xref: /freebsd/sys/geom/virstor/g_virstor.c (revision cc426dd31990b8b50b210efc450e404596548ca1)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 2006-2007 Ivan Voras <ivoras@freebsd.org>
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 /* Implementation notes:
30  * - "Components" are wrappers around providers that make up the
31  *   virtual storage (i.e. a virstor has "physical" components)
32  */
33 
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36 
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/kernel.h>
40 #include <sys/module.h>
41 #include <sys/lock.h>
42 #include <sys/mutex.h>
43 #include <sys/sx.h>
44 #include <sys/bio.h>
45 #include <sys/sbuf.h>
46 #include <sys/sysctl.h>
47 #include <sys/malloc.h>
48 #include <sys/time.h>
49 #include <sys/proc.h>
50 #include <sys/kthread.h>
51 #include <sys/mutex.h>
52 #include <vm/uma.h>
53 #include <geom/geom.h>
54 
55 #include <geom/virstor/g_virstor.h>
56 #include <geom/virstor/g_virstor_md.h>
57 
58 FEATURE(g_virstor, "GEOM virtual storage support");
59 
60 /* Declare malloc(9) label */
61 static MALLOC_DEFINE(M_GVIRSTOR, "gvirstor", "GEOM_VIRSTOR Data");
62 
63 /* GEOM class methods */
64 static g_init_t g_virstor_init;
65 static g_fini_t g_virstor_fini;
66 static g_taste_t g_virstor_taste;
67 static g_ctl_req_t g_virstor_config;
68 static g_ctl_destroy_geom_t g_virstor_destroy_geom;
69 
70 /* Declare & initialize class structure ("geom class") */
71 struct g_class g_virstor_class = {
72 	.name =		G_VIRSTOR_CLASS_NAME,
73 	.version =	G_VERSION,
74 	.init =		g_virstor_init,
75 	.fini =		g_virstor_fini,
76 	.taste =	g_virstor_taste,
77 	.ctlreq =	g_virstor_config,
78 	.destroy_geom = g_virstor_destroy_geom
79 	/* The .dumpconf and the rest are only usable for a geom instance, so
80 	 * they will be set when such instance is created. */
81 };
82 
83 /* Declare sysctl's and loader tunables */
84 SYSCTL_DECL(_kern_geom);
85 static SYSCTL_NODE(_kern_geom, OID_AUTO, virstor, CTLFLAG_RW, 0,
86     "GEOM_GVIRSTOR information");
87 
88 static u_int g_virstor_debug = 2; /* XXX: lower to 2 when released to public */
89 SYSCTL_UINT(_kern_geom_virstor, OID_AUTO, debug, CTLFLAG_RWTUN, &g_virstor_debug,
90     0, "Debug level (2=production, 5=normal, 15=excessive)");
91 
92 static u_int g_virstor_chunk_watermark = 100;
93 SYSCTL_UINT(_kern_geom_virstor, OID_AUTO, chunk_watermark, CTLFLAG_RWTUN,
94     &g_virstor_chunk_watermark, 0,
95     "Minimum number of free chunks before issuing administrative warning");
96 
97 static u_int g_virstor_component_watermark = 1;
98 SYSCTL_UINT(_kern_geom_virstor, OID_AUTO, component_watermark, CTLFLAG_RWTUN,
99     &g_virstor_component_watermark, 0,
100     "Minimum number of free components before issuing administrative warning");
101 
102 static int read_metadata(struct g_consumer *, struct g_virstor_metadata *);
103 static void write_metadata(struct g_consumer *, struct g_virstor_metadata *);
104 static int clear_metadata(struct g_virstor_component *);
105 static int add_provider_to_geom(struct g_virstor_softc *, struct g_provider *,
106     struct g_virstor_metadata *);
107 static struct g_geom *create_virstor_geom(struct g_class *,
108     struct g_virstor_metadata *);
109 static void virstor_check_and_run(struct g_virstor_softc *);
110 static u_int virstor_valid_components(struct g_virstor_softc *);
111 static int virstor_geom_destroy(struct g_virstor_softc *, boolean_t,
112     boolean_t);
113 static void remove_component(struct g_virstor_softc *,
114     struct g_virstor_component *, boolean_t);
115 static void bioq_dismantle(struct bio_queue_head *);
116 static int allocate_chunk(struct g_virstor_softc *,
117     struct g_virstor_component **, u_int *, u_int *);
118 static void delay_destroy_consumer(void *, int);
119 static void dump_component(struct g_virstor_component *comp);
120 #if 0
121 static void dump_me(struct virstor_map_entry *me, unsigned int nr);
122 #endif
123 
124 static void virstor_ctl_stop(struct gctl_req *, struct g_class *);
125 static void virstor_ctl_add(struct gctl_req *, struct g_class *);
126 static void virstor_ctl_remove(struct gctl_req *, struct g_class *);
127 static struct g_virstor_softc * virstor_find_geom(const struct g_class *,
128     const char *);
129 static void update_metadata(struct g_virstor_softc *);
130 static void fill_metadata(struct g_virstor_softc *, struct g_virstor_metadata *,
131     u_int, u_int);
132 
133 static void g_virstor_orphan(struct g_consumer *);
134 static int g_virstor_access(struct g_provider *, int, int, int);
135 static void g_virstor_start(struct bio *);
136 static void g_virstor_dumpconf(struct sbuf *, const char *, struct g_geom *,
137     struct g_consumer *, struct g_provider *);
138 static void g_virstor_done(struct bio *);
139 
140 static void invalid_call(void);
141 /*
142  * Initialise GEOM class (per-class callback)
143  */
144 static void
145 g_virstor_init(struct g_class *mp __unused)
146 {
147 
148 	/* Catch map struct size mismatch at compile time; Map entries must
149 	 * fit into MAXPHYS exactly, with no wasted space. */
150 	CTASSERT(VIRSTOR_MAP_BLOCK_ENTRIES*VIRSTOR_MAP_ENTRY_SIZE == MAXPHYS);
151 
152 	/* Init UMA zones, TAILQ's, other global vars */
153 }
154 
155 /*
156  * Finalise GEOM class (per-class callback)
157  */
158 static void
159 g_virstor_fini(struct g_class *mp __unused)
160 {
161 
162 	/* Deinit UMA zones & global vars */
163 }
164 
165 /*
166  * Config (per-class callback)
167  */
168 static void
169 g_virstor_config(struct gctl_req *req, struct g_class *cp, char const *verb)
170 {
171 	uint32_t *version;
172 
173 	g_topology_assert();
174 
175 	version = gctl_get_paraml(req, "version", sizeof(*version));
176 	if (version == NULL) {
177 		gctl_error(req, "Failed to get 'version' argument");
178 		return;
179 	}
180 	if (*version != G_VIRSTOR_VERSION) {
181 		gctl_error(req, "Userland and kernel versions out of sync");
182 		return;
183 	}
184 
185 	g_topology_unlock();
186 	if (strcmp(verb, "add") == 0)
187 		virstor_ctl_add(req, cp);
188 	else if (strcmp(verb, "stop") == 0 || strcmp(verb, "destroy") == 0)
189 		virstor_ctl_stop(req, cp);
190 	else if (strcmp(verb, "remove") == 0)
191 		virstor_ctl_remove(req, cp);
192 	else
193 		gctl_error(req, "unknown verb: '%s'", verb);
194 	g_topology_lock();
195 }
196 
197 /*
198  * "stop" verb from userland
199  */
200 static void
201 virstor_ctl_stop(struct gctl_req *req, struct g_class *cp)
202 {
203 	int *force, *nargs;
204 	int i;
205 
206 	nargs = gctl_get_paraml(req, "nargs", sizeof *nargs);
207 	if (nargs == NULL) {
208 		gctl_error(req, "Error fetching argument '%s'", "nargs");
209 		return;
210 	}
211 	if (*nargs < 1) {
212 		gctl_error(req, "Invalid number of arguments");
213 		return;
214 	}
215 	force = gctl_get_paraml(req, "force", sizeof *force);
216 	if (force == NULL) {
217 		gctl_error(req, "Error fetching argument '%s'", "force");
218 		return;
219 	}
220 
221 	g_topology_lock();
222 	for (i = 0; i < *nargs; i++) {
223 		char param[8];
224 		const char *name;
225 		struct g_virstor_softc *sc;
226 		int error;
227 
228 		sprintf(param, "arg%d", i);
229 		name = gctl_get_asciiparam(req, param);
230 		if (name == NULL) {
231 			gctl_error(req, "No 'arg%d' argument", i);
232 			g_topology_unlock();
233 			return;
234 		}
235 		sc = virstor_find_geom(cp, name);
236 		if (sc == NULL) {
237 			gctl_error(req, "Don't know anything about '%s'", name);
238 			g_topology_unlock();
239 			return;
240 		}
241 
242 		LOG_MSG(LVL_INFO, "Stopping %s by the userland command",
243 		    sc->geom->name);
244 		update_metadata(sc);
245 		if ((error = virstor_geom_destroy(sc, TRUE, TRUE)) != 0) {
246 			LOG_MSG(LVL_ERROR, "Cannot destroy %s: %d",
247 			    sc->geom->name, error);
248 		}
249 	}
250 	g_topology_unlock();
251 }
252 
253 /*
254  * "add" verb from userland - add new component(s) to the structure.
255  * This will be done all at once in here, without going through the
256  * .taste function for new components.
