svn commit: r212506 - head/sys/nfsclient

[Robert Watson]

On Sun, 12 Sep 2010, Konstantin Belousov wrote:

>  Do not fork nfsiod directly from the vop methods. This causes LORs between
>  vnode lock and several locks needed during fork, like fd lock.
>
>  Instead, schedule the task to be executed in the taskqueue context. We
>  still waiting for the fork to finish, but the context of the thread
>  executing the task does not make real LORs with our vnode lock.

Does this actually functionally improve things, or is all this complexity 
about suppressing the lock order reversal?  If we're waiting synchronously for 
the other thread to launch from the task queue, then the lock order reversal 
still exists, it's just not visible to WITNESS...  If we had a static analysis 
tool that could run on lock and sleep/wakeup traces, it would still show a 
deadlock opportunity.

Robert