xref: /freebsd/sys/geom/virstor/g_virstor.c (revision ce6a89e27cd190313be39bb479880aeda4778436)
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 #include <geom/geom_dbg.h>
55 
56 #include <geom/virstor/g_virstor.h>
57 #include <geom/virstor/g_virstor_md.h>
58 
59 FEATURE(g_virstor, "GEOM virtual storage support");
60 
61 /* Declare malloc(9) label */
62 static MALLOC_DEFINE(M_GVIRSTOR, "gvirstor", "GEOM_VIRSTOR Data");
63 
64 /* GEOM class methods */
65 static g_init_t g_virstor_init;
66 static g_fini_t g_virstor_fini;
67 static g_taste_t g_virstor_taste;
68 static g_ctl_req_t g_virstor_config;
69 static g_ctl_destroy_geom_t g_virstor_destroy_geom;
70 
71 /* Declare & initialize class structure ("geom class") */
72 struct g_class g_virstor_class = {
73 	.name =		G_VIRSTOR_CLASS_NAME,
74 	.version =	G_VERSION,
75 	.init =		g_virstor_init,
76 	.fini =		g_virstor_fini,
77 	.taste =	g_virstor_taste,
78 	.ctlreq =	g_virstor_config,
79 	.destroy_geom = g_virstor_destroy_geom
80 	/* The .dumpconf and the rest are only usable for a geom instance, so
81 	 * they will be set when such instance is created. */
82 };
83 
84 /* Declare sysctl's and loader tunables */
85 SYSCTL_DECL(_kern_geom);
86 static SYSCTL_NODE(_kern_geom, OID_AUTO, virstor,
87     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
88     "GEOM_GVIRSTOR information");
89 
90 static u_int g_virstor_debug = 2; /* XXX: lower to 2 when released to public */
91 SYSCTL_UINT(_kern_geom_virstor, OID_AUTO, debug, CTLFLAG_RWTUN, &g_virstor_debug,
92     0, "Debug level (2=production, 5=normal, 15=excessive)");
93 
94 static u_int g_virstor_chunk_watermark = 100;
95 SYSCTL_UINT(_kern_geom_virstor, OID_AUTO, chunk_watermark, CTLFLAG_RWTUN,
96     &g_virstor_chunk_watermark, 0,
97     "Minimum number of free chunks before issuing administrative warning");
98 
99 static u_int g_virstor_component_watermark = 1;
100 SYSCTL_UINT(_kern_geom_virstor, OID_AUTO, component_watermark, CTLFLAG_RWTUN,
101     &g_virstor_component_watermark, 0,
102     "Minimum number of free components before issuing administrative warning");
103 
104 static int read_metadata(struct g_consumer *, struct g_virstor_metadata *);
105 static void write_metadata(struct g_consumer *, struct g_virstor_metadata *);
106 static int clear_metadata(struct g_virstor_component *);
107 static int add_provider_to_geom(struct g_virstor_softc *, struct g_provider *,
108     struct g_virstor_metadata *);
109 static struct g_geom *create_virstor_geom(struct g_class *,
110     struct g_virstor_metadata *);
111 static void virstor_check_and_run(struct g_virstor_softc *);
112 static u_int virstor_valid_components(struct g_virstor_softc *);
113 static int virstor_geom_destroy(struct g_virstor_softc *, boolean_t,
114     boolean_t);
115 static void remove_component(struct g_virstor_softc *,
116     struct g_virstor_component *, boolean_t);
117 static void bioq_dismantle(struct bio_queue_head *);
118 static int allocate_chunk(struct g_virstor_softc *,
119     struct g_virstor_component **, u_int *, u_int *);
120 static void delay_destroy_consumer(void *, int);
121 static void dump_component(struct g_virstor_component *comp);
122 #if 0
123 static void dump_me(struct virstor_map_entry *me, unsigned int nr);
124 #endif
125 
126 static void virstor_ctl_stop(struct gctl_req *, struct g_class *);
127 static void virstor_ctl_add(struct gctl_req *, struct g_class *);
128 static void virstor_ctl_remove(struct gctl_req *, struct g_class *);
129 static struct g_virstor_softc * virstor_find_geom(const struct g_class *,
130     const char *);
131 static void update_metadata(struct g_virstor_softc *);
132 static void fill_metadata(struct g_virstor_softc *, struct g_virstor_metadata *,
133     u_int, u_int);
134 
135 static void g_virstor_orphan(struct g_consumer *);
136 static int g_virstor_access(struct g_provider *, int, int, int);
137 static void g_virstor_start(struct bio *);
138 static void g_virstor_dumpconf(struct sbuf *, const char *, struct g_geom *,
139     struct g_consumer *, struct g_provider *);
140 static void g_virstor_done(struct bio *);
141 
142 static void invalid_call(void);
143 /*
144  * Initialise GEOM class (per-class callback)
145  */
146 static void
147 g_virstor_init(struct g_class *mp __unused)
148 {
149 
150 	/* Catch map struct size mismatch at compile time; Map entries must
151 	 * fit into MAXPHYS exactly, with no wasted space. */
152 	CTASSERT(VIRSTOR_MAP_BLOCK_ENTRIES*VIRSTOR_MAP_ENTRY_SIZE == MAXPHYS);
153 
154 	/* Init UMA zones, TAILQ's, other global vars */
155 }
156 
157 /*
158  * Finalise GEOM class (per-class callback)
159  */
160 static void
161 g_virstor_fini(struct g_class *mp __unused)
162 {
163 
164 	/* Deinit UMA zones & global vars */
165 }
166 
167 /*
168  * Config (per-class callback)
169  */
170 static void
171 g_virstor_config(struct gctl_req *req, struct g_class *cp, char const *verb)
172 {
173 	uint32_t *version;
174 
175 	g_topology_assert();
176 
177 	version = gctl_get_paraml(req, "version", sizeof(*version));
178 	if (version == NULL) {
179 		gctl_error(req, "Failed to get 'version' argument");
180 		return;
181 	}
182 	if (*version != G_VIRSTOR_VERSION) {
183 		gctl_error(req, "Userland and kernel versions out of sync");
184 		return;
185 	}
186 
187 	g_topology_unlock();
188 	if (strcmp(verb, "add") == 0)
189 		virstor_ctl_add(req, cp);
190 	else if (strcmp(verb, "stop") == 0 || strcmp(verb, "destroy") == 0)
191 		virstor_ctl_stop(req, cp);
192 	else if (strcmp(verb, "remove") == 0)
193 		virstor_ctl_remove(req, cp);
194 	else
195 		gctl_error(req, "unknown verb: '%s'", verb);
196 	g_topology_lock();
197 }
198 
199 /*
200  * "stop" verb from userland
201  */
202 static void
203 virstor_ctl_stop(struct gctl_req *req, struct g_class *cp)
204 {
205 	int *force, *nargs;
206 	int i;
207 
208 	nargs = gctl_get_paraml(req, "nargs", sizeof *nargs);
209 	if (nargs == NULL) {
210 		gctl_error(req, "Error fetching argument '%s'", "nargs");
211 		return;
212 	}
213 	if (*nargs < 1) {
214 		gctl_error(req, "Invalid number of arguments");
215 		return;
216 	}
217 	force = gctl_get_paraml(req, "force", sizeof *force);
218 	if (force == NULL) {
219 		gctl_error(req, "Error fetching argument '%s'", "force");
220 		return;
221 	}
222 
223 	g_topology_lock();
224 	for (i = 0; i < *nargs; i++) {
225 		char param[8];
226 		const char *name;
227 		struct g_virstor_softc *sc;
228 		int error;
229 
230 		sprintf(param, "arg%d", i);
231 		name = gctl_get_asciiparam(req, param);
232 		if (name == NULL) {
233 			gctl_error(req, "No 'arg%d' argument", i);
234 			g_topology_unlock();
235 			return;
236 		}
237 		sc = virstor_find_geom(cp, name);
238 		if (sc == NULL) {
239 			gctl_error(req, "Don't know anything about '%s'", name);
240 			g_topology_unlock();
241 			return;
242 		}
243 
244 		LOG_MSG(LVL_INFO, "Stopping %s by the userland command",
245 		    sc->geom->name);
246 		update_metadata(sc);
247 		if ((error = virstor_geom_destroy(sc, TRUE, TRUE)) != 0) {
248 			LOG_MSG(LVL_ERROR, "Cannot destroy %s: %d",
249 			    sc->geom->name, error);
250 		}
251 	}
252 	g_topology_unlock();
253 }
254 
255 /*
256  * "add" verb from userland - add new component(s) to the structure.
257  * This will be done all at once in here, without going through the
258  * .taste function for new components.
