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SubjectRe: udf: Prevent write-unsupported filesystem to be remounted read-write
On Tue 15-01-19 09:31:11, Pali Rohár wrote:
> On Monday 14 January 2019 19:07:35 Michael Sabolish wrote:
> > I can try and make a pull-request for udftune, and I can just copy the API for tune2fs. It would work something like:
> >
> > udftune -O read-only device (to set read-only access type)
> >
> > or:
> >
> > udftune -O ^read-only device (to clear read-only access type (aka set rw))
>
> This API is ambiguous. What does it mean for ^read-only? In UDF you have
> following access types: overwritable, rewritable, writeonce, readonly,
> pseudo-overwritable, unknown.
>
> So you would need to know to which R/W access type to switch
> (overwritable, rewritable, writeonce or pseudo-overwritable).
>
> With information of media type, you could be able to guess correct
> access type. But for UDF images stored in VFS there is no media
> information. Also you can have uncommon setup, e.g. usage of CD-R
> writeonce setup on CD-R/W disc. So "autodetection" of media type would
> not work always correctly.
>
> So I think that it would be better to have following API:
>
> udftune --access-type=<new_access_type>
>
> or
>
> udftune --change-access-type=<new_access_type>
>
> I understand that you would like to have similar API as tune2fs, but UDF
> settings are too different from ext*.

If you wanted to follow tune2fs interface, you can have e.g.:

udftune -E access-type=<foo>

Another question about the feature is - the access type is actually per
partition and there can be multiple partitions on UDF media. So I think we
need to specify the partition number in the command and <foo> has to
actually be something like <partition number>,<access_type>.

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

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