[ENBD] Re: Enhanced NBD daemon on 2.4.3 kernel

[Peter T. Breuer]

"A month of sundays ago Jason A. Pattie wrote:"
> On an off-hunch, I started nbd-client (2.4.23) with 4 aliases to the 
> same IP address instead of only 1.  Now, I'm swapping just fine over the 

This means that you have somehow magicked swapping into being?! enbd was
never supposed to support swapping (swapping over the net strikes me as
crazy and I eliminated it from considerations early on).

> network.  Don't have a clue why.  And I'm no longer getting the net 
> errored on packet problem.

It might be an artifact of just "restarting".

> I'm going to drop the connection to 2 aliases instead of 4 and see if I 
> run into issues.  If I do (or don't) what would cause a lockup when only 
> using 1 alias?

Nothing that I know of. I do it often to test. I'll ask that it be
added to the test suite.

If you are swapping, then what happens if some of the nbd code is
swapped out? I seem to recall that that was the fundamental issue!
It can't work if one's running synchronously. And nbd DOES run sync.

With more than one thread running, it may be that you get out of
deadlock by letting the other thread retrieve the code that the first
thread needs. But I still think it will lock up eventually. If not
in nbd, then in tcp, or in vfs.

I have enabled an "async" option in my latest client code. The client
lies to the kernel that it has sent the packet when it hasn't yet.

Peter