Re: UDF label change since commit 2f2730bc77c9

[Jan Kara <jack@suse.cz>]

Hi,

On Wed 10-08-16 14:53:49, Pali Rohár wrote:
> On Wednesday 10 August 2016 14:38:59 Jan Kara wrote:
> > we have noticed that since commit 2f2730bc77c9 "libblkid: udf: Fix reading
> > LABEL, add support for UUID and other udf identifiers" some volumes have
> > changed labels which are reported by blkid. See [1] for an example.
> 
> "You are not authorized to access bug #983165."

Ah, sorry. I forgot the bug is reported against SLES and so is not
publically visible. Anyway, the initial comment which is interesting is:

I have a shared paritition with an UDF filesystem. In Win7 64bit its label
is 'ssd120_docs'. In SLES12SP1 its label is 'ssd120_dokumente'. In
Tumbleweed (and most likely also SP2 Beta) its label is 'ssd120_dosemut'
(or similar garbage).

I think there should be some consistency in /dev/disk/by-label/*.
---

As an explanation, SLES12SP1 uses util-linux 2.25 (i.e., before your patch),
Tumbleweed is the rolling distro with the latest & greatest version.
 
> > This is
> > because that commit changed what is used for the label - previously we have
> > used 'ident' in the Primary Volume Descriptor, and after that commit we use
> > Logical Volume ID.
> 
> Yes, thats true.
> 
> > I think it would be better to keep consistency with older util-linux
> > releases (e.g. valid /etc/fstab that uses labels may be broken by this
> > change) but I'm not sure whether there is a point once the new behavior
> > has been released in the util-linux release. But still I wanted to raise
> > this since I'm not sure how much util-linux cares about these changes and
> > also so that people are aware of the change...
> > 
> > 								Honza
> > 
> > [1] https://bugzilla.suse.com/show_bug.cgi?id=983165
> > 
> 
> Reason why I proposed that change is because all other software use
> Logical Volume Identifier as label. Just linux blkid used something
> other.
> 
> Basically Linux was incompatible with whole world and I think this was a
> bug. Also UDF specification say something that LVI is displayed to user.
> IIRC also Grub2 uses LVI as label identification.
> 
> So I do not agree with reverting back old behaviour which is
> incompatible with everything except old util-linux versions...

Well, this somewhat does not match the description in the bug. Apparently
Win7 uses yet another identifier in the UDF filesystem...

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR