[pve-devel] [PATCH qemu-server 2/4] add NBD server unix socket support in vm_start

[Fabian Grünbichler]

On March 11, 2020 11:44 am, Mira Limbeck wrote:
> As the NBD server spawned by qemu can only listen on a single socket,
> we're dependant on a version being passed to vm_start that indicates
> which protocol can be used (TCP or Unix) by the source node.
> 
> The change in socket type (TCP to Unix) comes with a different URI. For
> unix sockets it has the form: 'nbd:unix:<path/to/socket>:exportname=<device>'.
> 
> Signed-off-by: Mira Limbeck <m.limbeck at proxmox.com>
> ---
>  PVE/QemuServer.pm | 19 +++++++++++++++----
>  1 file changed, 15 insertions(+), 4 deletions(-)
> 
> diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
> index 24f2e16..7d2e0d4 100644
> --- a/PVE/QemuServer.pm
> +++ b/PVE/QemuServer.pm
> @@ -4696,7 +4696,8 @@ sub vmconfig_update_disk {
>  
>  sub vm_start {
>      my ($storecfg, $vmid, $statefile, $skiplock, $migratedfrom, $paused,
> -	$forcemachine, $spice_ticket, $migration_network, $migration_type, $targetstorage, $timeout) = @_;
> +	$forcemachine, $spice_ticket, $migration_network, $migration_type,
> +	$targetstorage, $timeout, $nbd_protocol_version) = @_;
>  
>      PVE::QemuConfig->lock_config($vmid, sub {
>  	my $conf = PVE::QemuConfig->load_config($vmid, $migratedfrom);
> @@ -4979,15 +4980,25 @@ sub vm_start {
>  	    my $pfamily = PVE::Tools::get_host_address_family($nodename);
>  	    my $storage_migrate_port = PVE::Tools::next_migrate_port($pfamily);
>  
> -	    mon_cmd($vmid, "nbd-server-start", addr => { type => 'inet', data => { host => "${localip}", port => "${storage_migrate_port}" } } );
> +	    # nbd_protocol_version > 0 for unix socket support
> +	    # this is communicated by the source node via STDIN

actually, this is a regular parameter in this part of the code, so this 
comment does not really belong here ;)

> +	    if ($nbd_protocol_version > 0 && $migration_type eq 'secure') {
> +		mon_cmd($vmid, "nbd-server-start", addr => { type => 'unix', data => { path => "/run/qemu-server/$vmid\_nbd.migrate" } } );
> +	    } else {
> +		mon_cmd($vmid, "nbd-server-start", addr => { type => 'inet', data => { host => "${localip}", port => "${storage_migrate_port}" } } );
> +	    }
>  
>  	    $localip = "[$localip]" if Net::IP::ip_is_ipv6($localip);

$localip is only used for the TCP migration, so we could actually put 
all that handling into the else branch above
>  
>  	    foreach my $opt (sort keys %$local_volumes) {
>  		my $drivestr = $local_volumes->{$opt};
>  		mon_cmd($vmid, "nbd-server-add", device => "drive-$opt", writable => JSON::true );
> -		my $migrate_storage_uri = "nbd:${localip}:${storage_migrate_port}:exportname=drive-$opt";
> -		print "storage migration listens on $migrate_storage_uri volume:$drivestr\n";
> +		if ($nbd_protocol_version > 0 && $migration_type eq 'secure') {
> +		    print "storage migration listens on nbd:unix:/run/qemu-server/$vmid\_nbd.migrate:exportname=drive-$opt volume:$drivestr\n";
> +		} else {
> +		    my $migrate_storage_uri = "nbd:${localip}:${storage_migrate_port}:exportname=drive-$opt";
> +		    print "storage migration listens on $migrate_storage_uri volume:$drivestr\n";
> +		}

and if we also generate the migrate_storage_uri prefix in the if/else 
branches where we call nbd-server-start, we can drop this if/else 
differentiation here and have all the UNIX vs TCP logic in one 
conditional

>  	    }
>  	}
>  
> -- 
> 2.20.1
> 
> 
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