257  */
258 static void
259 virstor_ctl_add(struct gctl_req *req, struct g_class *cp)
260 {
261 	/* Note: while this is going on, I/O is being done on
262 	 * the g_up and g_down threads. The idea is to make changes
263 	 * to softc members in a way that can atomically activate
264 	 * them all at once. */
265 	struct g_virstor_softc *sc;
266 	int *hardcode, *nargs;
267 	const char *geom_name;	/* geom to add a component to */
268 	struct g_consumer *fcp;
269 	struct g_virstor_bio_q *bq;
270 	u_int added;
271 	int error;
272 	int i;
273 
274 	nargs = gctl_get_paraml(req, "nargs", sizeof(*nargs));
275 	if (nargs == NULL) {
276 		gctl_error(req, "Error fetching argument '%s'", "nargs");
277 		return;
278 	}
279 	if (*nargs < 2) {
280 		gctl_error(req, "Invalid number of arguments");
281 		return;
282 	}
283 	hardcode = gctl_get_paraml(req, "hardcode", sizeof(*hardcode));
284 	if (hardcode == NULL) {
285 		gctl_error(req, "Error fetching argument '%s'", "hardcode");
286 		return;
287 	}
288 
289 	/* Find "our" geom */
290 	geom_name = gctl_get_asciiparam(req, "arg0");
291 	if (geom_name == NULL) {
292 		gctl_error(req, "Error fetching argument '%s'", "geom_name (arg0)");
293 		return;
294 	}
295 	sc = virstor_find_geom(cp, geom_name);
296 	if (sc == NULL) {
297 		gctl_error(req, "Don't know anything about '%s'", geom_name);
298 		return;
299 	}
300 
301 	if (virstor_valid_components(sc) != sc->n_components) {
302 		LOG_MSG(LVL_ERROR, "Cannot add components to incomplete "
303 		    "virstor %s", sc->geom->name);
304 		gctl_error(req, "Virstor %s is incomplete", sc->geom->name);
305 		return;
306 	}
307 
308 	fcp = sc->components[0].gcons;
309 	added = 0;
310 	g_topology_lock();
311 	for (i = 1; i < *nargs; i++) {
312 		struct g_virstor_metadata md;
313 		char aname[8];
314 		const char *prov_name;
315 		struct g_provider *pp;
316 		struct g_consumer *cp;
317 		u_int nc;
318 		u_int j;
319 
320 		snprintf(aname, sizeof aname, "arg%d", i);
321 		prov_name = gctl_get_asciiparam(req, aname);
322 		if (prov_name == NULL) {
323 			gctl_error(req, "Error fetching argument '%s'", aname);
324 			g_topology_unlock();
325 			return;
326 		}
327 		if (strncmp(prov_name, _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0)
328 			prov_name += sizeof(_PATH_DEV) - 1;
329 
330 		pp = g_provider_by_name(prov_name);
331 		if (pp == NULL) {
332 			/* This is the most common error so be verbose about it */
333 			if (added != 0) {
334 				gctl_error(req, "Invalid provider: '%s' (added"
335 				    " %u components)", prov_name, added);
336 				update_metadata(sc);
337 			} else {
338 				gctl_error(req, "Invalid provider: '%s'",
339 				    prov_name);
340 			}
341 			g_topology_unlock();
342 			return;
343 		}
344 		cp = g_new_consumer(sc->geom);
345 		if (cp == NULL) {
346 			gctl_error(req, "Cannot create consumer");
347 			g_topology_unlock();
348 			return;
349 		}
350 		error = g_attach(cp, pp);
351 		if (error != 0) {
352 			gctl_error(req, "Cannot attach a consumer to %s",
353 			    pp->name);
354 			g_destroy_consumer(cp);
355 			g_topology_unlock();
356 			return;
357 		}
358 		if (fcp->acr != 0 || fcp->acw != 0 || fcp->ace != 0) {
359 			error = g_access(cp, fcp->acr, fcp->acw, fcp->ace);
360 			if (error != 0) {
361 				gctl_error(req, "Access request failed for %s",
362 				    pp->name);
363 				g_destroy_consumer(cp);
364 				g_topology_unlock();
365 				return;
366 			}
367 		}
368 		if (fcp->provider->sectorsize != pp->sectorsize) {
369 			gctl_error(req, "Sector size doesn't fit for %s",
370 			    pp->name);
371 			g_destroy_consumer(cp);
372 			g_topology_unlock();
373 			return;
374 		}
375 		for (j = 0; j < sc->n_components; j++) {
376 			if (strcmp(sc->components[j].gcons->provider->name,
377 			    pp->name) == 0) {
378 				gctl_error(req, "Component %s already in %s",
379 				    pp->name, sc->geom->name);
380 				g_destroy_consumer(cp);
381 				g_topology_unlock();
382 				return;
383 			}
384 		}
385 		sc->components = realloc(sc->components,
386 		    sizeof(*sc->components) * (sc->n_components + 1),
387 		    M_GVIRSTOR, M_WAITOK);
388 
389 		nc = sc->n_components;
390 		sc->components[nc].gcons = cp;
391 		sc->components[nc].sc = sc;
392 		sc->components[nc].index = nc;
393 		sc->components[nc].chunk_count = cp->provider->mediasize /
394 		    sc->chunk_size;
395 		sc->components[nc].chunk_next = 0;
396 		sc->components[nc].chunk_reserved = 0;
397 
398 		if (sc->components[nc].chunk_count < 4) {
399 			gctl_error(req, "Provider too small: %s",
400 			    cp->provider->name);
401 			g_destroy_consumer(cp);
402 			g_topology_unlock();
403 			return;
404 		}
405 		fill_metadata(sc, &md, nc, *hardcode);
406 		write_metadata(cp, &md);
407 		/* The new component becomes visible when n_components is
408 		 * incremented */
409 		sc->n_components++;
410 		added++;
411 
412 	}
413 	/* This call to update_metadata() is critical. In case there's a
414 	 * power failure in the middle of it and some components are updated
415 	 * while others are not, there will be trouble on next .taste() iff
416 	 * a non-updated component is detected first */
417 	update_metadata(sc);
418 	g_topology_unlock();
419 	LOG_MSG(LVL_INFO, "Added %d component(s) to %s", added,
420 	    sc->geom->name);
421 	/* Fire off BIOs previously queued because there wasn't any
422 	 * physical space left. If the BIOs still can't be satisfied
423 	 * they will again be added to the end of the queue (during
424 	 * which the mutex will be recursed) */
425 	bq = malloc(sizeof(*bq), M_GVIRSTOR, M_WAITOK);
426 	bq->bio = NULL;
427 	mtx_lock(&sc->delayed_bio_q_mtx);
428 	/* First, insert a sentinel to the queue end, so we don't
429 	 * end up in an infinite loop if there's still no free
430 	 * space available. */
431 	STAILQ_INSERT_TAIL(&sc->delayed_bio_q, bq, linkage);
432 	while (!STAILQ_EMPTY(&sc->delayed_bio_q)) {
433 		bq = STAILQ_FIRST(&sc->delayed_bio_q);
434 		if (bq->bio != NULL) {
435 			g_virstor_start(bq->bio);
436 			STAILQ_REMOVE_HEAD(&sc->delayed_bio_q, linkage);
437 			free(bq, M_GVIRSTOR);
438 		} else {
439 			STAILQ_REMOVE_HEAD(&sc->delayed_bio_q, linkage);
440 			free(bq, M_GVIRSTOR);
441 			break;
442 		}
443 	}
444 	mtx_unlock(&sc->delayed_bio_q_mtx);
445 
446 }
447 
448 /*
449  * Find a geom handled by the class
450  */
451 static struct g_virstor_softc *
452 virstor_find_geom(const struct g_class *cp, const char *name)
453 {
454 	struct g_geom *gp;
455 
456 	LIST_FOREACH(gp, &cp->geom, geom) {
457 		if (strcmp(name, gp->name) == 0)
458 			return (gp->softc);
459 	}
460 	return (NULL);
461 }
462 
463 /*
464  * Update metadata on all components to reflect the current state
465  * of these fields:
466  *    - chunk_next
467  *    - flags
468  *    - md_count
469  * Expects things to be set up so write_metadata() can work, i.e.
470  * the topology lock must be held.
471  */
472 static void
473 update_metadata(struct g_virstor_softc *sc)
474 {
475 	struct g_virstor_metadata md;
476 	u_int n;
477 
478 	if (virstor_valid_components(sc) != sc->n_components)
479 		return; /* Incomplete device */
480 	LOG_MSG(LVL_DEBUG, "Updating metadata on components for %s",
481 	    sc->geom->name);
482 	/* Update metadata on components */
483 	g_trace(G_T_TOPOLOGY, "%s(%s, %s)", __func__,
484 	    sc->geom->class->name, sc->geom->name);
485 	g_topology_assert();
486 	for (n = 0; n < sc->n_components; n++) {
487 		read_metadata(sc->components[n].gcons, &md);
488 		md.chunk_next = sc->components[n].chunk_next;
489 		md.flags = sc->components[n].flags;
490 		md.md_count = sc->n_components;
491 		write_metadata(sc->components[n].gcons, &md);
492 	}
493 }
494 
495 /*
496  * Fills metadata (struct md) from information stored in softc and the nc'th
497  * component of virstor
498  */
499 static void
500 fill_metadata(struct g_virstor_softc *sc, struct g_virstor_metadata *md,
501     u_int nc, u_int hardcode)
502 {
503 	struct g_virstor_component *c;
504 
505 	bzero(md, sizeof *md);
506 	c = &sc->components[nc];
507 
508 	strncpy(md->md_magic, G_VIRSTOR_MAGIC, sizeof md->md_magic);
509 	md->md_version = G_VIRSTOR_VERSION;
510 	strncpy(md->md_name, sc->geom->name, sizeof md->md_name);
511 	md->md_id = sc->id;
512 	md->md_virsize = sc->virsize;
513 	md->md_chunk_size = sc->chunk_size;
514 	md->md_count = sc->n_components;
515 
516 	if (hardcode) {
517 		strncpy(md->provider, c->gcons->provider->name,
518 		    sizeof md->provider);
519 	}
520 	md->no = nc;
521 	md->provsize = c->gcons->provider->mediasize;
522 	md->chunk_count = c->chunk_count;
523 	md->chunk_next = c->chunk_next;
524 	md->chunk_reserved = c->chunk_reserved;
525 	md->flags = c->flags;
526 }
527 
528 /*
529  * Remove a component from virstor device.
