virtcontainers: Pass the PCI address for block based rootfs

Store the PCI address of rootfs in case the rootfs is block
based and passed using virtio-block.
This helps up get rid of prdicting the device name inside the
container for the block device. The agent will determine the device
node name using the PCI address.

Fixes #266

Signed-off-by: Archana Shinde <[email protected]>

virtcontainers/container.go

@@ -212,6 +212,17 @@ func (c *Container) setStateHotpluggedDrive(hotplugged bool) error {
 	return nil
 }
 
+func (c *Container) setContainerRootfsPCIAddr(addr string) error {
+	c.state.RootfsPCIAddr = addr
+
+	err := c.sandbox.storage.storeContainerResource(c.sandbox.id, c.id, stateFileType, c.state)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
 // GetAnnotations returns container's annotations
 func (c *Container) GetAnnotations() map[string]string {
 	return c.config.Annotations
@@ -791,6 +802,11 @@ func (c *Container) hotplugDrive() error {
 	if err := c.sandbox.hypervisor.hotplugAddDevice(&drive, blockDev); err != nil {
 		return err
 	}
+
+	if drive.PCIAddr != "" {
+		c.setContainerRootfsPCIAddr(drive.PCIAddr)
+	}
+
 	c.setStateHotpluggedDrive(true)
 
 	if err := c.setStateBlockIndex(driveIndex); err != nil {

virtcontainers/kata_agent.go

@@ -40,7 +40,6 @@ var (
 	kataGuestSharedDir          = "/run/kata-containers/shared/containers/"
 	mountGuest9pTag             = "kataShared"
 	type9pFs                    = "9p"
-	devPath                     = "/dev"
 	vsockSocketScheme           = "vsock"
 	kata9pDevType               = "9p"
 	kataBlkDevType              = "blk"
@@ -692,15 +691,8 @@ func (k *kataAgent) createContainer(sandbox *Sandbox, c *Container) (p *Process,
 		// If virtio-scsi driver, the agent will be able to find the
 		// device based on the provided address.
 		if sandbox.config.HypervisorConfig.BlockDeviceDriver == VirtioBlock {
-			// driveName is the predicted virtio-block guest name (the vd* in /dev/vd*).
-			driveName, err := getVirtDriveName(c.state.BlockIndex)
-			if err != nil {
-				return nil, err
-			}
-			virtPath := filepath.Join(devPath, driveName)
-
 			rootfs.Driver = kataBlkDevType
-			rootfs.Source = virtPath
+			rootfs.Source = c.state.RootfsPCIAddr
 		} else {
 			scsiAddr, err := getSCSIAddress(c.state.BlockIndex)
 			if err != nil {

virtcontainers/sandbox.go

@@ -60,6 +60,9 @@ type State struct {
 
 	// Bool to indicate if the drive for a container was hotplugged.
 	HotpluggedDrive bool `json:"hotpluggedDrive"`
+
+	// PCI slot at which the block device backing the container rootfs is attached.
+	RootfsPCIAddr string `json:"rootfsPCIAddr"`
 }
 
 // valid checks that the sandbox state is valid.