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vvfat: Fix partition table

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Unless parameter ":floppy:" is given, vvfat creates a virtual image
with DOS MBR defining a single partition which holds the FAT file
system.  The size of the virtual image depends on the width of the
FAT: 32 MiB (CHS 64, 16, 63) for 12 bit FAT, 504 MiB (CHS 1024, 16,
63) for 16 and 32 bit FAT, leaving (64*16-1)*63 = 64449 and
(1024*16-1)*64 = 1032129 sectors for the partition.

However, it screws up the end of the partition in the MBR:

    FAT width param.  start CHS  end CHS     start LBA  size
        :32:          0,1,1      1023,14,63       63    1032065
        :16:          0,1,1      1023,14,55       63    1032057
        :12:          0,1,1        63,14,55       63      64377

The actual FAT file system nevertheless assumes the partition has
1032129 or 64449 sectors.  Oops.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Markus Armbruster 2012-07-10 11:12:28 +02:00 committed by Kevin Wolf
parent 61a8d649ff
commit f91cbefe2d
1 changed files with 4 additions and 3 deletions
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7
block/vvfat.c
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@ -394,11 +394,12 @@ static void init_mbr(BDRVVVFATState* s)
/* LBA is used when partition is outside the CHS geometry */
lba = sector2CHS(s->bs, &partition->start_CHS, s->first_sectors_number-1);
lba|= sector2CHS(s->bs, &partition->end_CHS, s->sector_count);
lba |= sector2CHS(s->bs, &partition->end_CHS, s->bs->total_sectors - 1);
/*LBA partitions are identified only by start/length_sector_long not by CHS*/
partition->start_sector_long =cpu_to_le32(s->first_sectors_number-1);
partition->length_sector_long=cpu_to_le32(s->sector_count - s->first_sectors_number+1);
partition->start_sector_long = cpu_to_le32(s->first_sectors_number - 1);
partition->length_sector_long = cpu_to_le32(s->bs->total_sectors
- s->first_sectors_number + 1);
/* FAT12/FAT16/FAT32 */
/* DOS uses different types when partition is LBA,