xref: /freebsd/sys/geom/geom_disk.c (revision bb15ca603fa442c72dde3f3cb8b46db6970e3950)
1 /*-
2  * Copyright (c) 2002 Poul-Henning Kamp
3  * Copyright (c) 2002 Networks Associates Technology, Inc.
4  * All rights reserved.
5  *
6  * This software was developed for the FreeBSD Project by Poul-Henning Kamp
7  * and NAI Labs, the Security Research Division of Network Associates, Inc.
8  * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
9  * DARPA CHATS research program.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  * 3. The names of the authors may not be used to endorse or promote
20  *    products derived from this software without specific prior written
21  *    permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  */
35 
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
38 
39 #include "opt_geom.h"
40 
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/kernel.h>
44 #include <sys/sysctl.h>
45 #include <sys/bio.h>
46 #include <sys/ctype.h>
47 #include <sys/fcntl.h>
48 #include <sys/malloc.h>
49 #include <sys/sbuf.h>
50 #include <sys/sysctl.h>
51 #include <sys/devicestat.h>
52 #include <machine/md_var.h>
53 
54 #include <sys/lock.h>
55 #include <sys/mutex.h>
56 #include <geom/geom.h>
57 #include <geom/geom_disk.h>
58 #include <geom/geom_int.h>
59 
60 #include <dev/led/led.h>
61 
62 struct g_disk_softc {
63 	struct disk		*dp;
64 	struct sysctl_ctx_list	sysctl_ctx;
65 	struct sysctl_oid	*sysctl_tree;
66 	char			led[64];
67 	uint32_t		state;
68 };
69 
70 static struct mtx g_disk_done_mtx;
71 
72 static g_access_t g_disk_access;
73 static g_init_t g_disk_init;
74 static g_fini_t g_disk_fini;
75 static g_start_t g_disk_start;
76 static g_ioctl_t g_disk_ioctl;
77 static g_dumpconf_t g_disk_dumpconf;
78 
79 static struct g_class g_disk_class = {
80 	.name = "DISK",
81 	.version = G_VERSION,
82 	.init = g_disk_init,
83 	.fini = g_disk_fini,
84 	.start = g_disk_start,
85 	.access = g_disk_access,
86 	.ioctl = g_disk_ioctl,
87 	.dumpconf = g_disk_dumpconf,
88 };
89 
90 SYSCTL_DECL(_kern_geom);
91 static SYSCTL_NODE(_kern_geom, OID_AUTO, disk, CTLFLAG_RW, 0,
92     "GEOM_DISK stuff");
93 
94 static void
95 g_disk_init(struct g_class *mp __unused)
96 {
97 
98 	mtx_init(&g_disk_done_mtx, "g_disk_done", NULL, MTX_DEF);
99 }
100 
101 static void
102 g_disk_fini(struct g_class *mp __unused)
103 {
104 
105 	mtx_destroy(&g_disk_done_mtx);
106 }
107 
108 DECLARE_GEOM_CLASS(g_disk_class, g_disk);
109 
110 static void __inline
111 g_disk_lock_giant(struct disk *dp)
112 {
113 
114 	if (dp->d_flags & DISKFLAG_NEEDSGIANT)
115 		mtx_lock(&Giant);
116 }
117 
118 static void __inline
119 g_disk_unlock_giant(struct disk *dp)
120 {
121 
122 	if (dp->d_flags & DISKFLAG_NEEDSGIANT)
123 		mtx_unlock(&Giant);
124 }
125 
126 static int
127 g_disk_access(struct g_provider *pp, int r, int w, int e)
128 {
129 	struct disk *dp;
130 	struct g_disk_softc *sc;
131 	int error;
132 
133 	g_trace(G_T_ACCESS, "g_disk_access(%s, %d, %d, %d)",
134 	    pp->name, r, w, e);
135 	g_topology_assert();
136 	sc = pp->geom->softc;
137 	if (sc == NULL || (dp = sc->dp) == NULL || dp->d_destroyed) {
138 		/*
139 		 * Allow decreasing access count even if disk is not
140 		 * avaliable anymore.
