[Libguestfs] [PATCH v2 08/13] resize: add function mbr_part_type

[Richard W.M. Jones]

On Fri, Sep 19, 2014 at 03:39:10PM +0800, Hu Tao wrote:
> Function mbr_part_type returns one of "primary", "extended" and
> "logical". The type is used by parted when adding partitions.
> 
> Signed-off-by: Hu Tao <hutao at cn.fujitsu.com>
> ---
>  resize/resize.ml | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/resize/resize.ml b/resize/resize.ml
> index 2ffd26e..f57b2ff 100644
> --- a/resize/resize.ml
> +++ b/resize/resize.ml
> @@ -50,6 +50,7 @@ type partition = {
>    p_id : partition_id;           (* Partition (MBR/GPT) ID. *)
>    p_type : partition_content;    (* Content type and content size. *)
>    p_label : string option;       (* Label/name. *)
> +  p_part_num: int;               (* partition number *)

I don't think it's necessary to store p_part_num in the main
partitions struct.

Instead you can get to the partition number using:

  p.p_part.G.part_num

For example, mbr_part_type could be written:

  let mbr_part_type x =
    if x.p_part.G.part_num <= 4 && x.p_type <> ContentExtendedPartition then "primary"
  [etc]

> +  let mbr_part_type x =
> +    if x.p_part_num <= 4 && x.p_type <> ContentExtendedPartition then "primary"
> +    else if x.p_part_num <= 4 && x.p_type = ContentExtendedPartition then "extended"
> +    else "logical" in
> +
>    (* Now partition the target disk. *)
>    List.iter (
>      fun p ->
> -      g#part_add "/dev/sdb" "primary" p.p_target_start p.p_target_end
> +      g#part_add "/dev/sdb" (mbr_part_type p) p.p_target_start p.p_target_end
>    ) partitions;

The big problem with this is I think it doesn't work properly for GPT.
GPT has no idea what "extended" is -- such a concept does not exist.
So if you passed a GPT guest to virt-resize with >= 5 partitions in
it, then virt-resize will not work.

I think you need to check the partition table type somewhere.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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