[pve-devel] [PATCH qemu-server] migrate: cleanup forwarding code

[Fabian Grünbichler]

fixing the following two issues:
- the legacy code path was never converted to the new fork_tunnel
signature (which probably means that nothing triggers it in practice
anymore?)
- the NBD Unix socket got forwarded multiple times if more than one disk
was migrated via NBD (this is harmless, but wrong)

for the second issue I opted to keep the code compatible with the
possibility that Qemu starts supporting multiple NBD servers in the
future (and the target node could thus return multiple UNIX socket
paths). currently we can only start one NBD server on one socket, and
each drive-mirror simply starts a new connection over that single
socket.

I took the liberty of renaming the variables/keys since I found
'tunnel_addr' and 'sock_addr' rather confusing.

Signed-off-by: Fabian Grünbichler <f.gruenbichler at proxmox.com>
---
tested:
- migration with multiple disks with and without replication
- same, but forced migration and NBD to use TCP (stateuri == tcp,
  nbd_protocol_version == 0)
- insecure migration

alternatively, we could push the whole unix socket handling including
waiting for readyness into fork_tunnel, and just pass it the list of
unix sockets, and a list of extra forwarding strings (the latter being
used for the legacy TCP migration uri), with both being optional?

 PVE/QemuMigrate.pm | 41 ++++++++++++++++++++++-------------------
 1 file changed, 22 insertions(+), 19 deletions(-)

diff --git a/PVE/QemuMigrate.pm b/PVE/QemuMigrate.pm
index 0a6277d..829d84b 100644
--- a/PVE/QemuMigrate.pm
+++ b/PVE/QemuMigrate.pm
@@ -146,10 +146,10 @@ sub write_tunnel {
 }
 
 sub fork_tunnel {
-    my ($self, $tunnel_addr) = @_;
+    my ($self, $ssh_forward_info) = @_;
 
     my @localtunnelinfo = ();
-    foreach my $addr (@$tunnel_addr) {
+    foreach my $addr (@$ssh_forward_info) {
 	push @localtunnelinfo, '-L', $addr;
     }
 
@@ -191,9 +191,9 @@ sub finish_tunnel {
 
     $self->finish_command_pipe($tunnel, 30);
 
-    if ($tunnel->{sock_addr}) {
+    if (my $unix_sockets = $tunnel->{unix_sockets}) {
 	# ssh does not clean up on local host
-	my $cmd = ['rm', '-f', @{$tunnel->{sock_addr}}]; #
+	my $cmd = ['rm', '-f', @$unix_sockets];
 	PVE::Tools::run_command($cmd);
 
 	# .. and just to be sure check on remote side
@@ -701,8 +701,7 @@ sub phase2 {
     }
 
     my $spice_port;
-    my $tunnel_addr = [];
-    my $sock_addr = [];
+    my $unix_socket_info = {};
     # version > 0 for unix socket support
     my $nbd_protocol_version = 1;
     # TODO change to 'spice_ticket: <ticket>\n' in 7.0
@@ -755,8 +754,7 @@ sub phase2 {
 
 	    $self->{target_drive}->{$targetdrive}->{drivestr} = $drivestr;
 	    $self->{target_drive}->{$targetdrive}->{nbd_uri} = $nbd_uri;
-	    push @$tunnel_addr, "$nbd_unix_addr:$nbd_unix_addr";
-	    push @$sock_addr, $nbd_unix_addr;
+	    $unix_socket_info->{$nbd_unix_addr} = 1;
 	} elsif ($line =~ m/^re-using replicated volume: (\S+) - (.*)$/) {
 	    my $drive = $1;
 	    my $volid = $2;
@@ -782,22 +780,28 @@ sub phase2 {
     if ($migration_type eq 'secure') {
 
 	if ($ruri =~ /^unix:/) {
-	    unlink $raddr;
-	    push @$tunnel_addr, "$raddr:$raddr";
-	    $self->{tunnel} = $self->fork_tunnel($tunnel_addr);
-	    push @$sock_addr, $raddr;
+	    my $ssh_forward_info = ["$raddr:$raddr"];
+	    $unix_socket_info->{$raddr} = 1;
+
+	    my $unix_sockets = [ keys %$unix_socket_info ];
+	    for my $sock (@$unix_sockets) {
+		push @$ssh_forward_info, "$sock:$sock";
+		unlink $sock;
+	    }
+
+	    $self->{tunnel} = $self->fork_tunnel($ssh_forward_info);
 
 	    my $unix_socket_try = 0; # wait for the socket to become ready
 	    while ($unix_socket_try <= 100) {
 		$unix_socket_try++;
 		my $available = 0;
-		foreach my $sock (@$sock_addr) {
+		foreach my $sock (@$unix_sockets) {
 		    if (-S $sock) {
 			$available++;
 		    }
 		}
 
-		if ($available == @$sock_addr) {
+		if ($available == @$unix_sockets) {
 		    last;
 		}
 
@@ -808,17 +812,18 @@ sub phase2 {
 		$self->finish_tunnel($self->{tunnel});
 		die "Timeout, migration socket $ruri did not get ready";
 	    }
+	    $self->{tunnel}->{unix_sockets} = $unix_sockets if (@$unix_sockets);
 
 	} elsif ($ruri =~ /^tcp:/) {
-	    my $tunnel_addr;
+	    my $ssh_forward_info = [];
 	    if ($raddr eq "localhost") {
 		# for backwards compatibility with older qemu-server versions
 		my $pfamily = PVE::Tools::get_host_address_family($nodename);
 		my $lport = PVE::Tools::next_migrate_port($pfamily);
-		$tunnel_addr = "$lport:localhost:$rport";
+		push @$ssh_forward_info, "$lport:localhost:$rport";
 	    }
 
-	    $self->{tunnel} = $self->fork_tunnel($tunnel_addr);
+	    $self->{tunnel} = $self->fork_tunnel($ssh_forward_info);
 
 	} else {
 	    die "unsupported protocol in migration URI: $ruri\n";
@@ -827,8 +832,6 @@ sub phase2 {
 	#fork tunnel for insecure migration, to send faster commands like resume
 	$self->{tunnel} = $self->fork_tunnel();
     }
-    $self->{tunnel}->{sock_addr} = $sock_addr if (@$sock_addr);
-
     my $start = time();
 
     my $opt_bwlimit = $self->{opts}->{bwlimit};
-- 
2.20.1