530  * Can only be done if the component is unallocated.
531  */
532 static void
533 virstor_ctl_remove(struct gctl_req *req, struct g_class *cp)
534 {
535 	/* As this is executed in parallel to I/O, operations on virstor
536 	 * structures must be as atomic as possible. */
537 	struct g_virstor_softc *sc;
538 	int *nargs;
539 	const char *geom_name;
540 	u_int removed;
541 	int i;
542 
543 	nargs = gctl_get_paraml(req, "nargs", sizeof(*nargs));
544 	if (nargs == NULL) {
545 		gctl_error(req, "Error fetching argument '%s'", "nargs");
546 		return;
547 	}
548 	if (*nargs < 2) {
549 		gctl_error(req, "Invalid number of arguments");
550 		return;
551 	}
552 	/* Find "our" geom */
553 	geom_name = gctl_get_asciiparam(req, "arg0");
554 	if (geom_name == NULL) {
555 		gctl_error(req, "Error fetching argument '%s'",
556 		    "geom_name (arg0)");
557 		return;
558 	}
559 	sc = virstor_find_geom(cp, geom_name);
560 	if (sc == NULL) {
561 		gctl_error(req, "Don't know anything about '%s'", geom_name);
562 		return;
563 	}
564 
565 	if (virstor_valid_components(sc) != sc->n_components) {
566 		LOG_MSG(LVL_ERROR, "Cannot remove components from incomplete "
567 		    "virstor %s", sc->geom->name);
568 		gctl_error(req, "Virstor %s is incomplete", sc->geom->name);
569 		return;
570 	}
571 
572 	removed = 0;
573 	for (i = 1; i < *nargs; i++) {
574 		char param[8];
575 		const char *prov_name;
576 		int j, found;
577 		struct g_virstor_component *newcomp, *compbak;
578 
579 		sprintf(param, "arg%d", i);
580 		prov_name = gctl_get_asciiparam(req, param);
581 		if (prov_name == NULL) {
582 			gctl_error(req, "Error fetching argument '%s'", param);
583 			return;
584 		}
585 		if (strncmp(prov_name, _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0)
586 			prov_name += sizeof(_PATH_DEV) - 1;
587 
588 		found = -1;
589 		for (j = 0; j < sc->n_components; j++) {
590 			if (strcmp(sc->components[j].gcons->provider->name,
591 			    prov_name) == 0) {
592 				found = j;
593 				break;
594 			}
595 		}
596 		if (found == -1) {
597 			LOG_MSG(LVL_ERROR, "No %s component in %s",
598 			    prov_name, sc->geom->name);
599 			continue;
600 		}
601 
602 		compbak = sc->components;
603 		newcomp = malloc(sc->n_components * sizeof(*sc->components),
604 		    M_GVIRSTOR, M_WAITOK | M_ZERO);
605 		bcopy(sc->components, newcomp, found * sizeof(*sc->components));
606 		bcopy(&sc->components[found + 1], newcomp + found,
607 		    found * sizeof(*sc->components));
608 		if ((sc->components[j].flags & VIRSTOR_PROVIDER_ALLOCATED) != 0) {
609 			LOG_MSG(LVL_ERROR, "Allocated provider %s cannot be "
610 			    "removed from %s",
611 			    prov_name, sc->geom->name);
612 			free(newcomp, M_GVIRSTOR);
613 			/* We'll consider this non-fatal error */
614 			continue;
615 		}
616 		/* Renumerate unallocated components */
617 		for (j = 0; j < sc->n_components-1; j++) {
618 			if ((sc->components[j].flags &
619 			    VIRSTOR_PROVIDER_ALLOCATED) == 0) {
620 				sc->components[j].index = j;
621 			}
622 		}
623 		/* This is the critical section. If a component allocation
624 		 * event happens while both variables are not yet set,
625 		 * there will be trouble. Something will panic on encountering
626 		 * NULL sc->components[x].gcomp member.
627 		 * Luckily, component allocation happens very rarely and
628 		 * removing components is an abnormal action in any case. */
629 		sc->components = newcomp;
630 		sc->n_components--;
631 		/* End critical section */
632 
633 		g_topology_lock();
634 		if (clear_metadata(&compbak[found]) != 0) {
635 			LOG_MSG(LVL_WARNING, "Trouble ahead: cannot clear "
636 			    "metadata on %s", prov_name);
637 		}
638 		g_detach(compbak[found].gcons);
639 		g_destroy_consumer(compbak[found].gcons);
640 		g_topology_unlock();
641 
642 		free(compbak, M_GVIRSTOR);
643 
644 		removed++;
645 	}
646 
647 	/* This call to update_metadata() is critical. In case there's a
648 	 * power failure in the middle of it and some components are updated
649 	 * while others are not, there will be trouble on next .taste() iff
650 	 * a non-updated component is detected first */
651 	g_topology_lock();
652 	update_metadata(sc);
653 	g_topology_unlock();
654 	LOG_MSG(LVL_INFO, "Removed %d component(s) from %s", removed,
655 	    sc->geom->name);
656 }
657 
658 /*
659  * Clear metadata sector on component
660  */
661 static int
662 clear_metadata(struct g_virstor_component *comp)
663 {
664 	char *buf;
665 	int error;
666 
667 	LOG_MSG(LVL_INFO, "Clearing metadata on %s",
668 	    comp->gcons->provider->name);
669 	g_topology_assert();
670 	error = g_access(comp->gcons, 0, 1, 0);
671 	if (error != 0)
672 		return (error);
673 	buf = malloc(comp->gcons->provider->sectorsize, M_GVIRSTOR,
674 	    M_WAITOK | M_ZERO);
675 	error = g_write_data(comp->gcons,
676 	    comp->gcons->provider->mediasize -
677 	    comp->gcons->provider->sectorsize,
678 	    buf,
679 	    comp->gcons->provider->sectorsize);
680 	free(buf, M_GVIRSTOR);
681 	g_access(comp->gcons, 0, -1, 0);
682 	return (error);
683 }
684 
685 /*
686  * Destroy geom forcibly.
687  */
688 static int
689 g_virstor_destroy_geom(struct gctl_req *req __unused, struct g_class *mp,
690     struct g_geom *gp)
691 {
692 	struct g_virstor_softc *sc;
693 	int exitval;
694 
695 	sc = gp->softc;
696 	KASSERT(sc != NULL, ("%s: NULL sc", __func__));
697 
698 	exitval = 0;
699 	LOG_MSG(LVL_DEBUG, "%s called for %s, sc=%p", __func__, gp->name,
700 	    gp->softc);
701 
702 	if (sc != NULL) {
703 #ifdef INVARIANTS
704 		char *buf;
705 		int error;
706 		off_t off;
707 		int isclean, count;
708 		int n;
709 
710 		LOG_MSG(LVL_INFO, "INVARIANTS detected");
711 		LOG_MSG(LVL_INFO, "Verifying allocation "
712 		    "table for %s", sc->geom->name);
713 		count = 0;
714 		for (n = 0; n < sc->chunk_count; n++) {
715 			if (sc->map[n].flags || VIRSTOR_MAP_ALLOCATED != 0)
716 				count++;
717 		}
718 		LOG_MSG(LVL_INFO, "Device %s has %d allocated chunks",
719 		    sc->geom->name, count);
720 		n = off = count = 0;
721 		isclean = 1;
722 		if (virstor_valid_components(sc) != sc->n_components) {
723 			/* This is a incomplete virstor device (not all
724 			 * components have been found) */
725 			LOG_MSG(LVL_ERROR, "Device %s is incomplete",
726 			    sc->geom->name);
727 			goto bailout;
728 		}
729 		error = g_access(sc->components[0].gcons, 1, 0, 0);
730 		KASSERT(error == 0, ("%s: g_access failed (%d)", __func__,
731 		    error));
732 		/* Compare the whole on-disk allocation table with what's
733 		 * currently in memory */
734 		while (n < sc->chunk_count) {
735 			buf = g_read_data(sc->components[0].gcons, off,
736 			    sc->sectorsize, &error);
737 			KASSERT(buf != NULL, ("g_read_data returned NULL (%d) "
738 			    "for read at %jd", error, off));
739 			if (bcmp(buf, &sc->map[n], sc->sectorsize) != 0) {
740 				LOG_MSG(LVL_ERROR, "ERROR in allocation table, "
741 				    "entry %d, offset %jd", n, off);
742 				isclean = 0;
743 				count++;
744 			}
745 			n += sc->me_per_sector;
746 			off += sc->sectorsize;
747 			g_free(buf);
748 		}
749 		error = g_access(sc->components[0].gcons, -1, 0, 0);
750 		KASSERT(error == 0, ("%s: g_access failed (%d) on exit",
751 		    __func__, error));
752 		if (isclean != 1) {
753 			LOG_MSG(LVL_ERROR, "ALLOCATION TABLE CORRUPTED FOR %s "
754 			    "(%d sectors don't match, max %zu allocations)",
