Some partitioning tools may have a different opinion about disk

geometry and partitions may start from withing the first track.
If we found such partitions, then do not reserve space of the
first track, only first sector.

1 files changed, 7 insertions, 2 deletions

diff --git a/sys/geom/part/g_part_mbr.c b/sys/geom/part/g_part_mbr.c
index 0b40366..825a109 100644
--- a/sys/geom/part/g_part_mbr.c
+++ b/sys/geom/part/g_part_mbr.c
@@ -423,12 +423,13 @@ g_part_mbr_read(struct g_part_table *basetable, struct g_consumer *cp)
 	struct g_part_mbr_table *table;
 	struct g_part_mbr_entry *entry;
 	u_char *buf, *p;
-	off_t chs, msize;
+	off_t chs, msize, first;
 	u_int sectors, heads;
 	int error, index;
 
 	pp = cp->provider;
 	table = (struct g_part_mbr_table *)basetable;
+	first = basetable->gpt_sectors;
 	msize = MIN(pp->mediasize / pp->sectorsize, UINT32_MAX);
 
 	buf = g_read_data(cp, 0L, pp->sectorsize, &error);
@@ -461,7 +462,8 @@ g_part_mbr_read(struct g_part_table *basetable, struct g_consumer *cp)
 				basetable->gpt_heads = heads;
 			}
 		}
-
+		if (ent.dp_start < first)
+			first = ent.dp_start;
 		entry = (struct g_part_mbr_entry *)g_part_new_entry(basetable,
 		    index + 1, ent.dp_start, ent.dp_start + ent.dp_size - 1);
 		entry->ent = ent;
@@ -471,6 +473,9 @@ g_part_mbr_read(struct g_part_table *basetable, struct g_consumer *cp)
 	basetable->gpt_first = basetable->gpt_sectors;
 	basetable->gpt_last = msize - 1;
 
+	if (first < basetable->gpt_first)
+		basetable->gpt_first = 1;
+
 	g_free(buf);
 	return (0);
 }