drbd: Backport the "status" command

The status command originates the drbd9 code base. While for now we
keep the status information in /proc/drbd available, this commit
allows the user base to gracefully migrate their monitoring
infrastructure to the new status reporting interface.

In drbd9 no status information is exposed through /proc/drbd.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

include/linux/drbd_genl.h

@@ -453,6 +453,41 @@ GENL_op(DRBD_ADM_GET_TIMEOUT_TYPE, 26, GENL_doit(drbd_adm_get_timeout_type),
 GENL_op(DRBD_ADM_DOWN,		27, GENL_doit(drbd_adm_down),
 	GENL_tla_expected(DRBD_NLA_CFG_CONTEXT, DRBD_F_REQUIRED))
 
+GENL_op(DRBD_ADM_GET_RESOURCES, 30,
+	 GENL_op_init(
+		 .dumpit = drbd_adm_dump_resources,
+	 ),
+	 GENL_tla_expected(DRBD_NLA_CFG_CONTEXT, DRBD_GENLA_F_MANDATORY)
+	 GENL_tla_expected(DRBD_NLA_RESOURCE_INFO, DRBD_GENLA_F_MANDATORY)
+	 GENL_tla_expected(DRBD_NLA_RESOURCE_STATISTICS, DRBD_GENLA_F_MANDATORY))
+
+GENL_op(DRBD_ADM_GET_DEVICES, 31,
+	 GENL_op_init(
+		 .dumpit = drbd_adm_dump_devices,
+		 .done = drbd_adm_dump_devices_done,
+	 ),
+	 GENL_tla_expected(DRBD_NLA_CFG_CONTEXT, DRBD_GENLA_F_MANDATORY)
+	 GENL_tla_expected(DRBD_NLA_DEVICE_INFO, DRBD_GENLA_F_MANDATORY)
+	 GENL_tla_expected(DRBD_NLA_DEVICE_STATISTICS, DRBD_GENLA_F_MANDATORY))
+
+GENL_op(DRBD_ADM_GET_CONNECTIONS, 32,
+	 GENL_op_init(
+		 .dumpit = drbd_adm_dump_connections,
+		 .done = drbd_adm_dump_connections_done,
+	 ),
+	 GENL_tla_expected(DRBD_NLA_CFG_CONTEXT, DRBD_GENLA_F_MANDATORY)
+	 GENL_tla_expected(DRBD_NLA_CONNECTION_INFO, DRBD_GENLA_F_MANDATORY)
+	 GENL_tla_expected(DRBD_NLA_CONNECTION_STATISTICS, DRBD_GENLA_F_MANDATORY))
+
+GENL_op(DRBD_ADM_GET_PEER_DEVICES, 33,
+	 GENL_op_init(
+		 .dumpit = drbd_adm_dump_peer_devices,
+		 .done = drbd_adm_dump_peer_devices_done,
+	 ),
+	 GENL_tla_expected(DRBD_NLA_CFG_CONTEXT, DRBD_GENLA_F_MANDATORY)
+	 GENL_tla_expected(DRBD_NLA_PEER_DEVICE_INFO, DRBD_GENLA_F_MANDATORY)
+	 GENL_tla_expected(DRBD_NLA_PEER_DEVICE_STATISTICS, DRBD_GENLA_F_MANDATORY))
+
 GENL_notification(
 	DRBD_RESOURCE_STATE, 34, events,
 	GENL_tla_expected(DRBD_NLA_CFG_CONTEXT, DRBD_F_REQUIRED)

include/linux/idr.h

@@ -135,6 +135,20 @@ static inline void *idr_find(struct idr *idr, int id)
 #define idr_for_each_entry(idp, entry, id)			\
 	for (id = 0; ((entry) = idr_get_next(idp, &(id))) != NULL; ++id)
 
+/**
+ * idr_for_each_entry - continue iteration over an idr's elements of a given type
+ * @idp:     idr handle
+ * @entry:   the type * to use as cursor
+ * @id:      id entry's key
+ *
+ * Continue to iterate over list of given type, continuing after
+ * the current position.
+ */
+#define idr_for_each_entry_continue(idp, entry, id)			\
+	for ((entry) = idr_get_next((idp), &(id));			\
+	     entry;							\
+	     ++id, (entry) = idr_get_next((idp), &(id)))
+
 /*
  * IDA - IDR based id allocator, use when translation from id to
  * pointer isn't necessary.