259  */
260 static void
261 virstor_ctl_add(struct gctl_req *req, struct g_class *cp)
262 {
263 	/* Note: while this is going on, I/O is being done on
264 	 * the g_up and g_down threads. The idea is to make changes
265 	 * to softc members in a way that can atomically activate
266 	 * them all at once. */
267 	struct g_virstor_softc *sc;
268 	int *hardcode, *nargs;
269 	const char *geom_name;	/* geom to add a component to */
270 	struct g_consumer *fcp;
271 	struct g_virstor_bio_q *bq;
272 	u_int added;
273 	int error;
274 	int i;
275 
276 	nargs = gctl_get_paraml(req, "nargs", sizeof(*nargs));
277 	if (nargs == NULL) {
278 		gctl_error(req, "Error fetching argument '%s'", "nargs");
279 		return;
280 	}
281 	if (*nargs < 2) {
282 		gctl_error(req, "Invalid number of arguments");
283 		return;
284 	}
285 	hardcode = gctl_get_paraml(req, "hardcode", sizeof(*hardcode));
286 	if (hardcode == NULL) {
287 		gctl_error(req, "Error fetching argument '%s'", "hardcode");
288 		return;
289 	}
290 
291 	/* Find "our" geom */
292 	geom_name = gctl_get_asciiparam(req, "arg0");
293 	if (geom_name == NULL) {
294 		gctl_error(req, "Error fetching argument '%s'", "geom_name (arg0)");
295 		return;
296 	}
297 	sc = virstor_find_geom(cp, geom_name);
298 	if (sc == NULL) {
299 		gctl_error(req, "Don't know anything about '%s'", geom_name);
300 		return;
301 	}
302 
303 	if (virstor_valid_components(sc) != sc->n_components) {
304 		LOG_MSG(LVL_ERROR, "Cannot add components to incomplete "
305 		    "virstor %s", sc->geom->name);
306 		gctl_error(req, "Virstor %s is incomplete", sc->geom->name);
307 		return;
308 	}
309 
310 	fcp = sc->components[0].gcons;
311 	added = 0;
312 	g_topology_lock();
313 	for (i = 1; i < *nargs; i++) {
314 		struct g_virstor_metadata md;
315 		char aname[8];
316 		const char *prov_name;
317 		struct g_provider *pp;
318 		struct g_consumer *cp;
319 		u_int nc;
320 		u_int j;
321 
322 		snprintf(aname, sizeof aname, "arg%d", i);
323 		prov_name = gctl_get_asciiparam(req, aname);
324 		if (prov_name == NULL) {
325 			gctl_error(req, "Error fetching argument '%s'", aname);
326 			g_topology_unlock();
327 			return;
328 		}
329 		if (strncmp(prov_name, _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0)
330 			prov_name += sizeof(_PATH_DEV) - 1;
331 
332 		pp = g_provider_by_name(prov_name);
333 		if (pp == NULL) {
334 			/* This is the most common error so be verbose about it */
335 			if (added != 0) {
336 				gctl_error(req, "Invalid provider: '%s' (added"
337 				    " %u components)", prov_name, added);
338 				update_metadata(sc);
339 			} else {
340 				gctl_error(req, "Invalid provider: '%s'",
341 				    prov_name);
342 			}
343 			g_topology_unlock();
344 			return;
345 		}
346 		cp = g_new_consumer(sc->geom);
347 		if (cp == NULL) {
348 			gctl_error(req, "Cannot create consumer");
349 			g_topology_unlock();
350 			return;
351 		}
352 		error = g_attach(cp, pp);
353 		if (error != 0) {
354 			gctl_error(req, "Cannot attach a consumer to %s",
355 			    pp->name);
356 			g_destroy_consumer(cp);
357 			g_topology_unlock();
358 			return;
359 		}
360 		if (fcp->acr != 0 || fcp->acw != 0 || fcp->ace != 0) {
361 			error = g_access(cp, fcp->acr, fcp->acw, fcp->ace);
362 			if (error != 0) {
363 				gctl_error(req, "Access request failed for %s",
364 				    pp->name);
365 				g_destroy_consumer(cp);
366 				g_topology_unlock();
367 				return;
368 			}
369 		}
370 		if (fcp->provider->sectorsize != pp->sectorsize) {
371 			gctl_error(req, "Sector size doesn't fit for %s",
372 			    pp->name);
373 			g_destroy_consumer(cp);
374 			g_topology_unlock();
375 			return;
376 		}
377 		for (j = 0; j < sc->n_components; j++) {
378 			if (strcmp(sc->components[j].gcons->provider->name,
379 			    pp->name) == 0) {
380 				gctl_error(req, "Component %s already in %s",
381 				    pp->name, sc->geom->name);
382 				g_destroy_consumer(cp);
383 				g_topology_unlock();
384 				return;
385 			}
386 		}
387 		sc->components = realloc(sc->components,
388 		    sizeof(*sc->components) * (sc->n_components + 1),
389 		    M_GVIRSTOR, M_WAITOK);
390 
391 		nc = sc->n_components;
392 		sc->components[nc].gcons = cp;
393 		sc->components[nc].sc = sc;
394 		sc->components[nc].index = nc;
395 		sc->components[nc].chunk_count = cp->provider->mediasize /
396 		    sc->chunk_size;
397 		sc->components[nc].chunk_next = 0;
398 		sc->components[nc].chunk_reserved = 0;
399 
400 		if (sc->components[nc].chunk_count < 4) {
401 			gctl_error(req, "Provider too small: %s",
402 			    cp->provider->name);
403 			g_destroy_consumer(cp);
404 			g_topology_unlock();
405 			return;
406 		}
407 		fill_metadata(sc, &md, nc, *hardcode);
408 		write_metadata(cp, &md);
409 		/* The new component becomes visible when n_components is
410 		 * incremented */
411 		sc->n_components++;
412 		added++;
413 
414 	}
415 	/* This call to update_metadata() is critical. In case there's a
416 	 * power failure in the middle of it and some components are updated
417 	 * while others are not, there will be trouble on next .taste() iff
418 	 * a non-updated component is detected first */
419 	update_metadata(sc);
420 	g_topology_unlock();
421 	LOG_MSG(LVL_INFO, "Added %d component(s) to %s", added,
422 	    sc->geom->name);
423 	/* Fire off BIOs previously queued because there wasn't any
424 	 * physical space left. If the BIOs still can't be satisfied
425 	 * they will again be added to the end of the queue (during
426 	 * which the mutex will be recursed) */
427 	bq = malloc(sizeof(*bq), M_GVIRSTOR, M_WAITOK);
428 	bq->bio = NULL;
429 	mtx_lock(&sc->delayed_bio_q_mtx);
430 	/* First, insert a sentinel to the queue end, so we don't
431 	 * end up in an infinite loop if there's still no free
432 	 * space available. */
433 	STAILQ_INSERT_TAIL(&sc->delayed_bio_q, bq, linkage);
434 	while (!STAILQ_EMPTY(&sc->delayed_bio_q)) {
435 		bq = STAILQ_FIRST(&sc->delayed_bio_q);
436 		if (bq->bio != NULL) {
437 			g_virstor_start(bq->bio);
438 			STAILQ_REMOVE_HEAD(&sc->delayed_bio_q, linkage);
439 			free(bq, M_GVIRSTOR);
440 		} else {
441 			STAILQ_REMOVE_HEAD(&sc->delayed_bio_q, linkage);
442 			free(bq, M_GVIRSTOR);
443 			break;
444 		}
445 	}
446 	mtx_unlock(&sc->delayed_bio_q_mtx);
447 
448 }
449 
450 /*
451  * Find a geom handled by the class
452  */
453 static struct g_virstor_softc *
454 virstor_find_geom(const struct g_class *cp, const char *name)
455 {
456 	struct g_geom *gp;
457 
458 	LIST_FOREACH(gp, &cp->geom, geom) {
459 		if (strcmp(name, gp->name) == 0)
460 			return (gp->softc);
461 	}
462 	return (NULL);
463 }
464 
465 /*
466  * Update metadata on all components to reflect the current state
467  * of these fields:
468  *    - chunk_next
469  *    - flags
470  *    - md_count
471  * Expects things to be set up so write_metadata() can work, i.e.
472  * the topology lock must be held.
473  */
474 static void
475 update_metadata(struct g_virstor_softc *sc)
476 {
477 	struct g_virstor_metadata md;
478 	u_int n;
479 
480 	if (virstor_valid_components(sc) != sc->n_components)
481 		return; /* Incomplete device */
482 	LOG_MSG(LVL_DEBUG, "Updating metadata on components for %s",
483 	    sc->geom->name);
484 	/* Update metadata on components */
485 	g_trace(G_T_TOPOLOGY, "%s(%s, %s)", __func__,
486 	    sc->geom->class->name, sc->geom->name);
487 	g_topology_assert();
488 	for (n = 0; n < sc->n_components; n++) {
489 		read_metadata(sc->components[n].gcons, &md);
490 		md.chunk_next = sc->components[n].chunk_next;
491 		md.flags = sc->components[n].flags;
492 		md.md_count = sc->n_components;
493 		write_metadata(sc->components[n].gcons, &md);
494 	}
495 }
496 
497 /*
498  * Fills metadata (struct md) from information stored in softc and the nc'th
499  * component of virstor
500  */
501 static void
502 fill_metadata(struct g_virstor_softc *sc, struct g_virstor_metadata *md,
503     u_int nc, u_int hardcode)
504 {
505 	struct g_virstor_component *c;
506 
507 	bzero(md, sizeof *md);
508 	c = &sc->components[nc];
509 
510 	strncpy(md->md_magic, G_VIRSTOR_MAGIC, sizeof md->md_magic);
511 	md->md_version = G_VIRSTOR_VERSION;
512 	strncpy(md->md_name, sc->geom->name, sizeof md->md_name);
513 	md->md_id = sc->id;
514 	md->md_virsize = sc->virsize;
515 	md->md_chunk_size = sc->chunk_size;
516 	md->md_count = sc->n_components;
517 
518 	if (hardcode) {
519 		strncpy(md->provider, c->gcons->provider->name,
520 		    sizeof md->provider);
521 	}
522 	md->no = nc;
523 	md->provsize = c->gcons->provider->mediasize;
524 	md->chunk_count = c->chunk_count;
525 	md->chunk_next = c->chunk_next;
526 	md->chunk_reserved = c->chunk_reserved;
527 	md->flags = c->flags;
528 }
529 
530 /*
531  * Remove a component from virstor device.
