Newsgroups: comp.sys.sgi
Path: utzoo!news-server.csri.toronto.edu!helios.physics.utoronto.ca!aurora.physics.utoronto.ca!sysmark
From: sysmark@physics.utoronto.ca (Mark Bartelt)
Subject: lockf()/lockd problems
Message-ID: <1991Mar18.163241.13680@helios.physics.utoronto.ca>
Originator: sysmark@aurora.physics.utoronto.ca
Sender: news@helios.physics.utoronto.ca (News Administrator)
Nntp-Posting-Host: aurora.physics.utoronto.ca
Reply-To: sysmark@cita.utoronto.ca
Organization: University of Toronto Physics/Astronomy/CITA
Date: Mon, 18 Mar 1991 16:32:41 GMT

Am I just overlooking something obvious, or does lockf() not work properly on
NFS-mounted volumes?  More specifically, the lock gets created, but doesn't get
removed when the requesting process exits.

I R'ed TFM, and TFM claims (in the lockf(3c) man page) that

  All the locks for a process are removed when the process terminates.

However, this seems to happen only for local files, not for NFS-mounted ones.
For the latter, subsequent attempts to do a test-and-lock (by using F_TLOCK)
return EACCES.  For example:

  % x /usr/people/sysmark/tmp/foo             # This file is on the client
  /usr/people/sysmark/tmp/foo: ok
  % x /usr/people/sysmark/tmp/foo
  /usr/people/sysmark/tmp/foo: ok
  %
  % x /hemlock/sysmark/tmp/snarf              # This file is on the server
  /hemlock/sysmark/tmp/snarf: ok
  % x /hemlock/sysmark/tmp/snarf
  /hemlock/sysmark/tmp/snarf: lock error 13   # GACK!
  %

The trivial program "x" (source appended below) just does an open/lockf/close
for each file named on the command line.  Configuration details:  The program
was run on a 4D/25 running IRIX 3.3.1; the server is a 4D/280 running 3.3.2.
And lockd/statd are running on both systems.

Is this just a horrible botch in lockf() and/or lockd?  Or (more likely) have
I just missed something in TFM?

------------------------------------- x.c -------------------------------------

#include <unistd.h>

extern  int     errno;

main(ac,av)
int     ac;
char ** av;
{
        int     fd;

        while ( --ac > 0 )
                if ( (fd=open(*++av,2)) < 0 )
                        printf("%s: open error\n",*av);
                else {
                        if ( lockf(fd,F_TLOCK,0) < 0 )
                                printf("%s: lock error %d\n",*av,errno);
                        else
                                printf("%s: ok\n",*av);
                        close(fd);
                }
        exit(0);
}

-------------------------------------------------------------------------------

Mark Bartelt                                                       416/978-5619
Canadian Institute for                                 sysmark@cita.toronto.edu
Theoretical Astrophysics                               sysmark@cita.utoronto.ca