ext2: show all mount options

Using mtab is problematic for various reasons, one of them is that
unprivileged mounts won't turn up in there.  So we want to get rid of it, and
use /proc/mounts instead.

But most filesystems are lazy, and are not showing all mount options.  Which
means, that without mtab, the user won't be able to see some or all of the
options.

It would be nice if the generic code could remember the mount options, and
show them without the need to add extra code to filesystems.  But this is not
easy, because different filesystems handle mount options given options, and
not tough the rest.  This is not taken into account by mount(8) either, so
/etc/mtab will be broken in this case.

This series fixes up ->show_options() in ext[234].

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>