532  * Can only be done if the component is unallocated.
533  */
534 static void
535 virstor_ctl_remove(struct gctl_req *req, struct g_class *cp)
536 {
537 	/* As this is executed in parallel to I/O, operations on virstor
538 	 * structures must be as atomic as possible. */
539 	struct g_virstor_softc *sc;
540 	int *nargs;
541 	const char *geom_name;
542 	u_int removed;
543 	int i;
544 
545 	nargs = gctl_get_paraml(req, "nargs", sizeof(*nargs));
546 	if (nargs == NULL) {
547 		gctl_error(req, "Error fetching argument '%s'", "nargs");
548 		return;
549 	}
550 	if (*nargs < 2) {
551 		gctl_error(req, "Invalid number of arguments");
552 		return;
553 	}
554 	/* Find "our" geom */
555 	geom_name = gctl_get_asciiparam(req, "arg0");
556 	if (geom_name == NULL) {
557 		gctl_error(req, "Error fetching argument '%s'",
558 		    "geom_name (arg0)");
559 		return;
560 	}
561 	sc = virstor_find_geom(cp, geom_name);
562 	if (sc == NULL) {
563 		gctl_error(req, "Don't know anything about '%s'", geom_name);
564 		return;
565 	}
566 
567 	if (virstor_valid_components(sc) != sc->n_components) {
568 		LOG_MSG(LVL_ERROR, "Cannot remove components from incomplete "
569 		    "virstor %s", sc->geom->name);
570 		gctl_error(req, "Virstor %s is incomplete", sc->geom->name);
571 		return;
572 	}
573 
574 	removed = 0;
575 	for (i = 1; i < *nargs; i++) {
576 		char param[8];
577 		const char *prov_name;
578 		int j, found;
579 		struct g_virstor_component *newcomp, *compbak;
580 
581 		sprintf(param, "arg%d", i);
582 		prov_name = gctl_get_asciiparam(req, param);
583 		if (prov_name == NULL) {
584 			gctl_error(req, "Error fetching argument '%s'", param);
585 			return;
586 		}
587 		if (strncmp(prov_name, _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0)
588 			prov_name += sizeof(_PATH_DEV) - 1;
589 
590 		found = -1;
591 		for (j = 0; j < sc->n_components; j++) {
592 			if (strcmp(sc->components[j].gcons->provider->name,
593 			    prov_name) == 0) {
594 				found = j;
595 				break;
596 			}
597 		}
598 		if (found == -1) {
599 			LOG_MSG(LVL_ERROR, "No %s component in %s",
600 			    prov_name, sc->geom->name);
601 			continue;
602 		}
603 
604 		compbak = sc->components;
605 		newcomp = malloc(sc->n_components * sizeof(*sc->components),
606 		    M_GVIRSTOR, M_WAITOK | M_ZERO);
607 		bcopy(sc->components, newcomp, found * sizeof(*sc->components));
608 		bcopy(&sc->components[found + 1], newcomp + found,
609 		    found * sizeof(*sc->components));
610 		if ((sc->components[j].flags & VIRSTOR_PROVIDER_ALLOCATED) != 0) {
611 			LOG_MSG(LVL_ERROR, "Allocated provider %s cannot be "
612 			    "removed from %s",
613 			    prov_name, sc->geom->name);
614 			free(newcomp, M_GVIRSTOR);
615 			/* We'll consider this non-fatal error */
616 			continue;
617 		}
618 		/* Renumerate unallocated components */
619 		for (j = 0; j < sc->n_components-1; j++) {
620 			if ((sc->components[j].flags &
621 			    VIRSTOR_PROVIDER_ALLOCATED) == 0) {
622 				sc->components[j].index = j;
623 			}
624 		}
625 		/* This is the critical section. If a component allocation
626 		 * event happens while both variables are not yet set,
627 		 * there will be trouble. Something will panic on encountering
628 		 * NULL sc->components[x].gcomp member.
629 		 * Luckily, component allocation happens very rarely and
630 		 * removing components is an abnormal action in any case. */
631 		sc->components = newcomp;
632 		sc->n_components--;
633 		/* End critical section */
634 
635 		g_topology_lock();
636 		if (clear_metadata(&compbak[found]) != 0) {
637 			LOG_MSG(LVL_WARNING, "Trouble ahead: cannot clear "
638 			    "metadata on %s", prov_name);
639 		}
640 		g_detach(compbak[found].gcons);
641 		g_destroy_consumer(compbak[found].gcons);
642 		g_topology_unlock();
643 
644 		free(compbak, M_GVIRSTOR);
645 
646 		removed++;
647 	}
648 
649 	/* This call to update_metadata() is critical. In case there's a
650 	 * power failure in the middle of it and some components are updated
651 	 * while others are not, there will be trouble on next .taste() iff
652 	 * a non-updated component is detected first */
653 	g_topology_lock();
654 	update_metadata(sc);
655 	g_topology_unlock();
656 	LOG_MSG(LVL_INFO, "Removed %d component(s) from %s", removed,
657 	    sc->geom->name);
658 }
659 
660 /*
661  * Clear metadata sector on component
662  */
663 static int
664 clear_metadata(struct g_virstor_component *comp)
665 {
666 	char *buf;
667 	int error;
668 
669 	LOG_MSG(LVL_INFO, "Clearing metadata on %s",
670 	    comp->gcons->provider->name);
671 	g_topology_assert();
672 	error = g_access(comp->gcons, 0, 1, 0);
673 	if (error != 0)
674 		return (error);
675 	buf = malloc(comp->gcons->provider->sectorsize, M_GVIRSTOR,
676 	    M_WAITOK | M_ZERO);
677 	error = g_write_data(comp->gcons,
678 	    comp->gcons->provider->mediasize -
679 	    comp->gcons->provider->sectorsize,
680 	    buf,
681 	    comp->gcons->provider->sectorsize);
682 	free(buf, M_GVIRSTOR);
683 	g_access(comp->gcons, 0, -1, 0);
684 	return (error);
685 }
686 
687 /*
688  * Destroy geom forcibly.
689  */
690 static int
691 g_virstor_destroy_geom(struct gctl_req *req __unused, struct g_class *mp,
692     struct g_geom *gp)
693 {
694 	struct g_virstor_softc *sc;
695 	int exitval;
696 
697 	sc = gp->softc;
698 	KASSERT(sc != NULL, ("%s: NULL sc", __func__));
699 
700 	exitval = 0;
701 	LOG_MSG(LVL_DEBUG, "%s called for %s, sc=%p", __func__, gp->name,
702 	    gp->softc);
703 
704 	if (sc != NULL) {
705 #ifdef INVARIANTS
706 		char *buf;
707 		int error;
708 		off_t off;
709 		int isclean, count;
710 		int n;
711 
712 		LOG_MSG(LVL_INFO, "INVARIANTS detected");
713 		LOG_MSG(LVL_INFO, "Verifying allocation "
714 		    "table for %s", sc->geom->name);
715 		count = 0;
716 		for (n = 0; n < sc->chunk_count; n++) {
717 			if (sc->map[n].flags || VIRSTOR_MAP_ALLOCATED != 0)
718 				count++;
719 		}
720 		LOG_MSG(LVL_INFO, "Device %s has %d allocated chunks",
721 		    sc->geom->name, count);
722 		n = off = count = 0;
723 		isclean = 1;
724 		if (virstor_valid_components(sc) != sc->n_components) {
725 			/* This is a incomplete virstor device (not all
726 			 * components have been found) */
727 			LOG_MSG(LVL_ERROR, "Device %s is incomplete",
728 			    sc->geom->name);
729 			goto bailout;
730 		}
731 		error = g_access(sc->components[0].gcons, 1, 0, 0);
732 		KASSERT(error == 0, ("%s: g_access failed (%d)", __func__,
733 		    error));
734 		/* Compare the whole on-disk allocation table with what's
735 		 * currently in memory */
736 		while (n < sc->chunk_count) {
737 			buf = g_read_data(sc->components[0].gcons, off,
738 			    sc->sectorsize, &error);
739 			KASSERT(buf != NULL, ("g_read_data returned NULL (%d) "
740 			    "for read at %jd", error, off));
741 			if (bcmp(buf, &sc->map[n], sc->sectorsize) != 0) {
742 				LOG_MSG(LVL_ERROR, "ERROR in allocation table, "
743 				    "entry %d, offset %jd", n, off);
744 				isclean = 0;
745 				count++;
746 			}
747 			n += sc->me_per_sector;
748 			off += sc->sectorsize;
749 			g_free(buf);
750 		}
751 		error = g_access(sc->components[0].gcons, -1, 0, 0);
752 		KASSERT(error == 0, ("%s: g_access failed (%d) on exit",
753 		    __func__, error));
754 		if (isclean != 1) {
755 			LOG_MSG(LVL_ERROR, "ALLOCATION TABLE CORRUPTED FOR %s "
756 			    "(%d sectors don't match, max %zu allocations)",
