xref: /freebsd/sys/geom/part/g_part_ebr.c (revision 8ef24a0d4b28fe230e20637f56869cc4148cd2ca)
1 /*-
2  * Copyright (c) 2007-2009 Marcel Moolenaar
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  *
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  */
26 
27 #include "opt_geom.h"
28 
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31 
32 #include <sys/param.h>
33 #include <sys/bio.h>
34 #include <sys/diskmbr.h>
35 #include <sys/endian.h>
36 #include <sys/kernel.h>
37 #include <sys/kobj.h>
38 #include <sys/limits.h>
39 #include <sys/lock.h>
40 #include <sys/malloc.h>
41 #include <sys/mutex.h>
42 #include <sys/queue.h>
43 #include <sys/sbuf.h>
44 #include <sys/systm.h>
45 #include <sys/sysctl.h>
46 #include <geom/geom.h>
47 #include <geom/part/g_part.h>
48 
49 #include "g_part_if.h"
50 
51 FEATURE(geom_part_ebr,
52     "GEOM partitioning class for extended boot records support");
53 #if defined(GEOM_PART_EBR_COMPAT)
54 FEATURE(geom_part_ebr_compat,
55     "GEOM EBR partitioning class: backward-compatible partition names");
56 #endif
57 
58 #define	EBRSIZE		512
59 
60 struct g_part_ebr_table {
61 	struct g_part_table	base;
62 #ifndef GEOM_PART_EBR_COMPAT
63 	u_char		ebr[EBRSIZE];
64 #endif
65 };
66 
67 struct g_part_ebr_entry {
68 	struct g_part_entry	base;
69 	struct dos_partition	ent;
70 };
71 
72 static int g_part_ebr_add(struct g_part_table *, struct g_part_entry *,
73     struct g_part_parms *);
74 static int g_part_ebr_create(struct g_part_table *, struct g_part_parms *);
75 static int g_part_ebr_destroy(struct g_part_table *, struct g_part_parms *);
76 static void g_part_ebr_dumpconf(struct g_part_table *, struct g_part_entry *,
77     struct sbuf *, const char *);
78 static int g_part_ebr_dumpto(struct g_part_table *, struct g_part_entry *);
79 #if defined(GEOM_PART_EBR_COMPAT)
80 static void g_part_ebr_fullname(struct g_part_table *, struct g_part_entry *,
81     struct sbuf *, const char *);
82 #endif
83 static int g_part_ebr_modify(struct g_part_table *, struct g_part_entry *,
84     struct g_part_parms *);
85 static const char *g_part_ebr_name(struct g_part_table *, struct g_part_entry *,
86     char *, size_t);
87 static int g_part_ebr_precheck(struct g_part_table *, enum g_part_ctl,
88     struct g_part_parms *);
89 static int g_part_ebr_probe(struct g_part_table *, struct g_consumer *);
90 static int g_part_ebr_read(struct g_part_table *, struct g_consumer *);
91 static int g_part_ebr_setunset(struct g_part_table *, struct g_part_entry *,
92     const char *, unsigned int);
93 static const char *g_part_ebr_type(struct g_part_table *, struct g_part_entry *,
94     char *, size_t);
95 static int g_part_ebr_write(struct g_part_table *, struct g_consumer *);
96 static int g_part_ebr_resize(struct g_part_table *, struct g_part_entry *,
97     struct g_part_parms *);
98 
99 static kobj_method_t g_part_ebr_methods[] = {
100 	KOBJMETHOD(g_part_add,		g_part_ebr_add),
