FIRST(&sc->sc_disks);
605 		if (sc->sc_hint == NULL)
606 			return (NULL);
607 	}
608 	disk = sc->sc_hint;
609 	if (disk->d_state != G_MIRROR_DISK_STATE_ACTIVE) {
610 		disk = g_mirror_find_next(sc, disk);
611 		if (disk == NULL)
612 			return (NULL);
613 	}
614 	sc->sc_hint = g_mirror_find_next(sc, disk);
615 	return (disk);
616 }
617 
618 static int
619 g_mirror_write_metadata(struct g_mirror_disk *disk,
620     struct g_mirror_metadata *md)
621 {
622 	struct g_mirror_softc *sc;
623 	struct g_consumer *cp;
624 	off_t offset, length;
625 	u_char *sector;
626 	int error = 0;
627 
628 	g_topology_assert_not();
629 	sc = disk->d_softc;
630 	sx_assert(&sc->sc_lock, SX_LOCKED);
631 
632 	cp = disk->d_consumer;
633 	KASSERT(cp != NULL, ("NULL consumer (%s).", sc->sc_name));
634 	KASSERT(cp->provider != NULL, ("NULL provider (%s).", sc->sc_name));
635 	KASSERT(cp->acr >= 1 && cp->acw >= 1 && cp->ace >= 1,
636 	    ("Consumer %s closed? (r%dw%de%d).", cp->provider->name, cp->acr,
637 	    cp->acw, cp->ace));
638 	length = cp->provider->sectorsize;
639 	offset = cp->provider->mediasize - length;
640 	sector = malloc((size_t)length, M_MIRROR, M_WAITOK | M_ZERO);
641 	if (md != NULL)
642 		mirror_metadata_encode(md, sector);
643 	error = g_write_data(cp, offset, sector, length);
644 	free(sector, M_MIRROR);
645 	if (error != 0) {
646 		if ((disk->d_flags & G_MIRROR_DISK_FLAG_BROKEN) == 0) {
647 			disk->d_flags |= G_MIRROR_DISK_FLAG_BROKEN;
648 			G_MIRROR_DEBUG(0, "Cannot write metadata on %s "
649 			    "(device=%s, error=%d).",
650 			    g_mirror_get_diskname(disk), sc->sc_name, error);
651 		} else {
652 			G_MIRROR_DEBUG(1, "Cannot write metadata on %s "
653 			    "(device=%s, error=%d).",
654 			    g_mirror_get_diskname(disk), sc->sc_name, error);
655 		}
656 		if (g_mirror_disconnect_on_failure &&
657 		    g_mirror_ndisks(sc, G_MIRROR_DISK_STATE_ACTIVE) > 1) {
658 			sc->sc_bump_id |= G_MIRROR_BUMP_GENID;
659 			g_mirror_event_send(disk,
660 			    G_MIRROR_DISK_STATE_DISCONNECTED,
661 			    G_MIRROR_EVENT_DONTWAIT);
662 		}
663 	}
664 	return (error);
665 }
666 
667 static int
668 g_mirror_clear_metadata(struct g_mirror_disk *disk)
669 {
670 	int error;
671 
672 	g_topology_assert_not();
673 	sx_assert(&disk->d_softc->sc_lock, SX_LOCKED);
674 
675 	error = g_mirror_write_metadata(disk, NULL);
676 	if (error == 0) {
677 		G_MIRROR_DEBUG(2, "Metadata on %s cleared.",
678 		    g_mirror_get_diskname(disk));
679 	} else {
680 		G_MIRROR_DEBUG(0,
681 		    "Cannot clear metadata on disk %s (error=%d).",
682 		    g_mirror_get_diskname(disk), error);
683 	}
684 	return (error);
685 }
686 
687 void
688 g_mirror_fill_metadata(struct g_mirror_softc *sc, struct g_mirror_disk *disk,
689     struct g_mirror_metadata *md)
690 {
691 
692 	strlcpy(md->md_magic, G_MIRROR_MAGIC, sizeof(md->md_magic));
693 	md->md_version = G_MIRROR_VERSION;
694 	strlcpy(md->md_name, sc->sc_name, sizeof(md->md_name));
695 	md->md_mid = sc->sc_id;
696 	md->md_all = sc->sc_ndisks;
697 	md->md_slice = sc->sc_slice;
698 	md->md_balance = sc->sc_balance;
699 	md->md_genid = sc->sc_genid;
700 	md->md_mediasize = sc->sc_mediasize;
701 	md->md_sectorsize = sc->sc_sectorsize;
702 	md->md_mflags = (sc->sc_flags & G_MIRROR_DEVICE_FLAG_MASK);
703 	bzero(md->md_provider, sizeof(md->md_provider));
704 	if (disk == NULL) {
705 		md->md_did = arc4random();
706 		md->md_priority = 0;
707 		md->md_syncid = 0;
708 		md->md_dflags = 0;
709 		md->md_sync_offset = 0;
710 		md->md_provsize = 0;
711 	} else {
712 		md->md_did = disk->d_id;
713 		md->md_priority = disk->d_priority;
714 		md->md_syncid = disk->d_sync.ds_syncid;
715 		md->md_dflags = (disk->d_flags & G_MIRROR_DISK_FLAG_MASK);
716 		if (disk->d_state == G_MIRROR_DISK_STATE_SYNCHRONIZING)
717 			md->md_sync_offset = disk->d_sync.ds_offset_done;
718 		else
719 			md->md_sync_offset = 0;
720 		if ((disk->d_flags & G_MIRROR_DISK_FLAG_HARDCODED) != 0) {
721 			strlcpy(md->md_provider,
722 			    disk->d_consumer->provider->name,
723 			    sizeof(md->md_provider));
724 		}
725 		md->md_provsize = disk->d_consumer->provider->mediasize;
726 	}
727 }
728 
729 void
730 g_mirror_update_metadata(struct g_mirror_disk *disk)
731 {
732 	struct g_mirror_softc *sc;
733 	struct g_mirror_metadata md;
734 	int error;
735 
736 	g_topology_assert_not();
737 	sc = disk->d_softc;
738 	sx_assert(&sc->sc_lock, SX_LOCKED);
739 
740 	g_mirror_fill_metadata(sc, disk, &md);
741 	error = g_mirror_write_metadata(disk, &md);
742 	if (error == 0) {
743 		G_MIRROR_DEBUG(2, "Metadata on %s updated.",
744 		    g_mirror_get_diskname(disk));
745 	} else {
746 		G_MIRROR_DEBUG(0,
747 		    "Cannot update metadata on disk %s (error=%d).",
748 		    g_mirror_get_diskname(disk), error);
749 	}
750 }
751 
752 static void
753 g_mirror_bump_syncid(struct g_mirror_softc *sc)
754 {
755 	struct g_mirror_disk *disk;
756 
757 	g_topology_assert_not();
758 	sx_assert(&sc->sc_lock, SX_XLOCKED);
759 	KASSERT(g_mirror_ndisks(sc, G_MIRROR_DISK_STATE_ACTIVE) > 0,
760 	    ("%s called with no active disks (device=%s).", __func__,
761 	    sc->sc_name));
762 
763 	sc->sc_syncid++;
764 	G_MIRROR_DEBUG(1, "Device %s: syncid bumped to %u.", sc->sc_name,
765 	    sc->sc_syncid);
766 	LIST_FOREACH(disk, &sc->sc_disks, d_next) {
767 		if (disk->d_state == G_MIRROR_DISK_STATE_ACTIVE ||
768 		    disk->d_state == G_MIRROR_DISK_STATE_SYNCHRONIZING) {
769 			disk->d_sync.ds_syncid = sc->sc_syncid;
770 			g_mirror_update_metadata(disk);
771 		}
772 	}
773 }
774 
775 static void
776 g_mirror_bump_genid(struct g_mirror_softc *sc)
777 {
778 	struct g_mirror_disk *disk;
779 
780 	g_topology_assert_not();
781 	sx_assert(&sc->sc_lock, SX_XLOCKED);
782 	KASSERT(g_mirror_ndisks(sc, G_MIRROR_DISK_STATE_ACTIVE) > 0,
783 	    ("%s called with no active disks (device=%s).", __func__,
784 	    sc->sc_name));
785 
786 	sc->sc_genid++;
787 	G_MIRROR_DEBUG(1, "Device %s: genid bumped to %u.", sc->sc_name,
788 	    sc->sc_genid);
789 	LIST_FOREACH(disk, &sc->sc_disks, d_next) {
790 		if (disk->d_state == G_MIRROR_DISK_STATE_ACTIVE ||
791 		    disk->d_state == G_MIRROR_DISK_STATE_SYNCHRONIZING) {
792 			disk->d_genid = sc->sc_genid;
793 			g_mirror_update_metadata(disk);
794 		}
795 	}
796 }
797 
798 static int
799 g_mirror_idle(struct g_mirror_softc *sc, int acw)
800 {
801 	struct g_mirror_disk *disk;
802 	int timeout;
803 
804 	g_topology_assert_not();
805 	sx_assert(&sc->sc_lock, SX_XLOCKED);
806 
807 	if (sc->sc_provider == NULL)
808 		return (0);
809 	if ((sc->sc_flags & G_MIRROR_DEVICE_FLAG_NOFAILSYNC) != 0)
810 		return (0);
811 	if (sc->sc_idle)
812 		return (0);
813 	if (sc->sc_writes > 0)
814 		return (0);
815 	if (acw > 0 || (acw == -1 && sc->sc_provider->acw > 0)) {
816 		timeout = g_mirror_idletime - (time_uptime - sc->sc_last_write);
817 		if (!g_mirror_shutdown && timeout > 0)
818 			return (timeout);
819 	}
820 	sc->sc_idle = 1;
821 	LIST_FOREACH(disk, &sc->sc_disks, d_next) {
822 		if (disk->d_state != G_MIRROR_DISK_STATE_ACTIVE)
823 			continue;
824 		G_MIRROR_DEBUG(1, "Disk %s (device %s) marked as clean.",
825 		    g_mirror_get_diskname(disk), sc->sc_name);
826 		disk->d_flags &= ~G_MIRROR_DISK_FLAG_DIRTY;
827 		g_mirror_update_metadata(disk);
828 	}
829 	return (0);
830 }
831 
832 static void
833 g_mirror_unidle(struct g_mirror_softc *sc)
834 {
835 	struct g_mirror_disk *disk;
836 
837 	g_topology_assert_not();
838 	sx_assert(&sc->sc_lock, SX_XLOCKED);
839 
840 	if ((sc->sc_flags & G_MIRROR_DEVICE_FLAG_NOFAILSYNC) != 0)
841 		return;
842 	sc->sc_idle = 0;
843 	sc->sc_last_write = time_uptime;
844 	LIST_FOREACH(disk, &sc->sc_disks, d_next) {
845 		if (disk->d_state != G_MIRROR_DISK_STATE_ACTIVE)
846 			continue;
847 		G_MIRROR_DEBUG(1, "Disk %s (device %s) marked as dirty.",
848 		    g_mirror_get_diskname(disk), sc->sc_name);
849 		disk->d_flags |= G_MIRROR_DISK_FLAG_DIRTY;
850 		g_mirror_update_metadata(disk);
851 	}
852 }
853 
854 static void
855 g_mirror_done(struct bio *bp)
856 {
857 	struct g_mirror_softc *sc;
858 
859 	sc = bp->bio_from->geom->softc;
860 	bp->bio_cflags = G_MIRROR_BIO_FLAG_REGULAR;
861 	mtx_lock(&sc->sc_queue_mtx);
862 	bioq_disksort(&sc->sc_queue, bp);
863 	mtx_unlock(&sc->sc_queue_mtx);
864 	wakeup(sc);
865 }
866 
867 static void
868 g_mirror_regular_request(struct bio *bp)
869 {
870 	struct g_mirror_softc *sc;
871 	struct g_mirror_disk *disk;
872 	struct bio *pbp;
873 
874 	g_topology_assert_not();
875 
876 	pbp = bp->bio_parent;
877 	sc = pbp->bio_to->geom->softc;
878 	bp->bio_from->index--;
879 	if (bp->bio_cmd == BIO_WRITE)
880 		sc->sc_writes--;
881 	disk = bp->bio_from->private;
882 	if (disk == NULL) {
883 		g_topology_lock();
884 		g_mirror_kill_consumer(sc, bp->bio_from);
885 		g_topology_unlock();
886 	}
887 
888 	pbp->bio_inbed++;
889 	KASSERT(pbp->bio_inbed <= pbp->bio_children,
890 	    ("bio_inbed (%u) is bigger than bio_children (%u).", pbp->bio_inbed,
891 	    pbp->bio_children));
892 	if (bp->bio_error == 0 && pbp->bio_error == 0) {
893 		G_MIRROR_LOGREQ(3, bp, "Request delivered.");
894 		g_destroy_bio(bp);
895 		if (pbp->bio_children == pbp->bio_inbed) {
896 			G_MIRROR_LOGREQ(3, pbp, "Request delivered.");
897 			pbp->bio_completed = pbp->bio_length;
898 			if (pbp->bio_cmd == BIO_WRITE ||
899 			    pbp->bio_cmd == BIO_DELETE) {
900 				bioq_remove(&sc->sc_inflight, pbp);
901 				/* Release delayed sync requests if possible. */
902 				g_mirror_sync_release(sc);
903 			}
904 			g_io_deliver(pbp, pbp->bio_error);
905 		}
906 		return;
907 	} else if (bp->bio_error != 0) {
908 		if (pbp->bio_error == 0)
909 			pbp->bio_error = bp->bio_error;
910 		if (disk != NULL) {
911 			if ((disk->d_flags & G_MIRROR_DISK_FLAG_BROKEN) == 0) {
912 				disk->d_flags |= G_MIRROR_DISK_FLAG_BROKEN;
913 				G_MIRROR_LOGREQ(0, bp,
914 				    "Request failed (error=%d).",
915 				    bp->bio_error);
916 			} else {
917 				G_MIRROR_LOGREQ(1, bp,
918 				    "Request failed (error=%d).",
919 				    bp->bio_error);
920 			}
921 			if (g_mirror_disconnect_on_failure &&
922 			    g_mirror_ndisks(sc, G_MIRROR_DISK_STATE_ACTIVE) > 1)
923 			{
924 				sc->sc_bump_id |= G_MIRROR_BUMP_GENID;
925 				g_mirror_event_send(disk,
926 				    G_MIRROR_DISK_STATE_DISCONNECTED,
927 				    G_MIRROR_EVENT_DONTWAIT);
928 			}
929 		}
930 		switch (pbp->bio_cmd) {
931 		case BIO_DELETE:
932 		case BIO_WRITE:
933 			pbp->bio_inbed--;
934 			pbp->bio_children--;
935 			break;
936 		}
937 	}
938 	g_destroy_bio(bp);
939 
940 	switch (pbp->bio_cmd) {
941 	case BIO_READ:
942 		if (pbp->bio_inbed < pbp->bio_children)
943 			break;
944 		if (g_mirror_ndisks(sc, G_MIRROR_DISK_STATE_ACTIVE) == 1)
945 			g_io_deliver(pbp, pbp->bio_error);
946 		else {
947 			pbp->bio_error = 0;
948 			mtx_lock(&sc->sc_queue_mtx);
949 			bioq_disksort(&sc->sc_queue, pbp);
950 			mtx_unlock(&sc->sc_queue_mtx);
951 			G_MIRROR_DEBUG(4, "%s: Waking up %p.", __func__, sc);
952 			wakeup(sc);
953 		}
954 		break;
955 	case BIO_DELETE:
956 	case BIO_WRITE:
957 		if (pbp->bio_children == 0) {
958 			/*
959 			 * All requests failed.