757 			    sc->geom->name, count,
758 			    count * sc->me_per_sector);
759 		} else {
760 			LOG_MSG(LVL_INFO, "Allocation table ok for %s",
761 			    sc->geom->name);
762 		}
763 bailout:
764 #endif
765 		update_metadata(sc);
766 		virstor_geom_destroy(sc, FALSE, FALSE);
767 		exitval = EAGAIN;
768 	} else
769 		exitval = 0;
770 	return (exitval);
771 }
772 
773 /*
774  * Taste event (per-class callback)
775  * Examines a provider and creates geom instances if needed
776  */
777 static struct g_geom *
778 g_virstor_taste(struct g_class *mp, struct g_provider *pp, int flags)
779 {
780 	struct g_virstor_metadata md;
781 	struct g_geom *gp;
782 	struct g_consumer *cp;
783 	struct g_virstor_softc *sc;
784 	int error;
785 
786 	g_trace(G_T_TOPOLOGY, "%s(%s, %s)", __func__, mp->name, pp->name);
787 	g_topology_assert();
788 	LOG_MSG(LVL_DEBUG, "Tasting %s", pp->name);
789 
790 	/* We need a dummy geom to attach a consumer to the given provider */
791 	gp = g_new_geomf(mp, "virstor:taste.helper");
792 	gp->start = (void *)invalid_call;	/* XXX: hacked up so the        */
793 	gp->access = (void *)invalid_call;	/* compiler doesn't complain.   */
794 	gp->orphan = (void *)invalid_call;	/* I really want these to fail. */
795 
796 	cp = g_new_consumer(gp);
797 	g_attach(cp, pp);
798 	error = read_metadata(cp, &md);
799 	g_detach(cp);
800 	g_destroy_consumer(cp);
801 	g_destroy_geom(gp);
802 
803 	if (error != 0)
804 		return (NULL);
805 
806 	if (strcmp(md.md_magic, G_VIRSTOR_MAGIC) != 0)
807 		return (NULL);
808 	if (md.md_version != G_VIRSTOR_VERSION) {
809 		LOG_MSG(LVL_ERROR, "Kernel module version invalid "
810 		    "to handle %s (%s) : %d should be %d",
811 		    md.md_name, pp->name, md.md_version, G_VIRSTOR_VERSION);
812 		return (NULL);
813 	}
814 	if (md.provsize != pp->mediasize)
815 		return (NULL);
816 
817 	/* If the provider name is hardcoded, use the offered provider only
818 	 * if it's been offered with its proper name (the one used in
819 	 * the label command). */
820 	if (md.provider[0] != '\0' &&
821 	    !g_compare_names(md.provider, pp->name))
822 		return (NULL);
823 
824 	/* Iterate all geoms this class already knows about to see if a new
825 	 * geom instance of this class needs to be created (in case the provider
826 	 * is first from a (possibly) multi-consumer geom) or it just needs
827 	 * to be added to an existing instance. */
828 	sc = NULL;
829 	gp = NULL;
830 	LIST_FOREACH(gp, &mp->geom, geom) {
831 		sc = gp->softc;
832 		if (sc == NULL)
833 			continue;
834 		if (strcmp(md.md_name, sc->geom->name) != 0)
835 			continue;
836 		if (md.md_id != sc->id)
837 			continue;
838 		break;
839 	}
840 	if (gp != NULL) { /* We found an existing geom instance; add to it */
841 		LOG_MSG(LVL_INFO, "Adding %s to %s", pp->name, md.md_name);
842 		error = add_provider_to_geom(sc, pp, &md);
843 		if (error != 0) {
844 			LOG_MSG(LVL_ERROR, "Error adding %s to %s (error %d)",
845 			    pp->name, md.md_name, error);
846 			return (NULL);
847 		}
848 	} else { /* New geom instance needs to be created */
849 		gp = create_virstor_geom(mp, &md);
850 		if (gp == NULL) {
851 			LOG_MSG(LVL_ERROR, "Error creating new instance of "
852 			    "class %s: %s", mp->name, md.md_name);
853 			LOG_MSG(LVL_DEBUG, "Error creating %s at %s",
854 			    md.md_name, pp->name);
855 			return (NULL);
856 		}
857 		sc = gp->softc;
858 		LOG_MSG(LVL_INFO, "Adding %s to %s (first found)", pp->name,
859 		    md.md_name);
860 		error = add_provider_to_geom(sc, pp, &md);
861 		if (error != 0) {
862 			LOG_MSG(LVL_ERROR, "Error adding %s to %s (error %d)",
863 			    pp->name, md.md_name, error);
864 			virstor_geom_destroy(sc, TRUE, FALSE);
865 			return (NULL);
866 		}
867 	}
868 
869 	return (gp);
870 }
871 
872 /*
873  * Destroyes consumer passed to it in arguments. Used as a callback
874  * on g_event queue.
875  */
876 static void
877 delay_destroy_consumer(void *arg, int flags __unused)
878 {
879 	struct g_consumer *c = arg;
880 	KASSERT(c != NULL, ("%s: invalid consumer", __func__));
881 	LOG_MSG(LVL_DEBUG, "Consumer %s destroyed with delay",
882 	    c->provider->name);
883 	g_detach(c);
884 	g_destroy_consumer(c);
885 }
886 
887 /*
888  * Remove a component (consumer) from geom instance; If it's the first
889  * component being removed, orphan the provider to announce geom's being
890  * dismantled
891  */
892 static void
893 remove_component(struct g_virstor_softc *sc, struct g_virstor_component *comp,
894     boolean_t delay)
895 {
896 	struct g_consumer *c;
897 
898 	KASSERT(comp->gcons != NULL, ("Component with no consumer in %s",
899 	    sc->geom->name));
900 	c = comp->gcons;
901 
902 	comp->gcons = NULL;
903 	KASSERT(c->provider != NULL, ("%s: no provider", __func__));
904 	LOG_MSG(LVL_DEBUG, "Component %s removed from %s", c->provider->name,
905 	    sc->geom->name);
906 	if (sc->provider != NULL) {
907 		LOG_MSG(LVL_INFO, "Removing provider %s", sc->provider->name);
908 		g_wither_provider(sc->provider, ENXIO);
909 		sc->provider = NULL;
910 	}
911 
912 	if (c->acr > 0 || c->acw > 0 || c->ace > 0)
913 		return;
914 	if (delay) {
915 		/* Destroy consumer after it's tasted */
916 		g_post_event(delay_destroy_consumer, c, M_WAITOK, NULL);
917 	} else {
918 		g_detach(c);
919 		g_destroy_consumer(c);
920 	}
921 }
922 
923 /*
924  * Destroy geom - called internally
925  * See g_virstor_destroy_geom for the other one
926  */
927 static int
928 virstor_geom_destroy(struct g_virstor_softc *sc, boolean_t force,
929     boolean_t delay)
930 {
931 	struct g_provider *pp;
932 	struct g_geom *gp;
933 	u_int n;
934 
935 	g_topology_assert();
936 
937 	if (sc == NULL)
938 		return (ENXIO);
939 
940 	pp = sc->provider;
941 	if (pp != NULL && (pp->acr != 0 || pp->acw != 0 || pp->ace != 0)) {
942 		LOG_MSG(force ? LVL_WARNING : LVL_ERROR,
943 		    "Device %s is still open.", pp->name);
944 		if (!force)
945 			return (EBUSY);
946 	}
947 
948 	for (n = 0; n < sc->n_components; n++) {
949 		if (sc->components[n].gcons != NULL)
950 			remove_component(sc, &sc->components[n], delay);
951 	}
952 
953 	gp = sc->geom;
954 	gp->softc = NULL;
955 
956 	KASSERT(sc->provider == NULL, ("Provider still exists for %s",
957 	    gp->name));
958 
959 	/* XXX: This might or might not work, since we're called with
960 	 * the topology lock held. Also, it might panic the kernel if
961 	 * the error'd BIO is in softupdates code. */
962 	mtx_lock(&sc->delayed_bio_q_mtx);
963 	while (!STAILQ_EMPTY(&sc->delayed_bio_q)) {
964 		struct g_virstor_bio_q *bq;
965 		bq = STAILQ_FIRST(&sc->delayed_bio_q);
966 		bq->bio->bio_error = ENOSPC;
967 		g_io_deliver(bq->bio, EIO);
968 		STAILQ_REMOVE_HEAD(&sc->delayed_bio_q, linkage);
969 		free(bq, M_GVIRSTOR);
970 	}
971 	mtx_unlock(&sc->delayed_bio_q_mtx);
972 	mtx_destroy(&sc->delayed_bio_q_mtx);
973 
974 	free(sc->map, M_GVIRSTOR);
975 	free(sc->components, M_GVIRSTOR);
976 	bzero(sc, sizeof *sc);
977 	free(sc, M_GVIRSTOR);
978 
979 	pp = LIST_FIRST(&gp->provider); /* We only offer one provider */
980 	if (pp == NULL || (pp->acr == 0 && pp->acw == 0 && pp->ace == 0))
981 		LOG_MSG(LVL_DEBUG, "Device %s destroyed", gp->name);
982 
983 	g_wither_geom(gp, ENXIO);
984 
985 	return (0);
986 }
987 
988 /*
989  * Utility function: read metadata & decode. Wants topology lock to be
990  * held.
