g_part_ebr.c revision 265912
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: stable/10/sys/geom/part/g_part_ebr.c 265912 2014-05-12 12:04:44Z ae $");
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
51FEATURE(geom_part_ebr,
52    "GEOM partitioning class for extended boot records support");
53#if defined(GEOM_PART_EBR_COMPAT)
54FEATURE(geom_part_ebr_compat,
55    "GEOM EBR partitioning class: backward-compatible partition names");
56#endif
57
58#define	EBRSIZE		512
59
60struct 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
67struct g_part_ebr_entry {
68	struct g_part_entry	base;
69	struct dos_partition	ent;
70};
71
72static int g_part_ebr_add(struct g_part_table *, struct g_part_entry *,
73    struct g_part_parms *);
74static int g_part_ebr_create(struct g_part_table *, struct g_part_parms *);
75static int g_part_ebr_destroy(struct g_part_table *, struct g_part_parms *);
76static void g_part_ebr_dumpconf(struct g_part_table *, struct g_part_entry *,
77    struct sbuf *, const char *);
78static int g_part_ebr_dumpto(struct g_part_table *, struct g_part_entry *);
79#if defined(GEOM_PART_EBR_COMPAT)
80static void g_part_ebr_fullname(struct g_part_table *, struct g_part_entry *,
81    struct sbuf *, const char *);
82#endif
83static int g_part_ebr_modify(struct g_part_table *, struct g_part_entry *,
84    struct g_part_parms *);
85static const char *g_part_ebr_name(struct g_part_table *, struct g_part_entry *,
86    char *, size_t);
87static int g_part_ebr_precheck(struct g_part_table *, enum g_part_ctl,
88    struct g_part_parms *);
89static int g_part_ebr_probe(struct g_part_table *, struct g_consumer *);
90static int g_part_ebr_read(struct g_part_table *, struct g_consumer *);
91static int g_part_ebr_setunset(struct g_part_table *, struct g_part_entry *,
92    const char *, unsigned int);
93static const char *g_part_ebr_type(struct g_part_table *, struct g_part_entry *,
94    char *, size_t);
95static int g_part_ebr_write(struct g_part_table *, struct g_consumer *);
96static int g_part_ebr_resize(struct g_part_table *, struct g_part_entry *,
97    struct g_part_parms *);
98
99static 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
120static 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};
128G_PART_SCHEME_DECLARE(g_part_ebr);
129
130static 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
143static void ebr_set_chs(struct g_part_table *, uint32_t, u_char *, u_char *,
144    u_char *);
145
146static void
147ebr_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
161static void
162ebr_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
176static int
177ebr_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;
192	    i < sizeof(ebr_alias_match) / sizeof(ebr_alias_match[0]); i++) {
193		alias = g_part_alias_name(ebr_alias_match[i].alias);
194		if (strcasecmp(type, alias) == 0) {
195			*dp_typ = ebr_alias_match[i].typ;
196			return (0);
197		}
198	}
199	return (EINVAL);
200}
201
202
203static void
204ebr_set_chs(struct g_part_table *table, uint32_t lba, u_char *cylp, u_char *hdp,
205    u_char *secp)
206{
207	uint32_t cyl, hd, sec;
208
209	sec = lba % table->gpt_sectors + 1;
210	lba /= table->gpt_sectors;
211	hd = lba % table->gpt_heads;
212	lba /= table->gpt_heads;
213	cyl = lba;
214	if (cyl > 1023)
215		sec = hd = cyl = ~0;
216
217	*cylp = cyl & 0xff;
218	*hdp = hd & 0xff;
219	*secp = (sec & 0x3f) | ((cyl >> 2) & 0xc0);