101 	KOBJMETHOD(g_part_create,	g_part_ebr_create),
102 	KOBJMETHOD(g_part_destroy,	g_part_ebr_destroy),
103 	KOBJMETHOD(g_part_dumpconf,	g_part_ebr_dumpconf),
104 	KOBJMETHOD(g_part_dumpto,	g_part_ebr_dumpto),
105 #if defined(GEOM_PART_EBR_COMPAT)
106 	KOBJMETHOD(g_part_fullname,	g_part_ebr_fullname),
107 #endif
108 	KOBJMETHOD(g_part_modify,	g_part_ebr_modify),
109 	KOBJMETHOD(g_part_name,		g_part_ebr_name),
110 	KOBJMETHOD(g_part_precheck,	g_part_ebr_precheck),
111 	KOBJMETHOD(g_part_probe,	g_part_ebr_probe),
112 	KOBJMETHOD(g_part_read,		g_part_ebr_read),
113 	KOBJMETHOD(g_part_resize,	g_part_ebr_resize),
114 	KOBJMETHOD(g_part_setunset,	g_part_ebr_setunset),
115 	KOBJMETHOD(g_part_type,		g_part_ebr_type),
116 	KOBJMETHOD(g_part_write,	g_part_ebr_write),
117 	{ 0, 0 }
118 };
119 
120 static struct g_part_scheme g_part_ebr_scheme = {
121 	"EBR",
122 	g_part_ebr_methods,
123 	sizeof(struct g_part_ebr_table),
124 	.gps_entrysz = sizeof(struct g_part_ebr_entry),
125 	.gps_minent = 1,
126 	.gps_maxent = INT_MAX,
127 };
128 G_PART_SCHEME_DECLARE(g_part_ebr);
129 
130 static struct g_part_ebr_alias {
131 	u_char		typ;
132 	int		alias;
133 } ebr_alias_match[] = {
134 	{ DOSPTYP_386BSD,	G_PART_ALIAS_FREEBSD },
135 	{ DOSPTYP_NTFS,		G_PART_ALIAS_MS_NTFS },
136 	{ DOSPTYP_FAT32,	G_PART_ALIAS_MS_FAT32 },
137 	{ DOSPTYP_LINSWP,	G_PART_ALIAS_LINUX_SWAP },
138 	{ DOSPTYP_LINUX,	G_PART_ALIAS_LINUX_DATA },
139 	{ DOSPTYP_LINLVM,	G_PART_ALIAS_LINUX_LVM },
140 	{ DOSPTYP_LINRAID,	G_PART_ALIAS_LINUX_RAID },
141 };
142 
143 static void ebr_set_chs(struct g_part_table *, uint32_t, u_char *, u_char *,
144     u_char *);
145 
146 static void
147 ebr_entry_decode(const char *p, struct dos_partition *ent)
148 {
149 	ent->dp_flag = p[0];
150 	ent->dp_shd = p[1];
151 	ent->dp_ssect = p[2];
152 	ent->dp_scyl = p[3];
153 	ent->dp_typ = p[4];
154 	ent->dp_ehd = p[5];
155 	ent->dp_esect = p[6];
156 	ent->dp_ecyl = p[7];
157 	ent->dp_start = le32dec(p + 8);
158 	ent->dp_size = le32dec(p + 12);
159 }
160 
161 static void
162 ebr_entry_link(struct g_part_table *table, uint32_t start, uint32_t end,
163    u_char *buf)
164 {
165 
166 	buf[0] = 0 /* dp_flag */;
167 	ebr_set_chs(table, start, &buf[3] /* dp_scyl */, &buf[1] /* dp_shd */,
168 	    &buf[2] /* dp_ssect */);
169 	buf[4] = 5 /* dp_typ */;
170 	ebr_set_chs(table, end, &buf[7] /* dp_ecyl */, &buf[5] /* dp_ehd */,
171 	    &buf[6] /* dp_esect */);
172 	le32enc(buf + 8, start);
173 	le32enc(buf + 12, end - start + 1);
174 }
175 
176 static int
177 ebr_parse_type(const char *type, u_char *dp_typ)
178 {
179 	const char *alias;
180 	char *endp;
181 	long lt;
182 	int i;
183 
184 	if (type[0] == '!') {
185 		lt = strtol(type + 1, &endp, 0);
186 		if (type[1] == '\0' || *endp != '\0' || lt <= 0 || lt >= 256)
187 			return (EINVAL);
188 		*dp_typ = (u_char)lt;
189 		return (0);
190 	}
191 	for (i = 0; i < nitems(ebr_alias_match); i++) {
192 		alias = g_part_alias_name(ebr_alias_match[i].alias);