991  */
992 static int
993 read_metadata(struct g_consumer *cp, struct g_virstor_metadata *md)
994 {
995 	struct g_provider *pp;
996 	char *buf;
997 	int error;
998 
999 	g_topology_assert();
1000 	error = g_access(cp, 1, 0, 0);
1001 	if (error != 0)
1002 		return (error);
1003 	pp = cp->provider;
1004 	g_topology_unlock();
1005 	buf = g_read_data(cp, pp->mediasize - pp->sectorsize, pp->sectorsize,
1006 	    &error);
1007 	g_topology_lock();
1008 	g_access(cp, -1, 0, 0);
1009 	if (buf == NULL)
1010 		return (error);
1011 
1012 	virstor_metadata_decode(buf, md);
1013 	g_free(buf);
1014 
1015 	return (0);
1016 }
1017 
1018 /**
1019  * Utility function: encode & write metadata. Assumes topology lock is
1020  * held.
1021  *
1022  * There is no useful way of recovering from errors in this function,
1023  * not involving panicking the kernel. If the metadata cannot be written
1024  * the most we can do is notify the operator and hope he spots it and
1025  * replaces the broken drive.
1026  */
1027 static void
1028 write_metadata(struct g_consumer *cp, struct g_virstor_metadata *md)
1029 {
1030 	struct g_provider *pp;
1031 	char *buf;
1032 	int error;
1033 
1034 	KASSERT(cp != NULL && md != NULL && cp->provider != NULL,
1035 	    ("Something's fishy in %s", __func__));
1036 	LOG_MSG(LVL_DEBUG, "Writing metadata on %s", cp->provider->name);
1037 	g_topology_assert();
1038 	error = g_access(cp, 0, 1, 0);
1039 	if (error != 0) {
1040 		LOG_MSG(LVL_ERROR, "g_access(0,1,0) failed for %s: %d",
1041 		    cp->provider->name, error);
1042 		return;
1043 	}
1044 	pp = cp->provider;
1045 
1046 	buf = malloc(pp->sectorsize, M_GVIRSTOR, M_WAITOK);
1047 	bzero(buf, pp->sectorsize);
1048 	virstor_metadata_encode(md, buf);
1049 	g_topology_unlock();
1050 	error = g_write_data(cp, pp->mediasize - pp->sectorsize, buf,
1051 	    pp->sectorsize);
1052 	g_topology_lock();
1053 	g_access(cp, 0, -1, 0);
1054 	free(buf, M_GVIRSTOR);
1055 
1056 	if (error != 0)
1057 		LOG_MSG(LVL_ERROR, "Error %d writing metadata to %s",
1058 		    error, cp->provider->name);
1059 }
1060 
1061 /*
1062  * Creates a new instance of this GEOM class, initialise softc
1063  */
1064 static struct g_geom *
1065 create_virstor_geom(struct g_class *mp, struct g_virstor_metadata *md)
1066 {
1067 	struct g_geom *gp;
1068 	struct g_virstor_softc *sc;
1069 
1070 	LOG_MSG(LVL_DEBUG, "Creating geom instance for %s (id=%u)",
1071 	    md->md_name, md->md_id);
1072 
1073 	if (md->md_count < 1 || md->md_chunk_size < 1 ||
1074 	    md->md_virsize < md->md_chunk_size) {
1075 		/* This is bogus configuration, and probably means data is
1076 		 * somehow corrupted. Panic, maybe? */
1077 		LOG_MSG(LVL_ERROR, "Nonsensical metadata information for %s",
1078 		    md->md_name);
1079 		return (NULL);
1080 	}
1081 
1082 	/* Check if it's already created */
1083 	LIST_FOREACH(gp, &mp->geom, geom) {
1084 		sc = gp->softc;
1085 		if (sc != NULL && strcmp(sc->geom->name, md->md_name) == 0) {
1086 			LOG_MSG(LVL_WARNING, "Geom %s already exists",
1087 			    md->md_name);
1088 			if (sc->id != md->md_id) {
1089 				LOG_MSG(LVL_ERROR,
1090 				    "Some stale or invalid components "
1091 				    "exist for virstor device named %s. "
1092 				    "You will need to <CLEAR> all stale "
1093 				    "components and maybe reconfigure "
1094 				    "the virstor device. Tune "
1095 				    "kern.geom.virstor.debug sysctl up "
1096 				    "for more information.",
1097 				    sc->geom->name);
1098 			}
1099 			return (NULL);
1100 		}
1101 	}
1102 	gp = g_new_geomf(mp, "%s", md->md_name);
1103 	gp->softc = NULL; /* to circumevent races that test softc */
1104 
1105 	gp->start = g_virstor_start;
1106 	gp->spoiled = g_virstor_orphan;
1107 	gp->orphan = g_virstor_orphan;
1108 	gp->access = g_virstor_access;
1109 	gp->dumpconf = g_virstor_dumpconf;
1110 
1111 	sc = malloc(sizeof(*sc), M_GVIRSTOR, M_WAITOK | M_ZERO);
1112 	sc->id = md->md_id;
1113 	sc->n_components = md->md_count;
1114 	sc->components = malloc(sizeof(struct g_virstor_component) * md->md_count,
1115 	    M_GVIRSTOR, M_WAITOK | M_ZERO);
1116 	sc->chunk_size = md->md_chunk_size;
1117 	sc->virsize = md->md_virsize;
1118 	STAILQ_INIT(&sc->delayed_bio_q);
1119 	mtx_init(&sc->delayed_bio_q_mtx, "gvirstor_delayed_bio_q_mtx",
1120 	    "gvirstor", MTX_DEF | MTX_RECURSE);
1121 
1122 	sc->geom = gp;
1123 	sc->provider = NULL; /* virstor_check_and_run will create it */
1124 	gp->softc = sc;
1125 
1126 	LOG_MSG(LVL_ANNOUNCE, "Device %s created", sc->geom->name);
1127 
1128 	return (gp);
1129 }
1130 
1131 /*
1132  * Add provider to a GEOM class instance
1133  */
1134 static int
1135 add_provider_to_geom(struct g_virstor_softc *sc, struct g_provider *pp,
1136     struct g_virstor_metadata *md)
1137 {
1138 	struct g_virstor_component *component;
1139 	struct g_consumer *cp, *fcp;
1140 	struct g_geom *gp;
1141 	int error;
1142 
1143 	if (md->no >= sc->n_components)
1144 		return (EINVAL);
1145 
1146 	/* "Current" compontent */
1147 	component = &(sc->components[md->no]);
1148 	if (component->gcons != NULL)
1149 		return (EEXIST);
1150 
1151 	gp = sc->geom;
1152 	fcp = LIST_FIRST(&gp->consumer);
1153 
1154 	cp = g_new_consumer(gp);
1155 	error = g_attach(cp, pp);
1156 
1157 	if (error != 0) {
1158 		g_destroy_consumer(cp);
1159 		return (error);
1160 	}
1161 
1162 	if (fcp != NULL) {
1163 		if (fcp->provider->sectorsize != pp->sectorsize) {
1164 			/* TODO: this can be made to work */
1165 			LOG_MSG(LVL_ERROR, "Provider %s of %s has invalid "
1166 			    "sector size (%d)", pp->name, sc->geom->name,
1167 			    pp->sectorsize);
1168 			return (EINVAL);
1169 		}
1170 		if (fcp->acr > 0 || fcp->acw || fcp->ace > 0) {
1171 			/* Replicate access permissions from first "live" consumer
1172 			 * to the new one */
1173 			error = g_access(cp, fcp->acr, fcp->acw, fcp->ace);
1174 			if (error != 0) {
1175 				g_detach(cp);
1176 				g_destroy_consumer(cp);
1177 				return (error);
1178 			}
1179 		}
1180 	}
1181 
1182 	/* Bring up a new component */
1183 	cp->private = component;
1184 	component->gcons = cp;
1185 	component->sc = sc;
1186 	component->index = md->no;
1187 	component->chunk_count = md->chunk_count;
1188 	component->chunk_next = md->chunk_next;
1189 	component->chunk_reserved = md->chunk_reserved;
1190 	component->flags = md->flags;
1191 
1192 	LOG_MSG(LVL_DEBUG, "%s attached to %s", pp->name, sc->geom->name);
1193 
1194 	virstor_check_and_run(sc);
1195 	return (0);
1196 }
1197 
1198 /*
1199  * Check if everything's ready to create the geom provider & device entry,
1200  * create and start provider.