755 			    sc->geom->name, count,
756 			    count * sc->me_per_sector);
757 		} else {
758 			LOG_MSG(LVL_INFO, "Allocation table ok for %s",
759 			    sc->geom->name);
760 		}
761 bailout:
762 #endif
763 		update_metadata(sc);
764 		virstor_geom_destroy(sc, FALSE, FALSE);
765 		exitval = EAGAIN;
766 	} else
767 		exitval = 0;
768 	return (exitval);
769 }
770 
771 /*
772  * Taste event (per-class callback)
773  * Examines a provider and creates geom instances if needed
774  */
775 static struct g_geom *
776 g_virstor_taste(struct g_class *mp, struct g_provider *pp, int flags)
777 {
778 	struct g_virstor_metadata md;
779 	struct g_geom *gp;
780 	struct g_consumer *cp;
781 	struct g_virstor_softc *sc;
782 	int error;
783 
784 	g_trace(G_T_TOPOLOGY, "%s(%s, %s)", __func__, mp->name, pp->name);
785 	g_topology_assert();
786 	LOG_MSG(LVL_DEBUG, "Tasting %s", pp->name);
787 
788 	/* We need a dummy geom to attach a consumer to the given provider */
789 	gp = g_new_geomf(mp, "virstor:taste.helper");
790 	gp->start = (void *)invalid_call;	/* XXX: hacked up so the        */
791 	gp->access = (void *)invalid_call;	/* compiler doesn't complain.   */
792 	gp->orphan = (void *)invalid_call;	/* I really want these to fail. */
793 
794 	cp = g_new_consumer(gp);
795 	g_attach(cp, pp);
796 	error = read_metadata(cp, &md);
797 	g_detach(cp);
798 	g_destroy_consumer(cp);
799 	g_destroy_geom(gp);
800 
801 	if (error != 0)
802 		return (NULL);
803 
804 	if (strcmp(md.md_magic, G_VIRSTOR_MAGIC) != 0)
805 		return (NULL);
806 	if (md.md_version != G_VIRSTOR_VERSION) {
807 		LOG_MSG(LVL_ERROR, "Kernel module version invalid "
808 		    "to handle %s (%s) : %d should be %d",
809 		    md.md_name, pp->name, md.md_version, G_VIRSTOR_VERSION);
810 		return (NULL);
811 	}
812 	if (md.provsize != pp->mediasize)
813 		return (NULL);
814 
815 	/* If the provider name is hardcoded, use the offered provider only
816 	 * if it's been offered with its proper name (the one used in
817 	 * the label command). */
818 	if (md.provider[0] != '\0' &&
819 	    !g_compare_names(md.provider, pp->name))
820 		return (NULL);
821 
822 	/* Iterate all geoms this class already knows about to see if a new
823 	 * geom instance of this class needs to be created (in case the provider
824 	 * is first from a (possibly) multi-consumer geom) or it just needs
825 	 * to be added to an existing instance. */
826 	sc = NULL;
827 	gp = NULL;
828 	LIST_FOREACH(gp, &mp->geom, geom) {
829 		sc = gp->softc;
830 		if (sc == NULL)
831 			continue;
832 		if (strcmp(md.md_name, sc->geom->name) != 0)
833 			continue;
834 		if (md.md_id != sc->id)
835 			continue;
836 		break;
837 	}
838 	if (gp != NULL) { /* We found an existing geom instance; add to it */
839 		LOG_MSG(LVL_INFO, "Adding %s to %s", pp->name, md.md_name);
840 		error = add_provider_to_geom(sc, pp, &md);
841 		if (error != 0) {
842 			LOG_MSG(LVL_ERROR, "Error adding %s to %s (error %d)",
843 			    pp->name, md.md_name, error);
844 			return (NULL);
845 		}
846 	} else { /* New geom instance needs to be created */
847 		gp = create_virstor_geom(mp, &md);
848 		if (gp == NULL) {
849 			LOG_MSG(LVL_ERROR, "Error creating new instance of "
850 			    "class %s: %s", mp->name, md.md_name);
851 			LOG_MSG(LVL_DEBUG, "Error creating %s at %s",
852 			    md.md_name, pp->name);
853 			return (NULL);
854 		}
855 		sc = gp->softc;
856 		LOG_MSG(LVL_INFO, "Adding %s to %s (first found)", pp->name,
857 		    md.md_name);
858 		error = add_provider_to_geom(sc, pp, &md);
859 		if (error != 0) {
860 			LOG_MSG(LVL_ERROR, "Error adding %s to %s (error %d)",
861 			    pp->name, md.md_name, error);
862 			virstor_geom_destroy(sc, TRUE, FALSE);
863 			return (NULL);
864 		}
865 	}
866 
867 	return (gp);
868 }
869 
870 /*
871  * Destroyes consumer passed to it in arguments. Used as a callback
872  * on g_event queue.
873  */
874 static void
875 delay_destroy_consumer(void *arg, int flags __unused)
876 {
877 	struct g_consumer *c = arg;
878 	KASSERT(c != NULL, ("%s: invalid consumer", __func__));
879 	LOG_MSG(LVL_DEBUG, "Consumer %s destroyed with delay",
880 	    c->provider->name);
881 	g_detach(c);
882 	g_destroy_consumer(c);
883 }
884 
885 /*
886  * Remove a component (consumer) from geom instance; If it's the first
887  * component being removed, orphan the provider to announce geom's being
888  * dismantled
889  */
890 static void
891 remove_component(struct g_virstor_softc *sc, struct g_virstor_component *comp,
892     boolean_t delay)
893 {
894 	struct g_consumer *c;
895 
896 	KASSERT(comp->gcons != NULL, ("Component with no consumer in %s",
897 	    sc->geom->name));
898 	c = comp->gcons;
899 
900 	comp->gcons = NULL;
901 	KASSERT(c->provider != NULL, ("%s: no provider", __func__));
902 	LOG_MSG(LVL_DEBUG, "Component %s removed from %s", c->provider->name,
903 	    sc->geom->name);
904 	if (sc->provider != NULL) {
905 		LOG_MSG(LVL_INFO, "Removing provider %s", sc->provider->name);
906 		g_wither_provider(sc->provider, ENXIO);
907 		sc->provider = NULL;
908 	}
909 
910 	if (c->acr > 0 || c->acw > 0 || c->ace > 0)
911 		g_access(c, -c->acr, -c->acw, -c->ace);
912 	if (delay) {
913 		/* Destroy consumer after it's tasted */
914 		g_post_event(delay_destroy_consumer, c, M_WAITOK, NULL);
915 	} else {
916 		g_detach(c);
917 		g_destroy_consumer(c);
918 	}
919 }
920 
921 /*
922  * Destroy geom - called internally
923  * See g_virstor_destroy_geom for the other one
924  */
925 static int
926 virstor_geom_destroy(struct g_virstor_softc *sc, boolean_t force,
927     boolean_t delay)
928 {
929 	struct g_provider *pp;
930 	struct g_geom *gp;
931 	u_int n;
932 
933 	g_topology_assert();
934 
935 	if (sc == NULL)
936 		return (ENXIO);
937 
938 	pp = sc->provider;
939 	if (pp != NULL && (pp->acr != 0 || pp->acw != 0 || pp->ace != 0)) {
940 		LOG_MSG(force ? LVL_WARNING : LVL_ERROR,
941 		    "Device %s is still open.", pp->name);
942 		if (!force)
943 			return (EBUSY);
944 	}
945 
946 	for (n = 0; n < sc->n_components; n++) {
947 		if (sc->components[n].gcons != NULL)
948 			remove_component(sc, &sc->components[n], delay);
949 	}
950 
951 	gp = sc->geom;
952 	gp->softc = NULL;
953 
954 	KASSERT(sc->provider == NULL, ("Provider still exists for %s",
955 	    gp->name));
956 
957 	/* XXX: This might or might not work, since we're called with
958 	 * the topology lock held. Also, it might panic the kernel if
959 	 * the error'd BIO is in softupdates code. */
960 	mtx_lock(&sc->delayed_bio_q_mtx);
961 	while (!STAILQ_EMPTY(&sc->delayed_bio_q)) {
962 		struct g_virstor_bio_q *bq;
963 		bq = STAILQ_FIRST(&sc->delayed_bio_q);
964 		bq->bio->bio_error = ENOSPC;
965 		g_io_deliver(bq->bio, EIO);
966 		STAILQ_REMOVE_HEAD(&sc->delayed_bio_q, linkage);
967 		free(bq, M_GVIRSTOR);
968 	}
969 	mtx_unlock(&sc->delayed_bio_q_mtx);
970 	mtx_destroy(&sc->delayed_bio_q_mtx);
971 
972 	free(sc->map, M_GVIRSTOR);
973 	free(sc->components, M_GVIRSTOR);
974 	bzero(sc, sizeof *sc);
975 	free(sc, M_GVIRSTOR);
976 
977 	pp = LIST_FIRST(&gp->provider); /* We only offer one provider */
978 	if (pp == NULL || (pp->acr == 0 && pp->acw == 0 && pp->ace == 0))
979 		LOG_MSG(LVL_DEBUG, "Device %s destroyed", gp->name);
980 
981 	g_wither_geom(gp, ENXIO);
982 
983 	return (0);
984 }
985 
986 /*
987  * Utility function: read metadata & decode. Wants topology lock to be
988  * held.
