[parted-devel] Deleting loop partition clears XFS signatures

[Mike Fleetwood]

On 20 February 2015 at 16:19, Brian C. Lane <bcl at redhat.com> wrote:
> What do you expect to happen though? You've explicitly told parted to
> remove the 'partition' and that's what's happened. The fact that ext4
> survives is more of an accident than anything else. I also don't really
> see the utility of trying to use parted like this -- just make a real
> disk label and use that.

I'm coding GParted to support whole disk file systems and as it uses
libparted to do the disk querying and manipulation operations, how
libparted handles loop partitions mattered.  It seems common to put file
systems into Linux Software RAID arrays without further partitioning
them.  Additionally LVM is sometimes put on whole disks without
partitioning them first too.  These are cases where libparted does (or
should, but it doesn't recognise LVM PVs) present loop partition tables.
GParted then allows the user to graphically create, resize, reformat,
delete those whole disk partitions.

Ultimately to make GParted behave consistently over several versions of
libparted and provide a full capabilities to the users I wasn't able to
rely of libparted to work with loop partition tables other than to
recognise them.  As such I don't actually need libparted to behave
consistently in this case.

I saw what I though was a remaining inconsistency after Phillip's work
to improve loop partition handling in parted 3.2.  That for every file
system other than XFS, deletion of the virtual partition on a loop table
is a no-operation where as for XFS it damages it beyond recognition.  I
reasoned that making deletion of virtual partition on a loop table
should be made a no-operation.  But as I said above it doesn't actually
matter to me any more.

Mike