220}
221
222static int
223ebr_align(struct g_part_table *basetable, uint32_t *start, uint32_t *size)
224{
225	uint32_t sectors;
226
227	sectors = basetable->gpt_sectors;
228	if (*size < 2 * sectors)
229		return (EINVAL);
230	if (*start % sectors) {
231		*size += (*start % sectors) - sectors;
232		*start -= (*start % sectors) - sectors;
233	}
234	if (*size % sectors)
235		*size -= (*size % sectors);
236	if (*size < 2 * sectors)
237		return (EINVAL);
238	return (0);
239}
240
241
242static int
243g_part_ebr_add(struct g_part_table *basetable, struct g_part_entry *baseentry,
244    struct g_part_parms *gpp)
245{
246	struct g_provider *pp;
247	struct g_part_ebr_entry *entry;
248	uint32_t start, size;
249
250	if (gpp->gpp_parms & G_PART_PARM_LABEL)
251		return (EINVAL);
252
253	pp = LIST_FIRST(&basetable->gpt_gp->consumer)->provider;
254	entry = (struct g_part_ebr_entry *)baseentry;
255	start = gpp->gpp_start;
256	size = gpp->gpp_size;
257	if (ebr_align(basetable, &start, &size) != 0)
258		return (EINVAL);
259	if (baseentry->gpe_deleted)
260		bzero(&entry->ent, sizeof(entry->ent));
261
262	KASSERT(baseentry->gpe_start <= start, ("%s", __func__));
263	KASSERT(baseentry->gpe_end >= start + size - 1, ("%s", __func__));
264	baseentry->gpe_index = (start / basetable->gpt_sectors) + 1;
265	baseentry->gpe_offset =
266	    (off_t)(start + basetable->gpt_sectors) * pp->sectorsize;
267	baseentry->gpe_start = start;
268	baseentry->gpe_end = start + size - 1;
269	entry->ent.dp_start = basetable->gpt_sectors;
270	entry->ent.dp_size = size - basetable->gpt_sectors;
271	ebr_set_chs(basetable, entry->ent.dp_start, &entry->ent.dp_scyl,
272	    &entry->ent.dp_shd, &entry->ent.dp_ssect);
273	ebr_set_chs(basetable, baseentry->gpe_end, &entry->ent.dp_ecyl,
274	    &entry->ent.dp_ehd, &entry->ent.dp_esect);
275	return (ebr_parse_type(gpp->gpp_type, &entry->ent.dp_typ));
276}
277
278static int
279g_part_ebr_create(struct g_part_table *basetable, struct g_part_parms *gpp)
280{
281	char type[64];
282	struct g_consumer *cp;
283	struct g_provider *pp;
284	uint32_t msize;
285	int error;
286
287	pp = gpp->gpp_provider;
288
289	if (pp->sectorsize < EBRSIZE)
290		return (ENOSPC);
291	if (pp->sectorsize > 4096)
292		return (ENXIO);
293
294	/* Check that we have a parent and that it's a MBR. */
295	if (basetable->gpt_depth == 0)
296		return (ENXIO);
297	cp = LIST_FIRST(&pp->consumers);
298	error = g_getattr("PART::scheme", cp, &type);
299	if (error != 0)
300		return (error);
301	if (strcmp(type, "MBR") != 0)
302		return (ENXIO);
303	error = g_getattr("PART::type", cp, &type);
304	if (error != 0)
305		return (error);
306	if (strcmp(type, "ebr") != 0)
307		return (ENXIO);
308
309	msize = MIN(pp->mediasize / pp->sectorsize, UINT32_MAX);
310	basetable->gpt_first = 0;
311	basetable->gpt_last = msize - 1;
312	basetable->gpt_entries = msize / basetable->gpt_sectors;
313	return (0);
314}
315
316static int
317g_part_ebr_destroy(struct g_part_table *basetable, struct g_part_parms *gpp)
318{
319
320	/* Wipe the first sector to clear the partitioning. */
321	basetable->gpt_smhead |= 1;
322	return (0);
323}
324
325static void
326g_part_ebr_dumpconf(struct g_part_table *table, struct g_part_entry *baseentry,
327    struct sbuf *sb, const char *indent)
328{
329	struct g_part_ebr_entry *entry;
330
331	entry = (struct g_part_ebr_entry *)baseentry;
332	if (indent == NULL) {
333		/* conftxt: libdisk compatibility */
