lock violation in unionfs (9.0-STABLE r230270)

[Pavel Polyakov]

>> mount -t unionfs -o noatime /usr /mnt
>>
>> insmntque: mp-safe fs and non-locked vp: 0xfffffe01d96704f0 is not
>> exclusive locked but should be
>> KDB: enter: lock violation
>
> Pavel,
> can you give a spin to this patch?:
> http://www.freebsd.org/~attilio/unionfs_missing_insmntque_lock.patch
>
> I think that the unlocking is due at that point as the vnode lock can
> be switch later on.
>
> Let me know what you think about it and what the test does.

Thanks!
This patch fixes the problem with lock violation. Sorry I've tested it so
late.