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From: mb@ttidca.TTI.COM (Michael Bloom)
Newsgroups: comp.unix.wizards
Subject: Re: NFS and EWOULDBLOCK (why not?)
Message-ID: <900@ttidca.TTI.COM>
Date: Tue, 30-Jun-87 20:29:41 EDT
Article-I.D.: ttidca.900
Posted: Tue Jun 30 20:29:41 1987
Date-Received: Fri, 3-Jul-87 04:59:28 EDT
References: <1446@xanth.UUCP>
Reply-To: mb@ttidca.TTI.COM (Michael A. Bloom)
Organization: Citicorp/TTI, Santa Monica
Lines: 27

In article <1446@xanth.UUCP> kyle@xanth.UUCP (Kyle Jones) writes:

>Why can't the relevant system calls that can be blocked by an overloaded or
>dead NFS server return -1, with errno == EWOULDBLOCK?
>
>kyle jones   <kyle@xanth.cs.odu.edu>   old dominion university, norfolk, va

We do something like this at TTI. In the retry loop in rfscall (which
is right after the clget call in rfscall), we add a test for a server  being down.
If it is, we do the following:

		  {		/* MB, ER - Citicorp/TTI  */
		    status = rpcerr.re_status = RPC_SYSTEMERROR;
		    rpcerr.re_errno = EHOSTDOWN;
		    goto splitfast;
		  }

The splitfast label is added just before the mi_printed = 0 and clfree
call near the bottom of the routine

The way we test for a server being down is very site dependant,
allowing for a maximum of 4 class C networks. It uses a table, indexed
by network and host, that a daemon we call nfsmonitor modifies by
writing kmem.

- Michael Bloom
  Citicorp/TTI (213 450-9111x3097)