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authorStephen Warren <swarren@nvidia.com>2012-11-08 16:12:28 -0800
committerJens Axboe <axboe@kernel.dk>2012-11-23 14:28:58 +0100
commitd33b98fc82b0908e91fb05ae081acaed7323f9d2 (patch)
treefe5803ac8510ab46f0fcbcc1712343806699a5cb /block/partitions
parent283f8fc03927b0ef42a2faa60a0df5ec8c612edb (diff)
downloadlinux-linaro-stable-d33b98fc82b0908e91fb05ae081acaed7323f9d2.tar.gz
block: partition: msdos: provide UUIDs for partitions
The MSDOS/MBR partition table includes a 32-bit unique ID, often referred to as the NT disk signature. When combined with a partition number within the table, this can form a unique ID similar in concept to EFI/GPT's partition UUID. Constructing and recording this value in struct partition_meta_info allows MSDOS partitions to be referred to on the kernel command-line using the following syntax: root=PARTUUID=0002dd75-01 Signed-off-by: Stephen Warren <swarren@nvidia.com> Cc: Tejun Heo <tj@kernel.org> Cc: Will Drewry <wad@chromium.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/partitions')
-rw-r--r--block/partitions/msdos.c21
1 files changed, 19 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)