960 			 */
961 		} else if (pbp->bio_inbed < pbp->bio_children) {
962 			/* Do nothing. */
963 			break;
964 		} else if (pbp->bio_children == pbp->bio_inbed) {
965 			/* Some requests succeeded. */
966 			pbp->bio_error = 0;
967 			pbp->bio_completed = pbp->bio_length;
968 		}
969 		bioq_remove(&sc->sc_inflight, pbp);
970 		/* Release delayed sync requests if possible. */
971 		g_mirror_sync_release(sc);
972 		g_io_deliver(pbp, pbp->bio_error);
973 		break;
974 	default:
975 		KASSERT(1 == 0, ("Invalid request: %u.", pbp->bio_cmd));
976 		break;
977 	}
978 }
979 
980 static void
981 g_mirror_sync_done(struct bio *bp)
982 {
983 	struct g_mirror_softc *sc;
984 
985 	G_MIRROR_LOGREQ(3, bp, "Synchronization request delivered.");
986 	sc = bp->bio_from->geom->softc;
987 	bp->bio_cflags = G_MIRROR_BIO_FLAG_SYNC;
988 	mtx_lock(&sc->sc_queue_mtx);
989 	bioq_disksort(&sc->sc_queue, bp);
990 	mtx_unlock(&sc->sc_queue_mtx);
991 	wakeup(sc);
992 }
993 
994 static void
995 g_mirror_kernel_dump(struct bio *bp)
996 {
997 	struct g_mirror_softc *sc;
998 	struct g_mirror_disk *disk;
999 	struct bio *cbp;
1000 	struct g_kerneldump *gkd;
1001 
1002 	/*
1003 	 * We configure dumping to the first component, because this component
1004 	 * will be used for reading with 'prefer' balance algorithm.
1005 	 * If the component with the higest priority is currently disconnected
1006 	 * we will not be able to read the dump after the reboot if it will be
1007 	 * connected and synchronized later. Can we do something better?
1008 	 */
1009 	sc = bp->bio_to->geom->softc;
1010 	disk = LIST_FIRST(&sc->sc_disks);
1011 
1012 	gkd = (struct g_kerneldump *)bp->bio_data;
1013 	if (gkd->length > bp->bio_to->mediasize)
1014 		gkd->length = bp->bio_to->mediasize;
1015 	cbp = g_clone_bio(bp);
1016 	if (cbp == NULL) {
1017 		g_io_deliver(bp, ENOMEM);
1018 		return;
1019 	}
1020 	cbp->bio_done = g_std_done;
1021 	g_io_request(cbp, disk->d_consumer);
1022 	G_MIRROR_DEBUG(1, "Kernel dump will go to %s.",
1023 	    g_mirror_get_diskname(disk));
1024 }
1025 
1026 static void
1027 g_mirror_flush(struct g_mirror_softc *sc, struct bio *bp)
1028 {
1029 	struct bio_queue_head queue;
1030 	struct g_mirror_disk *disk;
1031 	struct g_consumer *cp;
1032 	struct bio *cbp;
1033 
1034 	bioq_init(&queue);
1035 	LIST_FOREACH(disk, &sc->sc_disks, d_next) {
1036 		if (disk->d_state != G_MIRROR_DISK_STATE_ACTIVE)
1037 			continue;
1038 		cbp = g_clone_bio(bp);
1039 		if (cbp == NULL) {
1040 			for (cbp = bioq_first(&queue); cbp != NULL;
1041 			    cbp = bioq_first(&queue)) {
1042 				bioq_remove(&queue, cbp);
1043 				g_destroy_bio(cbp);
1044 			}
1045 			if (bp->bio_error == 0)
1046 				bp->bio_error = ENOMEM;
1047 			g_io_deliver(bp, bp->bio_error);
1048 			return;
1049 		}
1050 		bioq_insert_tail(&queue, cbp);
1051 		cbp->bio_done = g_std_done;
1052 		cbp->bio_caller1 = disk;
1053 		cbp->bio_to = disk->d_consumer->provider;
1054 	}
1055 	for (cbp = bioq_first(&queue); cbp != NULL; cbp = bioq_first(&queue)) {
1056 		bioq_remove(&queue, cbp);
1057 		G_MIRROR_LOGREQ(3, cbp, "Sending request.");
1058 		disk = cbp->bio_caller1;
1059 		cbp->bio_caller1 = NULL;
1060 		cp = disk->d_consumer;
1061 		KASSERT(cp->acr >= 1 && cp->acw >= 1 && cp->ace >= 1,
1062 		    ("Consumer %s not opened (r%dw%de%d).", cp->provider->name,
1063 		    cp->acr, cp->acw, cp->ace));
1064 		g_io_request(cbp, disk->d_consumer);
1065 	}
1066 }
1067 
1068 static void
1069 g_mirror_start(struct bio *bp)
1070 {
1071 	struct g_mirror_softc *sc;
1072 
1073 	sc = bp->bio_to->geom->softc;
1074 	/*
1075 	 * If sc == NULL or there are no valid disks, provider's error
1076 	 * should be set and g_mirror_start() should not be called at all.
1077 	 */
1078 	KASSERT(sc != NULL && sc->sc_state == G_MIRROR_DEVICE_STATE_RUNNING,
1079 	    ("Provider's error should be set (error=%d)(mirror=%s).",
1080 	    bp->bio_to->error, bp->bio_to->name));
1081 	G_MIRROR_LOGREQ(3, bp, "Request received.");
1082 
1083 	switch (bp->bio_cmd) {
1084 	case BIO_READ:
1085 	case BIO_WRITE:
1086 	case BIO_DELETE:
1087 		break;
1088 	case BIO_FLUSH:
1089 		g_mirror_flush(sc, bp);
1090 		return;
1091 	case BIO_GETATTR:
1092 		if (g_handleattr_int(bp, "GEOM::candelete", 1))
1093 			return;
1094 		else if (strcmp("GEOM::kerneldump", bp->bio_attribute) == 0) {
1095 			g_mirror_kernel_dump(bp);
1096 			return;
1097 		}
1098 		/* FALLTHROUGH */
1099 	default:
1100 		g_io_deliver(bp, EOPNOTSUPP);
1101 		return;
1102 	}
1103 	mtx_lock(&sc->sc_queue_mtx);
1104 	bioq_disksort(&sc->sc_queue, bp);
1105 	mtx_unlock(&sc->sc_queue_mtx);
1106 	G_MIRROR_DEBUG(4, "%s: Waking up %p.", __func__, sc);
1107 	wakeup(sc);
1108 }
1109 
1110 /*
1111  * Return TRUE if the given request is colliding with a in-progress
1112  * synchronization request.
1113  */
1114 static int
1115 g_mirror_sync_collision(struct g_mirror_softc *sc, struct bio *bp)
1116 {
1117 	struct g_mirror_disk *disk;
1118 	struct bio *sbp;
1119 	off_t rstart, rend, sstart, send;
1120 	int i;
1121 
1122 	if (sc->sc_sync.ds_ndisks == 0)
1123 		return (0);
1124 	rstart = bp->bio_offset;
1125 	rend = bp->bio_offset + bp->bio_length;
1126 	LIST_FOREACH(disk, &sc->sc_disks, d_next) {
1127 		if (disk->d_state != G_MIRROR_DISK_STATE_SYNCHRONIZING)
1128 			continue;
1129 		for (i = 0; i < g_mirror_syncreqs; i++) {
1130 			sbp = disk->d_sync.ds_bios[i];
1131 			if (sbp == NULL)
1132 				continue;
1133 			sstart = sbp->bio_offset;
1134 			send = sbp->bio_offset + sbp->bio_length;
1135 			if (rend > sstart && rstart < send)
1136 				return (1);
1137 		}
1138 	}
1139 	return (0);
1140 }
1141 
1142 /*
1143  * Return TRUE if the given sync request is colliding with a in-progress regular
1144  * request.
1145  */
1146 static int
1147 g_mirror_regular_collision(struct g_mirror_softc *sc, struct bio *sbp)
1148 {
1149 	off_t rstart, rend, sstart, send;
1150 	struct bio *bp;
1151 
1152 	if (sc->sc_sync.ds_ndisks == 0)
1153 		return (0);
1154 	sstart = sbp->bio_offset;
1155 	send = sbp->bio_offset + sbp->bio_length;
1156 	TAILQ_FOREACH(bp, &sc->sc_inflight.queue, bio_queue) {
1157 		rstart = bp->bio_offset;
1158 		rend = bp->bio_offset + bp->bio_length;
1159 		if (rend > sstart && rstart < send)
1160 			return (1);
1161 	}
1162 	return (0);
1163 }
1164 
1165 /*
1166  * Puts request onto delayed queue.
1167  */
1168 static void
1169 g_mirror_regular_delay(struct g_mirror_softc *sc, struct bio *bp)
1170 {
1171 
1172 	G_MIRROR_LOGREQ(2, bp, "Delaying request.");
1173 	bioq_insert_head(&sc->sc_regular_delayed, bp);
1174 }
1175 
1176 /*
1177  * Puts synchronization request onto delayed queue.
1178  */
1179 static void
1180 g_mirror_sync_delay(struct g_mirror_softc *sc, struct bio *bp)
1181 {
1182 
1183 	G_MIRROR_LOGREQ(2, bp, "Delaying synchronization request.");
1184 	bioq_insert_tail(&sc->sc_sync_delayed, bp);
1185 }
1186 
1187 /*
1188  * Releases delayed regular requests which don't collide anymore with sync
1189  * requests.
1190  */
1191 static void
1192 g_mirror_regular_release(struct g_mirror_softc *sc)
1193 {
1194 	struct bio *bp, *bp2;
1195 
1196 	TAILQ_FOREACH_SAFE(bp, &sc->sc_regular_delayed.queue, bio_queue, bp2) {
1197 		if (g_mirror_sync_collision(sc, bp))
1198 			continue;
1199 		bioq_remove(&sc->sc_regular_delayed, bp);
1200 		G_MIRROR_LOGREQ(2, bp, "Releasing delayed request (%p).", bp);
1201 		mtx_lock(&sc->sc_queue_mtx);
1202 		bioq_insert_head(&sc->sc_queue, bp);
1203 #if 0
1204 		/*
1205 		 * wakeup() is not needed, because this function is called from
1206 		 * the worker thread.
1207 		 */
1208 		wakeup(&sc->sc_queue);
1209 #endif
1210 		mtx_unlock(&sc->sc_queue_mtx);
1211 	}
1212 }
1213 
1214 /*
1215  * Releases delayed sync requests which don't collide anymore with regular
1216  * requests.
1217  */
1218 static void
1219 g_mirror_sync_release(struct g_mirror_softc *sc)
1220 {
1221 	struct bio *bp, *bp2;
1222 
1223 	TAILQ_FOREACH_SAFE(bp, &sc->sc_sync_delayed.queue, bio_queue, bp2) {
1224 		if (g_mirror_regular_collision(sc, bp))
1225 			continue;
1226 		bioq_remove(&sc->sc_sync_delayed, bp);
1227 		G_MIRROR_LOGREQ(2, bp,
1228 		    "Releasing delayed synchronization request.");
1229 		g_io_request(bp, bp->bio_from);
1230 	}
1231 }
1232 
1233 /*
1234  * Handle synchronization requests.
1235  * Every synchronization request is two-steps process: first, READ request is
1236  * send to active provider and then WRITE request (with read data) to the provider
1237  * beeing synchronized. When WRITE is finished, new synchronization request is
1238  * send.
1239  */
1240 static void
1241 g_mirror_sync_request(struct bio *bp)
1242 {
1243 	struct g_mirror_softc *sc;
1244 	struct g_mirror_disk *disk;
1245 
1246 	bp->bio_from->index--;
1247 	sc = bp->bio_from->geom->softc;
1248 	disk = bp->bio_from->private;
1249 	if (disk == NULL) {
1250 		sx_xunlock(&sc->sc_lock); /* Avoid recursion on sc_lock. */
1251 		g_topology_lock();
1252 		g_mirror_kill_consumer(sc, bp->bio_from);
1253 		g_topology_unlock();
1254 		free(bp->bio_data, M_MIRROR);
1255 		g_destroy_bio(bp);
1256 		sx_xlock(&sc->sc_lock);
1257 		return;
1258 	}
1259 
1260 	/*
1261 	 * Synchronization request.
1262 	 */
1263 	switch (bp->bio_cmd) {
1264 	case BIO_READ:
1265 	    {
1266 		struct g_consumer *cp;
1267 
1268 		if (bp->bio_error != 0) {
1269 			G_MIRROR_LOGREQ(0, bp,
1270 			    "Synchronization request failed (error=%d).",
1271 			    bp->bio_error);
1272 			g_destroy_bio(bp);
1273 			return;
1274 		}
1275 		G_MIRROR_LOGREQ(3, bp,
1276 		    "Synchronization request half-finished.");
1277 		bp->bio_cmd = BIO_WRITE;
1278 		bp->bio_cflags = 0;
1279 		cp = disk->d_consumer;
1280 		KASSERT(cp->acr >= 1 && cp->acw >= 1 && cp->ace >= 1,
1281 		    ("Consumer %s not opened (r%dw%de%d).", cp->provider->name,
1282 		    cp->acr, cp->acw, cp->ace));
1283 		cp->index++;
1284 		g_io_request(bp, cp);
1285 		return;
1286 	    }
1287 	case BIO_WRITE:
1288 	    {
1289 		struct g_mirror_disk_sync *sync;
1290 		off_t offset;
1291 		void *data;
1292 		int i;
1293 
1294 		if (bp->bio_error != 0) {
1295 			G_MIRROR_LOGREQ(0, bp,
1296 			    "Synchronization request failed (error=%d).",
1297 			    bp->bio_error);
1298 			g_destroy_bio(bp);
1299 			sc->sc_bump_id |= G_MIRROR_BUMP_GENID;
1300 			g_mirror_event_send(disk,
1301 			    G_MIRROR_DISK_STATE_DISCONNECTED,
1302 			    G_MIRROR_EVENT_DONTWAIT);
1303 			return;
1304 		}
1305 		G_MIRROR_LOGREQ(3, bp, "Synchronization request finished.");
1306 		sync = &disk->d_sync;
1307 		if (sync->ds_offset == sc->sc_mediasize ||
1308 		    sync->ds_consumer == NULL ||
1309 		    (sc->sc_flags & G_MIRROR_DEVICE_FLAG_DESTROY) != 0) {
1310 			/* Don't send more synchronization requests. */
1311 			sync->ds_inflight--;
1312 			if (sync->ds_bios != NULL) {
1313 				i = (int)(uintptr_t)bp->bio_caller1;
1314 				sync->ds_bios[i] = NULL;
1315 			}
1316 			free(bp->bio_data, M_MIRROR);
1317 			g_destroy_bio(bp);
1318 			if (sync->ds_inflight > 0)
1319 				return;
1320 			if (sync->ds_consumer == NULL ||
1321 			    (sc->sc_flags & G_MIRROR_DEVICE_FLAG_DESTROY) != 0) {
1322 				return;
1323 			}
1324 			/* Disk up-to-date, activate it. */
1325 			g_mirror_event_send(disk, G_MIRROR_DISK_STATE_ACTIVE,
1326 			    G_MIRROR_EVENT_DONTWAIT);
1327 			return;
1328 		}
1329 
1330 		/* Send next synchronization request. */
1331 		data = bp->bio_data;
1332 		bzero(bp, sizeof(*bp));
1333 		bp->bio_cmd = BIO_READ;
1334 		bp->bio_offset = sync->ds_offset;
1335 		bp->bio_length = MIN(MAXPHYS, sc->sc_mediasize - bp->bio_offset);
1336 		sync->ds_offset += bp->bio_length;
1337 		bp->bio_done = g_mirror_sync_done;
1338 		bp->bio_data = data;
1339 		bp->bio_from = sync->ds_consumer;
1340 		bp->bio_to = sc->sc_provider;
1341 		G_MIRROR_LOGREQ(3, bp, "Sending synchronization request.");
1342 		sync->ds_consumer->index++;
1343 		/*
1344 		 * Delay the request if it is colliding with a regular request.