141 		 */
142 		if (r <= 0 && w <= 0 && e <= 0)
143 			return (0);
144 		return (ENXIO);
145 	}
146 	r += pp->acr;
147 	w += pp->acw;
148 	e += pp->ace;
149 	error = 0;
150 	if ((pp->acr + pp->acw + pp->ace) == 0 && (r + w + e) > 0) {
151 		if (dp->d_open != NULL) {
152 			g_disk_lock_giant(dp);
153 			error = dp->d_open(dp);
154 			if (bootverbose && error != 0)
155 				printf("Opened disk %s -> %d\n",
156 				    pp->name, error);
157 			g_disk_unlock_giant(dp);
158 		}
159 		pp->mediasize = dp->d_mediasize;
160 		pp->sectorsize = dp->d_sectorsize;
161 		if (dp->d_flags & DISKFLAG_CANDELETE)
162 			pp->flags |= G_PF_CANDELETE;
163 		else
164 			pp->flags &= ~G_PF_CANDELETE;
165 		pp->stripeoffset = dp->d_stripeoffset;
166 		pp->stripesize = dp->d_stripesize;
167 		dp->d_flags |= DISKFLAG_OPEN;
168 		if (dp->d_maxsize == 0) {
169 			printf("WARNING: Disk drive %s%d has no d_maxsize\n",
170 			    dp->d_name, dp->d_unit);
171 			dp->d_maxsize = DFLTPHYS;
172 		}
173 	} else if ((pp->acr + pp->acw + pp->ace) > 0 && (r + w + e) == 0) {
174 		if (dp->d_close != NULL) {
175 			g_disk_lock_giant(dp);
176 			error = dp->d_close(dp);
177 			if (error != 0)
178 				printf("Closed disk %s -> %d\n",
179 				    pp->name, error);
180 			g_disk_unlock_giant(dp);
181 		}
182 		sc->state = G_STATE_ACTIVE;
183 		if (sc->led[0] != 0)
184 			led_set(sc->led, "0");
185 		dp->d_flags &= ~DISKFLAG_OPEN;
186 	}
187 	return (error);
188 }
189 
190 static void
191 g_disk_kerneldump(struct bio *bp, struct disk *dp)
192 {
193 	struct g_kerneldump *gkd;
194 	struct g_geom *gp;
195 
196 	gkd = (struct g_kerneldump*)bp->bio_data;
197 	gp = bp->bio_to->geom;
198 	g_trace(G_T_TOPOLOGY, "g_disk_kernedump(%s, %jd, %jd)",
199 		gp->name, (intmax_t)gkd->offset, (intmax_t)gkd->length);
200 	if (dp->d_dump == NULL) {
201 		g_io_deliver(bp, ENODEV);
202 		return;
203 	}
204 	gkd->di.dumper = dp->d_dump;
205 	gkd->di.priv = dp;
206 	gkd->di.blocksize = dp->d_sectorsize;
207 	gkd->di.maxiosize = dp->d_maxsize;
208 	gkd->di.mediaoffset = gkd->offset;
209 	if ((gkd->offset + gkd->length) > dp->d_mediasize)
210 		gkd->length = dp->d_mediasize - gkd->offset;
211 	gkd->di.mediasize = gkd->length;
212 	g_io_deliver(bp, 0);
213 }
214 
215 static void
216 g_disk_setstate(struct bio *bp, struct g_disk_softc *sc)
217 {
218 	const char *cmd;
219 
220 	memcpy(&sc->state, bp->bio_data, sizeof(sc->state));
221 	if (sc->led[0] != 0) {
222 		switch (sc->state) {
223 		case G_STATE_FAILED:
224 			cmd = "1";
225 			break;
226 		case G_STATE_REBUILD:
227 			cmd = "f5";
228 			break;
229 		case G_STATE_RESYNC:
230 			cmd = "f1";
231 			break;
232 		default:
233 			cmd = "0";
