Re: Fwd: Re: util-linux: libblkid: UDF superblock

["Pali Rohár" <pali.rohar@gmail.com>]

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On Tuesday 09 December 2014 11:35:20 Karel Zak wrote:
> On Fri, Dec 05, 2014 at 03:25:06AM +0100, Pali Rohár wrote:
> > On Friday 05 December 2014 03:09:11 Dale R. Worley wrote:
> > > Pali Rohár <pali.rohar@gmail.com> writes:
> > > >> So I think that it is better to use
> > > >> LogicalVolumeIdentifier for libblkid LABEL. And not
> > > >> current VolumeIdentifier.
> > > >> 
> > > >> What do you think?
> > > 
> > > If you change how the LABEL value is read from the disk,
> > > every user will see different LABEL values than they saw
> > > in the past.
> > > 
> > > Dale
> > 
> > Yes, but apparently other systems are using LABEL from
> > LogicalVolumeIdentifier. So now you see different labels on
> > different systems which is not good too.
> > 
> > Also that bsd project UDFclient (which is working on Linux
> > too!) is using LogicalVolumeIdentifier as volume/disk name
> > in newfs_udf tool.
> > 
> > I looked into grub2 code and it is identifying UDF label
> > also from LogicalVolumeIdentifier. So if you want to boot
> > something from UDF FS via grub you probably see label
> > problems...
> > 
> > So I think that rather than using broken linux
> > implementation is better to fix it (which could bring
> > problems with different label names in new version). And I
> > would like to see human readable label as "555e3160".
> 
> It's more important to not introduce regression, if you have
> LABEL= in your fstab then you don't want to see that after
> util-linux update your setting is obsolete and filesystem
> unmounted.
> 
> It would be possible use another header field
> (LogicalVolumeIdentifier) for LABEL= only if the currently
> used field is empty.
> 
>     Karel

Karel, problem is that other software (for formatting udf fs) set 
VolumeIdentifier to some random string (like "555e3160"). Which 
means that in Linux we do not see correct LABEL. All other 
implementations which I saw are using LogicalVolumeIdentifier for 
LABEL (it is also written in specification). And more... grub2 
read LABEL from LogicalVolumeIdentifier, so you cannot specify 
UDF disk by its LABEL from linux for grub2. I think this is bug 
in util-linux which needs to be fixed. I understand that there 
could be regressions, but current implementation is not correct 
(it show wrong labels "555e3160"; show different as other 
systems; is not correct according to specification).

-- 
Pali Rohár
pali.rohar@gmail.com

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