lxd/instance/drivers: Get file descriptor and pass it over to qemu

Signed-off-by: hamistao <pedro.ribeiro@canonical.com>

lxd/instance/drivers/driver_qemu.go

@@ -1467,8 +1467,15 @@ func (d *qemu) start(stateful bool, op *operationlock.InstanceOperation) error {
 		cpuType += "," + strings.Join(cpuExtensions, ",")
 	}
 
+	socketFile, err := unixListener.(*net.UnixListener).File()
+	if err != nil {
+		return fmt.Errorf("Failed to get the file for the unix socket: %w", err)
+	}
+
+	configSockFD := d.addFileDescriptor(&fdFiles, socketFile)
+
 	// Generate the QEMU configuration.
-	confFile, monHooks, err := d.generateQemuConfigFile(cpuInfo, mountInfo, qemuBus, vsockFD, devConfs, &fdFiles)
+	confFile, monHooks, err := d.generateQemuConfigFile(cpuInfo, mountInfo, qemuBus, configSockFD, vsockFD, devConfs, &fdFiles)
 	if err != nil {
 		op.Done(err)
 		return err
@@ -3095,7 +3102,7 @@ func (d *qemu) deviceBootPriorities(base int) (map[string]int, error) {
 
 // generateQemuConfigFile writes the qemu config file and returns its location.
 // It writes the config file inside the VM's log path.
-func (d *qemu) generateQemuConfigFile(cpuInfo *cpuTopology, mountInfo *storagePools.MountInfo, busName string, vsockFD int, devConfs []*deviceConfig.RunConfig, fdFiles *[]*os.File) (string, []monitorHook, error) {
+func (d *qemu) generateQemuConfigFile(cpuInfo *cpuTopology, mountInfo *storagePools.MountInfo, busName string, configSockFD int, vsockFD int, devConfs []*deviceConfig.RunConfig, fdFiles *[]*os.File) (string, []monitorHook, error) {
 	var monHooks []monitorHook
 
 	cfg := qemuBase(&qemuBaseOpts{d.Architecture()})
@@ -3338,6 +3345,7 @@ func (d *qemu) generateQemuConfigFile(cpuInfo *cpuTopology, mountInfo *storagePo
 	// This is used by the lxd-agent in preference to 9p (due to its improved performance) and in scenarios
 	// where 9p isn't available in the VM guest OS.
 	configSockPath, _ := d.configVirtiofsdPaths()
+
 	if shared.PathExists(configSockPath) {
 		devBus, devAddr, multi = bus.allocate(busFunctionGroup9p)
 		driveConfigVirtioOpts := qemuDriveConfigOpts{
@@ -3348,7 +3356,7 @@ func (d *qemu) generateQemuConfigFile(cpuInfo *cpuTopology, mountInfo *storagePo
 				multifunction: multi,
 			},
 			protocol: "virtio-fs",
-			path:     configSockPath,
+			fd:       fmt.Sprintf("%d", configSockFD),
 		}
 
 		cfg = append(cfg, qemuDriveConfig(&driveConfigVirtioOpts)...)
@@ -3733,22 +3741,16 @@ func (d *qemu) addDriveDirConfig(cfg *[]cfgSection, bus *qemuBus, fdFiles *[]*os
 	// Record the 9p mount for the agent.
 	*agentMounts = append(*agentMounts, agentMount)
 
-	// Check if the disk device has provided a virtiofsd socket path.
-	var virtiofsdSockPath string
-	for _, opt := range driveConf.Opts {
-		if strings.HasPrefix(opt, fmt.Sprintf("%s=", device.DiskVirtiofsdSockMountOpt)) {
-			parts := strings.SplitN(opt, "=", 2)
-			virtiofsdSockPath = parts[1]
-		}
-	}
+	// If there is a virtiofsd socket listener setup the virtio-fs share.
+	if driveConf.VirtiofsdSocket != nil {
+		devBus, devAddr, multi := bus.allocate(busFunctionGroup9p)
 
-	// If there is a virtiofsd socket path setup the virtio-fs share.
-	if virtiofsdSockPath != "" {
-		if !shared.PathExists(virtiofsdSockPath) {
-			return fmt.Errorf("virtiofsd socket path %q doesn't exist", virtiofsdSockPath)
+		virtiofsdSocketFile, err := driveConf.VirtiofsdSocket.(*net.UnixListener).File()
+		if err != nil {
+			return fmt.Errorf("Failed to get the file for the unix socket: %w", err)
 		}
 
-		devBus, devAddr, multi := bus.allocate(busFunctionGroup9p)
+		virtiofsdSocketFD := d.addFileDescriptor(fdFiles, virtiofsdSocketFile)
 
 		// Add virtio-fs device as this will be preferred over 9p.
 		driveDirVirtioOpts := qemuDriveDirOpts{
@@ -3758,10 +3760,10 @@ func (d *qemu) addDriveDirConfig(cfg *[]cfgSection, bus *qemuBus, fdFiles *[]*os
 				devAddr:       devAddr,
 				multifunction: multi,
 			},
-			devName:  driveConf.DevName,
-			mountTag: mountTag,
-			path:     virtiofsdSockPath,
-			protocol: "virtio-fs",
+			devName:   driveConf.DevName,
+			mountTag:  mountTag,
+			devSockFD: virtiofsdSocketFD,
+			protocol:  "virtio-fs",
 		}
 		*cfg = append(*cfg, qemuDriveDir(&driveDirVirtioOpts)...)
 	}

lxd/instance/drivers/driver_qemu_templates.go

@@ -637,6 +637,7 @@ type qemuHostDriveOpts struct {
 	mountTag      string
 	securityModel string
 	path          string
+	fd            string
 	sockFd        string
 	readonly      bool
 	protocol      string
@@ -680,7 +681,7 @@ func qemuHostDrive(opts *qemuHostDriveOpts) []cfgSection {
 			comment: opts.comment,
 			entries: []cfgEntry{
 				{key: "backend", value: "socket"},
-				{key: "path", value: opts.path},
+				{key: "fd", value: opts.fd},
 			},
 		}
 
@@ -708,6 +709,7 @@ type qemuDriveConfigOpts struct {
 	dev      qemuDevOpts
 	protocol string
 	path     string
+	fd       string
 }
 
 func qemuDriveConfig(opts *qemuDriveConfigOpts) []cfgSection {
@@ -723,17 +725,19 @@ func qemuDriveConfig(opts *qemuDriveConfigOpts) []cfgSection {
 		readonly:      true,
 		securityModel: "none",
 		path:          opts.path,
+		fd:            opts.fd,
 	})
 }
 
 type qemuDriveDirOpts struct {
-	dev      qemuDevOpts
-	devName  string
-	mountTag string
-	path     string
-	protocol string
-	proxyFD  int
-	readonly bool
+	dev       qemuDevOpts
+	devName   string
+	mountTag  string
+	path      string
+	devSockFD int
+	protocol  string
+	proxyFD   int
+	readonly  bool
 }
 
 func qemuDriveDir(opts *qemuDriveDirOpts) []cfgSection {
@@ -746,7 +750,7 @@ func qemuDriveDir(opts *qemuDriveDirOpts) []cfgSection {
 		protocol: opts.protocol,
 		fsdriver: "proxy",
 		readonly: opts.readonly,
-		path:     opts.path,
+		fd:       fmt.Sprintf("%d", opts.devSockFD),
 		sockFd:   fmt.Sprintf("%d", opts.proxyFD),
 	})
 }