193 		if (strcasecmp(type, alias) == 0) {
194 			*dp_typ = ebr_alias_match[i].typ;
195 			return (0);
196 		}
197 	}
198 	return (EINVAL);
199 }
200 
201 
202 static void
203 ebr_set_chs(struct g_part_table *table, uint32_t lba, u_char *cylp, u_char *hdp,
204     u_char *secp)
205 {
206 	uint32_t cyl, hd, sec;
207 
208 	sec = lba % table->gpt_sectors + 1;
209 	lba /= table->gpt_sectors;
210 	hd = lba % table->gpt_heads;
211 	lba /= table->gpt_heads;
212 	cyl = lba;
213 	if (cyl > 1023)
214 		sec = hd = cyl = ~0;
215 
216 	*cylp = cyl & 0xff;
217 	*hdp = hd & 0xff;
218 	*secp = (sec & 0x3f) | ((cyl >> 2) & 0xc0);
219 }
220 
221 static int
222 ebr_align(struct g_part_table *basetable, uint32_t *start, uint32_t *size)
223 {
224 	uint32_t sectors;
225 
226 	sectors = basetable->gpt_sectors;
227 	if (*size < 2 * sectors)
228 		return (EINVAL);
229 	if (*start % sectors) {
230 		*size += (*start % sectors) - sectors;
231 		*start -= (*start % sectors) - sectors;
232 	}
233 	if (*size % sectors)
234 		*size -= (*size % sectors);
235 	if (*size < 2 * sectors)
236 		return (EINVAL);
237 	return (0);
238 }
239 
240 
241 static int
242 g_part_ebr_add(struct g_part_table *basetable, struct g_part_entry *baseentry,
243     struct g_part_parms *gpp)
244 {
245 	struct g_provider *pp;
246 	struct g_part_ebr_entry *entry;
247 	uint32_t start, size;
248 
249 	if (gpp->gpp_parms & G_PART_PARM_LABEL)
250 		return (EINVAL);
251 
252 	pp = LIST_FIRST(&basetable->gpt_gp->consumer)->provider;
253 	entry = (struct g_part_ebr_entry *)baseentry;
254 	start = gpp->gpp_start;
255 	size = gpp->gpp_size;
256 	if (ebr_align(basetable, &start, &size) != 0)
257 		return (EINVAL);
258 	if (baseentry->gpe_deleted)
259 		bzero(&entry->ent, sizeof(entry->ent));
260 
261 	KASSERT(baseentry->gpe_start <= start, ("%s", __func__));
262 	KASSERT(baseentry->gpe_end >= start + size - 1, ("%s", __func__));
263 	baseentry->gpe_index = (start / basetable->gpt_sectors) + 1;
264 	baseentry->gpe_offset =
265 	    (off_t)(start + basetable->gpt_sectors) * pp->sectorsize;
266 	baseentry->gpe_start = start;
267 	baseentry->gpe_end = start + size - 1;
268 	entry->ent.dp_start = basetable->gpt_sectors;
269 	entry->ent.dp_size = size - basetable->gpt_sectors;
270 	ebr_set_chs(basetable, entry->ent.dp_start, &entry->ent.dp_scyl,
271 	    &entry->ent.dp_shd, &entry->ent.dp_ssect);
272 	ebr_set_chs(basetable, baseentry->gpe_end, &entry->ent.dp_ecyl,
273 	    &entry->ent.dp_ehd, &entry->ent.dp_esect);
274 	return (ebr_parse_type(gpp->gpp_type, &entry->ent.dp_typ));
275 }
276 
277 static int
278 g_part_ebr_create(struct g_part_table *basetable, struct g_part_parms *gpp)
279 {
280 	char type[64];
281 	struct g_consumer *cp;
282 	struct g_provider *pp;
283 	uint32_t msize;
284 	int error;
285 
286 	pp = gpp->gpp_provider;
287 
288 	if (pp->sectorsize < EBRSIZE)
289 		return (ENOSPC);
290 	if (pp->sectorsize > 4096)
291 		return (ENXIO);
292 