234 			break;
235 		}
236 		led_set(sc->led, cmd);
237 	}
238 	g_io_deliver(bp, 0);
239 }
240 
241 static void
242 g_disk_done(struct bio *bp)
243 {
244 	struct bio *bp2;
245 	struct disk *dp;
246 	struct g_disk_softc *sc;
247 
248 	/* See "notes" for why we need a mutex here */
249 	/* XXX: will witness accept a mix of Giant/unGiant drivers here ? */
250 	mtx_lock(&g_disk_done_mtx);
251 	bp->bio_completed = bp->bio_length - bp->bio_resid;
252 
253 	bp2 = bp->bio_parent;
254 	if (bp2->bio_error == 0)
255 		bp2->bio_error = bp->bio_error;
256 	bp2->bio_completed += bp->bio_completed;
257 	if ((bp->bio_cmd & (BIO_READ|BIO_WRITE|BIO_DELETE)) != 0 &&
258 	    (sc = bp2->bio_to->geom->softc) != NULL &&
259 	    (dp = sc->dp) != NULL) {
260 		devstat_end_transaction_bio(dp->d_devstat, bp);
261 	}
262 	g_destroy_bio(bp);
263 	bp2->bio_inbed++;
264 	if (bp2->bio_children == bp2->bio_inbed) {
265 		bp2->bio_resid = bp2->bio_bcount - bp2->bio_completed;
266 		g_io_deliver(bp2, bp2->bio_error);
267 	}
268 	mtx_unlock(&g_disk_done_mtx);
269 }
270 
271 static int
272 g_disk_ioctl(struct g_provider *pp, u_long cmd, void * data, int fflag, struct thread *td)
273 {
274 	struct g_geom *gp;
275 	struct disk *dp;
276 	struct g_disk_softc *sc;
277 	int error;
278 
279 	gp = pp->geom;
280 	sc = gp->softc;
281 	dp = sc->dp;
282 
283 	if (dp->d_ioctl == NULL)
284 		return (ENOIOCTL);
285 	g_disk_lock_giant(dp);
286 	error = dp->d_ioctl(dp, cmd, data, fflag, td);
287 	g_disk_unlock_giant(dp);
288 	return (error);
289 }
290 
291 static void
292 g_disk_start(struct bio *bp)
293 {
294 	struct bio *bp2, *bp3;
295 	struct disk *dp;
296 	struct g_disk_softc *sc;
297 	int error;
298 	off_t off;
299 
300 	sc = bp->bio_to->geom->softc;
301 	if (sc == NULL || (dp = sc->dp) == NULL || dp->d_destroyed) {
302 		g_io_deliver(bp, ENXIO);
303 		return;
304 	}
305 	error = EJUSTRETURN;
306 	switch(bp->bio_cmd) {
307 	case BIO_DELETE:
308 		if (!(dp->d_flags & DISKFLAG_CANDELETE)) {
309 			error = EOPNOTSUPP;
310 			break;
311 		}
312 		/* fall-through */
313 	case BIO_READ:
314 	case BIO_WRITE:
315 		off = 0;
316 		bp3 = NULL;
317 		bp2 = g_clone_bio(bp);
318 		if (bp2 == NULL) {
319 			error = ENOMEM;
320 			break;
321 		}
322 		do {
323 			bp2->bio_offset += off;
324 			bp2->bio_length -= off;
325 			bp2->bio_data += off;
326 			if (bp2->bio_length > dp->d_maxsize) {
327 				/*
328 				 * XXX: If we have a stripesize we should really
329 				 * use it here.
330 				 */
331 				bp2->bio_length = dp->d_maxsize;
332 				off += dp->d_maxsize;
333 				/*
334 				 * To avoid a race, we need to grab the next bio
335 				 * before we schedule this one.  See "notes".
