Ensure getting the correct mountinfo corresponds to path

Signed-off-by: Yanqiang Miao <miao.yanqiang@zte.com.cn>

mount/lookup_unix.go

@@ -4,6 +4,9 @@ package mount
 
 import (
 	"fmt"
+	"path/filepath"
+	"sort"
+	"strings"
 	"syscall"
 
 	"github.com/pkg/errors"
@@ -12,6 +15,7 @@ import (
 // Lookup returns the mount info corresponds to the path.
 func Lookup(dir string) (Info, error) {
 	var dirStat syscall.Stat_t
+	dir = filepath.Clean(dir)
 	if err := syscall.Stat(dir, &dirStat); err != nil {
 		return Info{}, errors.Wrapf(err, "failed to access %q", dir)
 	}
@@ -20,6 +24,11 @@ func Lookup(dir string) (Info, error) {
 	if err != nil {
 		return Info{}, err
 	}
+
+	// Sort descending order by Info.Mountpoint
+	sort.Slice(mounts, func(i, j int) bool {
+		return mounts[j].Mountpoint < mounts[i].Mountpoint
+	})
 	for _, m := range mounts {
 		// Note that m.{Major, Minor} are generally unreliable for our purpose here
 		// https://www.spinics.net/lists/linux-btrfs/msg58908.html
@@ -28,7 +37,7 @@ func Lookup(dir string) (Info, error) {
 			// may fail; ignore err
 			continue
 		}
-		if st.Dev == dirStat.Dev {
+		if st.Dev == dirStat.Dev && strings.HasPrefix(dir, m.Mountpoint) {
 			return m, nil
 		}
 	}