1201  * Called ultimately by .taste, from g_event thread
1202  */
1203 static void
1204 virstor_check_and_run(struct g_virstor_softc *sc)
1205 {
1206 	off_t off;
1207 	size_t n, count;
1208 	int index;
1209 	int error;
1210 
1211 	if (virstor_valid_components(sc) != sc->n_components)
1212 		return;
1213 
1214 	if (virstor_valid_components(sc) == 0) {
1215 		/* This is actually a candidate for panic() */
1216 		LOG_MSG(LVL_ERROR, "No valid components for %s?",
1217 		    sc->provider->name);
1218 		return;
1219 	}
1220 
1221 	sc->sectorsize = sc->components[0].gcons->provider->sectorsize;
1222 
1223 	/* Initialise allocation map from the first consumer */
1224 	sc->chunk_count = sc->virsize / sc->chunk_size;
1225 	if (sc->chunk_count * (off_t)sc->chunk_size != sc->virsize) {
1226 		LOG_MSG(LVL_WARNING, "Device %s truncated to %ju bytes",
1227 		    sc->provider->name,
1228 		    sc->chunk_count * (off_t)sc->chunk_size);
1229 	}
1230 	sc->map_size = sc->chunk_count * sizeof *(sc->map);
1231 	/* The following allocation is in order of 4MB - 8MB */
1232 	sc->map = malloc(sc->map_size, M_GVIRSTOR, M_WAITOK);
1233 	KASSERT(sc->map != NULL, ("%s: Memory allocation error (%zu bytes) for %s",
1234 	    __func__, sc->map_size, sc->provider->name));
1235 	sc->map_sectors = sc->map_size / sc->sectorsize;
1236 
1237 	count = 0;
1238 	for (n = 0; n < sc->n_components; n++)
1239 		count += sc->components[n].chunk_count;
1240 	LOG_MSG(LVL_INFO, "Device %s has %zu physical chunks and %zu virtual "
1241 	    "(%zu KB chunks)",
1242 	    sc->geom->name, count, sc->chunk_count, sc->chunk_size / 1024);
1243 
1244 	error = g_access(sc->components[0].gcons, 1, 0, 0);
1245 	if (error != 0) {
1246 		LOG_MSG(LVL_ERROR, "Cannot acquire read access for %s to "
1247 		    "read allocation map for %s",
1248 		    sc->components[0].gcons->provider->name,
1249 		    sc->geom->name);
1250 		return;
1251 	}
1252 	/* Read in the allocation map */
1253 	LOG_MSG(LVL_DEBUG, "Reading map for %s from %s", sc->geom->name,
1254 	    sc->components[0].gcons->provider->name);
1255 	off = count = n = 0;
1256 	while (count < sc->map_size) {
1257 		struct g_virstor_map_entry *mapbuf;
1258 		size_t bs;
1259 
1260 		bs = MIN(MAXPHYS, sc->map_size - count);
1261 		if (bs % sc->sectorsize != 0) {
1262 			/* Check for alignment errors */
1263 			bs = rounddown(bs, sc->sectorsize);
1264 			if (bs == 0)
1265 				break;
1266 			LOG_MSG(LVL_ERROR, "Trouble: map is not sector-aligned "
1267 			    "for %s on %s", sc->geom->name,
1268 			    sc->components[0].gcons->provider->name);
1269 		}
1270 		mapbuf = g_read_data(sc->components[0].gcons, off, bs, &error);
1271 		if (mapbuf == NULL) {
1272 			free(sc->map, M_GVIRSTOR);
1273 			LOG_MSG(LVL_ERROR, "Error reading allocation map "
1274 			    "for %s from %s (offset %ju) (error %d)",
1275 			    sc->geom->name,
1276 			    sc->components[0].gcons->provider->name,
1277 			    off, error);
1278 			return;
1279 		}
1280 
1281 		bcopy(mapbuf, &sc->map[n], bs);
1282 		off += bs;
1283 		count += bs;
1284 		n += bs / sizeof *(sc->map);
1285 		g_free(mapbuf);
1286 	}
1287 	g_access(sc->components[0].gcons, -1, 0, 0);
1288 	LOG_MSG(LVL_DEBUG, "Read map for %s", sc->geom->name);
1289 
1290 	/* find first component with allocatable chunks */
1291 	index = -1;
1292 	for (n = 0; n < sc->n_components; n++) {
1293 		if (sc->components[n].chunk_next <
1294 		    sc->components[n].chunk_count) {
1295 			index = n;
1296 			break;
1297 		}
1298 	}
1299 	if (index == -1)
1300 		/* not found? set it to the last component and handle it
1301 		 * later */
1302 		index = sc->n_components - 1;
1303 
1304 	if (index >= sc->n_components - g_virstor_component_watermark - 1) {
1305 		LOG_MSG(LVL_WARNING, "Device %s running out of components "
1306 		    "(%d/%u: %s)", sc->geom->name,
1307 		    index+1,
1308 		    sc->n_components,
1309 		    sc->components[index].gcons->provider->name);
1310 	}
1311 	sc->curr_component = index;
1312 
1313 	if (sc->components[index].chunk_next >=
1314 	    sc->components[index].chunk_count - g_virstor_chunk_watermark) {
1315 		LOG_MSG(LVL_WARNING,
1316 		    "Component %s of %s is running out of free space "
1317 		    "(%u chunks left)",
1318 		    sc->components[index].gcons->provider->name,
1319 		    sc->geom->name, sc->components[index].chunk_count -
1320 		    sc->components[index].chunk_next);
1321 	}
1322 
1323 	sc->me_per_sector = sc->sectorsize / sizeof *(sc->map);
1324 	if (sc->sectorsize % sizeof *(sc->map) != 0) {
1325 		LOG_MSG(LVL_ERROR,
1326 		    "%s: Map entries don't fit exactly in a sector (%s)",
1327 		    __func__, sc->geom->name);
1328 		return;
1329 	}
1330 
1331 	/* Recalculate allocated chunks in components & at the same time
1332 	 * verify map data is sane. We could trust metadata on this, but
1333 	 * we want to make sure. */
1334 	for (n = 0; n < sc->n_components; n++)
1335 		sc->components[n].chunk_next = sc->components[n].chunk_reserved;
1336 
1337 	for (n = 0; n < sc->chunk_count; n++) {
1338 		if (sc->map[n].provider_no >= sc->n_components ||
1339 			sc->map[n].provider_chunk >=
1340 			sc->components[sc->map[n].provider_no].chunk_count) {
1341 			LOG_MSG(LVL_ERROR, "%s: Invalid entry %u in map for %s",
1342 			    __func__, (u_int)n, sc->geom->name);
1343 			LOG_MSG(LVL_ERROR, "%s: provider_no: %u, n_components: %u"
1344 			    " provider_chunk: %u, chunk_count: %u", __func__,
1345 			    sc->map[n].provider_no, sc->n_components,
1346 			    sc->map[n].provider_chunk,
1347 			    sc->components[sc->map[n].provider_no].chunk_count);
1348 			return;
1349 		}
1350 		if (sc->map[n].flags & VIRSTOR_MAP_ALLOCATED)
1351 			sc->components[sc->map[n].provider_no].chunk_next++;
1352 	}
1353 
1354 	sc->provider = g_new_providerf(sc->geom, "virstor/%s",
1355 	    sc->geom->name);
1356 
1357 	sc->provider->sectorsize = sc->sectorsize;
1358 	sc->provider->mediasize = sc->virsize;
1359 	g_error_provider(sc->provider, 0);
1360 
1361 	LOG_MSG(LVL_INFO, "%s activated", sc->provider->name);
1362 	LOG_MSG(LVL_DEBUG, "%s starting with current component %u, starting "
1363 	    "chunk %u", sc->provider->name, sc->curr_component,
1364 	    sc->components[sc->curr_component].chunk_next);
1365 }
1366 
1367 /*
1368  * Returns count of active providers in this geom instance
1369  */
1370 static u_int
1371 virstor_valid_components(struct g_virstor_softc *sc)
1372 {
1373 	unsigned int nc, i;
1374 
1375 	nc = 0;
1376 	KASSERT(sc != NULL, ("%s: softc is NULL", __func__));
1377 	KASSERT(sc->components != NULL, ("%s: sc->components is NULL", __func__));
1378 	for (i = 0; i < sc->n_components; i++)
1379 		if (sc->components[i].gcons != NULL)
1380 			nc++;
1381 	return (nc);
1382 }
1383 
1384 /*
1385  * Called when the consumer gets orphaned (?)
