Update mount creation to only use btrfs subvolume id

Signed-off-by: Derek McGowan <derek@mcgstyle.net>

vendor/github.com/containerd/btrfs/btrfs.go

@@ -3,8 +3,6 @@ package btrfs
 import "sort"
 
 /*
-#cgo LDFLAGS: -lbtrfs
-
 #include <stddef.h>
 #include <btrfs/ioctl.h>
 #include "btrfs.h"
@@ -20,7 +18,6 @@ static char* get_name_btrfs_ioctl_vol_args_v2(struct btrfs_ioctl_vol_args_v2* bt
 import "C"
 
 import (
-	"fmt"
 	"os"
 	"path/filepath"
 	"syscall"
@@ -49,6 +46,17 @@ func IsSubvolume(path string) error {
 	return isStatfsSubvol(&statfs)
 }
 
+// SubvolID returns the subvolume ID for the provided path
+func SubvolID(path string) (uint64, error) {
+	fp, err := openSubvolDir(path)
+	if err != nil {
+		return 0, err
+	}
+	defer fp.Close()
+
+	return subvolID(fp.Fd())
+}
+
 // SubvolInfo returns information about the subvolume at the provided path.
 func SubvolInfo(path string) (info Info, err error) {
 	path, err = filepath.EvalSymlinks(path)
@@ -301,7 +309,6 @@ func SubvolSnapshot(dst, src string, readonly bool) error {
 
 // SubvolDelete deletes the subvolumes under the given path.
 func SubvolDelete(path string) error {
-	fmt.Println("delete", path)
 	dir, name := filepath.Split(path)
 	fp, err := openSubvolDir(dir)
 	if err != nil {