293 	/* Check that we have a parent and that it's a MBR. */
294 	if (basetable->gpt_depth == 0)
295 		return (ENXIO);
296 	cp = LIST_FIRST(&pp->consumers);
297 	error = g_getattr("PART::scheme", cp, &type);
298 	if (error != 0)
299 		return (error);
300 	if (strcmp(type, "MBR") != 0)
301 		return (ENXIO);
302 	error = g_getattr("PART::type", cp, &type);
303 	if (error != 0)
304 		return (error);
305 	if (strcmp(type, "ebr") != 0)
306 		return (ENXIO);
307 
308 	msize = MIN(pp->mediasize / pp->sectorsize, UINT32_MAX);
309 	basetable->gpt_first = 0;
310 	basetable->gpt_last = msize - 1;
311 	basetable->gpt_entries = msize / basetable->gpt_sectors;
312 	return (0);
313 }
314 
315 static int
316 g_part_ebr_destroy(struct g_part_table *basetable, struct g_part_parms *gpp)
317 {
318 
319 	/* Wipe the first sector to clear the partitioning. */
320 	basetable->gpt_smhead |= 1;
321 	return (0);
322 }
323 
324 static void
325 g_part_ebr_dumpconf(struct g_part_table *table, struct g_part_entry *baseentry,
326     struct sbuf *sb, const char *indent)
327 {
328 	struct g_part_ebr_entry *entry;
329 
330 	entry = (struct g_part_ebr_entry *)baseentry;
331 	if (indent == NULL) {
332 		/* conftxt: libdisk compatibility */
333 		sbuf_printf(sb, " xs MBREXT xt %u", entry->ent.dp_typ);
334 	} else if (entry != NULL) {
335 		/* confxml: partition entry information */
336 		sbuf_printf(sb, "%s<rawtype>%u</rawtype>\n", indent,
337 		    entry->ent.dp_typ);
338 		if (entry->ent.dp_flag & 0x80)
339 			sbuf_printf(sb, "%s<attrib>active</attrib>\n", indent);
340 	} else {
341 		/* confxml: scheme information */
342 	}
343 }
344 
345 static int
346 g_part_ebr_dumpto(struct g_part_table *table, struct g_part_entry *baseentry)
347 {
348 	struct g_part_ebr_entry *entry;
349 
350 	/* Allow dumping to a FreeBSD partition or Linux swap partition only. */
351 	entry = (struct g_part_ebr_entry *)baseentry;
352 	return ((entry->ent.dp_typ == DOSPTYP_386BSD ||
353 	    entry->ent.dp_typ == DOSPTYP_LINSWP) ? 1 : 0);
354 }
355 
356 #if defined(GEOM_PART_EBR_COMPAT)
357 static void
358 g_part_ebr_fullname(struct g_part_table *table, struct g_part_entry *entry,
359     struct sbuf *sb, const char *pfx)
360 {
361 	struct g_part_entry *iter;
362 	u_int idx;
363 
364 	idx = 5;
365 	LIST_FOREACH(iter, &table->gpt_entry, gpe_entry) {
366 		if (iter == entry)
367 			break;
368 		idx++;
369 	}
370 	sbuf_printf(sb, "%.*s%u", (int)strlen(pfx) - 1, pfx, idx);
371 }
372 #endif
373 
374 static int
375 g_part_ebr_modify(struct g_part_table *basetable,
376     struct g_part_entry *baseentry, struct g_part_parms *gpp)
377 {
378 	struct g_part_ebr_entry *entry;
379 
380 	if (gpp->gpp_parms & G_PART_PARM_LABEL)
381 		return (EINVAL);
382 
383 	entry = (struct g_part_ebr_entry *)baseentry;
384 	if (gpp->gpp_parms & G_PART_PARM_TYPE)
385 		return (ebr_parse_type(gpp->gpp_type, &entry->ent.dp_typ));
386 	return (0);
387 }
388 
389 static int
390 g_part_ebr_resize(struct g_part_table *basetable,
