libceph: tcp_nodelay support

TCP_NODELAY socket option set on connection sockets,
disables Nagle’s algorithm and improves latency characteristics.
tcp_nodelay(default)/notcp_nodelay option flags provided to
enable/disable setting the socket option.

Signed-off-by: Chaitanya Huilgol <chaitanya.huilgol@sandisk.com>
[idryomov@redhat.com: NO_TCP_NODELAY -> TCP_NODELAY, minor adjustments]
Signed-off-by: Ilya Dryomov <idryomov@redhat.com>
diff --git a/net/ceph/ceph_common.c b/net/ceph/ceph_common.c
index 5d5ab67..ec56550 100644
--- a/net/ceph/ceph_common.c
+++ b/net/ceph/ceph_common.c
@@ -239,6 +239,8 @@
 	Opt_nocrc,
 	Opt_cephx_require_signatures,
 	Opt_nocephx_require_signatures,
+	Opt_tcp_nodelay,
+	Opt_notcp_nodelay,
 };
 
 static match_table_t opt_tokens = {
@@ -259,6 +261,8 @@
 	{Opt_nocrc, "nocrc"},
 	{Opt_cephx_require_signatures, "cephx_require_signatures"},
 	{Opt_nocephx_require_signatures, "nocephx_require_signatures"},
+	{Opt_tcp_nodelay, "tcp_nodelay"},
+	{Opt_notcp_nodelay, "notcp_nodelay"},
 	{-1, NULL}
 };
 
@@ -457,6 +461,7 @@
 		case Opt_nocrc:
 			opt->flags |= CEPH_OPT_NOCRC;
 			break;
+
 		case Opt_cephx_require_signatures:
 			opt->flags &= ~CEPH_OPT_NOMSGAUTH;
 			break;
@@ -464,6 +469,13 @@
 			opt->flags |= CEPH_OPT_NOMSGAUTH;
 			break;
 
+		case Opt_tcp_nodelay:
+			opt->flags |= CEPH_OPT_TCP_NODELAY;
+			break;
+		case Opt_notcp_nodelay:
+			opt->flags &= ~CEPH_OPT_TCP_NODELAY;
+			break;
+
 		default:
 			BUG_ON(token);
 		}
@@ -518,10 +530,12 @@
 	/* msgr */
 	if (ceph_test_opt(client, MYIP))
 		myaddr = &client->options->my_addr;
+
 	ceph_messenger_init(&client->msgr, myaddr,
 		client->supported_features,
 		client->required_features,
-		ceph_test_opt(client, NOCRC));
+		ceph_test_opt(client, NOCRC),
+		ceph_test_opt(client, TCP_NODELAY));
 
 	/* subsystems */
 	err = ceph_monc_init(&client->monc, client);