989  */
990 static int
991 read_metadata(struct g_consumer *cp, struct g_virstor_metadata *md)
992 {
993 	struct g_provider *pp;
994 	char *buf;
995 	int error;
996 
997 	g_topology_assert();
998 	error = g_access(cp, 1, 0, 0);
999 	if (error != 0)
1000 		return (error);
1001 	pp = cp->provider;
1002 	g_topology_unlock();
1003 	buf = g_read_data(cp, pp->mediasize - pp->sectorsize, pp->sectorsize,
1004 	    &error);
1005 	g_topology_lock();
1006 	g_access(cp, -1, 0, 0);
1007 	if (buf == NULL)
1008 		return (error);
1009 
1010 	virstor_metadata_decode(buf, md);
1011 	g_free(buf);
1012 
1013 	return (0);
1014 }
1015 
1016 /**
1017  * Utility function: encode & write metadata. Assumes topology lock is
1018  * held.
1019  *
1020  * There is no useful way of recovering from errors in this function,
1021  * not involving panicking the kernel. If the metadata cannot be written
1022  * the most we can do is notify the operator and hope he spots it and
1023  * replaces the broken drive.
1024  */
1025 static void
1026 write_metadata(struct g_consumer *cp, struct g_virstor_metadata *md)
1027 {
1028 	struct g_provider *pp;
1029 	char *buf;
1030 	int error;
1031 
1032 	KASSERT(cp != NULL && md != NULL && cp->provider != NULL,
1033 	    ("Something's fishy in %s", __func__));
1034 	LOG_MSG(LVL_DEBUG, "Writing metadata on %s", cp->provider->name);
1035 	g_topology_assert();
1036 	error = g_access(cp, 0, 1, 0);
1037 	if (error != 0) {
1038 		LOG_MSG(LVL_ERROR, "g_access(0,1,0) failed for %s: %d",
1039 		    cp->provider->name, error);
1040 		return;
1041 	}
1042 	pp = cp->provider;
1043 
1044 	buf = malloc(pp->sectorsize, M_GVIRSTOR, M_WAITOK);
1045 	bzero(buf, pp->sectorsize);
1046 	virstor_metadata_encode(md, buf);
1047 	g_topology_unlock();
1048 	error = g_write_data(cp, pp->mediasize - pp->sectorsize, buf,
1049 	    pp->sectorsize);
1050 	g_topology_lock();
1051 	g_access(cp, 0, -1, 0);
1052 	free(buf, M_GVIRSTOR);
1053 
1054 	if (error != 0)
1055 		LOG_MSG(LVL_ERROR, "Error %d writing metadata to %s",
1056 		    error, cp->provider->name);
1057 }
1058 
1059 /*
1060  * Creates a new instance of this GEOM class, initialise softc
1061  */
1062 static struct g_geom *
1063 create_virstor_geom(struct g_class *mp, struct g_virstor_metadata *md)
1064 {
1065 	struct g_geom *gp;
1066 	struct g_virstor_softc *sc;
1067 
1068 	LOG_MSG(LVL_DEBUG, "Creating geom instance for %s (id=%u)",
1069 	    md->md_name, md->md_id);
1070 
1071 	if (md->md_count < 1 || md->md_chunk_size < 1 ||
1072 	    md->md_virsize < md->md_chunk_size) {
1073 		/* This is bogus configuration, and probably means data is
1074 		 * somehow corrupted. Panic, maybe? */
1075 		LOG_MSG(LVL_ERROR, "Nonsensical metadata information for %s",
1076 		    md->md_name);
1077 		return (NULL);
1078 	}
1079 
1080 	/* Check if it's already created */
1081 	LIST_FOREACH(gp, &mp->geom, geom) {
1082 		sc = gp->softc;
1083 		if (sc != NULL && strcmp(sc->geom->name, md->md_name) == 0) {
1084 			LOG_MSG(LVL_WARNING, "Geom %s already exists",
1085 			    md->md_name);
1086 			if (sc->id != md->md_id) {
1087 				LOG_MSG(LVL_ERROR,
1088 				    "Some stale or invalid components "
1089 				    "exist for virstor device named %s. "
1090 				    "You will need to <CLEAR> all stale "
1091 				    "components and maybe reconfigure "
1092 				    "the virstor device. Tune "
1093 				    "kern.geom.virstor.debug sysctl up "
1094 				    "for more information.",
1095 				    sc->geom->name);
1096 			}
1097 			return (NULL);
1098 		}
1099 	}
1100 	gp = g_new_geomf(mp, "%s", md->md_name);
1101 	gp->softc = NULL; /* to circumevent races that test softc */
1102 
1103 	gp->start = g_virstor_start;
1104 	gp->spoiled = g_virstor_orphan;
1105 	gp->orphan = g_virstor_orphan;
1106 	gp->access = g_virstor_access;
1107 	gp->dumpconf = g_virstor_dumpconf;
1108 
1109 	sc = malloc(sizeof(*sc), M_GVIRSTOR, M_WAITOK | M_ZERO);
1110 	sc->id = md->md_id;
1111 	sc->n_components = md->md_count;
1112 	sc->components = malloc(sizeof(struct g_virstor_component) * md->md_count,
1113 	    M_GVIRSTOR, M_WAITOK | M_ZERO);
1114 	sc->chunk_size = md->md_chunk_size;
1115 	sc->virsize = md->md_virsize;
1116 	STAILQ_INIT(&sc->delayed_bio_q);
1117 	mtx_init(&sc->delayed_bio_q_mtx, "gvirstor_delayed_bio_q_mtx",
1118 	    "gvirstor", MTX_DEF | MTX_RECURSE);
1119 
1120 	sc->geom = gp;
1121 	sc->provider = NULL; /* virstor_check_and_run will create it */
1122 	gp->softc = sc;
1123 
1124 	LOG_MSG(LVL_ANNOUNCE, "Device %s created", sc->geom->name);
1125 
1126 	return (gp);
1127 }
1128 
1129 /*
1130  * Add provider to a GEOM class instance
1131  */
1132 static int
1133 add_provider_to_geom(struct g_virstor_softc *sc, struct g_provider *pp,
1134     struct g_virstor_metadata *md)
1135 {
1136 	struct g_virstor_component *component;
1137 	struct g_consumer *cp, *fcp;
1138 	struct g_geom *gp;
1139 	int error;
1140 
1141 	if (md->no >= sc->n_components)
1142 		return (EINVAL);
1143 
1144 	/* "Current" compontent */
1145 	component = &(sc->components[md->no]);
1146 	if (component->gcons != NULL)
1147 		return (EEXIST);
1148 
1149 	gp = sc->geom;
1150 	fcp = LIST_FIRST(&gp->consumer);
1151 
1152 	cp = g_new_consumer(gp);
1153 	error = g_attach(cp, pp);
1154 
1155 	if (error != 0) {
1156 		g_destroy_consumer(cp);
1157 		return (error);
1158 	}
1159 
1160 	if (fcp != NULL) {
1161 		if (fcp->provider->sectorsize != pp->sectorsize) {
1162 			/* TODO: this can be made to work */
1163 			LOG_MSG(LVL_ERROR, "Provider %s of %s has invalid "
1164 			    "sector size (%d)", pp->name, sc->geom->name,
1165 			    pp->sectorsize);
1166 			return (EINVAL);
1167 		}
1168 		if (fcp->acr > 0 || fcp->acw || fcp->ace > 0) {
1169 			/* Replicate access permissions from first "live" consumer
1170 			 * to the new one */
1171 			error = g_access(cp, fcp->acr, fcp->acw, fcp->ace);
1172 			if (error != 0) {
1173 				g_detach(cp);
1174 				g_destroy_consumer(cp);
1175 				return (error);
1176 			}
1177 		}
1178 	}
1179 
1180 	/* Bring up a new component */
1181 	cp->private = component;
1182 	component->gcons = cp;
1183 	component->sc = sc;
1184 	component->index = md->no;
1185 	component->chunk_count = md->chunk_count;
1186 	component->chunk_next = md->chunk_next;
1187 	component->chunk_reserved = md->chunk_reserved;
1188 	component->flags = md->flags;
1189 
1190 	LOG_MSG(LVL_DEBUG, "%s attached to %s", pp->name, sc->geom->name);
1191 
1192 	virstor_check_and_run(sc);
1193 	return (0);
1194 }
1195 
1196 /*
1197  * Check if everything's ready to create the geom provider & device entry,
1198  * create and start provider.
