[systemd-devel] [PATCH] rules: block - add dm devices to whitelist

[Peter Rajnoha]

On 07/10/2017 12:14 PM, Peter Rajnoha wrote:
> On 07/10/2017 11:53 AM, Lennart Poettering wrote:
>> On Mon, 10.07.17 11:37, David Disseldorp (ddiss at suse.de) wrote:
>>
>>> Thanks for the feedback, Lennart...
>>>
>>> On Mon, 10 Jul 2017 10:38:38 +0200, Lennart Poettering wrote:
>>>
>>>> On Wed, 05.07.17 13:01, David Disseldorp (ddiss at suse.de) wrote:
>>>>
>>>>> Ceph relies on by-partuuid symlinks, in order to locate the journal
>>>>> partition from a given OSD partition. For details, see
>>>>> http://tracker.ceph.com/issues/19489.  
>>>>
>>>> This appears way too broad, as it would apply to all LVM and all other
>>>> devices.
>>>>
>>>> It appears to me Ceph should do the same as LVM does for this, and
>>>> ship its own set of rules, and be careful to only match against the
>>>> actual devices it creates.
>>>
>>> We can certainly do this in a Ceph specific manner via the existing
>>> 95-ceph-osd.rules, but my impression was that the by-partuuid symlinks
>>> are "owned" by 60-persistent-storage.rules .
>>>
>>> If you don't think the existence of these symlinks for dm paths will be
>>> of use to others then I'll go ahead and propose it as a Ceph only
>>> change.
>>
>> Hmmm, so thinking about this again: "partuuid" is actually for GPT
>> partition UUIDs if I recall recorrectly, they wouldn't be generated
>> for DM devices anyway, since they are one layer removed from the GPT,
>> so are you even sure this will do what you are asking for?
>>
>> But even if this actually works: DM links so far are created by the
>> LVM/libdevicemapper/ packages, not by udev, and I don't think this
>> should change. Hence, please talk to the LVM/libdevicemapper folks
>> about this and ask them for including it.
>>
> 
> Yes, please, any rules for symlinks which should be created under
> /dev/disk for DM devices (including all its subsystems like LVM,
> mpath...) should go into 13-dm-disk.rules that is part of LVM/DM source
> tree:
> 
> https://sourceware.org/git/?p=lvm2.git;a=blob;f=udev/13-dm-disk.rules.in
> 
> Now, when we create a partition over a DM device, there's a new mapping
> created on top for each partition (either by calling kpartx manually or
> by having it created by partitioning tool directly if it supports that).
> So in this case, it's not the kernel directly who creates the
> partitions, but they're simply another DM devices created on top of the
> underlying DM device to represent these partitions. But I think that
> doesn't matter - we should still create those symlinks for people to
> still have a possibility to reference the device by its part uuid - I'll
> fix 13-dm-disk.rules to include this.
> 

Fixed here:

https://sourceware.org/git/?p=lvm2.git;a=commit;h=c48149cf80c6582c2369bc7f8a33d794021d9dae

-- 
Peter