fix container locking (avoid multiple restore processes)

Unlike flock, LockFile::Simple does not inherit locks to child process.
So we need to do the locking inside the child process.

PVE/API2/OpenVZ.pm

@@ -319,16 +319,6 @@ __PACKAGE__->register_method({
 	    }
 	};
 
-	my $code = sub {
-
-	    my $basecfg_fn = PVE::OpenVZ::config_file($vmid);
-
-	    if ($param->{force}) {
-		die "cant overwrite mounted container\n" if PVE::OpenVZ::check_mounted($conf, $vmid);
-	    } else {
-		die "CT $vmid already exists\n" if -f $basecfg_fn;
-	    }
-
 	my $ostemplate = extract_param($param, 'ostemplate');
 
 	my $archive;
@@ -359,13 +349,27 @@ __PACKAGE__->register_method({
 	    $param->{nameserver} = join(' ', @ns) if scalar(@ns);
 	}
 
+	my $basecfg_fn = PVE::OpenVZ::config_file($vmid);
+
+	my $check_vmid_usage = sub {
+	    if ($param->{force}) {
+		die "cant overwrite mounted container\n" 
+		    if PVE::OpenVZ::check_mounted($conf, $vmid);
+	    } else {
+		die "CT $vmid already exists\n" if -f $basecfg_fn;
+	    }
+	};
+
+	my $code = sub {
+
+	    &$check_vmid_usage(); # final check after locking
+
 	    PVE::OpenVZ::update_ovz_config($vmid, $conf, $param);
 
 	    my $rawconf = PVE::OpenVZ::generate_raw_config($pve_base_ovz_config, $conf);
 
 	    PVE::Cluster::check_cfs_quorum();
 
-	    my $realcmd = sub {
 	    if ($param->{restore}) {
 		&$restore_openvz($private, $archive, $vmid, $param->{force});
 
@@ -399,11 +403,12 @@ __PACKAGE__->register_method({
 	    PVE::AccessControl::lock_user_config($addVMtoPoolFn, "can't add VM to pool") if $pool;
 	};
 
+	my $realcmd = sub { PVE::OpenVZ::lock_container($vmid, 1, $code); };
+
+	&$check_vmid_usage(); # first check before locking
+
 	return $rpcenv->fork_worker($param->{restore} ? 'vzrestore' : 'vzcreate', 
 				    $vmid, $authuser, $realcmd);
-	};
-
-	return PVE::OpenVZ::lock_container($vmid, $code);
     }});
 
 my $vm_config_perm_list = [
@@ -473,7 +478,7 @@ __PACKAGE__->register_method({
 	    run_command($cmd);
 	};
 
-	PVE::OpenVZ::lock_container($vmid, $code);
+	PVE::OpenVZ::lock_container($vmid, undef, $code);
 
 	return undef;
     }});

PVE/OpenVZ.pm

@@ -1157,16 +1157,18 @@ sub generate_raw_config {
 }
 
 sub create_lock_manager {
+    my ($max) = @_;
+
     return LockFile::Simple->make(-format => '%f',
 				  -autoclean => 1,
-				  -max => 30, 
-				  -delay => 2, 
+				  -max => defined($max) ? $max : 60, 
+				  -delay => 1, 
 				  -stale => 1,
 				  -nfs => 0);
 }
 
 sub lock_container {
-    my ($vmid, $code, @param) = @_;
+    my ($vmid, $max, $code, @param) = @_;
 
     my $filename = $global_vzconf->{lockdir} . "/${vmid}.lck";
     my $lock;
@@ -1174,12 +1176,11 @@ sub lock_container {
 
     eval {
 
-	my $lockmgr = create_lock_manager();
+	my $lockmgr = create_lock_manager($max);
 
 	$lock = $lockmgr->lock($filename) || die "can't lock container $vmid\n";
 
         $res = &$code(@param);
-
     };
     my $err = $@;
 

PVE/OpenVZMigrate.pm

@@ -18,7 +18,7 @@ use base qw(PVE::AbstractMigrate);
 sub lock_vm {
     my ($self, $vmid, $code, @param) = @_;
     
-    return PVE::OpenVZ::lock_container($vmid, $code, @param);
+    return PVE::OpenVZ::lock_container($vmid, undef, $code, @param);
 }
 
 sub prepare {