1199  * Called ultimately by .taste, from g_event thread
1200  */
1201 static void
1202 virstor_check_and_run(struct g_virstor_softc *sc)
1203 {
1204 	off_t off;
1205 	size_t n, count;
1206 	int index;
1207 	int error;
1208 
1209 	if (virstor_valid_components(sc) != sc->n_components)
1210 		return;
1211 
1212 	if (virstor_valid_components(sc) == 0) {
1213 		/* This is actually a candidate for panic() */
1214 		LOG_MSG(LVL_ERROR, "No valid components for %s?",
1215 		    sc->provider->name);
1216 		return;
1217 	}
1218 
1219 	sc->sectorsize = sc->components[0].gcons->provider->sectorsize;
1220 
1221 	/* Initialise allocation map from the first consumer */
1222 	sc->chunk_count = sc->virsize / sc->chunk_size;
1223 	if (sc->chunk_count * (off_t)sc->chunk_size != sc->virsize) {
1224 		LOG_MSG(LVL_WARNING, "Device %s truncated to %ju bytes",
1225 		    sc->provider->name,
1226 		    sc->chunk_count * (off_t)sc->chunk_size);
1227 	}
1228 	sc->map_size = sc->chunk_count * sizeof *(sc->map);
1229 	/* The following allocation is in order of 4MB - 8MB */
1230 	sc->map = malloc(sc->map_size, M_GVIRSTOR, M_WAITOK);
1231 	KASSERT(sc->map != NULL, ("%s: Memory allocation error (%zu bytes) for %s",
1232 	    __func__, sc->map_size, sc->provider->name));
1233 	sc->map_sectors = sc->map_size / sc->sectorsize;
1234 
1235 	count = 0;
1236 	for (n = 0; n < sc->n_components; n++)
1237 		count += sc->components[n].chunk_count;
1238 	LOG_MSG(LVL_INFO, "Device %s has %zu physical chunks and %zu virtual "
1239 	    "(%zu KB chunks)",
1240 	    sc->geom->name, count, sc->chunk_count, sc->chunk_size / 1024);
1241 
1242 	error = g_access(sc->components[0].gcons, 1, 0, 0);
1243 	if (error != 0) {
1244 		LOG_MSG(LVL_ERROR, "Cannot acquire read access for %s to "
1245 		    "read allocation map for %s",
1246 		    sc->components[0].gcons->provider->name,
1247 		    sc->geom->name);
1248 		return;
1249 	}
1250 	/* Read in the allocation map */
1251 	LOG_MSG(LVL_DEBUG, "Reading map for %s from %s", sc->geom->name,
1252 	    sc->components[0].gcons->provider->name);
1253 	off = count = n = 0;
1254 	while (count < sc->map_size) {
1255 		struct g_virstor_map_entry *mapbuf;
1256 		size_t bs;
1257 
1258 		bs = MIN(MAXPHYS, sc->map_size - count);
1259 		if (bs % sc->sectorsize != 0) {
1260 			/* Check for alignment errors */
1261 			bs = rounddown(bs, sc->sectorsize);
1262 			if (bs == 0)
1263 				break;
1264 			LOG_MSG(LVL_ERROR, "Trouble: map is not sector-aligned "
1265 			    "for %s on %s", sc->geom->name,
1266 			    sc->components[0].gcons->provider->name);
1267 		}
1268 		mapbuf = g_read_data(sc->components[0].gcons, off, bs, &error);
1269 		if (mapbuf == NULL) {
1270 			free(sc->map, M_GVIRSTOR);
1271 			LOG_MSG(LVL_ERROR, "Error reading allocation map "
1272 			    "for %s from %s (offset %ju) (error %d)",
1273 			    sc->geom->name,
1274 			    sc->components[0].gcons->provider->name,
1275 			    off, error);
1276 			return;
1277 		}
1278 
1279 		bcopy(mapbuf, &sc->map[n], bs);
1280 		off += bs;
1281 		count += bs;
1282 		n += bs / sizeof *(sc->map);
1283 		g_free(mapbuf);
1284 	}
1285 	g_access(sc->components[0].gcons, -1, 0, 0);
1286 	LOG_MSG(LVL_DEBUG, "Read map for %s", sc->geom->name);
1287 
1288 	/* find first component with allocatable chunks */
1289 	index = -1;
1290 	for (n = 0; n < sc->n_components; n++) {
1291 		if (sc->components[n].chunk_next <
1292 		    sc->components[n].chunk_count) {
1293 			index = n;
1294 			break;
1295 		}
1296 	}
1297 	if (index == -1)
1298 		/* not found? set it to the last component and handle it
1299 		 * later */
1300 		index = sc->n_components - 1;
1301 
1302 	if (index >= sc->n_components - g_virstor_component_watermark - 1) {
1303 		LOG_MSG(LVL_WARNING, "Device %s running out of components "
1304 		    "(%d/%u: %s)", sc->geom->name,
1305 		    index+1,
1306 		    sc->n_components,
1307 		    sc->components[index].gcons->provider->name);
1308 	}
1309 	sc->curr_component = index;
1310 
1311 	if (sc->components[index].chunk_next >=
1312 	    sc->components[index].chunk_count - g_virstor_chunk_watermark) {
1313 		LOG_MSG(LVL_WARNING,
1314 		    "Component %s of %s is running out of free space "
1315 		    "(%u chunks left)",
1316 		    sc->components[index].gcons->provider->name,
1317 		    sc->geom->name, sc->components[index].chunk_count -
1318 		    sc->components[index].chunk_next);
1319 	}
1320 
1321 	sc->me_per_sector = sc->sectorsize / sizeof *(sc->map);
1322 	if (sc->sectorsize % sizeof *(sc->map) != 0) {
1323 		LOG_MSG(LVL_ERROR,
1324 		    "%s: Map entries don't fit exactly in a sector (%s)",
1325 		    __func__, sc->geom->name);
1326 		return;
1327 	}
1328 
1329 	/* Recalculate allocated chunks in components & at the same time
1330 	 * verify map data is sane. We could trust metadata on this, but
1331 	 * we want to make sure. */
1332 	for (n = 0; n < sc->n_components; n++)
1333 		sc->components[n].chunk_next = sc->components[n].chunk_reserved;
1334 
1335 	for (n = 0; n < sc->chunk_count; n++) {
1336 		if (sc->map[n].provider_no >= sc->n_components ||
1337 			sc->map[n].provider_chunk >=
1338 			sc->components[sc->map[n].provider_no].chunk_count) {
1339 			LOG_MSG(LVL_ERROR, "%s: Invalid entry %u in map for %s",
1340 			    __func__, (u_int)n, sc->geom->name);
1341 			LOG_MSG(LVL_ERROR, "%s: provider_no: %u, n_components: %u"
1342 			    " provider_chunk: %u, chunk_count: %u", __func__,
1343 			    sc->map[n].provider_no, sc->n_components,
1344 			    sc->map[n].provider_chunk,
1345 			    sc->components[sc->map[n].provider_no].chunk_count);
1346 			return;
1347 		}
1348 		if (sc->map[n].flags & VIRSTOR_MAP_ALLOCATED)
1349 			sc->components[sc->map[n].provider_no].chunk_next++;
1350 	}
1351 
1352 	sc->provider = g_new_providerf(sc->geom, "virstor/%s",
1353 	    sc->geom->name);
1354 
1355 	sc->provider->sectorsize = sc->sectorsize;
1356 	sc->provider->mediasize = sc->virsize;
1357 	g_error_provider(sc->provider, 0);
1358 
1359 	LOG_MSG(LVL_INFO, "%s activated", sc->provider->name);
1360 	LOG_MSG(LVL_DEBUG, "%s starting with current component %u, starting "
1361 	    "chunk %u", sc->provider->name, sc->curr_component,
1362 	    sc->components[sc->curr_component].chunk_next);
1363 }
1364 
1365 /*
1366  * Returns count of active providers in this geom instance
1367  */
1368 static u_int
1369 virstor_valid_components(struct g_virstor_softc *sc)
1370 {
1371 	unsigned int nc, i;
1372 
1373 	nc = 0;
1374 	KASSERT(sc != NULL, ("%s: softc is NULL", __func__));
1375 	KASSERT(sc->components != NULL, ("%s: sc->components is NULL", __func__));
1376 	for (i = 0; i < sc->n_components; i++)
1377 		if (sc->components[i].gcons != NULL)
1378 			nc++;
1379 	return (nc);
1380 }
1381 
1382 /*
1383  * Called when the consumer gets orphaned (?)