391     struct g_part_entry *baseentry, struct g_part_parms *gpp)
392 {
393 	struct g_provider *pp;
394 
395 	if (baseentry != NULL)
396 		return (EOPNOTSUPP);
397 	pp = LIST_FIRST(&basetable->gpt_gp->consumer)->provider;
398 	basetable->gpt_last = MIN(pp->mediasize / pp->sectorsize,
399 	    UINT32_MAX) - 1;
400 	return (0);
401 }
402 
403 static const char *
404 g_part_ebr_name(struct g_part_table *table, struct g_part_entry *entry,
405     char *buf, size_t bufsz)
406 {
407 
408 	snprintf(buf, bufsz, "+%08u", entry->gpe_index);
409 	return (buf);
410 }
411 
412 static int
413 g_part_ebr_precheck(struct g_part_table *table, enum g_part_ctl req,
414     struct g_part_parms *gpp)
415 {
416 #if defined(GEOM_PART_EBR_COMPAT)
417 	if (req == G_PART_CTL_DESTROY)
418 		return (0);
419 	return (ECANCELED);
420 #else
421 	/*
422 	 * The index is a function of the start of the partition.
423 	 * This is not something the user can override, nor is it
424 	 * something the common code will do right. We can set the
425 	 * index now so that we get what we need.
426 	 */
427 	if (req == G_PART_CTL_ADD)
428 		gpp->gpp_index = (gpp->gpp_start / table->gpt_sectors) + 1;
429 	return (0);
430 #endif
431 }
432 
433 static int
434 g_part_ebr_probe(struct g_part_table *table, struct g_consumer *cp)
435 {
436 	char type[64];
437 	struct g_provider *pp;
438 	u_char *buf, *p;
439 	int error, index, res;
440 	uint16_t magic;
441 
442 	pp = cp->provider;
443 
444 	/* Sanity-check the provider. */
445 	if (pp->sectorsize < EBRSIZE || pp->mediasize < pp->sectorsize)
446 		return (ENOSPC);
447 	if (pp->sectorsize > 4096)
448 		return (ENXIO);
449 
450 	/* Check that we have a parent and that it's a MBR. */
451 	if (table->gpt_depth == 0)
452 		return (ENXIO);
453 	error = g_getattr("PART::scheme", cp, &type);
454 	if (error != 0)
455 		return (error);
456 	if (strcmp(type, "MBR") != 0)
457 		return (ENXIO);
458 	/* Check that partition has type DOSPTYP_EBR. */
459 	error = g_getattr("PART::type", cp, &type);
460 	if (error != 0)
461 		return (error);
462 	if (strcmp(type, "ebr") != 0)
463 		return (ENXIO);
464 
465 	/* Check that there's a EBR. */
466 	buf = g_read_data(cp, 0L, pp->sectorsize, &error);
467 	if (buf == NULL)
468 		return (error);
469 
470 	/* We goto out on mismatch. */
471 	res = ENXIO;
472 
473 	magic = le16dec(buf + DOSMAGICOFFSET);
474 	if (magic != DOSMAGIC)
475 		goto out;
476 
477 	for (index = 0; index < 2; index++) {
478 		p = buf + DOSPARTOFF + index * DOSPARTSIZE;
479 		if (p[0] != 0 && p[0] != 0x80)
480 			goto out;
481 	}
482 	res = G_PART_PROBE_PRI_NORM;
483 
484  out:
485 	g_free(buf);
486 	return (res);
487 }
488 
489 static int
490 g_part_ebr_read(struct g_part_table *basetable, struct g_consumer *cp)
491 {
492 	struct dos_partition ent[2];
493 	struct g_provider *pp;
494 	struct g_part_entry *baseentry;
495 	struct g_part_ebr_table *table;
496 	struct g_part_ebr_entry *entry;