1345 		 */
1346 		if (g_mirror_regular_collision(sc, bp))
1347 			g_mirror_sync_delay(sc, bp);
1348 		else
1349 			g_io_request(bp, sync->ds_consumer);
1350 
1351 		/* Release delayed requests if possible. */
1352 		g_mirror_regular_release(sc);
1353 
1354 		/* Find the smallest offset */
1355 		offset = sc->sc_mediasize;
1356 		for (i = 0; i < g_mirror_syncreqs; i++) {
1357 			bp = sync->ds_bios[i];
1358 			if (bp->bio_offset < offset)
1359 				offset = bp->bio_offset;
1360 		}
1361 		if (sync->ds_offset_done + (MAXPHYS * 100) < offset) {
1362 			/* Update offset_done on every 100 blocks. */
1363 			sync->ds_offset_done = offset;
1364 			g_mirror_update_metadata(disk);
1365 		}
1366 		return;
1367 	    }
1368 	default:
1369 		KASSERT(1 == 0, ("Invalid command here: %u (device=%s)",
1370 		    bp->bio_cmd, sc->sc_name));
1371 		break;
1372 	}
1373 }
1374 
1375 static void
1376 g_mirror_request_prefer(struct g_mirror_softc *sc, struct bio *bp)
1377 {
1378 	struct g_mirror_disk *disk;
1379 	struct g_consumer *cp;
1380 	struct bio *cbp;
1381 
1382 	LIST_FOREACH(disk, &sc->sc_disks, d_next) {
1383 		if (disk->d_state == G_MIRROR_DISK_STATE_ACTIVE)
1384 			break;
1385 	}
1386 	if (disk == NULL) {
1387 		if (bp->bio_error == 0)
1388 			bp->bio_error = ENXIO;
1389 		g_io_deliver(bp, bp->bio_error);
1390 		return;
1391 	}
1392 	cbp = g_clone_bio(bp);
1393 	if (cbp == NULL) {
1394 		if (bp->bio_error == 0)
1395 			bp->bio_error = ENOMEM;
1396 		g_io_deliver(bp, bp->bio_error);
1397 		return;
1398 	}
1399 	/*
1400 	 * Fill in the component buf structure.
1401 	 */
1402 	cp = disk->d_consumer;
1403 	cbp->bio_done = g_mirror_done;
1404 	cbp->bio_to = cp->provider;
1405 	G_MIRROR_LOGREQ(3, cbp, "Sending request.");
1406 	KASSERT(cp->acr >= 1 && cp->acw >= 1 && cp->ace >= 1,
1407 	    ("Consumer %s not opened (r%dw%de%d).", cp->provider->name, cp->acr,
1408 	    cp->acw, cp->ace));
1409 	cp->index++;
1410 	g_io_request(cbp, cp);
1411 }
1412 
1413 static void
1414 g_mirror_request_round_robin(struct g_mirror_softc *sc, struct bio *bp)
1415 {
1416 	struct g_mirror_disk *disk;
1417 	struct g_consumer *cp;
1418 	struct bio *cbp;
1419 
1420 	disk = g_mirror_get_disk(sc);
1421 	if (disk == NULL) {
1422 		if (bp->bio_error == 0)
1423 			bp->bio_error = ENXIO;
1424 		g_io_deliver(bp, bp->bio_error);
1425 		return;
1426 	}
1427 	cbp = g_clone_bio(bp);
1428 	if (cbp == NULL) {
1429 		if (bp->bio_error == 0)
1430 			bp->bio_error = ENOMEM;
1431 		g_io_deliver(bp, bp->bio_error);
1432 		return;
1433 	}
1434 	/*
1435 	 * Fill in the component buf structure.
1436 	 */
1437 	cp = disk->d_consumer;
1438 	cbp->bio_done = g_mirror_done;
1439 	cbp->bio_to = cp->provider;
1440 	G_MIRROR_LOGREQ(3, cbp, "Sending request.");
1441 	KASSERT(cp->acr >= 1 && cp->acw >= 1 && cp->ace >= 1,
1442 	    ("Consumer %s not opened (r%dw%de%d).", cp->provider->name, cp->acr,
1443 	    cp->acw, cp->ace));
1444 	cp->index++;
1445 	g_io_request(cbp, cp);
1446 }
1447 
1448 #define TRACK_SIZE  (1 * 1024 * 1024)
1449 #define LOAD_SCALE	256
1450 #define ABS(x)		(((x) >= 0) ? (x) : (-(x)))
1451 
1452 static void
1453 g_mirror_request_load(struct g_mirror_softc *sc, struct bio *bp)
1454 {
1455 	struct g_mirror_disk *disk, *dp;
1456 	struct g_consumer *cp;
1457 	struct bio *cbp;
1458 	int prio, best;
1459 
1460 	/* Find a disk with the smallest load. */
1461 	disk = NULL;
1462 	best = INT_MAX;
1463 	LIST_FOREACH(dp, &sc->sc_disks, d_next) {
1464 		if (dp->d_state != G_MIRROR_DISK_STATE_ACTIVE)
1465 			continue;
1466 		prio = dp->load;
1467 		/* If disk head is precisely in position - highly prefer it. */
1468 		if (dp->d_last_offset == bp->bio_offset)
1469 			prio -= 2 * LOAD_SCALE;
1470 		else
1471 		/* If disk head is close to position - prefer it. */
1472 		if (ABS(dp->d_last_offset - bp->bio_offset) < TRACK_SIZE)
1473 			prio -= 1 * LOAD_SCALE;
1474 		if (prio <= best) {
1475 			disk = dp;
1476 			best = prio;
1477 		}
1478 	}
1479 	KASSERT(disk != NULL, ("NULL disk for %s.", sc->sc_name));
1480 	cbp = g_clone_bio(bp);
1481 	if (cbp == NULL) {
1482 		if (bp->bio_error == 0)
1483 			bp->bio_error = ENOMEM;
1484 		g_io_deliver(bp, bp->bio_error);
1485 		return;
1486 	}
1487 	/*
1488 	 * Fill in the component buf structure.
1489 	 */
1490 	cp = disk->d_consumer;
1491 	cbp->bio_done = g_mirror_done;
1492 	cbp->bio_to = cp->provider;
1493 	G_MIRROR_LOGREQ(3, cbp, "Sending request.");
1494 	KASSERT(cp->acr >= 1 && cp->acw >= 1 && cp->ace >= 1,
1495 	    ("Consumer %s not opened (r%dw%de%d).", cp->provider->name, cp->acr,
1496 	    cp->acw, cp->ace));
1497 	cp->index++;
1498 	/* Remember last head position */
1499 	disk->d_last_offset = bp->bio_offset + bp->bio_length;
1500 	/* Update loads. */
1501 	LIST_FOREACH(dp, &sc->sc_disks, d_next) {
1502 		dp->load = (dp->d_consumer->index * LOAD_SCALE +
1503 		    dp->load * 7) / 8;
1504 	}
1505 	g_io_request(cbp, cp);
1506 }
1507 
1508 static void
1509 g_mirror_request_split(struct g_mirror_softc *sc, struct bio *bp)
1510 {
1511 	struct bio_queue_head queue;
1512 	struct g_mirror_disk *disk;
1513 	struct g_consumer *cp;
1514 	struct bio *cbp;
1515 	off_t left, mod, offset, slice;
1516 	u_char *data;
1517 	u_int ndisks;
1518 
1519 	if (bp->bio_length <= sc->sc_slice) {
1520 		g_mirror_request_round_robin(sc, bp);
1521 		return;
1522 	}
1523 	ndisks = g_mirror_ndisks(sc, G_MIRROR_DISK_STATE_ACTIVE);
1524 	slice = bp->bio_length / ndisks;
1525 	mod = slice % sc->sc_provider->sectorsize;
1526 	if (mod != 0)
1527 		slice += sc->sc_provider->sectorsize - mod;
1528 	/*
1529 	 * Allocate all bios before sending any request, so we can
1530 	 * return ENOMEM in nice and clean way.
1531 	 */
1532 	left = bp->bio_length;
1533 	offset = bp->bio_offset;
1534 	data = bp->bio_data;
1535 	bioq_init(&queue);
1536 	LIST_FOREACH(disk, &sc->sc_disks, d_next) {
1537 		if (disk->d_state != G_MIRROR_DISK_STATE_ACTIVE)
1538 			continue;
1539 		cbp = g_clone_bio(bp);
1540 		if (cbp == NULL) {
1541 			for (cbp = bioq_first(&queue); cbp != NULL;
1542 			    cbp = bioq_first(&queue)) {
1543 				bioq_remove(&queue, cbp);
1544 				g_destroy_bio(cbp);
1545 			}
1546 			if (bp->bio_error == 0)
1547 				bp->bio_error = ENOMEM;
1548 			g_io_deliver(bp, bp->bio_error);
1549 			return;
1550 		}
1551 		bioq_insert_tail(&queue, cbp);
1552 		cbp->bio_done = g_mirror_done;
1553 		cbp->bio_caller1 = disk;
1554 		cbp->bio_to = disk->d_consumer->provider;
1555 		cbp->bio_offset = offset;
1556 		cbp->bio_data = data;
1557 		cbp->bio_length = MIN(left, slice);
1558 		left -= cbp->bio_length;
1559 		if (left == 0)
1560 			break;
1561 		offset += cbp->bio_length;
1562 		data += cbp->bio_length;
1563 	}
1564 	for (cbp = bioq_first(&queue); cbp != NULL; cbp = bioq_first(&queue)) {
1565 		bioq_remove(&queue, cbp);
1566 		G_MIRROR_LOGREQ(3, cbp, "Sending request.");
1567 		disk = cbp->bio_caller1;
1568 		cbp->bio_caller1 = NULL;
1569 		cp = disk->d_consumer;
1570 		KASSERT(cp->acr >= 1 && cp->acw >= 1 && cp->ace >= 1,
1571 		    ("Consumer %s not opened (r%dw%de%d).", cp->provider->name,
1572 		    cp->acr, cp->acw, cp->ace));
1573 		disk->d_consumer->index++;
1574 		g_io_request(cbp, disk->d_consumer);
1575 	}
1576 }
1577 
1578 static void
1579 g_mirror_register_request(struct bio *bp)
1580 {
1581 	struct g_mirror_softc *sc;
1582 
1583 	sc = bp->bio_to->geom->softc;
1584 	switch (bp->bio_cmd) {
1585 	case BIO_READ:
1586 		switch (sc->sc_balance) {
1587 		case G_MIRROR_BALANCE_LOAD:
1588 			g_mirror_request_load(sc, bp);
1589 			break;
1590 		case G_MIRROR_BALANCE_PREFER:
1591 			g_mirror_request_prefer(sc, bp);
1592 			break;
1593 		case G_MIRROR_BALANCE_ROUND_ROBIN:
1594 			g_mirror_request_round_robin(sc, bp);
1595 			break;
1596 		case G_MIRROR_BALANCE_SPLIT:
1597 			g_mirror_request_split(sc, bp);
1598 			break;
1599 		}
1600 		return;
1601 	case BIO_WRITE:
1602 	case BIO_DELETE:
1603 	    {
1604 		struct g_mirror_disk *disk;
1605 		struct g_mirror_disk_sync *sync;
1606 		struct bio_queue_head queue;
1607 		struct g_consumer *cp;
1608 		struct bio *cbp;
1609 
1610 		/*
1611 		 * Delay the request if it is colliding with a synchronization
1612 		 * request.
1613 		 */
1614 		if (g_mirror_sync_collision(sc, bp)) {
1615 			g_mirror_regular_delay(sc, bp);
1616 			return;
1617 		}
1618 
1619 		if (sc->sc_idle)
1620 			g_mirror_unidle(sc);
1621 		else
1622 			sc->sc_last_write = time_uptime;
1623 
1624 		/*
1625 		 * Allocate all bios before sending any request, so we can
1626 		 * return ENOMEM in nice and clean way.
1627 		 */
1628 		bioq_init(&queue);
1629 		LIST_FOREACH(disk, &sc->sc_disks, d_next) {
1630 			sync = &disk->d_sync;
1631 			switch (disk->d_state) {
1632 			case G_MIRROR_DISK_STATE_ACTIVE:
1633 				break;
1634 			case G_MIRROR_DISK_STATE_SYNCHRONIZING:
1635 				if (bp->bio_offset >= sync->ds_offset)
1636 					continue;
1637 				break;
1638 			default:
1639 				continue;
1640 			}
1641 			if (bp->bio_cmd == BIO_DELETE &&
1642 			    (disk->d_flags & G_MIRROR_DISK_FLAG_CANDELETE) == 0)
1643 				continue;
1644 			cbp = g_clone_bio(bp);
1645 			if (cbp == NULL) {
1646 				for (cbp = bioq_first(&queue); cbp != NULL;
1647 				    cbp = bioq_first(&queue)) {
1648 					bioq_remove(&queue, cbp);
1649 					g_destroy_bio(cbp);
1650 				}
1651 				if (bp->bio_error == 0)
1652 					bp->bio_error = ENOMEM;
1653 				g_io_deliver(bp, bp->bio_error);
1654 				return;
1655 			}
1656 			bioq_insert_tail(&queue, cbp);
1657 			cbp->bio_done = g_mirror_done;
1658 			cp = disk->d_consumer;
1659 			cbp->bio_caller1 = cp;
1660 			cbp->bio_to = cp->provider;
1661 			KASSERT(cp->acr >= 1 && cp->acw >= 1 && cp->ace >= 1,
1662 			    ("Consumer %s not opened (r%dw%de%d).",
1663 			    cp->provider->name, cp->acr, cp->acw, cp->ace));
1664 		}
1665 		for (cbp = bioq_first(&queue); cbp != NULL;
1666 		    cbp = bioq_first(&queue)) {
1667 			bioq_remove(&queue, cbp);
1668 			G_MIRROR_LOGREQ(3, cbp, "Sending request.");
1669 			cp = cbp->bio_caller1;
1670 			cbp->bio_caller1 = NULL;
1671 			cp->index++;
1672 			sc->sc_writes++;
1673 			g_io_request(cbp, cp);
1674 		}
1675 		/*
1676 		 * Put request onto inflight queue, so we can check if new
1677 		 * synchronization requests don't collide with it.