1386  */
1387 static void
1388 g_virstor_orphan(struct g_consumer *cp)
1389 {
1390 	struct g_virstor_softc *sc;
1391 	struct g_virstor_component *comp;
1392 	struct g_geom *gp;
1393 
1394 	g_topology_assert();
1395 	gp = cp->geom;
1396 	sc = gp->softc;
1397 	if (sc == NULL)
1398 		return;
1399 
1400 	comp = cp->private;
1401 	KASSERT(comp != NULL, ("%s: No component in private part of consumer",
1402 	    __func__));
1403 	remove_component(sc, comp, FALSE);
1404 	if (LIST_EMPTY(&gp->consumer))
1405 		virstor_geom_destroy(sc, TRUE, FALSE);
1406 }
1407 
1408 /*
1409  * Called to notify geom when it's been opened, and for what intent
1410  */
1411 static int
1412 g_virstor_access(struct g_provider *pp, int dr, int dw, int de)
1413 {
1414 	struct g_consumer *c, *c2, *tmp;
1415 	struct g_virstor_softc *sc;
1416 	struct g_geom *gp;
1417 	int error;
1418 
1419 	KASSERT(pp != NULL, ("%s: NULL provider", __func__));
1420 	gp = pp->geom;
1421 	KASSERT(gp != NULL, ("%s: NULL geom", __func__));
1422 	sc = gp->softc;
1423 
1424 	/* Grab an exclusive bit to propagate on our consumers on first open */
1425 	if (pp->acr == 0 && pp->acw == 0 && pp->ace == 0)
1426 		de++;
1427 	/* ... drop it on close */
1428 	if (pp->acr + dr == 0 && pp->acw + dw == 0 && pp->ace + de == 0) {
1429 		de--;
1430 		if (sc != NULL)
1431 			update_metadata(sc);
1432 	}
1433 
1434 	error = ENXIO;
1435 	LIST_FOREACH_SAFE(c, &gp->consumer, consumer, tmp) {
1436 		error = g_access(c, dr, dw, de);
1437 		if (error != 0)
1438 			goto fail;
1439 		if (c->acr == 0 && c->acw == 0 && c->ace == 0 &&
1440 		    c->flags & G_CF_ORPHAN) {
1441 			g_detach(c);
1442 			g_destroy_consumer(c);
1443 		}
1444 	}
1445 
1446 	if (sc != NULL && LIST_EMPTY(&gp->consumer))
1447 		virstor_geom_destroy(sc, TRUE, FALSE);
1448 
1449 	return (error);
1450 
1451 fail:
1452 	/* Backout earlier changes */
1453 	LIST_FOREACH(c2, &gp->consumer, consumer) {
1454 		if (c2 == c)
1455 			break;
1456 		g_access(c2, -dr, -dw, -de);
1457 	}
1458 	return (error);
1459 }
1460 
1461 /*
1462  * Generate XML dump of current state
1463  */
1464 static void
1465 g_virstor_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp,
1466     struct g_consumer *cp, struct g_provider *pp)
1467 {
1468 	struct g_virstor_softc *sc;
1469 
1470 	g_topology_assert();
1471 	sc = gp->softc;
1472 
1473 	if (sc == NULL || pp != NULL)
1474 		return;
1475 
1476 	if (cp != NULL) {
1477 		/* For each component */
1478 		struct g_virstor_component *comp;
1479 
1480 		comp = cp->private;
1481 		if (comp == NULL)
1482 			return;
1483 		sbuf_printf(sb, "%s<ComponentIndex>%u</ComponentIndex>\n",
1484 		    indent, comp->index);
1485 		sbuf_printf(sb, "%s<ChunkCount>%u</ChunkCount>\n",
1486 		    indent, comp->chunk_count);
1487 		sbuf_printf(sb, "%s<ChunksUsed>%u</ChunksUsed>\n",
1488 		    indent, comp->chunk_next);
1489 		sbuf_printf(sb, "%s<ChunksReserved>%u</ChunksReserved>\n",
1490 		    indent, comp->chunk_reserved);
1491 		sbuf_printf(sb, "%s<StorageFree>%u%%</StorageFree>\n",
1492 		    indent,
1493 		    comp->chunk_next > 0 ? 100 -
1494 		    ((comp->chunk_next + comp->chunk_reserved) * 100) /
1495 		    comp->chunk_count : 100);
1496 	} else {
1497 		/* For the whole thing */
1498 		u_int count, used, i;
1499 		off_t size;
1500 
1501 		count = used = size = 0;
1502 		for (i = 0; i < sc->n_components; i++) {
1503 			if (sc->components[i].gcons != NULL) {
1504 				count += sc->components[i].chunk_count;
1505 				used += sc->components[i].chunk_next +
1506 				    sc->components[i].chunk_reserved;
1507 				size += sc->components[i].gcons->
1508 				    provider->mediasize;
1509 			}
1510 		}
1511 
1512 		sbuf_printf(sb, "%s<Status>"
1513 		    "Components=%u, Online=%u</Status>\n", indent,
1514 		    sc->n_components, virstor_valid_components(sc));
1515 		sbuf_printf(sb, "%s<State>%u%% physical free</State>\n",
1516 		    indent, 100-(used * 100) / count);
1517 		sbuf_printf(sb, "%s<ChunkSize>%zu</ChunkSize>\n", indent,
1518 		    sc->chunk_size);
1519 		sbuf_printf(sb, "%s<PhysicalFree>%u%%</PhysicalFree>\n",
1520 		    indent, used > 0 ? 100 - (used * 100) / count : 100);
1521 		sbuf_printf(sb, "%s<ChunkPhysicalCount>%u</ChunkPhysicalCount>\n",
1522 		    indent, count);
1523 		sbuf_printf(sb, "%s<ChunkVirtualCount>%zu</ChunkVirtualCount>\n",
1524 		    indent, sc->chunk_count);
1525 		sbuf_printf(sb, "%s<PhysicalBacking>%zu%%</PhysicalBacking>\n",
1526 		    indent,
1527 		    (count * 100) / sc->chunk_count);
1528 		sbuf_printf(sb, "%s<PhysicalBackingSize>%jd</PhysicalBackingSize>\n",
1529 		    indent, size);
1530 		sbuf_printf(sb, "%s<VirtualSize>%jd</VirtualSize>\n", indent,
1531 		    sc->virsize);
1532 	}
1533 }
1534 
1535 /*
1536  * GEOM .done handler
1537  * Can't use standard handler because one requested IO may
1538  * fork into additional data IOs
1539  */
1540 static void
1541 g_virstor_done(struct bio *b)
1542 {
1543 	struct g_virstor_softc *sc;
1544 	struct bio *parent_b;
1545 
1546 	parent_b = b->bio_parent;
1547 	sc = parent_b->bio_to->geom->softc;
1548 
1549 	if (b->bio_error != 0) {
1550 		LOG_MSG(LVL_ERROR, "Error %d for offset=%ju, length=%ju, %s",
1551 		    b->bio_error, b->bio_offset, b->bio_length,
1552 		    b->bio_to->name);
1553 		if (parent_b->bio_error == 0)
1554 			parent_b->bio_error = b->bio_error;
1555 	}
1556 
1557 	parent_b->bio_inbed++;
1558 	parent_b->bio_completed += b->bio_completed;
1559 
1560 	if (parent_b->bio_children == parent_b->bio_inbed) {
1561 		parent_b->bio_completed = parent_b->bio_length;
1562 		g_io_deliver(parent_b, parent_b->bio_error);
1563 	}
1564 	g_destroy_bio(b);
1565 }
1566 
1567 /*
1568  * I/O starts here
1569  * Called in g_down thread
1570  */
1571 static void
1572 g_virstor_start(struct bio *b)
1573 {
1574 	struct g_virstor_softc *sc;
1575 	struct g_virstor_component *comp;
1576 	struct bio *cb;
1577 	struct g_provider *pp;
1578 	char *addr;
1579 	off_t offset, length;
1580 	struct bio_queue_head bq;
1581 	size_t chunk_size;	/* cached for convenience */
1582 	u_int count;
1583 
1584 	pp = b->bio_to;
1585 	sc = pp->geom->softc;
1586 	KASSERT(sc != NULL, ("%s: no softc (error=%d, device=%s)", __func__,
1587 	    b->bio_to->error, b->bio_to->name));
1588 
1589 	LOG_REQ(LVL_MOREDEBUG, b, "%s", __func__);
1590 
1591 	switch (b->bio_cmd) {
1592 	case BIO_READ:
1593 	case BIO_WRITE:
1594 	case BIO_DELETE:
1595 		break;
1596 	default:
1597 		g_io_deliver(b, EOPNOTSUPP);
1598 		return;
1599 	}
1600 
1601 	LOG_MSG(LVL_DEBUG2, "BIO arrived, size=%ju", b->bio_length);
1602 	bioq_init(&bq);
1603 
1604 	chunk_size = sc->chunk_size;
1605 	addr = b->bio_data;
1606 	offset = b->bio_offset;	/* virtual offset and length */
1607 	length = b->bio_length;
1608 
1609 	while (length > 0) {
1610 		size_t chunk_index, in_chunk_offset, in_chunk_length;
1611 		struct virstor_map_entry *me;
1612 
1613 		chunk_index = offset / chunk_size; /* round downwards */
1614 		in_chunk_offset = offset % chunk_size;
1615 		in_chunk_length = min(length, chunk_size - in_chunk_offset);
1616 		LOG_MSG(LVL_DEBUG, "Mapped %s(%ju, %ju) to (%zu,%zu,%zu)",
1617 		    b->bio_cmd == BIO_READ ? "R" : "W",
1618 		    offset, length,
1619 		    chunk_index, in_chunk_offset, in_chunk_length);
1620 		me = &sc->map[chunk_index];
1621 
1622 		if (b->bio_cmd == BIO_READ || b->bio_cmd == BIO_DELETE) {
1623 			if ((me->flags & VIRSTOR_MAP_ALLOCATED) == 0) {
1624 				/* Reads from unallocated chunks return zeroed
1625 				 * buffers */
1626 				if (b->bio_cmd == BIO_READ)
1627 					bzero(addr, in_chunk_length);
1628 			} else {
1629 				comp = &sc->components[me->provider_no];
1630 
1631 				cb = g_clone_bio(b);
1632 				if (cb == NULL) {
1633 					bioq_dismantle(&bq);
1634 					if (b->bio_error == 0)
1635 						b->bio_error = ENOMEM;
1636 					g_io_deliver(b, b->bio_error);
1637 					return;
1638 				}
1639 				cb->bio_to = comp->gcons->provider;
1640 				cb->bio_done = g_virstor_done;
1641 				cb->bio_offset =
1642 				    (off_t)me->provider_chunk * (off_t)chunk_size
1643 				    + in_chunk_offset;
1644 				cb->bio_length = in_chunk_length;
1645 				cb->bio_data = addr;
1646 				cb->bio_caller1 = comp;
1647 				bioq_disksort(&bq, cb);
1648 			}
1649 		} else { /* handle BIO_WRITE */
1650 			KASSERT(b->bio_cmd == BIO_WRITE,
1651 			    ("%s: Unknown command %d", __func__,
1652 			    b->bio_cmd));
1653 
1654 			if ((me->flags & VIRSTOR_MAP_ALLOCATED) == 0) {
1655 				/* We have a virtual chunk, represented by
1656 				 * the "me" entry, but it's not yet allocated
1657 				 * (tied to) a physical chunk. So do it now. */
1658 				struct virstor_map_entry *data_me;
1659 				u_int phys_chunk, comp_no;
1660 				off_t s_offset;
1661 				int error;
1662 
1663 				error = allocate_chunk(sc, &comp, &comp_no,
1664 				    &phys_chunk);
1665 				if (error != 0) {
1666 					/* We cannot allocate a physical chunk
1667 					 * to satisfy this request, so we'll
1668 					 * delay it to when we can...