334		sbuf_printf(sb, " xs MBREXT xt %u", entry->ent.dp_typ);
335	} else if (entry != NULL) {
336		/* confxml: partition entry information */
337		sbuf_printf(sb, "%s<rawtype>%u</rawtype>\n", indent,
338		    entry->ent.dp_typ);
339		if (entry->ent.dp_flag & 0x80)
340			sbuf_printf(sb, "%s<attrib>active</attrib>\n", indent);
341	} else {
342		/* confxml: scheme information */
343	}
344}
345
346static int
347g_part_ebr_dumpto(struct g_part_table *table, struct g_part_entry *baseentry)
348{
349	struct g_part_ebr_entry *entry;
350
351	/* Allow dumping to a FreeBSD partition or Linux swap partition only. */
352	entry = (struct g_part_ebr_entry *)baseentry;
353	return ((entry->ent.dp_typ == DOSPTYP_386BSD ||
354	    entry->ent.dp_typ == DOSPTYP_LINSWP) ? 1 : 0);
355}
356
357#if defined(GEOM_PART_EBR_COMPAT)
358static void
359g_part_ebr_fullname(struct g_part_table *table, struct g_part_entry *entry,
360    struct sbuf *sb, const char *pfx)
361{
362	struct g_part_entry *iter;
363	u_int idx;
364
365	idx = 5;
366	LIST_FOREACH(iter, &table->gpt_entry, gpe_entry) {
367		if (iter == entry)
368			break;
369		idx++;
370	}
371	sbuf_printf(sb, "%.*s%u", (int)strlen(pfx) - 1, pfx, idx);
372}
373#endif
374
375static int
376g_part_ebr_modify(struct g_part_table *basetable,
377    struct g_part_entry *baseentry, struct g_part_parms *gpp)
378{
379	struct g_part_ebr_entry *entry;
380
381	if (gpp->gpp_parms & G_PART_PARM_LABEL)
382		return (EINVAL);
383
384	entry = (struct g_part_ebr_entry *)baseentry;
385	if (gpp->gpp_parms & G_PART_PARM_TYPE)
386		return (ebr_parse_type(gpp->gpp_type, &entry->ent.dp_typ));
387	return (0);
388}
389
390static int
391g_part_ebr_resize(struct g_part_table *basetable,
392    struct g_part_entry *baseentry, struct g_part_parms *gpp)
393{
394	struct g_provider *pp;
395
396	if (baseentry != NULL)
397		return (EOPNOTSUPP);
398	pp = LIST_FIRST(&basetable->gpt_gp->consumer)->provider;
399	basetable->gpt_last = MIN(pp->mediasize / pp->sectorsize,
400	    UINT32_MAX) - 1;
401	return (0);
402}
403
404static const char *
405g_part_ebr_name(struct g_part_table *table, struct g_part_entry *entry,
406    char *buf, size_t bufsz)
407{
408
409	snprintf(buf, bufsz, "+%08u", entry->gpe_index);
410	return (buf);
411}
412
413static int
414g_part_ebr_precheck(struct g_part_table *table, enum g_part_ctl req,
415    struct g_part_parms *gpp)
416{
417#if defined(GEOM_PART_EBR_COMPAT)
418	if (req == G_PART_CTL_DESTROY)
419		return (0);
420	return (ECANCELED);
421#else
422	/*
423	 * The index is a function of the start of the partition.
424	 * This is not something the user can override, nor is it
425	 * something the common code will do right. We can set the
426	 * index now so that we get what we need.
427	 */
428	if (req == G_PART_CTL_ADD)
429		gpp->gpp_index = (gpp->gpp_start / table->gpt_sectors) + 1;
430	return (0);
431#endif
432}
433
434static int
435g_part_ebr_probe(struct g_part_table *table, struct g_consumer *cp)
436{
437	char type[64];
438	struct g_provider *pp;
439	u_char *buf, *p;
440	int error, index, res;
441	uint16_t magic;
442
443	pp = cp->provider;
444
445	/* Sanity-check the provider. */
446	if (pp->sectorsize < EBRSIZE || pp->mediasize < pp->sectorsize)
447		return (ENOSPC);
448	if (pp->sectorsize > 4096)
449		return (ENXIO);
450
451	/* Check that we have a parent and that it's a MBR. */
452	if (table->gpt_depth == 0)
453		return (ENXIO);