1678 		 */
1679 		bioq_insert_tail(&sc->sc_inflight, bp);
1680 		/*
1681 		 * Bump syncid on first write.
1682 		 */
1683 		if ((sc->sc_bump_id & G_MIRROR_BUMP_SYNCID) != 0) {
1684 			sc->sc_bump_id &= ~G_MIRROR_BUMP_SYNCID;
1685 			g_mirror_bump_syncid(sc);
1686 		}
1687 		return;
1688 	    }
1689 	default:
1690 		KASSERT(1 == 0, ("Invalid command here: %u (device=%s)",
1691 		    bp->bio_cmd, sc->sc_name));
1692 		break;
1693 	}
1694 }
1695 
1696 static int
1697 g_mirror_can_destroy(struct g_mirror_softc *sc)
1698 {
1699 	struct g_geom *gp;
1700 	struct g_consumer *cp;
1701 
1702 	g_topology_assert();
1703 	gp = sc->sc_geom;
1704 	if (gp->softc == NULL)
1705 		return (1);
1706 	if ((sc->sc_flags & G_MIRROR_DEVICE_FLAG_TASTING) != 0)
1707 		return (0);
1708 	LIST_FOREACH(cp, &gp->consumer, consumer) {
1709 		if (g_mirror_is_busy(sc, cp))
1710 			return (0);
1711 	}
1712 	gp = sc->sc_sync.ds_geom;
1713 	LIST_FOREACH(cp, &gp->consumer, consumer) {
1714 		if (g_mirror_is_busy(sc, cp))
1715 			return (0);
1716 	}
1717 	G_MIRROR_DEBUG(2, "No I/O requests for %s, it can be destroyed.",
1718 	    sc->sc_name);
1719 	return (1);
1720 }
1721 
1722 static int
1723 g_mirror_try_destroy(struct g_mirror_softc *sc)
1724 {
1725 
1726 	if (sc->sc_rootmount != NULL) {
1727 		G_MIRROR_DEBUG(1, "root_mount_rel[%u] %p", __LINE__,
1728 		    sc->sc_rootmount);
1729 		root_mount_rel(sc->sc_rootmount);
1730 		sc->sc_rootmount = NULL;
1731 	}
1732 	g_topology_lock();
1733 	if (!g_mirror_can_destroy(sc)) {
1734 		g_topology_unlock();
1735 		return (0);
1736 	}
1737 	sc->sc_geom->softc = NULL;
1738 	sc->sc_sync.ds_geom->softc = NULL;
1739 	if ((sc->sc_flags & G_MIRROR_DEVICE_FLAG_WAIT) != 0) {
1740 		g_topology_unlock();
1741 		G_MIRROR_DEBUG(4, "%s: Waking up %p.", __func__,
1742 		    &sc->sc_worker);
1743 		/* Unlock sc_lock here, as it can be destroyed after wakeup. */
1744 		sx_xunlock(&sc->sc_lock);
1745 		wakeup(&sc->sc_worker);
1746 		sc->sc_worker = NULL;
1747 	} else {
1748 		g_topology_unlock();
1749 		g_mirror_destroy_device(sc);
1750 		free(sc, M_MIRROR);
1751 	}
1752 	return (1);
1753 }
1754 
1755 /*
1756  * Worker thread.
1757  */
1758 static void
1759 g_mirror_worker(void *arg)
1760 {
1761 	struct g_mirror_softc *sc;
1762 	struct g_mirror_event *ep;
1763 	struct bio *bp;
1764 	int timeout;
1765 
1766 	sc = arg;
1767 	thread_lock(curthread);
1768 	sched_prio(curthread, PRIBIO);
1769 	thread_unlock(curthread);
1770 
1771 	sx_xlock(&sc->sc_lock);
1772 	for (;;) {
1773 		G_MIRROR_DEBUG(5, "%s: Let's see...", __func__);
1774 		/*
1775 		 * First take a look at events.
1776 		 * This is important to handle events before any I/O requests.
1777 		 */
1778 		ep = g_mirror_event_get(sc);
1779 		if (ep != NULL) {
1780 			g_mirror_event_remove(sc, ep);
1781 			if ((ep->e_flags & G_MIRROR_EVENT_DEVICE) != 0) {
1782 				/* Update only device status. */
1783 				G_MIRROR_DEBUG(3,
1784 				    "Running event for device %s.",
1785 				    sc->sc_name);
1786 				ep->e_error = 0;
1787 				g_mirror_update_device(sc, 1);
1788 			} else {
1789 				/* Update disk status. */
1790 				G_MIRROR_DEBUG(3, "Running event for disk %s.",
1791 				     g_mirror_get_diskname(ep->e_disk));
1792 				ep->e_error = g_mirror_update_disk(ep->e_disk,
1793 				    ep->e_state);
1794 				if (ep->e_error == 0)
1795 					g_mirror_update_device(sc, 0);
1796 			}
1797 			if ((ep->e_flags & G_MIRROR_EVENT_DONTWAIT) != 0) {
1798 				KASSERT(ep->e_error == 0,
1799 				    ("Error cannot be handled."));
1800 				g_mirror_event_free(ep);
1801 			} else {
1802 				ep->e_flags |= G_MIRROR_EVENT_DONE;
1803 				G_MIRROR_DEBUG(4, "%s: Waking up %p.", __func__,
1804 				    ep);
1805 				mtx_lock(&sc->sc_events_mtx);
1806 				wakeup(ep);
1807 				mtx_unlock(&sc->sc_events_mtx);
1808 			}
1809 			if ((sc->sc_flags &
1810 			    G_MIRROR_DEVICE_FLAG_DESTROY) != 0) {
1811 				if (g_mirror_try_destroy(sc)) {
1812 					curthread->td_pflags &= ~TDP_GEOM;
1813 					G_MIRROR_DEBUG(1, "Thread exiting.");
1814 					kproc_exit(0);
1815 				}
1816 			}
1817 			G_MIRROR_DEBUG(5, "%s: I'm here 1.", __func__);
1818 			continue;
1819 		}
1820 		/*
1821 		 * Check if we can mark array as CLEAN and if we can't take
1822 		 * how much seconds should we wait.
1823 		 */
1824 		timeout = g_mirror_idle(sc, -1);
1825 		/*
1826 		 * Now I/O requests.
1827 		 */
1828 		/* Get first request from the queue. */
1829 		mtx_lock(&sc->sc_queue_mtx);
1830 		bp = bioq_first(&sc->sc_queue);
1831 		if (bp == NULL) {
1832 			if ((sc->sc_flags &
1833 			    G_MIRROR_DEVICE_FLAG_DESTROY) != 0) {
1834 				mtx_unlock(&sc->sc_queue_mtx);
1835 				if (g_mirror_try_destroy(sc)) {
1836 					curthread->td_pflags &= ~TDP_GEOM;
1837 					G_MIRROR_DEBUG(1, "Thread exiting.");
1838 					kproc_exit(0);
1839 				}
1840 				mtx_lock(&sc->sc_queue_mtx);
1841 			}
1842 			sx_xunlock(&sc->sc_lock);
1843 			/*
1844 			 * XXX: We can miss an event here, because an event
1845 			 *      can be added without sx-device-lock and without
1846 			 *      mtx-queue-lock. Maybe I should just stop using
1847 			 *      dedicated mutex for events synchronization and
1848 			 *      stick with the queue lock?
1849 			 *      The event will hang here until next I/O request
1850 			 *      or next event is received.
1851 			 */
1852 			MSLEEP(sc, &sc->sc_queue_mtx, PRIBIO | PDROP, "m:w1",
1853 			    timeout * hz);
1854 			sx_xlock(&sc->sc_lock);
1855 			G_MIRROR_DEBUG(5, "%s: I'm here 4.", __func__);
1856 			continue;
1857 		}
1858 		bioq_remove(&sc->sc_queue, bp);
1859 		mtx_unlock(&sc->sc_queue_mtx);
1860 
1861 		if (bp->bio_from->geom == sc->sc_sync.ds_geom &&
1862 		    (bp->bio_cflags & G_MIRROR_BIO_FLAG_SYNC) != 0) {
1863 			g_mirror_sync_request(bp);	/* READ */
1864 		} else if (bp->bio_to != sc->sc_provider) {
1865 			if ((bp->bio_cflags & G_MIRROR_BIO_FLAG_REGULAR) != 0)
1866 				g_mirror_regular_request(bp);
1867 			else if ((bp->bio_cflags & G_MIRROR_BIO_FLAG_SYNC) != 0)
1868 				g_mirror_sync_request(bp);	/* WRITE */
1869 			else {
1870 				KASSERT(0,
1871 				    ("Invalid request cflags=0x%hhx to=%s.",
1872 				    bp->bio_cflags, bp->bio_to->name));
1873 			}
1874 		} else {
1875 			g_mirror_register_request(bp);
1876 		}
1877 		G_MIRROR_DEBUG(5, "%s: I'm here 9.", __func__);
1878 	}
1879 }
1880 
1881 static void
1882 g_mirror_update_idle(struct g_mirror_softc *sc, struct g_mirror_disk *disk)
1883 {
1884 
1885 	sx_assert(&sc->sc_lock, SX_LOCKED);
1886 
1887 	if ((sc->sc_flags & G_MIRROR_DEVICE_FLAG_NOFAILSYNC) != 0)
1888 		return;
1889 	if (!sc->sc_idle && (disk->d_flags & G_MIRROR_DISK_FLAG_DIRTY) == 0) {
1890 		G_MIRROR_DEBUG(1, "Disk %s (device %s) marked as dirty.",
1891 		    g_mirror_get_diskname(disk), sc->sc_name);
1892 		disk->d_flags |= G_MIRROR_DISK_FLAG_DIRTY;
1893 	} else if (sc->sc_idle &&
1894 	    (disk->d_flags & G_MIRROR_DISK_FLAG_DIRTY) != 0) {
1895 		G_MIRROR_DEBUG(1, "Disk %s (device %s) marked as clean.",
1896 		    g_mirror_get_diskname(disk), sc->sc_name);
1897 		disk->d_flags &= ~G_MIRROR_DISK_FLAG_DIRTY;
1898 	}
1899 }
1900 
1901 static void
1902 g_mirror_sync_start(struct g_mirror_disk *disk)
1903 {
1904 	struct g_mirror_softc *sc;
1905 	struct g_consumer *cp;
1906 	struct bio *bp;
1907 	int error, i;
1908 
1909 	g_topology_assert_not();
1910 	sc = disk->d_softc;
1911 	sx_assert(&sc->sc_lock, SX_LOCKED);
1912 
1913 	KASSERT(disk->d_state == G_MIRROR_DISK_STATE_SYNCHRONIZING,
1914 	    ("Disk %s is not marked for synchronization.",
1915 	    g_mirror_get_diskname(disk)));
1916 	KASSERT(sc->sc_state == G_MIRROR_DEVICE_STATE_RUNNING,
1917 	    ("Device not in RUNNING state (%s, %u).", sc->sc_name,
1918 	    sc->sc_state));
1919 
1920 	sx_xunlock(&sc->sc_lock);
1921 	g_topology_lock();
1922 	cp = g_new_consumer(sc->sc_sync.ds_geom);
1923 	error = g_attach(cp, sc->sc_provider);
1924 	KASSERT(error == 0,
1925 	    ("Cannot attach to %s (error=%d).", sc->sc_name, error));
1926 	error = g_access(cp, 1, 0, 0);
1927 	KASSERT(error == 0, ("Cannot open %s (error=%d).", sc->sc_name, error));
1928 	g_topology_unlock();
1929 	sx_xlock(&sc->sc_lock);
1930 
1931 	G_MIRROR_DEBUG(0, "Device %s: rebuilding provider %s.", sc->sc_name,
1932 	    g_mirror_get_diskname(disk));
1933 	if ((sc->sc_flags & G_MIRROR_DEVICE_FLAG_NOFAILSYNC) == 0)
1934 		disk->d_flags |= G_MIRROR_DISK_FLAG_DIRTY;
1935 	KASSERT(disk->d_sync.ds_consumer == NULL,
1936 	    ("Sync consumer already exists (device=%s, disk=%s).",
1937 	    sc->sc_name, g_mirror_get_diskname(disk)));
1938 
1939 	disk->d_sync.ds_consumer = cp;
1940 	disk->d_sync.ds_consumer->private = disk;
1941 	disk->d_sync.ds_consumer->index = 0;
1942 
1943 	/*
1944 	 * Allocate memory for synchronization bios and initialize them.
1945 	 */
1946 	disk->d_sync.ds_bios = malloc(sizeof(struct bio *) * g_mirror_syncreqs,
1947 	    M_MIRROR, M_WAITOK);
1948 	for (i = 0; i < g_mirror_syncreqs; i++) {
1949 		bp = g_alloc_bio();
1950 		disk->d_sync.ds_bios[i] = bp;
1951 		bp->bio_parent = NULL;
1952 		bp->bio_cmd = BIO_READ;
1953 		bp->bio_data = malloc(MAXPHYS, M_MIRROR, M_WAITOK);
1954 		bp->bio_cflags = 0;
1955 		bp->bio_offset = disk->d_sync.ds_offset;
1956 		bp->bio_length = MIN(MAXPHYS, sc->sc_mediasize - bp->bio_offset);
1957 		disk->d_sync.ds_offset += bp->bio_length;
1958 		bp->bio_done = g_mirror_sync_done;
1959 		bp->bio_from = disk->d_sync.ds_consumer;
1960 		bp->bio_to = sc->sc_provider;
1961 		bp->bio_caller1 = (void *)(uintptr_t)i;
1962 	}
1963 
1964 	/* Increase the number of disks in SYNCHRONIZING state. */
1965 	sc->sc_sync.ds_ndisks++;
1966 	/* Set the number of in-flight synchronization requests. */
1967 	disk->d_sync.ds_inflight = g_mirror_syncreqs;
1968 
1969 	/*
1970 	 * Fire off first synchronization requests.
1971 	 */
1972 	for (i = 0; i < g_mirror_syncreqs; i++) {
1973 		bp = disk->d_sync.ds_bios[i];
1974 		G_MIRROR_LOGREQ(3, bp, "Sending synchronization request.");
1975 		disk->d_sync.ds_consumer->index++;
1976 		/*
1977 		 * Delay the request if it is colliding with a regular request.
1978 		 */
1979 		if (g_mirror_regular_collision(sc, bp))
1980 			g_mirror_sync_delay(sc, bp);
1981 		else
1982 			g_io_request(bp, disk->d_sync.ds_consumer);
1983 	}
1984 }
1985 
1986 /*
1987  * Stop synchronization process.
