+ if (flags & BTRFS_SNAPSHOT_READ_ONLY) {
+ /* If the snapshot is read-only we
+ * need to mark it writable
+ * temporarily, to put the subsnapshot
+ * into place. */
+
+ if (subvolume_fd < 0) {
+ subvolume_fd = openat(new_fd, subvolume, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
+ if (subvolume_fd < 0)
+ return -errno;
+ }
+
+ r = btrfs_subvol_set_read_only_fd(subvolume_fd, false);
+ if (r < 0)
+ return r;
+ }
+