1669 					 * XXX: this will prevent the fs from
1670 					 * being umounted! */
1671 					struct g_virstor_bio_q *biq;
1672 					biq = malloc(sizeof *biq, M_GVIRSTOR,
1673 					    M_NOWAIT);
1674 					if (biq == NULL) {
1675 						bioq_dismantle(&bq);
1676 						if (b->bio_error == 0)
1677 							b->bio_error = ENOMEM;
1678 						g_io_deliver(b, b->bio_error);
1679 						return;
1680 					}
1681 					biq->bio = b;
1682 					mtx_lock(&sc->delayed_bio_q_mtx);
1683 					STAILQ_INSERT_TAIL(&sc->delayed_bio_q,
1684 					    biq, linkage);
1685 					mtx_unlock(&sc->delayed_bio_q_mtx);
1686 					LOG_MSG(LVL_WARNING, "Delaying BIO "
1687 					    "(size=%ju) until free physical "
1688 					    "space can be found on %s",
1689 					    b->bio_length,
1690 					    sc->provider->name);
1691 					return;
1692 				}
1693 				LOG_MSG(LVL_DEBUG, "Allocated chunk %u on %s "
1694 				    "for %s",
1695 				    phys_chunk,
1696 				    comp->gcons->provider->name,
1697 				    sc->provider->name);
1698 
1699 				me->provider_no = comp_no;
1700 				me->provider_chunk = phys_chunk;
1701 				me->flags |= VIRSTOR_MAP_ALLOCATED;
1702 
1703 				cb = g_clone_bio(b);
1704 				if (cb == NULL) {
1705 					me->flags &= ~VIRSTOR_MAP_ALLOCATED;
1706 					me->provider_no = 0;
1707 					me->provider_chunk = 0;
1708 					bioq_dismantle(&bq);
1709 					if (b->bio_error == 0)
1710 						b->bio_error = ENOMEM;
1711 					g_io_deliver(b, b->bio_error);
1712 					return;
1713 				}
1714 
1715 				/* The allocation table is stored continuously
1716 				 * at the start of the drive. We need to
1717 				 * calculate the offset of the sector that holds
1718 				 * this map entry both on the drive and in the
1719 				 * map array.
1720 				 * sc_offset will end up pointing to the drive
1721 				 * sector. */
1722 				s_offset = chunk_index * sizeof *me;
1723 				s_offset = rounddown(s_offset, sc->sectorsize);
1724 
1725 				/* data_me points to map entry sector
1726 				 * in memory (analogous to offset) */
1727 				data_me = &sc->map[rounddown(chunk_index,
1728 				    sc->me_per_sector)];
1729 
1730 				/* Commit sector with map entry to storage */
1731 				cb->bio_to = sc->components[0].gcons->provider;
1732 				cb->bio_done = g_virstor_done;
1733 				cb->bio_offset = s_offset;
1734 				cb->bio_data = (char *)data_me;
1735 				cb->bio_length = sc->sectorsize;
1736 				cb->bio_caller1 = &sc->components[0];
1737 				bioq_disksort(&bq, cb);
1738 			}
1739 
1740 			comp = &sc->components[me->provider_no];
1741 			cb = g_clone_bio(b);
1742 			if (cb == NULL) {
1743 				bioq_dismantle(&bq);
1744 				if (b->bio_error == 0)
1745 					b->bio_error = ENOMEM;
1746 				g_io_deliver(b, b->bio_error);
1747 				return;
1748 			}
1749 			/* Finally, handle the data */
1750 			cb->bio_to = comp->gcons->provider;
1751 			cb->bio_done = g_virstor_done;
1752 			cb->bio_offset = (off_t)me->provider_chunk*(off_t)chunk_size +
1753 			    in_chunk_offset;
1754 			cb->bio_length = in_chunk_length;
1755 			cb->bio_data = addr;
1756 			cb->bio_caller1 = comp;
1757 			bioq_disksort(&bq, cb);
1758 		}
1759 		addr += in_chunk_length;
1760 		length -= in_chunk_length;
1761 		offset += in_chunk_length;
1762 	}
1763 
1764 	/* Fire off bio's here */
1765 	count = 0;
1766 	for (cb = bioq_first(&bq); cb != NULL; cb = bioq_first(&bq)) {
1767 		bioq_remove(&bq, cb);
1768 		LOG_REQ(LVL_MOREDEBUG, cb, "Firing request");
1769 		comp = cb->bio_caller1;
1770 		cb->bio_caller1 = NULL;
1771 		LOG_MSG(LVL_DEBUG, " firing bio, offset=%ju, length=%ju",
1772 		    cb->bio_offset, cb->bio_length);
1773 		g_io_request(cb, comp->gcons);
1774 		count++;
1775 	}
1776 	if (count == 0) { /* We handled everything locally */
1777 		b->bio_completed = b->bio_length;
1778 		g_io_deliver(b, 0);
1779 	}
1780 
1781 }
1782 
1783 /*
1784  * Allocate a chunk from a physical provider. Returns physical component,
1785  * chunk index relative to the component and the component's index.
1786  */
1787 static int
1788 allocate_chunk(struct g_virstor_softc *sc, struct g_virstor_component **comp,
1789     u_int *comp_no_p, u_int *chunk)
1790 {
1791 	u_int comp_no;
1792 
1793 	KASSERT(sc->curr_component < sc->n_components,
1794 	    ("%s: Invalid curr_component: %u",  __func__, sc->curr_component));
1795 
1796 	comp_no = sc->curr_component;
1797 	*comp = &sc->components[comp_no];
1798 	dump_component(*comp);
1799 	if ((*comp)->chunk_next >= (*comp)->chunk_count) {
1800 		/* This component is full. Allocate next component */
1801 		if (comp_no >= sc->n_components-1) {
1802 			LOG_MSG(LVL_ERROR, "All physical space allocated for %s",
1803 			    sc->geom->name);
1804 			return (-1);
1805 		}
1806 		(*comp)->flags &= ~VIRSTOR_PROVIDER_CURRENT;
1807 		sc->curr_component = ++comp_no;
1808 
1809 		*comp = &sc->components[comp_no];
1810 		if (comp_no >= sc->n_components - g_virstor_component_watermark-1)
1811 			LOG_MSG(LVL_WARNING, "Device %s running out of components "
1812 			    "(switching to %u/%u: %s)", sc->geom->name,
1813 			    comp_no+1, sc->n_components,
1814 			    (*comp)->gcons->provider->name);
1815 		/* Take care not to overwrite reserved chunks */
1816 		if ( (*comp)->chunk_reserved > 0 &&
1817 		    (*comp)->chunk_next < (*comp)->chunk_reserved)
1818 			(*comp)->chunk_next = (*comp)->chunk_reserved;
1819 
1820 		(*comp)->flags |=
1821 		    VIRSTOR_PROVIDER_ALLOCATED | VIRSTOR_PROVIDER_CURRENT;
1822 		dump_component(*comp);
1823 		*comp_no_p = comp_no;
1824 		*chunk = (*comp)->chunk_next++;
1825 	} else {
1826 		*comp_no_p = comp_no;
1827 		*chunk = (*comp)->chunk_next++;
1828 	}
1829 	return (0);
1830 }
1831 
1832 /* Dump a component */
1833 static void
1834 dump_component(struct g_virstor_component *comp)
1835 {
1836 
1837 	if (g_virstor_debug < LVL_DEBUG2)
1838 		return;
1839 	printf("Component %d: %s\n", comp->index, comp->gcons->provider->name);
1840 	printf("  chunk_count: %u\n", comp->chunk_count);
1841 	printf("   chunk_next: %u\n", comp->chunk_next);
1842 	printf("        flags: %u\n", comp->flags);
1843 }
1844 
1845 #if 0
1846 /* Dump a map entry */
1847 static void
1848 dump_me(struct virstor_map_entry *me, unsigned int nr)
1849 {
1850 	if (g_virstor_debug < LVL_DEBUG)
1851 		return;
1852 	printf("VIRT. CHUNK #%d: ", nr);
1853 	if ((me->flags & VIRSTOR_MAP_ALLOCATED) == 0)
1854 		printf("(unallocated)\n");
1855 	else
1856 		printf("allocated at provider %u, provider_chunk %u\n",
1857 		    me->provider_no, me->provider_chunk);
1858 }
1859 #endif
1860 
1861 /*
1862  * Dismantle bio_queue and destroy its components
1863  */
1864 static void
1865 bioq_dismantle(struct bio_queue_head *bq)
1866 {
1867 	struct bio *b;
1868 
1869 	for (b = bioq_first(bq); b != NULL; b = bioq_first(bq)) {
1870 		bioq_remove(bq, b);
1871 		g_destroy_bio(b);
1872 	}
1873 }
1874 
1875 /*
1876  * The function that shouldn't be called.
1877  * When this is called, the stack is already garbled because of
1878  * argument mismatch. There's nothing to do now but panic, which is
1879  * accidentally the whole purpose of this function.
1880  * Motivation: to guard from accidentally calling geom methods when
1881  * they shouldn't be called. (see g_..._taste)
1882  */
1883 static void
1884 invalid_call(void)
1885 {
1886 	panic("invalid_call() has just been called. Something's fishy here.");
1887 }
1888 
1889 DECLARE_GEOM_CLASS(g_virstor_class, g_virstor); /* Let there be light */
1890 MODULE_VERSION(geom_virstor, 0);
1891