fix(csi): ensure the bind mount point for block volume

longhorn-12006

Signed-off-by: Raphanus Lo <yunchang.lo@suse.com>

Author: COLDTURNIP

csi/node_server.go

@@ -364,18 +364,27 @@ func (ns *NodeServer) nodePublishBlockVolume(volumeID, devicePath, targetPath st
 
 	// we ensure the parent directory exists and is valid
 	if _, err := ensureDirectory(filepath.Dir(targetPath)); err != nil {
-		return status.Errorf(codes.Internal, "failed to prepare mount point for block device %v: %v", devicePath, err)
+		return status.Errorf(codes.Internal, "failed to prepare mount point directory for block device %v: %v", devicePath, err)
+	}
+
+	// ensure the bind mount point is clear
+	if err := ensureBindMountPoint(targetPath); err != nil {
+		return status.Errorf(codes.Internal, "failed to prepare mount point file for block device %v: %v", devicePath, err)
 	}
 
 	// create file where we can bind mount the device to
 	if err := makeFile(targetPath); err != nil {
+		if removeErr := unmountAndCleanupMountPoint(targetPath, mount.New("")); removeErr != nil {
+			log.WithError(removeErr).Errorf("Failed to clean up the mount target %q for failed bind mount point", targetPath)
+		}
 		return status.Errorf(codes.Internal, "failed to create file %v: %v", targetPath, err)
 	}
 
 	log.Infof("Bind mounting device %v at %v", devicePath, targetPath)
 	if err := mounter.Mount(devicePath, targetPath, "", []string{"bind"}); err != nil {
-		if removeErr := os.Remove(targetPath); removeErr != nil {
-			log.WithError(removeErr).Errorf("Failed to remove failed mount target %q", targetPath)
+		log.WithError(err).Infof("Clean up the mount target %s because of mount error", targetPath)
+		if removeErr := unmountAndCleanupMountPoint(targetPath, mount.New("")); removeErr != nil {
+			log.WithError(removeErr).Errorf("Failed to clean up the mount target %q for failed mounting", targetPath)
 		}
 		return status.Errorf(codes.Internal, "failed to bind mount %q at %q: %v", devicePath, targetPath, err)
 	}

csi/util.go

@@ -338,6 +338,31 @@ func ensureMountPoint(path string, mounter mount.Interface) (bool, error) {
 	return isMnt, err
 }
 
+// ensureBindMountPoint evaluates whether a path is a valid mount point for bind mount.
+// In case the path does not exists, it will create a regular file for bind mount.
+// In case where the mount point exists but is not a regular file, the mount point will be replaced by a regular file.
+func ensureBindMountPoint(path string) error {
+	logrus.Infof("Trying to ensure bind mount point %v", path)
+	info, statErr := os.Lstat(path)
+	if statErr != nil {
+		if !os.IsNotExist(statErr) {
+			return errors.Wrapf(statErr, "failed to check bind mount at %s", path)
+		}
+	} else {
+		if !info.Mode().IsRegular() {
+			logrus.Infof("Bind mount point %v is not a regular file, clean up", path)
+			if rmErr := os.Remove(path); rmErr != nil {
+				return errors.Wrapf(rmErr, "failed to remove corrupt bind mount point at %s", path)
+			}
+		}
+	}
+
+	if makeFileErr := makeFile(path); makeFileErr != nil {
+		return errors.Wrapf(makeFileErr, "failed to create regular file for bind mount at %s", path)
+	}
+	return nil
+}
+
 // ensureDirectory checks if a folder exists at the specified path.
 // If not, it creates the folder and returns true, otherwise returns false.
 // If the path exists but is not a folder, it returns an error.
@@ -439,7 +464,7 @@ func getFilesystemStatistics(volumePath string) (*volumeFilesystemStatistics, er
 	return volStats, nil
 }
 
-// makeFile creates an empty file.
+// makeFile creates an empty regular file.
 // If pathname already exists, whether a file or directory, no error is returned.
 func makeFile(pathname string) error {
 	f, err := os.OpenFile(pathname, os.O_CREATE, os.FileMode(0644))