Re: [patch 1/1] [mdadm] Add partition checks when creating a new array

[Asdo <asdo@shiftmail.org>]

Luca Berra wrote:
> On Fri, Nov 13, 2009 at 01:49:24PM +1100, Neil Brown wrote:
>> Is there a good library that we could use?
>> libparted might be a possibility, but it seems rather over-weight.
>> /lib/libparted-1.9.so.12.0.0 is larger than /sbin/mdadm !!!
>>
>> Are there any other libraries for reading different partition tables?
>> I guess we can open-code it if we have to but I'd be happy if another
>> solution could be found.
>
> i don't think so,
> but there are two tools
> partx from util-linux
> kpartix from multipath-tools (which is based on the former)
>
> so we could either grab code from those or just invoke
> partx -l (i believe every distro installs util-linux by default)
>
> L.

I'm probably missing something obvious but...
why don't you use the kernel directly to detect if there are partitions
on the device?

Like if the user wants to make a raid on /dev/sdg but the device
/dev/sdg1 exists, that's a problem, you fail the creation. (*)

This would support all the partition types that the kernel supports.

Probing the partitions on the disks and adding them to /dev/sd?N is done
automatically in all recent distributions even for hotpluggable devices 
so it's quite guaranteed that it would work

(*) Are there other situations that would overwrite a partition?