497 	u_char *buf;
498 	off_t ofs, msize;
499 	u_int lba;
500 	int error, index;
501 
502 	pp = cp->provider;
503 	table = (struct g_part_ebr_table *)basetable;
504 	msize = MIN(pp->mediasize / pp->sectorsize, UINT32_MAX);
505 
506 	lba = 0;
507 	while (1) {
508 		ofs = (off_t)lba * pp->sectorsize;
509 		buf = g_read_data(cp, ofs, pp->sectorsize, &error);
510 		if (buf == NULL)
511 			return (error);
512 
513 		ebr_entry_decode(buf + DOSPARTOFF + 0 * DOSPARTSIZE, ent + 0);
514 		ebr_entry_decode(buf + DOSPARTOFF + 1 * DOSPARTSIZE, ent + 1);
515 
516 		/* The 3rd & 4th entries should be zeroes. */
517 		if (le64dec(buf + DOSPARTOFF + 2 * DOSPARTSIZE) +
518 		    le64dec(buf + DOSPARTOFF + 3 * DOSPARTSIZE) != 0) {
519 			basetable->gpt_corrupt = 1;
520 			printf("GEOM: %s: invalid entries in the EBR ignored.\n",
521 			    pp->name);
522 		}
523 #ifndef GEOM_PART_EBR_COMPAT
524 		/* Save the first EBR, it can contain a boot code */
525 		if (lba == 0)
526 			bcopy(buf, table->ebr, sizeof(table->ebr));
527 #endif
528 		g_free(buf);
529 
530 		if (ent[0].dp_typ == 0)
531 			break;
532 
533 		if (ent[0].dp_typ == 5 && ent[1].dp_typ == 0) {
534 			lba = ent[0].dp_start;
535 			continue;
536 		}
537 
538 		index = (lba / basetable->gpt_sectors) + 1;
539 		baseentry = (struct g_part_entry *)g_part_new_entry(basetable,
540 		    index, lba, lba + ent[0].dp_start + ent[0].dp_size - 1);
541 		baseentry->gpe_offset = (off_t)(lba + ent[0].dp_start) *
542 		    pp->sectorsize;
543 		entry = (struct g_part_ebr_entry *)baseentry;
544 		entry->ent = ent[0];
545 
546 		if (ent[1].dp_typ == 0)
547 			break;
548 
549 		lba = ent[1].dp_start;
550 	}
551 
552 	basetable->gpt_entries = msize / basetable->gpt_sectors;
553 	basetable->gpt_first = 0;
554 	basetable->gpt_last = msize - 1;
555 	return (0);
556 }
557 
558 static int
559 g_part_ebr_setunset(struct g_part_table *table, struct g_part_entry *baseentry,
560     const char *attrib, unsigned int set)
561 {
562 	struct g_part_entry *iter;
563 	struct g_part_ebr_entry *entry;
564 	int changed;
565 
566 	if (baseentry == NULL)
567 		return (ENODEV);
568 	if (strcasecmp(attrib, "active") != 0)
569 		return (EINVAL);
570 
571 	/* Only one entry can have the active attribute. */
572 	LIST_FOREACH(iter, &table->gpt_entry, gpe_entry) {
573 		if (iter->gpe_deleted)
574 			continue;
575 		changed = 0;
576 		entry = (struct g_part_ebr_entry *)iter;
577 		if (iter == baseentry) {
578 			if (set && (entry->ent.dp_flag & 0x80) == 0) {
579 				entry->ent.dp_flag |= 0x80;
580 				changed = 1;
581 			} else if (!set && (entry->ent.dp_flag & 0x80)) {
582 				entry->ent.dp_flag &= ~0x80;
583 				changed = 1;
584 			}
585 		} else {
586 			if (set && (entry->ent.dp_flag & 0x80)) {
587 				entry->ent.dp_flag &= ~0x80;
588 				changed = 1;
589 			}
590 		}
591 		if (changed && !iter->gpe_created)
592 			iter->gpe_modified = 1;
593 	}
594 	return (0);
595 }
596 
597 static const char *