454	error = g_getattr("PART::scheme", cp, &type);
455	if (error != 0)
456		return (error);
457	if (strcmp(type, "MBR") != 0)
458		return (ENXIO);
459	/* Check that partition has type DOSPTYP_EBR. */
460	error = g_getattr("PART::type", cp, &type);
461	if (error != 0)
462		return (error);
463	if (strcmp(type, "ebr") != 0)
464		return (ENXIO);
465
466	/* Check that there's a EBR. */
467	buf = g_read_data(cp, 0L, pp->sectorsize, &error);
468	if (buf == NULL)
469		return (error);
470
471	/* We goto out on mismatch. */
472	res = ENXIO;
473
474	magic = le16dec(buf + DOSMAGICOFFSET);
475	if (magic != DOSMAGIC)
476		goto out;
477
478	for (index = 0; index < 2; index++) {
479		p = buf + DOSPARTOFF + index * DOSPARTSIZE;
480		if (p[0] != 0 && p[0] != 0x80)
481			goto out;
482	}
483	res = G_PART_PROBE_PRI_NORM;
484
485 out:
486	g_free(buf);
487	return (res);
488}
489
490static int
491g_part_ebr_read(struct g_part_table *basetable, struct g_consumer *cp)
492{
493	struct dos_partition ent[2];
494	struct g_provider *pp;
495	struct g_part_entry *baseentry;
496	struct g_part_ebr_table *table;
497	struct g_part_ebr_entry *entry;
498	u_char *buf;
499	off_t ofs, msize;
500	u_int lba;
501	int error, index;
502
503	pp = cp->provider;
504	table = (struct g_part_ebr_table *)basetable;
505	msize = MIN(pp->mediasize / pp->sectorsize, UINT32_MAX);
506
507	lba = 0;
508	while (1) {
509		ofs = (off_t)lba * pp->sectorsize;
510		buf = g_read_data(cp, ofs, pp->sectorsize, &error);
511		if (buf == NULL)
512			return (error);
513
514		ebr_entry_decode(buf + DOSPARTOFF + 0 * DOSPARTSIZE, ent + 0);
515		ebr_entry_decode(buf + DOSPARTOFF + 1 * DOSPARTSIZE, ent + 1);
516
517		/* The 3rd & 4th entries should be zeroes. */
518		if (le64dec(buf + DOSPARTOFF + 2 * DOSPARTSIZE) +
519		    le64dec(buf + DOSPARTOFF + 3 * DOSPARTSIZE) != 0) {
520			basetable->gpt_corrupt = 1;
521			printf("GEOM: %s: invalid entries in the EBR ignored.\n",
522			    pp->name);
523		}
524#ifndef GEOM_PART_EBR_COMPAT
525		/* Save the first EBR, it can contain a boot code */
526		if (lba == 0)
527			bcopy(buf, table->ebr, sizeof(table->ebr));
528#endif
529		g_free(buf);
530
531		if (ent[0].dp_typ == 0)
532			break;
533
534		if (ent[0].dp_typ == 5 && ent[1].dp_typ == 0) {
535			lba = ent[0].dp_start;
536			continue;
537		}
538
539		index = (lba / basetable->gpt_sectors) + 1;
540		baseentry = (struct g_part_entry *)g_part_new_entry(basetable,
541		    index, lba, lba + ent[0].dp_start + ent[0].dp_size - 1);
542		baseentry->gpe_offset = (off_t)(lba + ent[0].dp_start) *
543		    pp->sectorsize;
544		entry = (struct g_part_ebr_entry *)baseentry;
545		entry->ent = ent[0];
546
547		if (ent[1].dp_typ == 0)
548			break;
549
550		lba = ent[1].dp_start;
551	}
552
553	basetable->gpt_entries = msize / basetable->gpt_sectors;
554	basetable->gpt_first = 0;
555	basetable->gpt_last = msize - 1;
556	return (0);
557}
558
559static int
560g_part_ebr_setunset(struct g_part_table *table, struct g_part_entry *baseentry,
561    const char *attrib, unsigned int set)
562{
563	struct g_part_entry *iter;
564	struct g_part_ebr_entry *entry;
565	int changed;
566
567	if (baseentry == NULL)
568		return (ENODEV);
569	if (strcasecmp(attrib, "active") != 0)
570		return (EINVAL);
571
572	/* Only one entry can have the active attribute. */
573	LIST_FOREACH(iter, &table->gpt_entry, gpe_entry) {
574		if (iter->gpe_deleted)
575			continue;
576		changed = 0;
