On 7 Jun 00 at 5:12, Alexander Viro wrote:
> > > A) suppose we have a bunch of filesystems union-mounted on
> > > /foo/bar. We do chdir("/foo/bar"), what should become busy? Variants:
> > > mountpoint, first element, last element, all of them.
> >
> > I believe that all of them. Or, we can make alternative and mark
> > none of them busy (together with Tigran yet-to-write force unmount) -
> > if there is reason why cwd should make filesystem busy at all...
>
> Ouch. "All" means that we can't, e.g expire elements of union.
Then I ask otherwise - do we need to make anything busy? Then `mountpoint',
r first element. If you choose last element (last mounted, that is),
it is unintuive.
> > > C) we start with the normal mount and union-mount something else.
> > > Question: what is the desired result (almost definitely the set of old and
> > > new mounted stuff) and who should become busy?
> >
> > With or without (A)? Output should be merge of both filesystems. And if
> > mountpoint was busy before, union-mount should not suceed...
>
> Why?
Because of with my previous answer you were not allowed to operate on
busy mountpoints... OK, I'm corrected. Mountpoint should become busy -
you can unmount any of two filesystems, but not both (if it can be
implemented).
> > >From `stat' or `statfs'? From `[lf]stat' I'd expect data about file on
> > which open/read/write will operate...
> > For `statfs', I have no idea... (I did not look what happens if you
> > create new file) Maybe data about filesystem which will be used for
> > new files?
>
> Erm... The _only_ question is handling of the (common) mountpoint -
> everything else is obvious. There you have several directories joined, so
> which should we ask about ->stat()?
Does not same thing apply also for common subdirectories? Intuitive is
use (except n_links) data from first mount. But this implies that you
should be able to unmount first filesystem only after all others :-(
Best regards,
Petr Vandrovec
vandrove@vc.cvut.cz
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Wed Jun 07 2000 - 21:00:28 EST