Re: silent semantic changes with reiser4

Helge Hafting
2004-09-16T08:18:26Z

Timothy Miller wrote:

> I'm probably not the first to suggest this idea, and it's probably not
> a very good idea, but here's my idea anyhow:
>
> You have a file "/usr/bin/emacs"
> with a metadata property in the overlaid namespace
> "/usr/bin/emacs/[[..]metas/]icon"
>
> According to some, this could cause some confusion. Howabout instead:
>
> You have a file "/usr/bin/emacs"
> with a metadata property in a slightly separated namespace
> "/metas/usr/bin/emacs/icon"
>
And the problem with such a "solution" is
mv /usr/bin/emacs /usr/bin/old-emacs
Do this with an ordinary fs, and the /metas/usr/bin/emacs/icon
won't move with it. Now metas might might not be an ordinary fs,
so perhaps the move happens automatically there, but if so
it will be unexpected.

> This has the advantage of still having the metadata in the filesystem
> namespace but without the confusion of having files-as-directories,
> ambiguity of filename, backup issues, etc. This is the reverse of
> having the namespaces overlaid with a "/nometas" view which is separate.
>
> Furthermore, you can split things further like this:
>
> You have a file "/usr/bin/emacs"
> with an automatically-generated metadata property that you don't want
> to back up in "/autometas/usr/bin/emacs/modification_date"
> and a manually generated metadata property that you MAY want to backup
> in "/staticmetas/usr/bin/emacs/icon".
>
> This is inelegant, I know. But if we do this, we can add the extra
> features of reiser4 without confusing existing apps or having to
> modify them to support the new functionality.
>
> Furthermore, you can easily hide the extra features by not mounting
> the meta top-level directories (assuming they're mounted like separate
> filesystems, rather than just magically appearing there, which is okay
> too).

Having to go up to root and then down a similar but different path to
reach a
file's metadata seems very counterintuitive to me. And you have to
update all
tools to do this automatically, or it'll be hopeless to actually use.

Helge Hafting