336 				 */
337 				bp3 = g_clone_bio(bp);
338 				if (bp3 == NULL)
339 					bp->bio_error = ENOMEM;
340 			}
341 			bp2->bio_done = g_disk_done;
342 			bp2->bio_pblkno = bp2->bio_offset / dp->d_sectorsize;
343 			bp2->bio_bcount = bp2->bio_length;
344 			bp2->bio_disk = dp;
345 			devstat_start_transaction_bio(dp->d_devstat, bp2);
346 			g_disk_lock_giant(dp);
347 			dp->d_strategy(bp2);
348 			g_disk_unlock_giant(dp);
349 			bp2 = bp3;
350 			bp3 = NULL;
351 		} while (bp2 != NULL);
352 		break;
353 	case BIO_GETATTR:
354 		/* Give the driver a chance to override */
355 		if (dp->d_getattr != NULL) {
356 			if (bp->bio_disk == NULL)
357 				bp->bio_disk = dp;
358 			error = dp->d_getattr(bp);
359 			if (error != -1)
360 				break;
361 			error = EJUSTRETURN;
362 		}
363 		if (g_handleattr_int(bp, "GEOM::candelete",
364 		    (dp->d_flags & DISKFLAG_CANDELETE) != 0))
365 			break;
366 		else if (g_handleattr_int(bp, "GEOM::fwsectors",
367 		    dp->d_fwsectors))
368 			break;
369 		else if (g_handleattr_int(bp, "GEOM::fwheads", dp->d_fwheads))
370 			break;
371 		else if (g_handleattr_off_t(bp, "GEOM::frontstuff", 0))
372 			break;
373 		else if (g_handleattr_str(bp, "GEOM::ident", dp->d_ident))
374 			break;
375 		else if (g_handleattr(bp, "GEOM::hba_vendor",
376 		    &dp->d_hba_vendor, 2))
377 			break;
378 		else if (g_handleattr(bp, "GEOM::hba_device",
379 		    &dp->d_hba_device, 2))
380 			break;
381 		else if (g_handleattr(bp, "GEOM::hba_subvendor",
382 		    &dp->d_hba_subvendor, 2))
383 			break;
384 		else if (g_handleattr(bp, "GEOM::hba_subdevice",
385 		    &dp->d_hba_subdevice, 2))
386 			break;
387 		else if (!strcmp(bp->bio_attribute, "GEOM::kerneldump"))
388 			g_disk_kerneldump(bp, dp);
389 		else if (!strcmp(bp->bio_attribute, "GEOM::setstate"))
390 			g_disk_setstate(bp, sc);
391 		else
392 			error = ENOIOCTL;
393 		break;
394 	case BIO_FLUSH:
395 		g_trace(G_T_TOPOLOGY, "g_disk_flushcache(%s)",
396 		    bp->bio_to->name);
397 		if (!(dp->d_flags & DISKFLAG_CANFLUSHCACHE)) {
398 			error = EOPNOTSUPP;
399 			break;
400 		}
401 		bp2 = g_clone_bio(bp);
402 		if (bp2 == NULL) {
403 			g_io_deliver(bp, ENOMEM);
404 			return;
405 		}
406 		bp2->bio_done = g_disk_done;
407 		bp2->bio_disk = dp;
408 		g_disk_lock_giant(dp);
409 		dp->d_strategy(bp2);
410 		g_disk_unlock_giant(dp);
411 		break;
412 	default:
413 		error = EOPNOTSUPP;
414 		break;
415 	}
416 	if (error != EJUSTRETURN)
417 		g_io_deliver(bp, error);
418 	return;
419 }
420 
421 static void
422 g_disk_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp, struct g_consumer *cp, struct g_provider *pp)
423 {
424 	struct disk *dp;
425 	struct g_disk_softc *sc;
426 
427 	sc = gp->softc;