1384  */
1385 static void
1386 g_virstor_orphan(struct g_consumer *cp)
1387 {
1388 	struct g_virstor_softc *sc;
1389 	struct g_virstor_component *comp;
1390 	struct g_geom *gp;
1391 
1392 	g_topology_assert();
1393 	gp = cp->geom;
1394 	sc = gp->softc;
1395 	if (sc == NULL)
1396 		return;
1397 
1398 	comp = cp->private;
1399 	KASSERT(comp != NULL, ("%s: No component in private part of consumer",
1400 	    __func__));
1401 	remove_component(sc, comp, FALSE);
1402 	if (virstor_valid_components(sc) == 0)
1403 		virstor_geom_destroy(sc, TRUE, FALSE);
1404 }
1405 
1406 /*
1407  * Called to notify geom when it's been opened, and for what intent
1408  */
1409 static int
1410 g_virstor_access(struct g_provider *pp, int dr, int dw, int de)
1411 {
1412 	struct g_consumer *c;
1413 	struct g_virstor_softc *sc;
1414 	struct g_geom *gp;
1415 	int error;
1416 
1417 	KASSERT(pp != NULL, ("%s: NULL provider", __func__));
1418 	gp = pp->geom;
1419 	KASSERT(gp != NULL, ("%s: NULL geom", __func__));
1420 	sc = gp->softc;
1421 
1422 	if (sc == NULL) {
1423 		/* It seems that .access can be called with negative dr,dw,dx
1424 		 * in this case but I want to check for myself */
1425 		LOG_MSG(LVL_WARNING, "access(%d, %d, %d) for %s",
1426 		    dr, dw, de, pp->name);
1427 		/* This should only happen when geom is withered so
1428 		 * allow only negative requests */
1429 		KASSERT(dr <= 0 && dw <= 0 && de <= 0,
1430 		    ("%s: Positive access for %s", __func__, pp->name));
1431 		if (pp->acr + dr == 0 && pp->acw + dw == 0 && pp->ace + de == 0)
1432 			LOG_MSG(LVL_DEBUG, "Device %s definitely destroyed",
1433 			    pp->name);
1434 		return (0);
1435 	}
1436 
1437 	/* Grab an exclusive bit to propagate on our consumers on first open */
1438 	if (pp->acr == 0 && pp->acw == 0 && pp->ace == 0)
1439 		de++;
1440 	/* ... drop it on close */
1441 	if (pp->acr + dr == 0 && pp->acw + dw == 0 && pp->ace + de == 0) {
1442 		de--;
1443 		update_metadata(sc);	/* Writes statistical information */
1444 	}
1445 
1446 	error = ENXIO;
1447 	LIST_FOREACH(c, &gp->consumer, consumer) {
1448 		KASSERT(c != NULL, ("%s: consumer is NULL", __func__));
1449 		error = g_access(c, dr, dw, de);
1450 		if (error != 0) {
1451 			struct g_consumer *c2;
1452 
1453 			/* Backout earlier changes */
1454 			LIST_FOREACH(c2, &gp->consumer, consumer) {
1455 				if (c2 == c) /* all eariler components fixed */
1456 					return (error);
1457 				g_access(c2, -dr, -dw, -de);
1458 			}
1459 		}
1460 	}
1461 
1462 	return (error);
1463 }
1464 
1465 /*
1466  * Generate XML dump of current state
1467  */
1468 static void
1469 g_virstor_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp,
1470     struct g_consumer *cp, struct g_provider *pp)
1471 {
1472 	struct g_virstor_softc *sc;
1473 
1474 	g_topology_assert();
1475 	sc = gp->softc;
1476 
1477 	if (sc == NULL || pp != NULL)
1478 		return;
1479 
1480 	if (cp != NULL) {
1481 		/* For each component */
1482 		struct g_virstor_component *comp;
1483 
1484 		comp = cp->private;
1485 		if (comp == NULL)
1486 			return;
1487 		sbuf_printf(sb, "%s<ComponentIndex>%u</ComponentIndex>\n",
1488 		    indent, comp->index);
1489 		sbuf_printf(sb, "%s<ChunkCount>%u</ChunkCount>\n",
1490 		    indent, comp->chunk_count);
1491 		sbuf_printf(sb, "%s<ChunksUsed>%u</ChunksUsed>\n",
1492 		    indent, comp->chunk_next);
1493 		sbuf_printf(sb, "%s<ChunksReserved>%u</ChunksReserved>\n",
1494 		    indent, comp->chunk_reserved);
1495 		sbuf_printf(sb, "%s<StorageFree>%u%%</StorageFree>\n",
1496 		    indent,
1497 		    comp->chunk_next > 0 ? 100 -
1498 		    ((comp->chunk_next + comp->chunk_reserved) * 100) /
1499 		    comp->chunk_count : 100);
1500 	} else {
1501 		/* For the whole thing */
1502 		u_int count, used, i;
1503 		off_t size;
1504 
1505 		count = used = size = 0;
1506 		for (i = 0; i < sc->n_components; i++) {
1507 			if (sc->components[i].gcons != NULL) {
1508 				count += sc->components[i].chunk_count;
1509 				used += sc->components[i].chunk_next +
1510 				    sc->components[i].chunk_reserved;
1511 				size += sc->components[i].gcons->
1512 				    provider->mediasize;
1513 			}
1514 		}
1515 
1516 		sbuf_printf(sb, "%s<Status>"
1517 		    "Components=%u, Online=%u</Status>\n", indent,
1518 		    sc->n_components, virstor_valid_components(sc));
1519 		sbuf_printf(sb, "%s<State>%u%% physical free</State>\n",
1520 		    indent, 100-(used * 100) / count);
1521 		sbuf_printf(sb, "%s<ChunkSize>%zu</ChunkSize>\n", indent,
1522 		    sc->chunk_size);
1523 		sbuf_printf(sb, "%s<PhysicalFree>%u%%</PhysicalFree>\n",
1524 		    indent, used > 0 ? 100 - (used * 100) / count : 100);
1525 		sbuf_printf(sb, "%s<ChunkPhysicalCount>%u</ChunkPhysicalCount>\n",
1526 		    indent, count);
1527 		sbuf_printf(sb, "%s<ChunkVirtualCount>%zu</ChunkVirtualCount>\n",
1528 		    indent, sc->chunk_count);
1529 		sbuf_printf(sb, "%s<PhysicalBacking>%zu%%</PhysicalBacking>\n",
1530 		    indent,
1531 		    (count * 100) / sc->chunk_count);
1532 		sbuf_printf(sb, "%s<PhysicalBackingSize>%jd</PhysicalBackingSize>\n",
1533 		    indent, size);
1534 		sbuf_printf(sb, "%s<VirtualSize>%jd</VirtualSize>\n", indent,
1535 		    sc->virsize);
1536 	}
1537 }
1538 
1539 /*
1540  * GEOM .done handler
1541  * Can't use standard handler because one requested IO may
1542  * fork into additional data IOs
1543  */
1544 static void
1545 g_virstor_done(struct bio *b)
1546 {
1547 	struct g_virstor_softc *sc;
1548 	struct bio *parent_b;
1549 
1550 	parent_b = b->bio_parent;
1551 	sc = parent_b->bio_to->geom->softc;
1552 
1553 	if (b->bio_error != 0) {
1554 		LOG_MSG(LVL_ERROR, "Error %d for offset=%ju, length=%ju, %s",
1555 		    b->bio_error, b->bio_offset, b->bio_length,
1556 		    b->bio_to->name);
1557 		if (parent_b->bio_error == 0)
1558 			parent_b->bio_error = b->bio_error;
1559 	}
1560 
1561 	parent_b->bio_inbed++;
1562 	parent_b->bio_completed += b->bio_completed;
1563 
1564 	if (parent_b->bio_children == parent_b->bio_inbed) {
1565 		parent_b->bio_completed = parent_b->bio_length;
1566 		g_io_deliver(parent_b, parent_b->bio_error);
1567 	}
1568 	g_destroy_bio(b);
1569 }
1570 
1571 /*
1572  * I/O starts here
1573  * Called in g_down thread
1574  */
1575 static void
1576 g_virstor_start(struct bio *b)
1577 {
1578 	struct g_virstor_softc *sc;
1579 	struct g_virstor_component *comp;
1580 	struct bio *cb;
1581 	struct g_provider *pp;
1582 	char *addr;
1583 	off_t offset, length;
1584 	struct bio_queue_head bq;
1585 	size_t chunk_size;	/* cached for convenience */
1586 	u_int count;
1587 
1588 	pp = b->bio_to;
1589 	sc = pp->geom->softc;
1590 	KASSERT(sc != NULL, ("%s: no softc (error=%d, device=%s)", __func__,
1591 	    b->bio_to->error, b->bio_to->name));
1592 
1593 	LOG_REQ(LVL_MOREDEBUG, b, "%s", __func__);
1594 
1595 	switch (b->bio_cmd) {
1596 	case BIO_READ:
1597 	case BIO_WRITE:
1598 	case BIO_DELETE:
1599 		break;
1600 	default:
1601 		g_io_deliver(b, EOPNOTSUPP);
1602 		return;
1603 	}
1604 
1605 	LOG_MSG(LVL_DEBUG2, "BIO arrived, size=%ju", b->bio_length);
1606 	bioq_init(&bq);
1607 
1608 	chunk_size = sc->chunk_size;
1609 	addr = b->bio_data;
1610 	offset = b->bio_offset;	/* virtual offset and length */
1611 	length = b->bio_length;
1612 
1613 	while (length > 0) {
1614 		size_t chunk_index, in_chunk_offset, in_chunk_length;
1615 		struct virstor_map_entry *me;
1616 
1617 		chunk_index = offset / chunk_size; /* round downwards */
1618 		in_chunk_offset = offset % chunk_size;
1619 		in_chunk_length = min(length, chunk_size - in_chunk_offset);
1620 		LOG_MSG(LVL_DEBUG, "Mapped %s(%ju, %ju) to (%zu,%zu,%zu)",
1621 		    b->bio_cmd == BIO_READ ? "R" : "W",
1622 		    offset, length,
1623 		    chunk_index, in_chunk_offset, in_chunk_length);
1624 		me = &sc->map[chunk_index];
1625 
1626 		if (b->bio_cmd == BIO_READ || b->bio_cmd == BIO_DELETE) {
1627 			if ((me->flags & VIRSTOR_MAP_ALLOCATED) == 0) {
1628 				/* Reads from unallocated chunks return zeroed
1629 				 * buffers */
1630 				if (b->bio_cmd == BIO_READ)
1631 					bzero(addr, in_chunk_length);
1632 			} else {
1633 				comp = &sc->components[me->provider_no];
1634 
1635 				cb = g_clone_bio(b);
1636 				if (cb == NULL) {
1637 					bioq_dismantle(&bq);
1638 					if (b->bio_error == 0)
1639 						b->bio_error = ENOMEM;
1640 					g_io_deliver(b, b->bio_error);
1641 					return;
1642 				}
1643 				cb->bio_to = comp->gcons->provider;
1644 				cb->bio_done = g_virstor_done;
1645 				cb->bio_offset =
1646 				    (off_t)me->provider_chunk * (off_t)chunk_size
1647 				    + in_chunk_offset;
1648 				cb->bio_length = in_chunk_length;
1649 				cb->bio_data = addr;
1650 				cb->bio_caller1 = comp;
1651 				bioq_disksort(&bq, cb);
1652 			}
1653 		} else { /* handle BIO_WRITE */
1654 			KASSERT(b->bio_cmd == BIO_WRITE,
1655 			    ("%s: Unknown command %d", __func__,
1656 			    b->bio_cmd));
1657 
1658 			if ((me->flags & VIRSTOR_MAP_ALLOCATED) == 0) {
1659 				/* We have a virtual chunk, represented by
1660 				 * the "me" entry, but it's not yet allocated
1661 				 * (tied to) a physical chunk. So do it now. */
1662 				struct virstor_map_entry *data_me;
1663 				u_int phys_chunk, comp_no;
1664 				off_t s_offset;
1665 				int error;
1666 
1667 				error = allocate_chunk(sc, &comp, &comp_no,
1668 				    &phys_chunk);
1669 				if (error != 0) {
1670 					/* We cannot allocate a physical chunk
1671 					 * to satisfy this request, so we'll
1672 					 * delay it to when we can...
