Merge tag 'rxrpc-rewrite-20170606' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

David Howells says:

====================
rxrpc: Support service upgrade

Here's a set of patches that allow AF_RXRPC to support the AuriStor service
upgrade facility.  This allows the server to change the service ID
requested to an upgraded service if the client requests it upon the
initiation of a connection.

This is used by the AuriStor AFS-compatible servers to implement IPv6
handling and improved facilities by providing improved volume location,
volume, protection, file and cache management services.  Note that certain
parts of the AFS protocol carry hard-coded IPv4 addresses.

The reason AuriStor does it this way is that probing the improved service
ID first will not incur an ABORT or any other response on some servers if
the server is not listening on it - and so one have to employ a timeout.

This is implemented in the server by allowing an AF_RXRPC server to call
bind() twice on a socket to allow it to listen on two service IDs and then
call setsockopt() to instruct the server to upgrade one into the other if
the client requests it (by setting userStatus to 1 on the first DATA packet
on a connection).  If the upgrade occurs, all further operations on that
connection are done with the new service ID.  AF_RXRPC has to handle this
automatically as connections are not exposed to userspace.

Clients can request this facility by setting an RXRPC_UPGRADE_SERVICE
command in the sendmsg() control buffer and then observing the resultant
service ID in the msg_addr returned by recvmsg().  This should only be used
to probe the service.  Clients should then use the returned service ID in
all subsequent communications with that server.  Note that the kernel will
not retain this information should the connection expire from its cache.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/rxrpc.h b/include/linux/rxrpc.h
index c68307bc306f..707910c6c6c5 100644
--- a/include/linux/rxrpc.h
+++ b/include/linux/rxrpc.h
@@ -37,6 +37,7 @@ struct sockaddr_rxrpc {
 #define RXRPC_SECURITY_KEYRING		2	/* [srvr] set ring of server security keys */
 #define RXRPC_EXCLUSIVE_CONNECTION	3	/* Deprecated; use RXRPC_EXCLUSIVE_CALL instead */
 #define RXRPC_MIN_SECURITY_LEVEL	4	/* minimum security level */
+#define RXRPC_UPGRADEABLE_SERVICE	5	/* Upgrade service[0] -> service[1] */
 
 /*
  * RxRPC control messages
@@ -53,6 +54,7 @@ struct sockaddr_rxrpc {
 #define RXRPC_NEW_CALL		8	/* -r: [Service] new incoming call notification */
 #define RXRPC_ACCEPT		9	/* s-: [Service] accept request */
 #define RXRPC_EXCLUSIVE_CALL	10	/* s-: Call should be on exclusive connection */
+#define RXRPC_UPGRADE_SERVICE	11	/* s-: Request service upgrade for client call */
 
 /*
  * RxRPC security levels
diff --git a/include/rxrpc/packet.h b/include/rxrpc/packet.h
index 703a64b4681a..a2dcfb850b9f 100644
--- a/include/rxrpc/packet.h
+++ b/include/rxrpc/packet.h
@@ -58,6 +58,8 @@ struct rxrpc_wire_header {
 #define RXRPC_SLOW_START_OK	0x20		/* [ACK] slow start supported */
 
 	uint8_t		userStatus;	/* app-layer defined status */
+#define RXRPC_USERSTATUS_SERVICE_UPGRADE 0x01	/* AuriStor service upgrade request */
+	
 	uint8_t		securityIndex;	/* security protocol ID */
 	union {
 		__be16	_rsvd;		/* reserved */
diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h
index 29a3d53a4015..ebe96796027a 100644
--- a/include/trace/events/rxrpc.h
+++ b/include/trace/events/rxrpc.h
@@ -233,6 +233,7 @@ enum rxrpc_congest_change {
 	EM(RXRPC_CONN_CLIENT_INACTIVE,		"Inac") \
 	EM(RXRPC_CONN_CLIENT_WAITING,		"Wait") \
 	EM(RXRPC_CONN_CLIENT_ACTIVE,		"Actv") \
+	EM(RXRPC_CONN_CLIENT_UPGRADE,		"Upgd") \
 	EM(RXRPC_CONN_CLIENT_CULLED,		"Cull") \
 	E_(RXRPC_CONN_CLIENT_IDLE,		"Idle") \