Re: is it possible to add a new filter to detect unusable partition types

[Demi Marie Obenour]

On Tue, Dec 17, 2024 at 11:21:26AM +0100, Zdenek Kabelac wrote:
> Dne 17. 12. 24 v 10:13 Glass Su napsal(a):
> > 
> > > On Dec 17, 2024, at 16:34, Heming Zhao <heming.zhao@suse.com> wrote:
> > > 
> > > Hi LVM2 maintainers,
> > > 
> > > One of SUSE's customers encountered an issue with LVM2. The user created 
> > > several partitions, one of which was marked as "BIOS boot" (4) instead of 
> > > "LINUX LVM" (8E). Subsequently, the user ran pvcreate/vgcreate/lvcreate 
> > > on this partition. During a system update, grub2-install installed GRUB2 
> > > in the "BIOS boot" partition, resulting in LVM2 metadata corruption.
> > > 
> > > The root cause of this issue is that grub2-install targets the "BIOS 
> > > boot" partition when this lvm2 device is specified for installation. If 
> > > the user had initially marked the partition as "LINUX LVM", grub2-install 
> > > would not have chosen this partition.
> > > 
> > > On the other hand, it would be beneficial if LVM2 could implement a new 
> > > filter or a filter function to detect and exclude the "BIOS boot" 
> > > partition from being considered a valid target for LVM2 device creation. 
> > > This could involve issuing a warning or error message to alert the user 
> > > of the potential conflict. This may also help user to notice the issue 
> > > more easily.
> 
> Hi
> 
> lvm2 is using  blkid to detect 'present' signature on a block device - and
> normally prompt to confirm wiping such signature.
> 
> We may possibly add similar logic for 'partition signatures'.
> 
> However there is still the plain fact that lvm2  with  --force  or even just
> '--yes' option is assumed to simply proceed  and clean&clear such
> conflicting signatures and simply makes the block device to be a PV.
> 
> All that said IMHO primary bug here is within  'grub2-install'  which simply
> should not be blindingly overwriting  block device which is in use - this
> should be fixed ASAP as there is the biggest risk of data loss, although I
> guess everyone is using  'grub2-install --force'  - as without this option
> (even in my personal experience) is typically refusing to do any work....
> 
> And same applies to most UI tools I've seen that use lvm2 - all seem to be
> pushing  '--force & --yes' with each it emitted lvm2 command...

If prompts were in a machine-parsable format, tools that used lvm2 could
differentiate between ones that should automatically be responded to
with "yes" and ones that should not.
-- 
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab

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