[Ocfs2-devel] [PATCH] [RFC] Mount option trap for users

[Jan Kara]

On Thu 17-09-09 16:00:37, Mark Fasheh wrote:
> On Tue, Sep 15, 2009 at 11:24:24AM +0200, Jan Kara wrote:
> > On Mon 14-09-09 12:44:05, Joel Becker wrote:
> > > On Mon, Sep 14, 2009 at 04:56:22PM +0200, Jan Kara wrote:
> > > >   OCFS2 mount option 'acl' is a small trap for users. When xattr feature
> > > > is not enabled and 'acl' mount option is specified, it is just silently
> > > > cleared during mount. IMHO that's not a good behavior - when admin requests
> > > > ACLs and we are not able to provide them, we should just fail the mount.
> > > 
> > > 	See
> > > http://www.mail-archive.com/ocfs2-devel@oss.oracle.com/msg03836.html for
> > > previous discussion.
> >   Thanks for the pointer. I didn't know about this discussion. Actually,
> > this is a bit different situation because you won't so easily disable the
> > feature on the filesystem as opposed to just booting a kernel without ACL
> > support.
> >   Also filesystems like ext3/ext4/reiserfs just silently enable the XATTR
> > feature when you use is for the first time and the kernel supports it (for
> > these filesystems XATTRs are implemented as COMPAT features). OCFS2 will
> > fail the syscall (and it cannot really silently enable the feature because
> > it is an INCOMPAT one) so that's a difference anyway... So I still think
> > my change makes sence.
> 
> Another thing to consider is which scenario is more likely - a user
> compiling their kernel without acl support (because really, all major
> distros have this turned on), or a user mounts an existing (nor newly
> created with the wrong mkfs options) ocfs2 file system with '-oacl' that
> doesn't have acl turned on in the feature flags.
> 
> Regarding other file systems, I really wish we could do it their way, but as
> Jan points out we can't magically enable acls like they can and we
> definitely can't assume they're always on. So really, today's behavior is
> *NOT* like those file systems in the first place - instead of magically
> enabling the feature, we silently ignore the acl flag.
  Joel, so what is your final decision? I still think we should fail the
mount when acl mount option is specified but xattr feature is disabled...
  Should I resend the patch?

									Honza
-- 
Jan Kara <jack at suse.cz>
SUSE Labs, CR