mxmount: Add option --noexport

When mxmount is called by mxmount.service during boot, we do want to
mount the filesystems and produce /etc/exports, but we do not need
to call `exportfs -ra`. This is done by the startup of nfsd.service
anyway.

When `exportfs -ra` is used, the hostnames in /etc/exports are looked
up via dns. This might be a problem, if dns is not yet available.

Add option --noexport and use it in mxmount.service.

mxmount/mxmount

@@ -20,9 +20,10 @@ my %D;
 our $USAGE=<<"_EOF_";
 usage: $0
        $0 --reexport-only
+       $0 --noexport
 _EOF_
 
-our ($opt_reexport_only);
+our ($opt_reexport_only,$opt_noexport);
 
 $fullhostname = hostname();
 ($hostname) = $fullhostname =~ /^([^.]*)/;
@@ -52,12 +53,13 @@ add_data0_if_not_present();
 my %options;
 GetOptions (
     'reexport-only' => \$opt_reexport_only,
+    'noexport' => \$opt_noexport,
 ) or die $USAGE;
 @ARGV and die $USAGE;
 
 mount_all() unless $opt_reexport_only;
 create_exports();
-system("exportfs -ra");
+system("exportfs -ra") unless $opt_noexport;
 
 sub safe_qx { open my $pipe,'-|',@_; return join('',<$pipe>) }
 

mxmount/mxmount.service

@@ -5,7 +5,7 @@ ConditionPathExists=/etc/mxmounts
 
 [Service]
 Type=oneshot
-ExecStart=/usr/bin/mxmount
+ExecStart=/usr/bin/mxmount --noexport
 RemainAfterExit=yes
 
 [Install]