staging: lustre: obdclass: add LCT_SERVER_SESSION for server session

Add LCT_SERVER_SESSION for server session, and separate the
server session flag from LCT_SESSION, so to avoid allocating
session info for client stack for each server request, if
client and server are on the same node.
Signed-off-by: Wang Di <di.wang@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3806
Reviewed-on: http://review.whamcloud.com/7412Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@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/include/lu_object.h

@@ -1005,6 +1005,10 @@ enum lu_context_tag {
 	 * Context for local operations
 	 */
 	LCT_LOCAL = 1 << 7,
+	/**
+	 * session for server thread
+	 **/
+	LCT_SERVER_SESSION = BIT(8),
 	/**
 	 * Set when at least one of keys, having values in this context has
 	 * non-NULL lu_context_key::lct_exit() method. This is used to

drivers/staging/lustre/lustre/include/obd_class.h

@@ -477,7 +477,7 @@ static inline int obd_setup(struct obd_device *obd, struct lustre_cfg *cfg)
 		struct lu_context  session_ctx;
 		struct lu_env env;
 
-		lu_context_init(&session_ctx, LCT_SESSION);
+		lu_context_init(&session_ctx, LCT_SESSION | LCT_SERVER_SESSION);
 		session_ctx.lc_thread = NULL;
 		lu_context_enter(&session_ctx);
 

drivers/staging/lustre/lustre/ptlrpc/service.c

@@ -1649,7 +1649,8 @@ ptlrpc_server_handle_request(struct ptlrpc_service_part *svcpt,
 				    at_get(&svcpt->scp_at_estimate));
 	}
 
-	rc = lu_context_init(&request->rq_session, LCT_SESSION | LCT_NOREF);
+	rc = lu_context_init(&request->rq_session, LCT_SERVER_SESSION |
+						   LCT_NOREF);
 	if (rc) {
 		CERROR("Failure to initialize session: %d\n", rc);
 		goto out_req;