staging: lustre: ptlrpc: enlarge OST_MAXREQSIZE for 4MB RPC

This patch enlarges OST_MAXREQSIZE so as to make the
request size large enough for 4MB RPC.
Signed-off-by: Li Xi <lixi@ddn.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4755
Reviewed-on: http://review.whamcloud.com/9599Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.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/lustre_net.h

@@ -261,7 +261,10 @@
 
 #define MDS_MAXREQSIZE		(5 * 1024)	/* >= 4736 */
 
-#define OST_MAXREQSIZE		(5 * 1024)
+/**
+ * FIEMAP request can be 4K+ for now
+ */
+#define OST_MAXREQSIZE		(16 * 1024)
 
 /* Macro to hide a typecast. */
 #define ptlrpc_req_async_args(req) ((void *)&req->rq_async_args)