+/**
+ * Deallocate the given number of bytes from the input queue.
+ *
+ * \param btrn The buffer tree node.
+ * \param numbytes The number of bytes to be deallocated.
+ *
+ * This function must be used to get rid of existing buffer references in the
+ * node's input queue. If no references to a buffer remain, the underlying
+ * buffers are either freed (in the non-buffer tree case) or the read head of
+ * the buffer pool is being advanced.
+ *
+ * Note that \a numbytes may be smaller than the buffer size. In this case the
+ * buffer is not deallocated and subsequent calls to btr_next_buffer() return
+ * the remaining part of the buffer.
+ */