RDMA/rtrs: a bit of documentation

README with description of major sysfs entries, sysfs documentation has
been moved to ABI dir as suggested by Bart.

Link: https://lore.kernel.org/r/20200511135131.27580-15-danil.kipnis@cloud.ionos.comSigned-off-by: Danil Kipnis <danil.kipnis@cloud.ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

Documentation/ABI/testing/sysfs-class-rtrs-client

+What:		/sys/class/rtrs-client
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	When a user of RTRS API creates a new session, a directory entry with
+		the name of that session is created under /sys/class/rtrs-client/<session-name>/
+
+What:		/sys/class/rtrs-client/<session-name>/add_path
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RW, adds a new path (connection) to an existing session. Expected format is the
+		following:
+
+		<[source addr,]destination addr>
+		*addr ::= [ ip:<ipv4|ipv6> | gid:<gid> ]
+
+What:		/sys/class/rtrs-client/<session-name>/max_reconnect_attempts
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Maximum number reconnect attempts the client should make before giving up
+		after connection breaks unexpectedly.
+
+What:		/sys/class/rtrs-client/<session-name>/mp_policy
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Multipath policy specifies which path should be selected on each IO:
+
+		round-robin (0):
+		select path in per CPU round-robin manner.
+
+		min-inflight (1):
+		select path with minimum inflights.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Each path belonging to a given session is listed here by its source and
+		destination address. When a new path is added to a session by writing to
+		the "add_path" entry, a directory <src@dst> is created.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/state
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains "connected" if the session is connected to the peer and fully
+		functional.  Otherwise the file contains "disconnected"
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/reconnect
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Write "1" to the file in order to reconnect the path.
+		Operation is blocking and returns 0 if reconnect was successful.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/disconnect
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Write "1" to the file in order to disconnect the path.
+		Operation blocks until RTRS path is disconnected.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/remove_path
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Write "1" to the file in order to disconnected and remove the path
+		from the session.  Operation blocks until the path is disconnected
+		and removed from the session.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/hca_name
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains the the name of HCA the connection established on.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/hca_port
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains the port number of active port traffic is going through.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/src_addr
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains the source address of the path
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/dst_addr
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains the destination address of the path
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/stats/reset_all
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RW, Read will return usage help, write 0 will clear all the statistics.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/stats/cpu_migration
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RTRS expects that each HCA IRQ is pinned to a separate CPU. If it's
+		not the case, the processing of an I/O response could be processed on a
+		different CPU than where it was originally submitted.  This file shows
+		how many interrupts where generated on a non expected CPU.
+		"from:" is the CPU on which the IRQ was expected, but not generated.
+		"to:" is the CPU on which the IRQ was generated, but not expected.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/stats/reconnects
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Contains 2 unsigned int values, the first one records number of successful
+		reconnects in the path lifetime, the second one records number of failed
+		reconnects in the path lifetime.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/stats/rdma
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Contains statistics regarding rdma operations and inflight operations.
+		The output consists of 6 values:
+
+		<read-count> <read-total-size> <write-count> <write-total-size> \
+		<inflights> <failovered>

Documentation/ABI/testing/sysfs-class-rtrs-server

+What:		/sys/class/rtrs-server
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	When a user of RTRS API creates a new session on a client side, a
+		directory entry with the name of that session is created in here.
+
+What:		/sys/class/rtrs-server/<session-name>/paths/
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	When new path is created by writing to "add_path" entry on client side,
+		a directory entry named as <source address>@<destination address> is created
+		on server.
+
+What:		/sys/class/rtrs-server/<session-name>/paths/<src@dst>/disconnect
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	When "1" is written to the file, the RTRS session is being disconnected.
+		Operations is non-blocking and returns control immediately to the caller.
+
+What:		/sys/class/rtrs-server/<session-name>/paths/<src@dst>/hca_name
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains the the name of HCA the connection established on.
+
+What:		/sys/class/rtrs-server/<session-name>/paths/<src@dst>/hca_port
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains the port number of active port traffic is going through.
+
+What:		/sys/class/rtrs-server/<session-name>/paths/<src@dst>/src_addr
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains the source address of the path
+
+What:		/sys/class/rtrs-server/<session-name>/paths/<src@dst>/dst_addr
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains the destination address of the path
+
+What:		/sys/class/rtrs-server/<session-name>/paths/<src@dst>/stats/rdma
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Contains statistics regarding rdma operations and inflight operations.
+		The output consists of 5 values:
+		<read-count> <read-total-size> <write-count> <write-total-size> <inflights>