block/vmdk: Fix the endian problem of buf_len and lba

The problem was triggered by qemu-iotests case 055. It failed when it
was comparing the compressed vmdk image with original test.img.

The cause is that buf_len in vmdk_write_extent wasn't converted to
little-endian before it was stored to disk. But later vmdk_read_extent
read it and converted it from little-endian to cpu endian.
If the cpu is big-endian like s390, the problem will happen and
the data length read by vmdk_read_extent will become invalid!
The fix is to add the conversion in vmdk_write_extent, meanwhile,
repair the endianness problem of lba field which shall also be converted
to little-endian before storing to disk.

Cc: qemu-stable@nongnu.org
Signed-off-by: QingFeng Hao <haoqf@linux.vnet.ibm.com>
Signed-off-by: Jing Liu <liujbjl@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 20161216052040.53067-2-haoqf@linux.vnet.ibm.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
(cherry picked from commit 4545d4f)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

block/vmdk.c

@@ -1354,8 +1354,8 @@ static int vmdk_write_extent(VmdkExtent *extent, int64_t cluster_offset,
             goto out;
         }
 
-        data->lba = offset >> BDRV_SECTOR_BITS;
-        data->size = buf_len;
+        data->lba = cpu_to_le64(offset >> BDRV_SECTOR_BITS);
+        data->size = cpu_to_le32(buf_len);
 
         n_bytes = buf_len + sizeof(VmdkGrainMarker);
         iov = (struct iovec) {