staging: lustre: ptlrpc: quiet warning for 2.1/2.5 connections

The Lustre 2.5.4 client will print a warning about connections with
2.1.3 servers, yet they are still supposed to be interoperable.
Increase the window of warning to be up to Lustre 2.5.50, since we
do not intend to allow interoperability between 2.1 and 2.6 systems.
This was from the time when major releases like Lustre 1.4 and 1.8
were many years apart would have no chance for interoperation.

Only print this message once per client, to avoid flooding the console
for connections to many servers or frequent network reconnections.
Server versions should all be nearly the same in any case.
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-2528
Reviewed-on: http://review.whamcloud.com/7916Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/ptlrpc/import.c

@@ -1001,6 +1001,8 @@ static int ptlrpc_connect_interpret(const struct lu_env *env,
 			return 0;
 		}
 	} else {
+		static bool warned;
+
 		spin_lock(&imp->imp_lock);
 		list_del(&imp->imp_conn_current->oic_item);
 		list_add(&imp->imp_conn_current->oic_item, &imp->imp_conn_list);
@@ -1020,7 +1022,7 @@ static int ptlrpc_connect_interpret(const struct lu_env *env,
 			goto out;
 		}
 
-		if ((ocd->ocd_connect_flags & OBD_CONNECT_VERSION) &&
+		if (!warned && (ocd->ocd_connect_flags & OBD_CONNECT_VERSION) &&
 		    (ocd->ocd_version > LUSTRE_VERSION_CODE +
 					LUSTRE_VERSION_OFFSET_WARN ||
 		     ocd->ocd_version < LUSTRE_VERSION_CODE -
@@ -1028,10 +1030,8 @@ static int ptlrpc_connect_interpret(const struct lu_env *env,
 			/* Sigh, some compilers do not like #ifdef in the middle
 			 * of macro arguments
 			 */
-			const char *older = "older. Consider upgrading server or downgrading client"
-				;
-			const char *newer = "newer than client version. Consider upgrading client"
-					    ;
+			const char *older = "older than client. Consider upgrading server";
+			const char *newer = "newer than client. Consider recompiling application";
 
 			LCONSOLE_WARN("Server %s version (%d.%d.%d.%d) is much %s (%s)\n",
 				      obd2cli_tgt(imp->imp_obd),
@@ -1041,6 +1041,7 @@ static int ptlrpc_connect_interpret(const struct lu_env *env,
 				      OBD_OCD_VERSION_FIX(ocd->ocd_version),
 				      ocd->ocd_version > LUSTRE_VERSION_CODE ?
 				      newer : older, LUSTRE_VERSION_STRING);
+			warned = true;
 		}
 
 #if LUSTRE_VERSION_CODE < OBD_OCD_VERSION(3, 2, 50, 0)