Detect device root from driver root

Signed-off-by: Evan Lezar <[email protected]>

cmd/nvidia-dra-plugin/cdi.go

@@ -50,6 +50,7 @@ type CDIHandler struct {
 	nvcdi            nvcdi.Interface
 	registry         cdiapi.Registry
 	driverRoot       string
+	devRoot          string
 	targetDriverRoot string
 	nvidiaCTKPath    string
 
@@ -84,6 +85,7 @@ func NewCDIHandler(opts ...cdiOption) (*CDIHandler, error) {
 		nvcdilib, err := nvcdi.New(
 			nvcdi.WithDeviceLib(h.nvdevice),
 			nvcdi.WithDriverRoot(h.driverRoot),
+			nvcdi.WithDevRoot(h.devRoot),
 			nvcdi.WithLogger(h.logger),
 			nvcdi.WithNvmlLib(h.nvml),
 			nvcdi.WithMode("nvml"),

cmd/nvidia-dra-plugin/device_state.go

@@ -22,6 +22,7 @@ import (
 	"sync"
 
 	"github.com/NVIDIA/go-nvlib/pkg/nvml"
+	"k8s.io/klog/v2"
 
 	nascrd "github.com/NVIDIA/k8s-dra-driver/api/nvidia.com/resource/gpu/nas/v1alpha1"
 )
@@ -126,7 +127,8 @@ type DeviceState struct {
 }
 
 func NewDeviceState(ctx context.Context, config *Config) (*DeviceState, error) {
-	nvdevlib, err := newDeviceLib(root(config.flags.containerDriverRoot))
+	containerDriverRoot := root(config.flags.containerDriverRoot)
+	nvdevlib, err := newDeviceLib(containerDriverRoot)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create device library: %w", err)
 	}
@@ -136,12 +138,15 @@ func NewDeviceState(ctx context.Context, config *Config) (*DeviceState, error) {
 		return nil, fmt.Errorf("error enumerating all possible devices: %w", err)
 	}
 
+	devRoot := containerDriverRoot.getDevRoot()
+	klog.Infof("using devRoot=%v", devRoot)
+
 	hostDriverRoot := config.flags.hostDriverRoot
-	containerDriverRoot := config.flags.containerDriverRoot
 	cdi, err := NewCDIHandler(
 		WithNvml(nvdevlib.nvmllib),
 		WithDeviceLib(nvdevlib),
-		WithDriverRoot(containerDriverRoot),
+		WithDriverRoot(string(containerDriverRoot)),
+		WithDevRoot(devRoot),
 		WithTargetDriverRoot(hostDriverRoot),
 		WithNvidiaCTKPath(config.flags.nvidiaCTKPath),
 		WithCDIRoot(config.flags.cdiRoot),

cmd/nvidia-dra-plugin/find.go

@@ -18,6 +18,7 @@ package main
 
 import (
 	"fmt"
+	"os"
 	"path/filepath"
 )
 
@@ -60,6 +61,25 @@ func (r root) getNvidiaSMIPath() (string, error) {
 	return binaryPath, nil
 }
 
+// isDevRoot checks whether the specified root is a dev root.
+// A dev root is defined as a root containing a /dev folder.
+func (r root) isDevRoot() bool {
+	stat, err := os.Stat(filepath.Join(string(r), "dev"))
+	if err != nil {
+		return false
+	}
+	return stat.IsDir()
+}
+
+// getDevRoot returns the dev root associated with the root.
+// If the root is not a dev root, this defaults to "/".
+func (r root) getDevRoot() string {
+	if r.isDevRoot() {
+		return string(r)
+	}
+	return "/"
+}
+
 // findFile searches the root for a specified file.
 // A number of folders can be specified to search in addition to the root itself.
 // If the file represents a symlink, this is resolved and the final path is returned.

cmd/nvidia-dra-plugin/options.go

@@ -31,6 +31,13 @@ func WithDriverRoot(root string) cdiOption {
 	}
 }
 
+// WithDevRoot provides a cdiOption to set the device root used by the 'cdi' interface.
+func WithDevRoot(root string) cdiOption {
+	return func(c *CDIHandler) {
+		c.devRoot = root
+	}
+}
+
 // WithTargetDriverRoot provides an cdiOption to set the target driver root used by the 'cdi' interface.
 func WithTargetDriverRoot(root string) cdiOption {
 	return func(c *CDIHandler) {