1988  * type: 0 - synchronization finished
1989  *       1 - synchronization stopped
1990  */
1991 static void
1992 g_mirror_sync_stop(struct g_mirror_disk *disk, int type)
1993 {
1994 	struct g_mirror_softc *sc;
1995 	struct g_consumer *cp;
1996 
1997 	g_topology_assert_not();
1998 	sc = disk->d_softc;
1999 	sx_assert(&sc->sc_lock, SX_LOCKED);
2000 
2001 	KASSERT(disk->d_state == G_MIRROR_DISK_STATE_SYNCHRONIZING,
2002 	    ("Wrong disk state (%s, %s).", g_mirror_get_diskname(disk),
2003 	    g_mirror_disk_state2str(disk->d_state)));
2004 	if (disk->d_sync.ds_consumer == NULL)
2005 		return;
2006 
2007 	if (type == 0) {
2008 		G_MIRROR_DEBUG(0, "Device %s: rebuilding provider %s finished.",
2009 		    sc->sc_name, g_mirror_get_diskname(disk));
2010 	} else /* if (type == 1) */ {
2011 		G_MIRROR_DEBUG(0, "Device %s: rebuilding provider %s stopped.",
2012 		    sc->sc_name, g_mirror_get_diskname(disk));
2013 	}
2014 	free(disk->d_sync.ds_bios, M_MIRROR);
2015 	disk->d_sync.ds_bios = NULL;
2016 	cp = disk->d_sync.ds_consumer;
2017 	disk->d_sync.ds_consumer = NULL;
2018 	disk->d_flags &= ~G_MIRROR_DISK_FLAG_DIRTY;
2019 	sc->sc_sync.ds_ndisks--;
2020 	sx_xunlock(&sc->sc_lock); /* Avoid recursion on sc_lock. */
2021 	g_topology_lock();
2022 	g_mirror_kill_consumer(sc, cp);
2023 	g_topology_unlock();
2024 	sx_xlock(&sc->sc_lock);
2025 }
2026 
2027 static void
2028 g_mirror_launch_provider(struct g_mirror_softc *sc)
2029 {
2030 	struct g_mirror_disk *disk;
2031 	struct g_provider *pp, *dp;
2032 
2033 	sx_assert(&sc->sc_lock, SX_LOCKED);
2034 
2035 	g_topology_lock();
2036 	pp = g_new_providerf(sc->sc_geom, "mirror/%s", sc->sc_name);
2037 	pp->mediasize = sc->sc_mediasize;
2038 	pp->sectorsize = sc->sc_sectorsize;
2039 	pp->stripesize = 0;
2040 	pp->stripeoffset = 0;
2041 
2042 	/* Splitting of unmapped BIO's could work but isn't implemented now */
2043 	if (sc->sc_balance != G_MIRROR_BALANCE_SPLIT)
2044 		pp->flags |= G_PF_ACCEPT_UNMAPPED;
2045 
2046 	LIST_FOREACH(disk, &sc->sc_disks, d_next) {
2047 		if (disk->d_consumer && disk->d_consumer->provider) {
2048 			dp = disk->d_consumer->provider;
2049 			if (dp->stripesize > pp->stripesize) {
2050 				pp->stripesize = dp->stripesize;
2051 				pp->stripeoffset = dp->stripeoffset;
2052 			}
2053 			/* A provider underneath us doesn't support unmapped */
2054 			if ((dp->flags & G_PF_ACCEPT_UNMAPPED) == 0) {
2055 				G_MIRROR_DEBUG(0, "cancelling unmapped "
2056 				    "because of %s\n", dp->name);
2057 				pp->flags &= ~G_PF_ACCEPT_UNMAPPED;
2058 			}
2059 		}
2060 	}
2061 	sc->sc_provider = pp;
2062 	g_error_provider(pp, 0);
2063 	g_topology_unlock();
2064 	G_MIRROR_DEBUG(0, "Device %s launched (%u/%u).", pp->name,
2065 	    g_mirror_ndisks(sc, G_MIRROR_DISK_STATE_ACTIVE), sc->sc_ndisks);
2066 	LIST_FOREACH(disk, &sc->sc_disks, d_next) {
2067 		if (disk->d_state == G_MIRROR_DISK_STATE_SYNCHRONIZING)
2068 			g_mirror_sync_start(disk);
2069 	}
2070 }
2071 
2072 static void
2073 g_mirror_destroy_provider(struct g_mirror_softc *sc)
2074 {
2075 	struct g_mirror_disk *disk;
2076 	struct bio *bp;
2077 
2078 	g_topology_assert_not();
2079 	KASSERT(sc->sc_provider != NULL, ("NULL provider (device=%s).",
2080 	    sc->sc_name));
2081 
2082 	g_topology_lock();
2083 	g_error_provider(sc->sc_provider, ENXIO);
2084 	mtx_lock(&sc->sc_queue_mtx);
2085 	while ((bp = bioq_first(&sc->sc_queue)) != NULL) {
2086 		bioq_remove(&sc->sc_queue, bp);
2087 		g_io_deliver(bp, ENXIO);
2088 	}
2089 	mtx_unlock(&sc->sc_queue_mtx);
2090 	G_MIRROR_DEBUG(0, "Device %s: provider %s destroyed.", sc->sc_name,
2091 	    sc->sc_provider->name);
2092 	sc->sc_provider->flags |= G_PF_WITHER;
2093 	g_orphan_provider(sc->sc_provider, ENXIO);
2094 	g_topology_unlock();
2095 	sc->sc_provider = NULL;
2096 	LIST_FOREACH(disk, &sc->sc_disks, d_next) {
2097 		if (disk->d_state == G_MIRROR_DISK_STATE_SYNCHRONIZING)
2098 			g_mirror_sync_stop(disk, 1);
2099 	}
2100 }
2101 
2102 static void
2103 g_mirror_go(void *arg)
2104 {
2105 	struct g_mirror_softc *sc;
2106 
2107 	sc = arg;
2108 	G_MIRROR_DEBUG(0, "Force device %s start due to timeout.", sc->sc_name);
2109 	g_mirror_event_send(sc, 0,
2110 	    G_MIRROR_EVENT_DONTWAIT | G_MIRROR_EVENT_DEVICE);
2111 }
2112 
2113 static u_int
2114 g_mirror_determine_state(struct g_mirror_disk *disk)
2115 {
2116 	struct g_mirror_softc *sc;
2117 	u_int state;
2118 
2119 	sc = disk->d_softc;
2120 	if (sc->sc_syncid == disk->d_sync.ds_syncid) {
2121 		if ((disk->d_flags &
2122 		    G_MIRROR_DISK_FLAG_SYNCHRONIZING) == 0) {
2123 			/* Disk does not need synchronization. */
2124 			state = G_MIRROR_DISK_STATE_ACTIVE;
2125 		} else {
2126 			if ((sc->sc_flags &
2127 			     G_MIRROR_DEVICE_FLAG_NOAUTOSYNC) == 0 ||
2128 			    (disk->d_flags &
2129 			     G_MIRROR_DISK_FLAG_FORCE_SYNC) != 0) {
2130 				/*
2131 				 * We can start synchronization from
2132 				 * the stored offset.
2133 				 */
2134 				state = G_MIRROR_DISK_STATE_SYNCHRONIZING;
2135 			} else {
2136 				state = G_MIRROR_DISK_STATE_STALE;
2137 			}
2138 		}
2139 	} else if (disk->d_sync.ds_syncid < sc->sc_syncid) {
2140 		/*
2141 		 * Reset all synchronization data for this disk,
2142 		 * because if it even was synchronized, it was
2143 		 * synchronized to disks with different syncid.
2144 		 */
2145 		disk->d_flags |= G_MIRROR_DISK_FLAG_SYNCHRONIZING;
2146 		disk->d_sync.ds_offset = 0;
2147 		disk->d_sync.ds_offset_done = 0;
2148 		disk->d_sync.ds_syncid = sc->sc_syncid;
2149 		if ((sc->sc_flags & G_MIRROR_DEVICE_FLAG_NOAUTOSYNC) == 0 ||
2150 		    (disk->d_flags & G_MIRROR_DISK_FLAG_FORCE_SYNC) != 0) {
2151 			state = G_MIRROR_DISK_STATE_SYNCHRONIZING;
2152 		} else {
2153 			state = G_MIRROR_DISK_STATE_STALE;
2154 		}
2155 	} else /* if (sc->sc_syncid < disk->d_sync.ds_syncid) */ {
2156 		/*
2157 		 * Not good, NOT GOOD!
2158 		 * It means that mirror was started on stale disks
2159 		 * and more fresh disk just arrive.
2160 		 * If there were writes, mirror is broken, sorry.
2161 		 * I think the best choice here is don't touch
2162 		 * this disk and inform the user loudly.
2163 		 */
2164 		G_MIRROR_DEBUG(0, "Device %s was started before the freshest "
2165 		    "disk (%s) arrives!! It will not be connected to the "
2166 		    "running device.", sc->sc_name,
2167 		    g_mirror_get_diskname(disk));
2168 		g_mirror_destroy_disk(disk);
2169 		state = G_MIRROR_DISK_STATE_NONE;
2170 		/* Return immediately, because disk was destroyed. */
2171 		return (state);
2172 	}
2173 	G_MIRROR_DEBUG(3, "State for %s disk: %s.",
2174 	    g_mirror_get_diskname(disk), g_mirror_disk_state2str(state));
2175 	return (state);
2176 }
2177 
2178 /*
2179  * Update device state.
2180  */
2181 static void
2182 g_mirror_update_device(struct g_mirror_softc *sc, boolean_t force)
2183 {
2184 	struct g_mirror_disk *disk;
2185 	u_int state;
2186 
2187 	sx_assert(&sc->sc_lock, SX_XLOCKED);
2188 
2189 	switch (sc->sc_state) {
2190 	case G_MIRROR_DEVICE_STATE_STARTING:
2191 	    {
2192 		struct g_mirror_disk *pdisk, *tdisk;
2193 		u_int dirty, ndisks, genid, syncid;
2194 
2195 		KASSERT(sc->sc_provider == NULL,
2196 		    ("Non-NULL provider in STARTING state (%s).", sc->sc_name));
2197 		/*
2198 		 * Are we ready? We are, if all disks are connected or
2199 		 * if we have any disks and 'force' is true.
2200 		 */
2201 		ndisks = g_mirror_ndisks(sc, -1);
2202 		if (sc->sc_ndisks == ndisks || (force && ndisks > 0)) {
2203 			;
2204 		} else if (ndisks == 0) {
2205 			/*
2206 			 * Disks went down in starting phase, so destroy
2207 			 * device.
2208 			 */
2209 			callout_drain(&sc->sc_callout);
2210 			sc->sc_flags |= G_MIRROR_DEVICE_FLAG_DESTROY;
2211 			G_MIRROR_DEBUG(1, "root_mount_rel[%u] %p", __LINE__,
2212 			    sc->sc_rootmount);
2213 			root_mount_rel(sc->sc_rootmount);
2214 			sc->sc_rootmount = NULL;
2215 			return;
2216 		} else {
2217 			return;
2218 		}
2219 
2220 		/*
2221 		 * Activate all disks with the biggest syncid.
2222 		 */
2223 		if (force) {
2224 			/*
2225 			 * If 'force' is true, we have been called due to
2226 			 * timeout, so don't bother canceling timeout.
2227 			 */
2228 			ndisks = 0;
2229 			LIST_FOREACH(disk, &sc->sc_disks, d_next) {
2230 				if ((disk->d_flags &
2231 				    G_MIRROR_DISK_FLAG_SYNCHRONIZING) == 0) {
2232 					ndisks++;
2233 				}
2234 			}
2235 			if (ndisks == 0) {
2236 				/* No valid disks found, destroy device. */
2237 				sc->sc_flags |= G_MIRROR_DEVICE_FLAG_DESTROY;
2238 				G_MIRROR_DEBUG(1, "root_mount_rel[%u] %p",
2239 				    __LINE__, sc->sc_rootmount);
2240 				root_mount_rel(sc->sc_rootmount);
2241 				sc->sc_rootmount = NULL;
2242 				return;
2243 			}
2244 		} else {
2245 			/* Cancel timeout. */
2246 			callout_drain(&sc->sc_callout);
2247 		}
2248 
2249 		/*
2250 		 * Find the biggest genid.
2251 		 */
2252 		genid = 0;
2253 		LIST_FOREACH(disk, &sc->sc_disks, d_next) {
2254 			if (disk->d_genid > genid)
2255 				genid = disk->d_genid;
2256 		}
2257 		sc->sc_genid = genid;
2258 		/*
2259 		 * Remove all disks without the biggest genid.
2260 		 */
2261 		LIST_FOREACH_SAFE(disk, &sc->sc_disks, d_next, tdisk) {
2262 			if (disk->d_genid < genid) {
2263 				G_MIRROR_DEBUG(0,
2264 				    "Component %s (device %s) broken, skipping.",
2265 				    g_mirror_get_diskname(disk), sc->sc_name);
2266 				g_mirror_destroy_disk(disk);
2267 			}
2268 		}
2269 
2270 		/*
2271 		 * Find the biggest syncid.
2272 		 */
2273 		syncid = 0;
2274 		LIST_FOREACH(disk, &sc->sc_disks, d_next) {
2275 			if (disk->d_sync.ds_syncid > syncid)
2276 				syncid = disk->d_sync.ds_syncid;
2277 		}
2278 
2279 		/*
2280 		 * Here we need to look for dirty disks and if all disks
2281 		 * with the biggest syncid are dirty, we have to choose
2282 		 * one with the biggest priority and rebuild the rest.
2283 		 */
2284 		/*
2285 		 * Find the number of dirty disks with the biggest syncid.
2286 		 * Find the number of disks with the biggest syncid.
2287 		 * While here, find a disk with the biggest priority.
2288 		 */
2289 		dirty = ndisks = 0;
2290 		pdisk = NULL;
2291 		LIST_FOREACH(disk, &sc->sc_disks, d_next) {
2292 			if (disk->d_sync.ds_syncid != syncid)
2293 				continue;
2294 			if ((disk->d_flags &
2295 			    G_MIRROR_DISK_FLAG_SYNCHRONIZING) != 0) {
2296 				continue;
2297 			}
2298 			ndisks++;
2299 			if ((disk->d_flags & G_MIRROR_DISK_FLAG_DIRTY) != 0) {
2300 				dirty++;
2301 				if (pdisk == NULL ||
2302 				    pdisk->d_priority < disk->d_priority) {
2303 					pdisk = disk;
2304 				}
2305 			}
2306 		}
2307 		if (dirty == 0) {
2308 			/* No dirty disks at all, great. */
2309 		} else if (dirty == ndisks) {
2310 			/*
2311 			 * Force synchronization for all dirty disks except one
2312 			 * with the biggest priority.
2313 			 */
2314 			KASSERT(pdisk != NULL, ("pdisk == NULL"));
2315 			G_MIRROR_DEBUG(1, "Using disk %s (device %s) as a "
2316 			    "master disk for synchronization.",
2317 			    g_mirror_get_diskname(pdisk), sc->sc_name);
2318 			LIST_FOREACH(disk, &sc->sc_disks, d_next) {
2319 				if (disk->d_sync.ds_syncid != syncid)
2320 					continue;
2321 				if ((disk->d_flags &
2322 				    G_MIRROR_DISK_FLAG_SYNCHRONIZING) != 0) {
2323 					continue;
2324 				}
2325 				KASSERT((disk->d_flags &
2326 				    G_MIRROR_DISK_FLAG_DIRTY) != 0,
2327 				    ("Disk %s isn't marked as dirty.",
2328 				    g_mirror_get_diskname(disk)));
2329 				/* Skip the disk with the biggest priority. */
2330 				if (disk == pdisk)
2331 					continue;
2332 				disk->d_sync.ds_syncid = 0;
2333 			}
2334 		} else if (dirty < ndisks) {
2335 			/*
2336 			 * Force synchronization for all dirty disks.
