Hello, I'm posting the patch series which makes unionmount transparent. I hope the goal of all the patches will be clear from their commit messages, so won't enumerate what they do in this mail.
The necessity of having non-transparent union mounts was discussed on the IRC and the possible debugging use-case was pointed out. OTOH, in non-transparent mode unionmount behaves a lot like unionfs, allowing to add directories dynamically. Although these advantages may be considered weak, it's not too hard to maintain two variants of union mount functionality, so these options will persist. Another topic for discussion was whether a non-transparent unionmount should shut down the mountee on going away. I believe such functionality is necessary, because it is unionmount who starts the mountee, so it bears some responsibility for its child process. If this argument is considered bad, it's easy to modify the functionality accordingly. Regards, scolobb