577		entry = (struct g_part_ebr_entry *)iter;
578		if (iter == baseentry) {
579			if (set && (entry->ent.dp_flag & 0x80) == 0) {
580				entry->ent.dp_flag |= 0x80;
581				changed = 1;
582			} else if (!set && (entry->ent.dp_flag & 0x80)) {
583				entry->ent.dp_flag &= ~0x80;
584				changed = 1;
585			}
586		} else {
587			if (set && (entry->ent.dp_flag & 0x80)) {
588				entry->ent.dp_flag &= ~0x80;
589				changed = 1;
590			}
591		}
592		if (changed && !iter->gpe_created)
593			iter->gpe_modified = 1;
594	}
595	return (0);
596}
597
598static const char *
599g_part_ebr_type(struct g_part_table *basetable, struct g_part_entry *baseentry,
600    char *buf, size_t bufsz)
601{
602	struct g_part_ebr_entry *entry;
603	int i;
604
605	entry = (struct g_part_ebr_entry *)baseentry;
606	for (i = 0;
607	    i < sizeof(ebr_alias_match) / sizeof(ebr_alias_match[0]); i++) {
608		if (ebr_alias_match[i].typ == entry->ent.dp_typ)
609			return (g_part_alias_name(ebr_alias_match[i].alias));
610	}
611	snprintf(buf, bufsz, "!%d", entry->ent.dp_typ);
612	return (buf);
613}
614
615static int
616g_part_ebr_write(struct g_part_table *basetable, struct g_consumer *cp)
617{
618#ifndef GEOM_PART_EBR_COMPAT
619	struct g_part_ebr_table *table;
620#endif
621	struct g_provider *pp;
622	struct g_part_entry *baseentry, *next;
623	struct g_part_ebr_entry *entry;
624	u_char *buf;
625	u_char *p;
626	int error;
627
628	pp = cp->provider;
629	buf = g_malloc(pp->sectorsize, M_WAITOK | M_ZERO);
630#ifndef GEOM_PART_EBR_COMPAT
631	table = (struct g_part_ebr_table *)basetable;
632	bcopy(table->ebr, buf, DOSPARTOFF);
633#endif
634	le16enc(buf + DOSMAGICOFFSET, DOSMAGIC);
635
636	baseentry = LIST_FIRST(&basetable->gpt_entry);
637	while (baseentry != NULL && baseentry->gpe_deleted)
638		baseentry = LIST_NEXT(baseentry, gpe_entry);
639
640	/* Wipe-out the first EBR when there are no slices. */
641	if (baseentry == NULL) {
642		error = g_write_data(cp, 0, buf, pp->sectorsize);
643		goto out;
644	}
645
646	/*
647	 * If the first partition is not in LBA 0, we need to
648	 * put a "link" EBR in LBA 0.
649	 */
650	if (baseentry->gpe_start != 0) {
651		ebr_entry_link(basetable, (uint32_t)baseentry->gpe_start,
652		    (uint32_t)baseentry->gpe_end, buf + DOSPARTOFF);
653		error = g_write_data(cp, 0, buf, pp->sectorsize);
654		if (error)
655			goto out;
656	}
657
658	do {
659		entry = (struct g_part_ebr_entry *)baseentry;
660
661		p = buf + DOSPARTOFF;
662		p[0] = entry->ent.dp_flag;
663		p[1] = entry->ent.dp_shd;
664		p[2] = entry->ent.dp_ssect;
665		p[3] = entry->ent.dp_scyl;
666		p[4] = entry->ent.dp_typ;
667		p[5] = entry->ent.dp_ehd;
668		p[6] = entry->ent.dp_esect;
669		p[7] = entry->ent.dp_ecyl;
670		le32enc(p + 8, entry->ent.dp_start);
671		le32enc(p + 12, entry->ent.dp_size);
672
673		next = LIST_NEXT(baseentry, gpe_entry);
674		while (next != NULL && next->gpe_deleted)
675			next = LIST_NEXT(next, gpe_entry);
676
677		p += DOSPARTSIZE;
678		if (next != NULL)
679			ebr_entry_link(basetable, (uint32_t)next->gpe_start,
680			    (uint32_t)next->gpe_end, p);
681		else
682			bzero(p, DOSPARTSIZE);
683
684		error = g_write_data(cp, baseentry->gpe_start * pp->sectorsize,
685		    buf, pp->sectorsize);
686#ifndef GEOM_PART_EBR_COMPAT
687		if (baseentry->gpe_start == 0)
688			bzero(buf, DOSPARTOFF);
689#endif
690		baseentry = next;
691	} while (!error && baseentry != NULL);
692
693 out:
694	g_free(buf);
695	return (error);
696}
697