Strange mounting issue with ext3

[Ludwig Nussel]

Roderich Schupp wrote:
> On Tue, Apr 7, 2009 at 11:27 AM, Patryk Zawadzki <patrys at pld-linux.org> wrote:
> > The proper solution is to make the root of the filesystem owned and/or
> > writable by your user of choice. This is the part you should do after
> 
> This is the traditional Unix answer. But this predates drives as easily
> movable around as an USB stick, because it assumes the user
> (1) has an account on every machine she wants to mount the stick on
> and (2) this account has the _same_ uid on every machine (because
> it's the uid that's stored in the filesystem on the media).
> 
> What is needed here is a new mount option: "forget about the
> uids on the drive, just pretend any file is owned by the mounting user".

I had that idea years ago already but never came around actually
implementing something acceptable for inclusion in the kernel.

I'll attach the PoC ext2 patch I made back then for reference. It
only fakes the uid for files owned uid 0 and also writes back files
with uid 0. This has the advantage that on unpatched systems files
are consistently owned by root rather than a mixture of uids.

A more generic implementation would do it at higher level instead of
a specific file system I guess. A special mount option wouldn't be
needed either, the generic implementation just needs to catch the
uid option that already exists for some file systems. I suppose
someone who is into kernel development and has some vfs knowledge
could implement that feature on a recent kernel in a few minutes.

cu
Ludwig

-- 
 (o_   Ludwig Nussel
 //\   
 V_/_  http://www.suse.de/
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