598 g_part_ebr_type(struct g_part_table *basetable, struct g_part_entry *baseentry,
599     char *buf, size_t bufsz)
600 {
601 	struct g_part_ebr_entry *entry;
602 	int i;
603 
604 	entry = (struct g_part_ebr_entry *)baseentry;
605 	for (i = 0; i < nitems(ebr_alias_match); i++) {
606 		if (ebr_alias_match[i].typ == entry->ent.dp_typ)
607 			return (g_part_alias_name(ebr_alias_match[i].alias));
608 	}
609 	snprintf(buf, bufsz, "!%d", entry->ent.dp_typ);
610 	return (buf);
611 }
612 
613 static int
614 g_part_ebr_write(struct g_part_table *basetable, struct g_consumer *cp)
615 {
616 #ifndef GEOM_PART_EBR_COMPAT
617 	struct g_part_ebr_table *table;
618 #endif
619 	struct g_provider *pp;
620 	struct g_part_entry *baseentry, *next;
621 	struct g_part_ebr_entry *entry;
622 	u_char *buf;
623 	u_char *p;
624 	int error;
625 
626 	pp = cp->provider;
627 	buf = g_malloc(pp->sectorsize, M_WAITOK | M_ZERO);
628 #ifndef GEOM_PART_EBR_COMPAT
629 	table = (struct g_part_ebr_table *)basetable;
630 	bcopy(table->ebr, buf, DOSPARTOFF);
631 #endif
632 	le16enc(buf + DOSMAGICOFFSET, DOSMAGIC);
633 
634 	baseentry = LIST_FIRST(&basetable->gpt_entry);
635 	while (baseentry != NULL && baseentry->gpe_deleted)
636 		baseentry = LIST_NEXT(baseentry, gpe_entry);
637 
638 	/* Wipe-out the first EBR when there are no slices. */
639 	if (baseentry == NULL) {
640 		error = g_write_data(cp, 0, buf, pp->sectorsize);
641 		goto out;
642 	}
643 
644 	/*
645 	 * If the first partition is not in LBA 0, we need to
646 	 * put a "link" EBR in LBA 0.
647 	 */
648 	if (baseentry->gpe_start != 0) {
649 		ebr_entry_link(basetable, (uint32_t)baseentry->gpe_start,
650 		    (uint32_t)baseentry->gpe_end, buf + DOSPARTOFF);
651 		error = g_write_data(cp, 0, buf, pp->sectorsize);
652 		if (error)
653 			goto out;
654 	}
655 
656 	do {
657 		entry = (struct g_part_ebr_entry *)baseentry;
658 
659 		p = buf + DOSPARTOFF;
660 		p[0] = entry->ent.dp_flag;
661 		p[1] = entry->ent.dp_shd;
662 		p[2] = entry->ent.dp_ssect;
663 		p[3] = entry->ent.dp_scyl;
664 		p[4] = entry->ent.dp_typ;
665 		p[5] = entry->ent.dp_ehd;
666 		p[6] = entry->ent.dp_esect;
667 		p[7] = entry->ent.dp_ecyl;
668 		le32enc(p + 8, entry->ent.dp_start);
669 		le32enc(p + 12, entry->ent.dp_size);
670 
671 		next = LIST_NEXT(baseentry, gpe_entry);
672 		while (next != NULL && next->gpe_deleted)
673 			next = LIST_NEXT(next, gpe_entry);
674 
675 		p += DOSPARTSIZE;
676 		if (next != NULL)
677 			ebr_entry_link(basetable, (uint32_t)next->gpe_start,
678 			    (uint32_t)next->gpe_end, p);
679 		else
680 			bzero(p, DOSPARTSIZE);
681 
682 		error = g_write_data(cp, baseentry->gpe_start * pp->sectorsize,
683 		    buf, pp->sectorsize);
684 #ifndef GEOM_PART_EBR_COMPAT
685 		if (baseentry->gpe_start == 0)
686 			bzero(buf, DOSPARTOFF);
687 #endif
688 		baseentry = next;
689 	} while (!error && baseentry != NULL);
690 
691  out:
692 	g_free(buf);
693 	return (error);
694 }
695