2337 			 * We have some non-dirty disks.
2338 			 */
2339 			LIST_FOREACH(disk, &sc->sc_disks, d_next) {
2340 				if (disk->d_sync.ds_syncid != syncid)
2341 					continue;
2342 				if ((disk->d_flags &
2343 				    G_MIRROR_DISK_FLAG_SYNCHRONIZING) != 0) {
2344 					continue;
2345 				}
2346 				if ((disk->d_flags &
2347 				    G_MIRROR_DISK_FLAG_DIRTY) == 0) {
2348 					continue;
2349 				}
2350 				disk->d_sync.ds_syncid = 0;
2351 			}
2352 		}
2353 
2354 		/* Reset hint. */
2355 		sc->sc_hint = NULL;
2356 		sc->sc_syncid = syncid;
2357 		if (force) {
2358 			/* Remember to bump syncid on first write. */
2359 			sc->sc_bump_id |= G_MIRROR_BUMP_SYNCID;
2360 		}
2361 		state = G_MIRROR_DEVICE_STATE_RUNNING;
2362 		G_MIRROR_DEBUG(1, "Device %s state changed from %s to %s.",
2363 		    sc->sc_name, g_mirror_device_state2str(sc->sc_state),
2364 		    g_mirror_device_state2str(state));
2365 		sc->sc_state = state;
2366 		LIST_FOREACH(disk, &sc->sc_disks, d_next) {
2367 			state = g_mirror_determine_state(disk);
2368 			g_mirror_event_send(disk, state,
2369 			    G_MIRROR_EVENT_DONTWAIT);
2370 			if (state == G_MIRROR_DISK_STATE_STALE)
2371 				sc->sc_bump_id |= G_MIRROR_BUMP_SYNCID;
2372 		}
2373 		break;
2374 	    }
2375 	case G_MIRROR_DEVICE_STATE_RUNNING:
2376 		if (g_mirror_ndisks(sc, G_MIRROR_DISK_STATE_ACTIVE) == 0 &&
2377 		    g_mirror_ndisks(sc, G_MIRROR_DISK_STATE_NEW) == 0) {
2378 			/*
2379 			 * No active disks or no disks at all,
2380 			 * so destroy device.
2381 			 */
2382 			if (sc->sc_provider != NULL)
2383 				g_mirror_destroy_provider(sc);
2384 			sc->sc_flags |= G_MIRROR_DEVICE_FLAG_DESTROY;
2385 			break;
2386 		} else if (g_mirror_ndisks(sc,
2387 		    G_MIRROR_DISK_STATE_ACTIVE) > 0 &&
2388 		    g_mirror_ndisks(sc, G_MIRROR_DISK_STATE_NEW) == 0) {
2389 			/*
2390 			 * We have active disks, launch provider if it doesn't
2391 			 * exist.
2392 			 */
2393 			if (sc->sc_provider == NULL)
2394 				g_mirror_launch_provider(sc);
2395 			if (sc->sc_rootmount != NULL) {
2396 				G_MIRROR_DEBUG(1, "root_mount_rel[%u] %p",
2397 				    __LINE__, sc->sc_rootmount);
2398 				root_mount_rel(sc->sc_rootmount);
2399 				sc->sc_rootmount = NULL;
2400 			}
2401 		}
2402 		/*
2403 		 * Genid should be bumped immediately, so do it here.
2404 		 */
2405 		if ((sc->sc_bump_id & G_MIRROR_BUMP_GENID) != 0) {
2406 			sc->sc_bump_id &= ~G_MIRROR_BUMP_GENID;
2407 			g_mirror_bump_genid(sc);
2408 		}
2409 		break;
2410 	default:
2411 		KASSERT(1 == 0, ("Wrong device state (%s, %s).",
2412 		    sc->sc_name, g_mirror_device_state2str(sc->sc_state)));
2413 		break;
2414 	}
2415 }
2416 
2417 /*
2418  * Update disk state and device state if needed.
2419  */
2420 #define	DISK_STATE_CHANGED()	G_MIRROR_DEBUG(1,			\
2421 	"Disk %s state changed from %s to %s (device %s).",		\
2422 	g_mirror_get_diskname(disk),					\
2423 	g_mirror_disk_state2str(disk->d_state),				\
2424 	g_mirror_disk_state2str(state), sc->sc_name)
2425 static int
2426 g_mirror_update_disk(struct g_mirror_disk *disk, u_int state)
2427 {
2428 	struct g_mirror_softc *sc;
2429 
2430 	sc = disk->d_softc;
2431 	sx_assert(&sc->sc_lock, SX_XLOCKED);
2432 
2433 again:
2434 	G_MIRROR_DEBUG(3, "Changing disk %s state from %s to %s.",
2435 	    g_mirror_get_diskname(disk), g_mirror_disk_state2str(disk->d_state),
2436 	    g_mirror_disk_state2str(state));
2437 	switch (state) {
2438 	case G_MIRROR_DISK_STATE_NEW:
2439 		/*
2440 		 * Possible scenarios:
2441 		 * 1. New disk arrive.
2442 		 */
2443 		/* Previous state should be NONE. */
2444 		KASSERT(disk->d_state == G_MIRROR_DISK_STATE_NONE,
2445 		    ("Wrong disk state (%s, %s).", g_mirror_get_diskname(disk),
2446 		    g_mirror_disk_state2str(disk->d_state)));
2447 		DISK_STATE_CHANGED();
2448 
2449 		disk->d_state = state;
2450 		if (LIST_EMPTY(&sc->sc_disks))
2451 			LIST_INSERT_HEAD(&sc->sc_disks, disk, d_next);
2452 		else {
2453 			struct g_mirror_disk *dp;
2454 
2455 			LIST_FOREACH(dp, &sc->sc_disks, d_next) {
2456 				if (disk->d_priority >= dp->d_priority) {
2457 					LIST_INSERT_BEFORE(dp, disk, d_next);
2458 					dp = NULL;
2459 					break;
2460 				}
2461 				if (LIST_NEXT(dp, d_next) == NULL)
2462 					break;
2463 			}
2464 			if (dp != NULL)
2465 				LIST_INSERT_AFTER(dp, disk, d_next);
2466 		}
2467 		G_MIRROR_DEBUG(1, "Device %s: provider %s detected.",
2468 		    sc->sc_name, g_mirror_get_diskname(disk));
2469 		if (sc->sc_state == G_MIRROR_DEVICE_STATE_STARTING)
2470 			break;
2471 		KASSERT(sc->sc_state == G_MIRROR_DEVICE_STATE_RUNNING,
2472 		    ("Wrong device state (%s, %s, %s, %s).", sc->sc_name,
2473 		    g_mirror_device_state2str(sc->sc_state),
2474 		    g_mirror_get_diskname(disk),
2475 		    g_mirror_disk_state2str(disk->d_state)));
2476 		state = g_mirror_determine_state(disk);
2477 		if (state != G_MIRROR_DISK_STATE_NONE)
2478 			goto again;
2479 		break;
2480 	case G_MIRROR_DISK_STATE_ACTIVE:
2481 		/*
2482 		 * Possible scenarios:
2483 		 * 1. New disk does not need synchronization.
2484 		 * 2. Synchronization process finished successfully.
2485 		 */
2486 		KASSERT(sc->sc_state == G_MIRROR_DEVICE_STATE_RUNNING,
2487 		    ("Wrong device state (%s, %s, %s, %s).", sc->sc_name,
2488 		    g_mirror_device_state2str(sc->sc_state),
2489 		    g_mirror_get_diskname(disk),
2490 		    g_mirror_disk_state2str(disk->d_state)));
2491 		/* Previous state should be NEW or SYNCHRONIZING. */
2492 		KASSERT(disk->d_state == G_MIRROR_DISK_STATE_NEW ||
2493 		    disk->d_state == G_MIRROR_DISK_STATE_SYNCHRONIZING,
2494 		    ("Wrong disk state (%s, %s).", g_mirror_get_diskname(disk),
2495 		    g_mirror_disk_state2str(disk->d_state)));
2496 		DISK_STATE_CHANGED();
2497 
2498 		if (disk->d_state == G_MIRROR_DISK_STATE_SYNCHRONIZING) {
2499 			disk->d_flags &= ~G_MIRROR_DISK_FLAG_SYNCHRONIZING;
2500 			disk->d_flags &= ~G_MIRROR_DISK_FLAG_FORCE_SYNC;
2501 			g_mirror_sync_stop(disk, 0);
2502 		}
2503 		disk->d_state = state;
2504 		disk->d_sync.ds_offset = 0;
2505 		disk->d_sync.ds_offset_done = 0;
2506 		g_mirror_update_idle(sc, disk);
2507 		g_mirror_update_metadata(disk);
2508 		G_MIRROR_DEBUG(1, "Device %s: provider %s activated.",
2509 		    sc->sc_name, g_mirror_get_diskname(disk));
2510 		break;
2511 	case G_MIRROR_DISK_STATE_STALE:
2512 		/*
2513 		 * Possible scenarios:
2514 		 * 1. Stale disk was connected.
2515 		 */
2516 		/* Previous state should be NEW. */
2517 		KASSERT(disk->d_state == G_MIRROR_DISK_STATE_NEW,
2518 		    ("Wrong disk state (%s, %s).", g_mirror_get_diskname(disk),
2519 		    g_mirror_disk_state2str(disk->d_state)));
2520 		KASSERT(sc->sc_state == G_MIRROR_DEVICE_STATE_RUNNING,
2521 		    ("Wrong device state (%s, %s, %s, %s).", sc->sc_name,
2522 		    g_mirror_device_state2str(sc->sc_state),
2523 		    g_mirror_get_diskname(disk),
2524 		    g_mirror_disk_state2str(disk->d_state)));
2525 		/*
2526 		 * STALE state is only possible if device is marked
2527 		 * NOAUTOSYNC.
2528 		 */
2529 		KASSERT((sc->sc_flags & G_MIRROR_DEVICE_FLAG_NOAUTOSYNC) != 0,
2530 		    ("Wrong device state (%s, %s, %s, %s).", sc->sc_name,
2531 		    g_mirror_device_state2str(sc->sc_state),
2532 		    g_mirror_get_diskname(disk),
2533 		    g_mirror_disk_state2str(disk->d_state)));
2534 		DISK_STATE_CHANGED();
2535 
2536 		disk->d_flags &= ~G_MIRROR_DISK_FLAG_DIRTY;
2537 		disk->d_state = state;
2538 		g_mirror_update_metadata(disk);
2539 		G_MIRROR_DEBUG(0, "Device %s: provider %s is stale.",
2540 		    sc->sc_name, g_mirror_get_diskname(disk));
2541 		break;
2542 	case G_MIRROR_DISK_STATE_SYNCHRONIZING:
2543 		/*
2544 		 * Possible scenarios:
2545 		 * 1. Disk which needs synchronization was connected.
2546 		 */
2547 		/* Previous state should be NEW. */
2548 		KASSERT(disk->d_state == G_MIRROR_DISK_STATE_NEW,
2549 		    ("Wrong disk state (%s, %s).", g_mirror_get_diskname(disk),
2550 		    g_mirror_disk_state2str(disk->d_state)));
2551 		KASSERT(sc->sc_state == G_MIRROR_DEVICE_STATE_RUNNING,
2552 		    ("Wrong device state (%s, %s, %s, %s).", sc->sc_name,
2553 		    g_mirror_device_state2str(sc->sc_state),
2554 		    g_mirror_get_diskname(disk),
2555 		    g_mirror_disk_state2str(disk->d_state)));
2556 		DISK_STATE_CHANGED();
2557 
2558 		if (disk->d_state == G_MIRROR_DISK_STATE_NEW)
2559 			disk->d_flags &= ~G_MIRROR_DISK_FLAG_DIRTY;
2560 		disk->d_state = state;
2561 		if (sc->sc_provider != NULL) {
2562 			g_mirror_sync_start(disk);
2563 			g_mirror_update_metadata(disk);
2564 		}
2565 		break;
2566 	case G_MIRROR_DISK_STATE_DISCONNECTED:
2567 		/*
2568 		 * Possible scenarios:
2569 		 * 1. Device wasn't running yet, but disk disappear.
2570 		 * 2. Disk was active and disapppear.
2571 		 * 3. Disk disappear during synchronization process.
2572 		 */
2573 		if (sc->sc_state == G_MIRROR_DEVICE_STATE_RUNNING) {
2574 			/*
2575 			 * Previous state should be ACTIVE, STALE or
2576 			 * SYNCHRONIZING.
2577 			 */
2578 			KASSERT(disk->d_state == G_MIRROR_DISK_STATE_ACTIVE ||
2579 			    disk->d_state == G_MIRROR_DISK_STATE_STALE ||
2580 			    disk->d_state == G_MIRROR_DISK_STATE_SYNCHRONIZING,
2581 			    ("Wrong disk state (%s, %s).",
2582 			    g_mirror_get_diskname(disk),
2583 			    g_mirror_disk_state2str(disk->d_state)));
2584 		} else if (sc->sc_state == G_MIRROR_DEVICE_STATE_STARTING) {
2585 			/* Previous state should be NEW. */
2586 			KASSERT(disk->d_state == G_MIRROR_DISK_STATE_NEW,
2587 			    ("Wrong disk state (%s, %s).",
2588 			    g_mirror_get_diskname(disk),
2589 			    g_mirror_disk_state2str(disk->d_state)));
2590 			/*
2591 			 * Reset bumping syncid if disk disappeared in STARTING
2592 			 * state.
