On Tue, Mar 29, 2011 at 10:48:44AM +0200, Miklos Szeredi wrote:
> On Tue, 2011-03-29 at 10:28 +0200, Karel Zak wrote:
> > On Mon, Mar 28, 2011 at 04:23:20PM +0200, Miklos Szeredi wrote:
> > > On Mon, 2011-03-28 at 16:04 +0200, Petr Uzel wrote:
> > > > Hi all,
> > > >
> > > > I hacked the following patch with which it is possible to use
> > > > "umount $dir" instead of "fusermount -u $dir", which IMHO is an
> > > > improvement in usability. It seems to work (at least for me), however,
> > > > I have to admit that I don't like it very much, because:
> > > > - it complicates umount
> > > > - duplicates code from fusermount
> > >
> > > And this is not the only one that would have to be duplicated. The
> > > mount and umount races that were fixed in fusermount in recently and not
> > > so recently would also have to be added to util-linux, which would
> > > actually be a good thing, since in theory they could affect fstab based
> > > user mounts as well (though that is much more unlikely than with fuse,
> > > where the user chooses the mountpoint).
> >
> > Maybe we need to call umount2() with UMOUNT_NOFOLLOW flag for
> > non-root users in umount(8). I think it should be enough for
> > umount(8) (where almost all is controlled by system admin in fstab).
> >
> > See below. Comments?
>
> UMOUNT_NOFOLLOW is a good idea but not enough, it will only deal with
> last path component changing to a symlink. If previous path component
> is changed then UMOUNT_NOFOLLOW will not have any effect.
>
> What fusermount does is change cwd to the parent directory, check if cwd
> matches that of the intended path, and then umount with UMOUNT_NOFOLLOW.
Ah.. I see the code. Thanks.
It would be nice to have
mountat(dirfd, ...)
umountat(dirfd, ...)
syscalls to avoid any races :-)
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
http://karelzak.blogspot.com
--
To unsubscribe from this list: send the line "unsubscribe util-linux" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
