Re: refactoring relation extension and BufferAlloc(), faster COPY

> v2-0006-bufmgr-Support-multiple-in-progress-IOs-by-using-.patch

This looks straightforward. My only concern is that it changes the order 
that things happen at abort. Currently, AbortBufferIO() is called very 
early in AbortTransaction(), and this patch moves it much later. I don't 
see any immediate problems from that, but it feels scary.


> @@ -2689,7 +2685,6 @@ InitBufferPoolAccess(void)
>  static void
>  AtProcExit_Buffers(int code, Datum arg)
>  {
> -    AbortBufferIO();
>      UnlockBuffers();
>  
>      CheckForBufferLeaks();

Hmm, do we call AbortTransaction() and ResourceOwnerRelease() on 
elog(FATAL)? Do we need to worry about that?

- Heikki