fs: Include filename in mknod errors

internal/fs/mknod_unix.go

@@ -3,8 +3,16 @@
 
 package fs
 
-import "golang.org/x/sys/unix"
+import (
+	"os"
 
-func mknod(path string, mode uint32, dev uint64) (err error) {
-	return unix.Mknod(path, mode, int(dev))
+	"golang.org/x/sys/unix"
+)
+
+func mknod(path string, mode uint32, dev uint64) error {
+	err := unix.Mknod(path, mode, int(dev))
+	if err != nil {
+		err = &os.PathError{Op: "mknod", Path: path, Err: err}
+	}
+	return err
 }