2 files changed, 23 insertions, 2 deletions

diff --git a/block/partitions/msdos.c b/block/partitions/msdos.c
index 5f79a6677c69..8752a5d26565 100644
--- a/block/partitions/msdos.c
+++ b/block/partitions/msdos.c
@@ -94,6 +94,17 @@ static int aix_magic_present(struct parsed_partitions *state, unsigned char *p)
         return ret;
 }
 
+static void set_info(struct parsed_partitions *state, int slot,
+                     u32 disksig)
+{
+        struct partition_meta_info *info = &state->parts[slot].info;
+
+        snprintf(info->uuid, sizeof(info->uuid), "%08x-%02x", disksig,
+                 slot);
+        info->volname[0] = 0;
+        state->parts[slot].has_info = true;
+}
+
 /*
  * Create devices for each logical partition in an extended partition.
  * The logical partitions form a linked list, with each entry being
@@ -106,7 +117,8 @@ static int aix_magic_present(struct parsed_partitions *state, unsigned char *p)
  */
 
 static void parse_extended(struct parsed_partitions *state,
-                           sector_t first_sector, sector_t first_size)
+                           sector_t first_sector, sector_t first_size,
+                           u32 disksig)
 {
         struct partition *p;
         Sector sect;
@@ -166,6 +178,7 @@ static void parse_extended(struct parsed_partitions *state,
                         }
 
                         put_partition(state, state->next, next, size);
+                        set_info(state, state->next, disksig);
                         if (SYS_IND(p) == LINUX_RAID_PARTITION)
                                 state->parts[state->next].flags = ADDPART_FLAG_RAID;
                         loopct = 0;
@@ -437,6 +450,7 @@ int msdos_partition(struct parsed_partitions *state)
         struct partition *p;
         struct fat_boot_sector *fb;
         int slot;
+        u32 disksig;
 
         data = read_part_sector(state, 0, &sect);
         if (!data)
@@ -491,6 +505,8 @@ int msdos_partition(struct parsed_partitions *state)
 #endif
         p = (struct partition *) (data + 0x1be);
 
+        disksig = le32_to_cpup((__le32 *)(data + 0x1b8));
+
         /*
          * Look for partitions in two passes:
          * First find the primary and DOS-type extended partitions.
@@ -515,11 +531,12 @@ int msdos_partition(struct parsed_partitions *state)
                         put_partition(state, slot, start, n);
 
                         strlcat(state->pp_buf, " <", PAGE_SIZE);
-                        parse_extended(state, start, size);
+                        parse_extended(state, start, size, disksig);
                         strlcat(state->pp_buf, " >", PAGE_SIZE);
                         continue;
                 }
                 put_partition(state, slot, start, size);
+                set_info(state, slot, disksig);
                 if (SYS_IND(p) == LINUX_RAID_PARTITION)
                         state->parts[slot].flags = ADDPART_FLAG_RAID;
                 if (SYS_IND(p) == DM6_PARTITION)
diff --git a/init/do_mounts.c b/init/do_mounts.c
index c950d7c93f98..1d1b6348f903 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -189,6 +189,10 @@ done:
  *         used when disk name of partitioned disk ends on a digit.
  *      6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
  *         unique id of a partition if the partition table provides it.
+ *         The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
+ *         partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
+ *         filled hex representation of the 32-bit "NT disk signature", and PP
+ *         is a zero-filled hex representation of the 1-based partition number.
  *      7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
  *         a partition with a known unique id.
  *