1673 					 * XXX: this will prevent the fs from
1674 					 * being umounted! */
1675 					struct g_virstor_bio_q *biq;
1676 					biq = malloc(sizeof *biq, M_GVIRSTOR,
1677 					    M_NOWAIT);
1678 					if (biq == NULL) {
1679 						bioq_dismantle(&bq);
1680 						if (b->bio_error == 0)
1681 							b->bio_error = ENOMEM;
1682 						g_io_deliver(b, b->bio_error);
1683 						return;
1684 					}
1685 					biq->bio = b;
1686 					mtx_lock(&sc->delayed_bio_q_mtx);
1687 					STAILQ_INSERT_TAIL(&sc->delayed_bio_q,
1688 					    biq, linkage);
1689 					mtx_unlock(&sc->delayed_bio_q_mtx);
1690 					LOG_MSG(LVL_WARNING, "Delaying BIO "
1691 					    "(size=%ju) until free physical "
1692 					    "space can be found on %s",
1693 					    b->bio_length,
1694 					    sc->provider->name);
1695 					return;
1696 				}
1697 				LOG_MSG(LVL_DEBUG, "Allocated chunk %u on %s "
1698 				    "for %s",
1699 				    phys_chunk,
1700 				    comp->gcons->provider->name,
1701 				    sc->provider->name);
1702 
1703 				me->provider_no = comp_no;
1704 				me->provider_chunk = phys_chunk;
1705 				me->flags |= VIRSTOR_MAP_ALLOCATED;
1706 
1707 				cb = g_clone_bio(b);
1708 				if (cb == NULL) {
1709 					me->flags &= ~VIRSTOR_MAP_ALLOCATED;
1710 					me->provider_no = 0;
1711 					me->provider_chunk = 0;
1712 					bioq_dismantle(&bq);
1713 					if (b->bio_error == 0)
1714 						b->bio_error = ENOMEM;
1715 					g_io_deliver(b, b->bio_error);
1716 					return;
1717 				}
1718 
1719 				/* The allocation table is stored continuously
1720 				 * at the start of the drive. We need to
1721 				 * calculate the offset of the sector that holds
1722 				 * this map entry both on the drive and in the
1723 				 * map array.
1724 				 * sc_offset will end up pointing to the drive
1725 				 * sector. */
1726 				s_offset = chunk_index * sizeof *me;
1727 				s_offset = rounddown(s_offset, sc->sectorsize);
1728 
1729 				/* data_me points to map entry sector
1730 				 * in memory (analogous to offset) */
1731 				data_me = &sc->map[rounddown(chunk_index,
1732 				    sc->me_per_sector)];
1733 
1734 				/* Commit sector with map entry to storage */
1735 				cb->bio_to = sc->components[0].gcons->provider;
1736 				cb->bio_done = g_virstor_done;
1737 				cb->bio_offset = s_offset;
1738 				cb->bio_data = (char *)data_me;
1739 				cb->bio_length = sc->sectorsize;
1740 				cb->bio_caller1 = &sc->components[0];
1741 				bioq_disksort(&bq, cb);
1742 			}
1743 
1744 			comp = &sc->components[me->provider_no];
1745 			cb = g_clone_bio(b);
1746 			if (cb == NULL) {
1747 				bioq_dismantle(&bq);
1748 				if (b->bio_error == 0)
1749 					b->bio_error = ENOMEM;
1750 				g_io_deliver(b, b->bio_error);
1751 				return;
1752 			}
1753 			/* Finally, handle the data */
1754 			cb->bio_to = comp->gcons->provider;
1755 			cb->bio_done = g_virstor_done;
1756 			cb->bio_offset = (off_t)me->provider_chunk*(off_t)chunk_size +
1757 			    in_chunk_offset;
1758 			cb->bio_length = in_chunk_length;
1759 			cb->bio_data = addr;
1760 			cb->bio_caller1 = comp;
1761 			bioq_disksort(&bq, cb);
1762 		}
1763 		addr += in_chunk_length;
1764 		length -= in_chunk_length;
1765 		offset += in_chunk_length;
1766 	}
1767 
1768 	/* Fire off bio's here */
1769 	count = 0;
1770 	for (cb = bioq_first(&bq); cb != NULL; cb = bioq_first(&bq)) {
1771 		bioq_remove(&bq, cb);
1772 		LOG_REQ(LVL_MOREDEBUG, cb, "Firing request");
1773 		comp = cb->bio_caller1;
1774 		cb->bio_caller1 = NULL;
1775 		LOG_MSG(LVL_DEBUG, " firing bio, offset=%ju, length=%ju",
1776 		    cb->bio_offset, cb->bio_length);
1777 		g_io_request(cb, comp->gcons);
1778 		count++;
1779 	}
1780 	if (count == 0) { /* We handled everything locally */
1781 		b->bio_completed = b->bio_length;
1782 		g_io_deliver(b, 0);
1783 	}
1784 
1785 }
1786 
1787 /*
1788  * Allocate a chunk from a physical provider. Returns physical component,
1789  * chunk index relative to the component and the component's index.
1790  */
1791 static int
1792 allocate_chunk(struct g_virstor_softc *sc, struct g_virstor_component **comp,
1793     u_int *comp_no_p, u_int *chunk)
1794 {
1795 	u_int comp_no;
1796 
1797 	KASSERT(sc->curr_component < sc->n_components,
1798 	    ("%s: Invalid curr_component: %u",  __func__, sc->curr_component));
1799 
1800 	comp_no = sc->curr_component;
1801 	*comp = &sc->components[comp_no];
1802 	dump_component(*comp);
1803 	if ((*comp)->chunk_next >= (*comp)->chunk_count) {
1804 		/* This component is full. Allocate next component */
1805 		if (comp_no >= sc->n_components-1) {
1806 			LOG_MSG(LVL_ERROR, "All physical space allocated for %s",
1807 			    sc->geom->name);
1808 			return (-1);
1809 		}
1810 		(*comp)->flags &= ~VIRSTOR_PROVIDER_CURRENT;
1811 		sc->curr_component = ++comp_no;
1812 
1813 		*comp = &sc->components[comp_no];
1814 		if (comp_no >= sc->n_components - g_virstor_component_watermark-1)
1815 			LOG_MSG(LVL_WARNING, "Device %s running out of components "
1816 			    "(switching to %u/%u: %s)", sc->geom->name,
1817 			    comp_no+1, sc->n_components,
1818 			    (*comp)->gcons->provider->name);
1819 		/* Take care not to overwrite reserved chunks */
1820 		if ( (*comp)->chunk_reserved > 0 &&
1821 		    (*comp)->chunk_next < (*comp)->chunk_reserved)
1822 			(*comp)->chunk_next = (*comp)->chunk_reserved;
1823 
1824 		(*comp)->flags |=
1825 		    VIRSTOR_PROVIDER_ALLOCATED | VIRSTOR_PROVIDER_CURRENT;
1826 		dump_component(*comp);
1827 		*comp_no_p = comp_no;
1828 		*chunk = (*comp)->chunk_next++;
1829 	} else {
1830 		*comp_no_p = comp_no;
1831 		*chunk = (*comp)->chunk_next++;
1832 	}
1833 	return (0);
1834 }
1835 
1836 /* Dump a component */
1837 static void
1838 dump_component(struct g_virstor_component *comp)
1839 {
1840 
1841 	if (g_virstor_debug < LVL_DEBUG2)
1842 		return;
1843 	printf("Component %d: %s\n", comp->index, comp->gcons->provider->name);
1844 	printf("  chunk_count: %u\n", comp->chunk_count);
1845 	printf("   chunk_next: %u\n", comp->chunk_next);
1846 	printf("        flags: %u\n", comp->flags);
1847 }
1848 
1849 #if 0
1850 /* Dump a map entry */
1851 static void
1852 dump_me(struct virstor_map_entry *me, unsigned int nr)
1853 {
1854 	if (g_virstor_debug < LVL_DEBUG)
1855 		return;
1856 	printf("VIRT. CHUNK #%d: ", nr);
1857 	if ((me->flags & VIRSTOR_MAP_ALLOCATED) == 0)
1858 		printf("(unallocated)\n");
1859 	else
1860 		printf("allocated at provider %u, provider_chunk %u\n",
1861 		    me->provider_no, me->provider_chunk);
1862 }
1863 #endif
1864 
1865 /*
1866  * Dismantle bio_queue and destroy its components
1867  */
1868 static void
1869 bioq_dismantle(struct bio_queue_head *bq)
1870 {
1871 	struct bio *b;
1872 
1873 	for (b = bioq_first(bq); b != NULL; b = bioq_first(bq)) {
1874 		bioq_remove(bq, b);
1875 		g_destroy_bio(b);
1876 	}
1877 }
1878 
1879 /*
1880  * The function that shouldn't be called.
1881  * When this is called, the stack is already garbled because of
1882  * argument mismatch. There's nothing to do now but panic, which is
1883  * accidentally the whole purpose of this function.
1884  * Motivation: to guard from accidentally calling geom methods when
1885  * they shouldn't be called. (see g_..._taste)
1886  */
1887 static void
1888 invalid_call(void)
1889 {
1890 	panic("invalid_call() has just been called. Something's fishy here.");
1891 }
1892 
1893 DECLARE_GEOM_CLASS(g_virstor_class, g_virstor); /* Let there be light */
1894 MODULE_VERSION(geom_virstor, 0);
1895