Re: silent semantic changes with reiser4

Andrew Morton
2004-08-26T11:04:29Z

Spam <spam@tnonline.net> wrote:
>
>
>
> > Spam <spam@tnonline.net> wrote:
> >>
> >>
> >>
> >> > Spam <spam@tnonline.net> wrote:
> >> >>
> >> >> Yes, for example documents, image files etc. The multiple data
> >> >> streams can contain thumbnails, info about who is editing the file
> >> >> (useful for networked files) etc. Could be used for version handling
> >> >> and much more.
> >>
> >> > All of which can be handled in userspace library code.
> >>
> >> > What compelling reason is there for doing this in the kernel?
> >>
> >>
> >> Because having user space tools and code will make it not work with
> >> everything. Keeping stuff in the kernel should make the new features
> >> transparent to the applications.
> >>
> >> Applications that support the new features will benefit, all others
> >> will continue to work without destroying data.
>
> > Sorry, but that all sounds a bit fluffy. Please provide some examples.
>
> We already had the examples with cp and mv. Both should continue to
> work and the files will still be copied. The same with Konqueror and
> Nautilus. Files and their meta-files/streams/attributes will be
> retained as long as applications are using the OS API.
>
> However, if things are to implemented in user-space, then old
> applications will not work correctly and there is risk that all the
> extra information will be lost or corrupted.
>
> You said it would be socially hard. I think it would be very much
> close to impossible to get it right. Imagine that Gnome and Nautilus
> would implement support for these. I doubt that cp, mv, KDE, mc,
> app-xyz would implement this anytime soon and in the meantime the
> data is at risk.
>

No. All of the applications which you initially identified can be
implemented by putting the various bits of data into a single file and
getting applications to agree on the format of that file.

For example, some image file formats already support embedded metadata, do
they not?