2593 			 */
2594 			if ((sc->sc_bump_id & G_MIRROR_BUMP_SYNCID) != 0)
2595 				sc->sc_bump_id &= ~G_MIRROR_BUMP_SYNCID;
2596 #ifdef	INVARIANTS
2597 		} else {
2598 			KASSERT(1 == 0, ("Wrong device state (%s, %s, %s, %s).",
2599 			    sc->sc_name,
2600 			    g_mirror_device_state2str(sc->sc_state),
2601 			    g_mirror_get_diskname(disk),
2602 			    g_mirror_disk_state2str(disk->d_state)));
2603 #endif
2604 		}
2605 		DISK_STATE_CHANGED();
2606 		G_MIRROR_DEBUG(0, "Device %s: provider %s disconnected.",
2607 		    sc->sc_name, g_mirror_get_diskname(disk));
2608 
2609 		g_mirror_destroy_disk(disk);
2610 		break;
2611 	case G_MIRROR_DISK_STATE_DESTROY:
2612 	    {
2613 		int error;
2614 
2615 		error = g_mirror_clear_metadata(disk);
2616 		if (error != 0)
2617 			return (error);
2618 		DISK_STATE_CHANGED();
2619 		G_MIRROR_DEBUG(0, "Device %s: provider %s destroyed.",
2620 		    sc->sc_name, g_mirror_get_diskname(disk));
2621 
2622 		g_mirror_destroy_disk(disk);
2623 		sc->sc_ndisks--;
2624 		LIST_FOREACH(disk, &sc->sc_disks, d_next) {
2625 			g_mirror_update_metadata(disk);
2626 		}
2627 		break;
2628 	    }
2629 	default:
2630 		KASSERT(1 == 0, ("Unknown state (%u).", state));
2631 		break;
2632 	}
2633 	return (0);
2634 }
2635 #undef	DISK_STATE_CHANGED
2636 
2637 int
2638 g_mirror_read_metadata(struct g_consumer *cp, struct g_mirror_metadata *md)
2639 {
2640 	struct g_provider *pp;
2641 	u_char *buf;
2642 	int error;
2643 
2644 	g_topology_assert();
2645 
2646 	error = g_access(cp, 1, 0, 0);
2647 	if (error != 0)
2648 		return (error);
2649 	pp = cp->provider;
2650 	g_topology_unlock();
2651 	/* Metadata are stored on last sector. */
2652 	buf = g_read_data(cp, pp->mediasize - pp->sectorsize, pp->sectorsize,
2653 	    &error);
2654 	g_topology_lock();
2655 	g_access(cp, -1, 0, 0);
2656 	if (buf == NULL) {
2657 		G_MIRROR_DEBUG(1, "Cannot read metadata from %s (error=%d).",
2658 		    cp->provider->name, error);
2659 		return (error);
2660 	}
2661 
2662 	/* Decode metadata. */
2663 	error = mirror_metadata_decode(buf, md);
2664 	g_free(buf);
2665 	if (strcmp(md->md_magic, G_MIRROR_MAGIC) != 0)
2666 		return (EINVAL);
2667 	if (md->md_version > G_MIRROR_VERSION) {
2668 		G_MIRROR_DEBUG(0,
2669 		    "Kernel module is too old to handle metadata from %s.",
2670 		    cp->provider->name);
2671 		return (EINVAL);
2672 	}
2673 	if (error != 0) {
2674 		G_MIRROR_DEBUG(1, "MD5 metadata hash mismatch for provider %s.",
2675 		    cp->provider->name);
2676 		return (error);
2677 	}
2678 
2679 	return (0);
2680 }
2681 
2682 static int
2683 g_mirror_check_metadata(struct g_mirror_softc *sc, struct g_provider *pp,
2684     struct g_mirror_metadata *md)
2685 {
2686 
2687 	if (g_mirror_id2disk(sc, md->md_did) != NULL) {
2688 		G_MIRROR_DEBUG(1, "Disk %s (id=%u) already exists, skipping.",
2689 		    pp->name, md->md_did);
2690 		return (EEXIST);
2691 	}
2692 	if (md->md_all != sc->sc_ndisks) {
2693 		G_MIRROR_DEBUG(1,
2694 		    "Invalid '%s' field on disk %s (device %s), skipping.",
2695 		    "md_all", pp->name, sc->sc_name);
2696 		return (EINVAL);
2697 	}
2698 	if (md->md_slice != sc->sc_slice) {
2699 		G_MIRROR_DEBUG(1,
2700 		    "Invalid '%s' field on disk %s (device %s), skipping.",
2701 		    "md_slice", pp->name, sc->sc_name);
2702 		return (EINVAL);
2703 	}
2704 	if (md->md_balance != sc->sc_balance) {
2705 		G_MIRROR_DEBUG(1,
2706 		    "Invalid '%s' field on disk %s (device %s), skipping.",
2707 		    "md_balance", pp->name, sc->sc_name);
2708 		return (EINVAL);
2709 	}
2710 	if (md->md_mediasize != sc->sc_mediasize) {
2711 		G_MIRROR_DEBUG(1,
2712 		    "Invalid '%s' field on disk %s (device %s), skipping.",
2713 		    "md_mediasize", pp->name, sc->sc_name);
2714 		return (EINVAL);
2715 	}
2716 	if (sc->sc_mediasize > pp->mediasize) {
2717 		G_MIRROR_DEBUG(1,
2718 		    "Invalid size of disk %s (device %s), skipping.", pp->name,
2719 		    sc->sc_name);
2720 		return (EINVAL);
2721 	}
2722 	if (md->md_sectorsize != sc->sc_sectorsize) {
2723 		G_MIRROR_DEBUG(1,
2724 		    "Invalid '%s' field on disk %s (device %s), skipping.",
2725 		    "md_sectorsize", pp->name, sc->sc_name);
2726 		return (EINVAL);
2727 	}
2728 	if ((sc->sc_sectorsize % pp->sectorsize) != 0) {
2729 		G_MIRROR_DEBUG(1,
2730 		    "Invalid sector size of disk %s (device %s), skipping.",
2731 		    pp->name, sc->sc_name);
2732 		return (EINVAL);
2733 	}
2734 	if ((md->md_mflags & ~G_MIRROR_DEVICE_FLAG_MASK) != 0) {
2735 		G_MIRROR_DEBUG(1,
2736 		    "Invalid device flags on disk %s (device %s), skipping.",
2737 		    pp->name, sc->sc_name);
2738 		return (EINVAL);
2739 	}
2740 	if ((md->md_dflags & ~G_MIRROR_DISK_FLAG_MASK) != 0) {
2741 		G_MIRROR_DEBUG(1,
2742 		    "Invalid disk flags on disk %s (device %s), skipping.",
2743 		    pp->name, sc->sc_name);
2744 		return (EINVAL);
2745 	}
2746 	return (0);
2747 }
2748 
2749 int
2750 g_mirror_add_disk(struct g_mirror_softc *sc, struct g_provider *pp,
2751     struct g_mirror_metadata *md)
2752 {
2753 	struct g_mirror_disk *disk;
2754 	int error;
2755 
2756 	g_topology_assert_not();
2757 	G_MIRROR_DEBUG(2, "Adding disk %s.", pp->name);
2758 
2759 	error = g_mirror_check_metadata(sc, pp, md);
2760 	if (error != 0)
2761 		return (error);
2762 	if (sc->sc_state == G_MIRROR_DEVICE_STATE_RUNNING &&
2763 	    md->md_genid < sc->sc_genid) {
2764 		G_MIRROR_DEBUG(0, "Component %s (device %s) broken, skipping.",
2765 		    pp->name, sc->sc_name);
2766 		return (EINVAL);
2767 	}
2768 	disk = g_mirror_init_disk(sc, pp, md, &error);
2769 	if (disk == NULL)
2770 		return (error);
2771 	error = g_mirror_event_send(disk, G_MIRROR_DISK_STATE_NEW,
2772 	    G_MIRROR_EVENT_WAIT);
2773 	if (error != 0)
2774 		return (error);
2775 	if (md->md_version < G_MIRROR_VERSION) {
2776 		G_MIRROR_DEBUG(0, "Upgrading metadata on %s (v%d->v%d).",
2777 		    pp->name, md->md_version, G_MIRROR_VERSION);
2778 		g_mirror_update_metadata(disk);
2779 	}
2780 	return (0);
2781 }
2782 
2783 static void
2784 g_mirror_destroy_delayed(void *arg, int flag)
2785 {
2786 	struct g_mirror_softc *sc;
2787 	int error;
2788 
2789 	if (flag == EV_CANCEL) {
2790 		G_MIRROR_DEBUG(1, "Destroying canceled.");
2791 		return;
2792 	}
2793 	sc = arg;
2794 	g_topology_unlock();
2795 	sx_xlock(&sc->sc_lock);
2796 	KASSERT((sc->sc_flags & G_MIRROR_DEVICE_FLAG_DESTROY) == 0,
2797 	    ("DESTROY flag set on %s.", sc->sc_name));
2798 	KASSERT((sc->sc_flags & G_MIRROR_DEVICE_FLAG_DESTROYING) != 0,
2799 	    ("DESTROYING flag not set on %s.", sc->sc_name));
2800 	G_MIRROR_DEBUG(1, "Destroying %s (delayed).", sc->sc_name);
2801 	error = g_mirror_destroy(sc, G_MIRROR_DESTROY_SOFT);
2802 	if (error != 0) {
2803 		G_MIRROR_DEBUG(0, "Cannot destroy %s.", sc->sc_name);
2804 		sx_xunlock(&sc->sc_lock);
2805 	}
2806 	g_topology_lock();
2807 }
2808 
2809 static int
2810 g_mirror_access(struct g_provider *pp, int acr, int acw, int ace)
2811 {
2812 	struct g_mirror_softc *sc;
2813 	int dcr, dcw, dce, error = 0;
2814 
2815 	g_topology_assert();
2816 	G_MIRROR_DEBUG(2, "Access request for %s: r%dw%de%d.", pp->name, acr,
2817 	    acw, ace);
2818 
2819 	sc = pp->geom->softc;
2820 	if (sc == NULL && acr <= 0 && acw <= 0 && ace <= 0)
2821 		return (0);
2822 	KASSERT(sc != NULL, ("NULL softc (provider=%s).", pp->name));
2823 
2824 	dcr = pp->acr + acr;
2825 	dcw = pp->acw + acw;
2826 	dce = pp->ace + ace;
2827 
2828 	g_topology_unlock();
2829 	sx_xlock(&sc->sc_lock);
2830 	if ((sc->sc_flags & G_MIRROR_DEVICE_FLAG_DESTROY) != 0 ||
2831 	    LIST_EMPTY(&sc->sc_disks)) {
2832 		if (acr > 0 || acw > 0 || ace > 0)
2833 			error = ENXIO;
2834 		goto end;
2835 	}
2836 	if (dcw == 0)
2837 		g_mirror_idle(sc, dcw);
2838 	if ((sc->sc_flags & G_MIRROR_DEVICE_FLAG_DESTROYING) != 0) {
2839 		if (acr > 0 || acw > 0 || ace > 0) {
2840 			error = ENXIO;
2841 			goto end;
2842 		}
2843 		if (dcr == 0 && dcw == 0 && dce == 0) {
2844 			g_post_event(g_mirror_destroy_delayed, sc, M_WAITOK,
2845 			    sc, NULL);
2846 		}
2847 	}
2848 end:
2849 	sx_xunlock(&sc->sc_lock);
2850 	g_topology_lock();
2851 	return (error);
2852 }
2853 
2854 static struct g_geom *
2855 g_mirror_create(struct g_class *mp, const struct g_mirror_metadata *md)
2856 {
2857 	struct g_mirror_softc *sc;
2858 	struct g_geom *gp;
2859 	int error, timeout;
2860 
2861 	g_topology_assert();
2862 	G_MIRROR_DEBUG(1, "Creating device %s (id=%u).", md->md_name,
2863 	    md->md_mid);
2864 
2865 	/* One disk is minimum. */
2866 	if (md->md_all < 1)
2867 		return (NULL);
2868 	/*
2869 	 * Action geom.
2870 	 */
2871 	gp = g_new_geomf(mp, "%s", md->md_name);
2872 	sc = malloc(sizeof(*sc), M_MIRROR, M_WAITOK | M_ZERO);
2873 	gp->start = g_mirror_start;
2874 	gp->orphan = g_mirror_orphan;
2875 	gp->access = g_mirror_access;
2876 	gp->dumpconf = g_mirror_dumpconf;
2877 
2878 	sc->sc_id = md->md_mid;
2879 	sc->sc_slice = md->md_slice;
2880 	sc->sc_balance = md->md_balance;
2881 	sc->sc_mediasize = md->md_mediasize;
2882 	sc->sc_sectorsize = md->md_sectorsize;
2883 	sc->sc_ndisks = md->md_all;
2884 	sc->sc_flags = md->md_mflags;
2885 	sc->sc_bump_id = 0;
2886 	sc->sc_idle = 1;
2887 	sc->sc_last_write = time_uptime;
2888 	sc->sc_writes = 0;
2889 	sx_init(&sc->sc_lock, "gmirror:lock");
2890 	bioq_init(&sc->sc_queue);
2891 	mtx_init(&sc->sc_queue_mtx, "gmirror:queue", NULL, MTX_DEF);
2892 	bioq_init(&sc->sc_regular_delayed);
2893 	bioq_init(&sc->sc_inflight);
2894 	bioq_init(&sc->sc_sync_delayed);
2895 	LIST_INIT(&sc->sc_disks);
2896 	TAILQ_INIT(&sc->sc_events);
2897 	mtx_init(&sc->sc_events_mtx, "gmirror:events", NULL, MTX_DEF);
2898 	callout_init(&sc->sc_callout, CALLOUT_MPSAFE);
2899 	sc->sc_state = G_MIRROR_DEVICE_STATE_STARTING;
2900 	gp->softc = sc;
2901 	sc->sc_geom = gp;
2902 	sc->sc_provider = NULL;
2903 	/*
2904 	 * Synchronization geom.
2905 	 */
2906 	gp = g_new_geomf(mp, "%s.sync", md->md_name);
2907 	gp->softc = sc;
2908 	gp->orphan = g_mirror_orphan;
2909 	sc->sc_sync.ds_geom = gp;
2910 	sc->sc_sync.ds_ndisks = 0;
2911 	error = kproc_create(g_mirror_worker, sc, &sc->sc_worker, 0, 0,
2912 	    "g_mirror %s", md->md_name);
2913 	if (error != 0) {
2914 		G_MIRROR_DEBUG(1, "Cannot create kernel thread for %s.",
2915 		    sc->sc_name);
2916 		g_destroy_geom(sc->sc_sync.ds_geom);
2917 		mtx_destroy(&sc->sc_events_mtx);
2918 		mtx_destroy(&sc->sc_queue_mtx);
2919 		sx_destroy(&sc->sc_lock);
2920 		g_destroy_geom(sc->sc_geom);
2921 		free(sc, M_MIRROR);
2922 		return (NULL);
2923 	}
2924 
2925 	G_MIRROR_DEBUG(1, "Device %s created (%u components, id=%u).",
2926 	    sc->sc_name, sc->sc_ndisks, sc->sc_id);
2927 
2928 	sc->sc_rootmount = root_mount_hold("GMIRROR");
2929 	G_MIRROR_DEBUG(1, "root_mount_hold %p", sc->sc_rootmount);
2930 	/*
2931 	 * Run timeout.