428 	if (sc == NULL || (dp = sc->dp) == NULL)
429 		return;
430 	if (indent == NULL) {
431 		sbuf_printf(sb, " hd %u", dp->d_fwheads);
432 		sbuf_printf(sb, " sc %u", dp->d_fwsectors);
433 		return;
434 	}
435 	if (pp != NULL) {
436 		sbuf_printf(sb, "%s<fwheads>%u</fwheads>\n",
437 		    indent, dp->d_fwheads);
438 		sbuf_printf(sb, "%s<fwsectors>%u</fwsectors>\n",
439 		    indent, dp->d_fwsectors);
440 		sbuf_printf(sb, "%s<ident>%s</ident>\n", indent, dp->d_ident);
441 		sbuf_printf(sb, "%s<descr>%s</descr>\n", indent, dp->d_descr);
442 	}
443 }
444 
445 static void
446 g_disk_create(void *arg, int flag)
447 {
448 	struct g_geom *gp;
449 	struct g_provider *pp;
450 	struct disk *dp;
451 	struct g_disk_softc *sc;
452 	char tmpstr[80];
453 
454 	if (flag == EV_CANCEL)
455 		return;
456 	g_topology_assert();
457 	dp = arg;
458 	sc = g_malloc(sizeof(*sc), M_WAITOK | M_ZERO);
459 	sc->dp = dp;
460 	gp = g_new_geomf(&g_disk_class, "%s%d", dp->d_name, dp->d_unit);
461 	gp->softc = sc;
462 	pp = g_new_providerf(gp, "%s", gp->name);
463 	pp->mediasize = dp->d_mediasize;
464 	pp->sectorsize = dp->d_sectorsize;
465 	if (dp->d_flags & DISKFLAG_CANDELETE)
466 		pp->flags |= G_PF_CANDELETE;
467 	pp->stripeoffset = dp->d_stripeoffset;
468 	pp->stripesize = dp->d_stripesize;
469 	if (bootverbose)
470 		printf("GEOM: new disk %s\n", gp->name);
471 	sysctl_ctx_init(&sc->sysctl_ctx);
472 	snprintf(tmpstr, sizeof(tmpstr), "GEOM disk %s", gp->name);
473 	sc->sysctl_tree = SYSCTL_ADD_NODE(&sc->sysctl_ctx,
474 		SYSCTL_STATIC_CHILDREN(_kern_geom_disk), OID_AUTO, gp->name,
475 		CTLFLAG_RD, 0, tmpstr);
476 	if (sc->sysctl_tree != NULL) {
477 		snprintf(tmpstr, sizeof(tmpstr),
478 		    "kern.geom.disk.%s.led", gp->name);
479 		TUNABLE_STR_FETCH(tmpstr, sc->led, sizeof(sc->led));
480 		SYSCTL_ADD_STRING(&sc->sysctl_ctx,
481 		    SYSCTL_CHILDREN(sc->sysctl_tree), OID_AUTO, "led",
482 		    CTLFLAG_RW | CTLFLAG_TUN, sc->led, sizeof(sc->led),
483 		    "LED name");
484 	}
485 	pp->private = sc;
486 	dp->d_geom = gp;
487 	g_error_provider(pp, 0);
488 }
489 
490 static void
491 g_disk_destroy(void *ptr, int flag)
492 {
493 	struct disk *dp;
494 	struct g_geom *gp;
495 	struct g_disk_softc *sc;
496 
497 	g_topology_assert();
498 	dp = ptr;
499 	gp = dp->d_geom;
500 	if (gp != NULL) {
501 		sc = gp->softc;
502 		if (sc->sysctl_tree != NULL) {
503 			sysctl_ctx_free(&sc->sysctl_ctx);
504 			sc->sysctl_tree = NULL;
505 		}
506 		if (sc->led[0] != 0) {
507 			led_set(sc->led, "0");
508 			sc->led[0] = 0;
509 		}
510 		g_free(sc);
511 		gp->softc = NULL;
512 		g_wither_geom(gp, ENXIO);
513 	}
514 	g_free(dp);
515 }
516 
517 /*
518  * We only allow printable characters in disk ident,
519  * the rest is converted to 'x<HH>'.
