+/*
+ * ptlrpc history sequence is used as "position" of seq_file, in some case,
+ * seq_read() will increase "position" to indicate reading the next
+ * element, however, low bits of history sequence are reserved for CPT id
+ * (check the details from comments before ptlrpc_req_add_history), which
+ * means seq_read() might change CPT id of history sequence and never
+ * finish reading of requests on a CPT. To make it work, we have to shift
+ * CPT id to high bits and timestamp to low bits, so seq_read() will only
+ * increase timestamp which can correctly indicate the next position.
+ */
+
+/* convert seq_file pos to cpt */
+#define PTLRPC_REQ_POS2CPT(svc, pos) \
+ ((svc)->srv_cpt_bits == 0 ? 0 : \
+ (__u64)(pos) >> (64 - (svc)->srv_cpt_bits))
+
+/* make up seq_file pos from cpt */
+#define PTLRPC_REQ_CPT2POS(svc, cpt) \
+ ((svc)->srv_cpt_bits == 0 ? 0 : \
+ (cpt) << (64 - (svc)->srv_cpt_bits))
+
+/* convert sequence to position */
+#define PTLRPC_REQ_SEQ2POS(svc, seq) \
+ ((svc)->srv_cpt_bits == 0 ? (seq) : \
+ ((seq) >> (svc)->srv_cpt_bits) | \
+ ((seq) << (64 - (svc)->srv_cpt_bits)))
+
+/* convert position to sequence */
+#define PTLRPC_REQ_POS2SEQ(svc, pos) \
+ ((svc)->srv_cpt_bits == 0 ? (pos) : \
+ ((__u64)(pos) << (svc)->srv_cpt_bits) | \
+ ((__u64)(pos) >> (64 - (svc)->srv_cpt_bits)))
+