2932 	 */
2933 	timeout = g_mirror_timeout * hz;
2934 	callout_reset(&sc->sc_callout, timeout, g_mirror_go, sc);
2935 	return (sc->sc_geom);
2936 }
2937 
2938 int
2939 g_mirror_destroy(struct g_mirror_softc *sc, int how)
2940 {
2941 	struct g_mirror_disk *disk;
2942 	struct g_provider *pp;
2943 
2944 	g_topology_assert_not();
2945 	if (sc == NULL)
2946 		return (ENXIO);
2947 	sx_assert(&sc->sc_lock, SX_XLOCKED);
2948 
2949 	pp = sc->sc_provider;
2950 	if (pp != NULL && (pp->acr != 0 || pp->acw != 0 || pp->ace != 0)) {
2951 		switch (how) {
2952 		case G_MIRROR_DESTROY_SOFT:
2953 			G_MIRROR_DEBUG(1,
2954 			    "Device %s is still open (r%dw%de%d).", pp->name,
2955 			    pp->acr, pp->acw, pp->ace);
2956 			return (EBUSY);
2957 		case G_MIRROR_DESTROY_DELAYED:
2958 			G_MIRROR_DEBUG(1,
2959 			    "Device %s will be destroyed on last close.",
2960 			    pp->name);
2961 			LIST_FOREACH(disk, &sc->sc_disks, d_next) {
2962 				if (disk->d_state ==
2963 				    G_MIRROR_DISK_STATE_SYNCHRONIZING) {
2964 					g_mirror_sync_stop(disk, 1);
2965 				}
2966 			}
2967 			sc->sc_flags |= G_MIRROR_DEVICE_FLAG_DESTROYING;
2968 			return (EBUSY);
2969 		case G_MIRROR_DESTROY_HARD:
2970 			G_MIRROR_DEBUG(1, "Device %s is still open, so it "
2971 			    "can't be definitely removed.", pp->name);
2972 		}
2973 	}
2974 
2975 	g_topology_lock();
2976 	if (sc->sc_geom->softc == NULL) {
2977 		g_topology_unlock();
2978 		return (0);
2979 	}
2980 	sc->sc_geom->softc = NULL;
2981 	sc->sc_sync.ds_geom->softc = NULL;
2982 	g_topology_unlock();
2983 
2984 	sc->sc_flags |= G_MIRROR_DEVICE_FLAG_DESTROY;
2985 	sc->sc_flags |= G_MIRROR_DEVICE_FLAG_WAIT;
2986 	G_MIRROR_DEBUG(4, "%s: Waking up %p.", __func__, sc);
2987 	sx_xunlock(&sc->sc_lock);
2988 	mtx_lock(&sc->sc_queue_mtx);
2989 	wakeup(sc);
2990 	mtx_unlock(&sc->sc_queue_mtx);
2991 	G_MIRROR_DEBUG(4, "%s: Sleeping %p.", __func__, &sc->sc_worker);
2992 	while (sc->sc_worker != NULL)
2993 		tsleep(&sc->sc_worker, PRIBIO, "m:destroy", hz / 5);
2994 	G_MIRROR_DEBUG(4, "%s: Woken up %p.", __func__, &sc->sc_worker);
2995 	sx_xlock(&sc->sc_lock);
2996 	g_mirror_destroy_device(sc);
2997 	free(sc, M_MIRROR);
2998 	return (0);
2999 }
3000 
3001 static void
3002 g_mirror_taste_orphan(struct g_consumer *cp)
3003 {
3004 
3005 	KASSERT(1 == 0, ("%s called while tasting %s.", __func__,
3006 	    cp->provider->name));
3007 }
3008 
3009 static struct g_geom *
3010 g_mirror_taste(struct g_class *mp, struct g_provider *pp, int flags __unused)
3011 {
3012 	struct g_mirror_metadata md;
3013 	struct g_mirror_softc *sc;
3014 	struct g_consumer *cp;
3015 	struct g_geom *gp;
3016 	int error;
3017 
3018 	g_topology_assert();
3019 	g_trace(G_T_TOPOLOGY, "%s(%s, %s)", __func__, mp->name, pp->name);
3020 	G_MIRROR_DEBUG(2, "Tasting %s.", pp->name);
3021 
3022 	gp = g_new_geomf(mp, "mirror:taste");
3023 	/*
3024 	 * This orphan function should be never called.
3025 	 */
3026 	gp->orphan = g_mirror_taste_orphan;
3027 	cp = g_new_consumer(gp);
3028 	g_attach(cp, pp);
3029 	error = g_mirror_read_metadata(cp, &md);
3030 	g_detach(cp);
3031 	g_destroy_consumer(cp);
3032 	g_destroy_geom(gp);
3033 	if (error != 0)
3034 		return (NULL);
3035 	gp = NULL;
3036 
3037 	if (md.md_provider[0] != '\0' &&
3038 	    !g_compare_names(md.md_provider, pp->name))
3039 		return (NULL);
3040 	if (md.md_provsize != 0 && md.md_provsize != pp->mediasize)
3041 		return (NULL);
3042 	if ((md.md_dflags & G_MIRROR_DISK_FLAG_INACTIVE) != 0) {
3043 		G_MIRROR_DEBUG(0,
3044 		    "Device %s: provider %s marked as inactive, skipping.",
3045 		    md.md_name, pp->name);
3046 		return (NULL);
3047 	}
3048 	if (g_mirror_debug >= 2)
3049 		mirror_metadata_dump(&md);
3050 
3051 	/*
3052 	 * Let's check if device already exists.
3053 	 */
3054 	sc = NULL;
3055 	LIST_FOREACH(gp, &mp->geom, geom) {
3056 		sc = gp->softc;
3057 		if (sc == NULL)
3058 			continue;
3059 		if (sc->sc_sync.ds_geom == gp)
3060 			continue;
3061 		if (strcmp(md.md_name, sc->sc_name) != 0)
3062 			continue;
3063 		if (md.md_mid != sc->sc_id) {
3064 			G_MIRROR_DEBUG(0, "Device %s already configured.",
3065 			    sc->sc_name);
3066 			return (NULL);
3067 		}
3068 		break;
3069 	}
3070 	if (gp == NULL) {
3071 		gp = g_mirror_create(mp, &md);
3072 		if (gp == NULL) {
3073 			G_MIRROR_DEBUG(0, "Cannot create device %s.",
3074 			    md.md_name);
3075 			return (NULL);
3076 		}
3077 		sc = gp->softc;
3078 	}
3079 	G_MIRROR_DEBUG(1, "Adding disk %s to %s.", pp->name, gp->name);
3080 	g_topology_unlock();
3081 	sx_xlock(&sc->sc_lock);
3082 	sc->sc_flags |= G_MIRROR_DEVICE_FLAG_TASTING;
3083 	error = g_mirror_add_disk(sc, pp, &md);
3084 	if (error != 0) {
3085 		G_MIRROR_DEBUG(0, "Cannot add disk %s to %s (error=%d).",
3086 		    pp->name, gp->name, error);
3087 		if (LIST_EMPTY(&sc->sc_disks)) {
3088 			g_cancel_event(sc);
3089 			g_mirror_destroy(sc, G_MIRROR_DESTROY_HARD);
3090 			g_topology_lock();
3091 			return (NULL);
3092 		}
3093 		gp = NULL;
3094 	}
3095 	sc->sc_flags &= ~G_MIRROR_DEVICE_FLAG_TASTING;
3096 	if ((sc->sc_flags & G_MIRROR_DEVICE_FLAG_DESTROY) != 0) {
3097 		g_mirror_destroy(sc, G_MIRROR_DESTROY_HARD);
3098 		g_topology_lock();
3099 		return (NULL);
3100 	}
3101 	sx_xunlock(&sc->sc_lock);
3102 	g_topology_lock();
3103 	return (gp);
3104 }
3105 
3106 static int
3107 g_mirror_destroy_geom(struct gctl_req *req __unused,
3108     struct g_class *mp __unused, struct g_geom *gp)
3109 {
3110 	struct g_mirror_softc *sc;
3111 	int error;
3112 
3113 	g_topology_unlock();
3114 	sc = gp->softc;
3115 	sx_xlock(&sc->sc_lock);
3116 	g_cancel_event(sc);
3117 	error = g_mirror_destroy(gp->softc, G_MIRROR_DESTROY_SOFT);
3118 	if (error != 0)
3119 		sx_xunlock(&sc->sc_lock);
3120 	g_topology_lock();
3121 	return (error);
3122 }
3123 
3124 static void
3125 g_mirror_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp,
3126     struct g_consumer *cp, struct g_provider *pp)
3127 {
3128 	struct g_mirror_softc *sc;
3129 
3130 	g_topology_assert();
3131 
3132 	sc = gp->softc;
3133 	if (sc == NULL)
3134 		return;
3135 	/* Skip synchronization geom. */
3136 	if (gp == sc->sc_sync.ds_geom)
3137 		return;
3138 	if (pp != NULL) {
3139 		/* Nothing here. */
3140 	} else if (cp != NULL) {
3141 		struct g_mirror_disk *disk;
3142 
3143 		disk = cp->private;
3144 		if (disk == NULL)
3145 			return;
3146 		g_topology_unlock();
3147 		sx_xlock(&sc->sc_lock);
3148 		sbuf_printf(sb, "%s<ID>%u</ID>\n", indent, (u_int)disk->d_id);
3149 		if (disk->d_state == G_MIRROR_DISK_STATE_SYNCHRONIZING) {
3150 			sbuf_printf(sb, "%s<Synchronized>", indent);
3151 			if (disk->d_sync.ds_offset == 0)
3152 				sbuf_printf(sb, "0%%");
3153 			else {
3154 				sbuf_printf(sb, "%u%%",
3155 				    (u_int)((disk->d_sync.ds_offset * 100) /
3156 				    sc->sc_provider->mediasize));
3157 			}
3158 			sbuf_printf(sb, "</Synchronized>\n");
3159 			if (disk->d_sync.ds_offset > 0) {
3160 				sbuf_printf(sb, "%s<BytesSynced>%jd"
3161 				    "</BytesSynced>\n", indent,
3162 				    (intmax_t)disk->d_sync.ds_offset);
3163 			}
3164 		}
3165 		sbuf_printf(sb, "%s<SyncID>%u</SyncID>\n", indent,
3166 		    disk->d_sync.ds_syncid);
3167 		sbuf_printf(sb, "%s<GenID>%u</GenID>\n", indent,
3168 		    disk->d_genid);
3169 		sbuf_printf(sb, "%s<Flags>", indent);
3170 		if (disk->d_flags == 0)
3171 			sbuf_printf(sb, "NONE");
3172 		else {
3173 			int first = 1;
3174 
3175 #define	ADD_FLAG(flag, name)	do {					\
3176 	if ((disk->d_flags & (flag)) != 0) {				\
3177 		if (!first)						\
3178 			sbuf_printf(sb, ", ");				\
3179 		else							\
3180 			first = 0;					\
3181 		sbuf_printf(sb, name);					\
3182 	}								\
3183 } while (0)
3184 			ADD_FLAG(G_MIRROR_DISK_FLAG_DIRTY, "DIRTY");
3185 			ADD_FLAG(G_MIRROR_DISK_FLAG_HARDCODED, "HARDCODED");
3186 			ADD_FLAG(G_MIRROR_DISK_FLAG_INACTIVE, "INACTIVE");
3187 			ADD_FLAG(G_MIRROR_DISK_FLAG_SYNCHRONIZING,
3188 			    "SYNCHRONIZING");
3189 			ADD_FLAG(G_MIRROR_DISK_FLAG_FORCE_SYNC, "FORCE_SYNC");
3190 			ADD_FLAG(G_MIRROR_DISK_FLAG_BROKEN, "BROKEN");
3191 #undef	ADD_FLAG
3192 		}
3193 		sbuf_printf(sb, "</Flags>\n");
3194 		sbuf_printf(sb, "%s<Priority>%u</Priority>\n", indent,
3195 		    disk->d_priority);
3196 		sbuf_printf(sb, "%s<State>%s</State>\n", indent,
3197 		    g_mirror_disk_state2str(disk->d_state));
3198 		sx_xunlock(&sc->sc_lock);
3199 		g_topology_lock();
3200 	} else {
3201 		g_topology_unlock();
3202 		sx_xlock(&sc->sc_lock);
3203 		sbuf_printf(sb, "%s<ID>%u</ID>\n", indent, (u_int)sc->sc_id);
3204 		sbuf_printf(sb, "%s<SyncID>%u</SyncID>\n", indent, sc->sc_syncid);
3205 		sbuf_printf(sb, "%s<GenID>%u</GenID>\n", indent, sc->sc_genid);
3206 		sbuf_printf(sb, "%s<Flags>", indent);
3207 		if (sc->sc_flags == 0)
3208 			sbuf_printf(sb, "NONE");
3209 		else {
3210 			int first = 1;
3211 
3212 #define	ADD_FLAG(flag, name)	do {					\
3213 	if ((sc->sc_flags & (flag)) != 0) {				\
3214 		if (!first)						\
3215 			sbuf_printf(sb, ", ");				\
3216 		else							\
3217 			first = 0;					\
3218 		sbuf_printf(sb, name);					\
3219 	}								\
3220 } while (0)
3221 			ADD_FLAG(G_MIRROR_DEVICE_FLAG_NOFAILSYNC, "NOFAILSYNC");
3222 			ADD_FLAG(G_MIRROR_DEVICE_FLAG_NOAUTOSYNC, "NOAUTOSYNC");
3223 #undef	ADD_FLAG
3224 		}
3225 		sbuf_printf(sb, "</Flags>\n");
3226 		sbuf_printf(sb, "%s<Slice>%u</Slice>\n", indent,
3227 		    (u_int)sc->sc_slice);
3228 		sbuf_printf(sb, "%s<Balance>%s</Balance>\n", indent,
3229 		    balance_name(sc->sc_balance));
3230 		sbuf_printf(sb, "%s<Components>%u</Components>\n", indent,
3231 		    sc->sc_ndisks);
3232 		sbuf_printf(sb, "%s<State>", indent);
3233 		if (sc->sc_state == G_MIRROR_DEVICE_STATE_STARTING)
3234 			sbuf_printf(sb, "%s", "STARTING");
3235 		else if (sc->sc_ndisks ==
3236 		    g_mirror_ndisks(sc, G_MIRROR_DISK_STATE_ACTIVE))
3237 			sbuf_printf(sb, "%s", "COMPLETE");
3238 		else
3239 			sbuf_printf(sb, "%s", "DEGRADED");
3240 		sbuf_printf(sb, "</State>\n");
3241 		sx_xunlock(&sc->sc_lock);
3242 		g_topology_lock();
3243 	}
3244 }
3245 
3246 static void
3247 g_mirror_shutdown_post_sync(void *arg, int howto)
3248 {
3249 	struct g_class *mp;
3250 	struct g_geom *gp, *gp2;
3251 	struct g_mirror_softc *sc;
3252 	int error;
3253 
3254 	mp = arg;
3255 	DROP_GIANT();
3256 	g_topology_lock();
3257 	g_mirror_shutdown = 1;
3258 	LIST_FOREACH_SAFE(gp, &mp->geom, geom, gp2) {
3259 		if ((sc = gp->softc) == NULL)
3260 			continue;
3261 		/* Skip synchronization geom. */
3262 		if (gp == sc->sc_sync.ds_geom)
3263 			continue;
3264 		g_topology_unlock();
3265 		sx_xlock(&sc->sc_lock);
3266 		g_mirror_idle(sc, -1);
3267 		g_cancel_event(sc);
3268 		error = g_mirror_destroy(sc, G_MIRROR_DESTROY_DELAYED);
3269 		if (error != 0)
3270 			sx_xunlock(&sc->sc_lock);
3271 		g_topology_lock();
3272 	}
3273 	g_topology_unlock();
3274 	PICKUP_GIANT();
3275 }
3276 
3277 static void
3278 g_mirror_init(struct g_class *mp)
3279 {
3280 
3281 	g_mirror_post_sync = EVENTHANDLER_REGISTER(shutdown_post_sync,
3282 	    g_mirror_shutdown_post_sync, mp, SHUTDOWN_PRI_FIRST);
3283 	if (g_mirror_post_sync == NULL)
3284 		G_MIRROR_DEBUG(0, "Warning! Cannot register shutdown event.");
3285 }
3286 
3287 static void
3288 g_mirror_fini(struct g_class *mp)
3289 {
3290 
3291 	if (g_mirror_post_sync != NULL)
3292 		EVENTHANDLER_DEREGISTER(shutdown_post_sync, g_mirror_post_sync);
3293 }
3294 
3295 DECLARE_GEOM_CLASS(g_mirror_class, g_mirror);
3296