520  */
521 static void
522 g_disk_ident_adjust(char *ident, size_t size)
523 {
524 	char *p, tmp[4], newid[DISK_IDENT_SIZE];
525 
526 	newid[0] = '\0';
527 	for (p = ident; *p != '\0'; p++) {
528 		if (isprint(*p)) {
529 			tmp[0] = *p;
530 			tmp[1] = '\0';
531 		} else {
532 			snprintf(tmp, sizeof(tmp), "x%02hhx",
533 			    *(unsigned char *)p);
534 		}
535 		if (strlcat(newid, tmp, sizeof(newid)) >= sizeof(newid))
536 			break;
537 	}
538 	bzero(ident, size);
539 	strlcpy(ident, newid, size);
540 }
541 
542 struct disk *
543 disk_alloc(void)
544 {
545 
546 	return (g_malloc(sizeof(struct disk), M_WAITOK | M_ZERO));
547 }
548 
549 void
550 disk_create(struct disk *dp, int version)
551 {
552 
553 	if (version != DISK_VERSION_00 && version != DISK_VERSION_01) {
554 		printf("WARNING: Attempt to add disk %s%d %s",
555 		    dp->d_name, dp->d_unit,
556 		    " using incompatible ABI version of disk(9)\n");
557 		printf("WARNING: Ignoring disk %s%d\n",
558 		    dp->d_name, dp->d_unit);
559 		return;
560 	}
561 	KASSERT(dp->d_strategy != NULL, ("disk_create need d_strategy"));
562 	KASSERT(dp->d_name != NULL, ("disk_create need d_name"));
563 	KASSERT(*dp->d_name != 0, ("disk_create need d_name"));
564 	KASSERT(strlen(dp->d_name) < SPECNAMELEN - 4, ("disk name too long"));
565 	if (dp->d_devstat == NULL)
566 		dp->d_devstat = devstat_new_entry(dp->d_name, dp->d_unit,
567 		    dp->d_sectorsize, DEVSTAT_ALL_SUPPORTED,
568 		    DEVSTAT_TYPE_DIRECT, DEVSTAT_PRIORITY_MAX);
569 	dp->d_geom = NULL;
570 	g_disk_ident_adjust(dp->d_ident, sizeof(dp->d_ident));
571 	g_post_event(g_disk_create, dp, M_WAITOK, dp, NULL);
572 }
573 
574 void
575 disk_destroy(struct disk *dp)
576 {
577 
578 	g_cancel_event(dp);
579 	dp->d_destroyed = 1;
580 	if (dp->d_devstat != NULL)
581 		devstat_remove_entry(dp->d_devstat);
582 	g_post_event(g_disk_destroy, dp, M_WAITOK, NULL);
583 }
584 
585 void
586 disk_gone(struct disk *dp)
587 {
588 	struct g_geom *gp;
589 	struct g_provider *pp;
590 
591 	gp = dp->d_geom;
592 	if (gp != NULL)
593 		LIST_FOREACH(pp, &gp->provider, provider)
594 			g_wither_provider(pp, ENXIO);
595 }
596 
597 void
598 disk_attr_changed(struct disk *dp, const char *attr, int flag)
599 {
600 	struct g_geom *gp;
601 	struct g_provider *pp;
602 
603 	gp = dp->d_geom;
604 	if (gp != NULL)
605 		LIST_FOREACH(pp, &gp->provider, provider)
606 			(void)g_attr_changed(pp, attr, flag);
607 }
608 
609 static void
610 g_kern_disks(void *p, int flag __unused)
611 {
612 	struct sbuf *sb;
613 	struct g_geom *gp;
614 	char *sp;
615 
616 	sb = p;
617 	sp = "";
618 	g_topology_assert();
619 	LIST_FOREACH(gp, &g_disk_class.geom, geom) {
620 		sbuf_printf(sb, "%s%s", sp, gp->name);
621 		sp = " ";
622 	}
623 	sbuf_finish(sb);
624 }
625 
626 static int
627 sysctl_disks(SYSCTL_HANDLER_ARGS)
628 {
629 	int error;
630 	struct sbuf *sb;
631 
632 	sb = sbuf_new_auto();
633 	g_waitfor_event(g_kern_disks, sb, M_WAITOK, NULL);
634 	error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1);
635 	sbuf_delete(sb);
636 	return error;
637 }
638 
639 SYSCTL_PROC(_kern, OID_AUTO, disks,
640     CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
641     sysctl_disks, "A", "names of available disks");
642