[PATCH v2 024/127] smb: smbdirect: introduce smbdirect_connection_negotiate_rdma_resources()

[Stefan Metzmacher]

This is a copy of the same logic used in client and server,
it's inlined there, but they will use the new helper function
soon.

Cc: Steve French <smfrench at gmail.com>
Cc: Tom Talpey <tom at talpey.com>
Cc: Long Li <longli at microsoft.com>
Cc: Namjae Jeon <linkinjeon at kernel.org>
Cc: linux-cifs at vger.kernel.org
Cc: samba-technical at lists.samba.org
Signed-off-by: Stefan Metzmacher <metze at samba.org>
Signed-off-by: Steve French <stfrench at microsoft.com>
---
 .../common/smbdirect/smbdirect_connection.c   | 62 +++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/fs/smb/common/smbdirect/smbdirect_connection.c b/fs/smb/common/smbdirect/smbdirect_connection.c
index 5afb27f790a5..7a8a351d0484 100644
--- a/fs/smb/common/smbdirect/smbdirect_connection.c
+++ b/fs/smb/common/smbdirect/smbdirect_connection.c
@@ -356,6 +356,68 @@ smbdirect_connection_reassembly_first_recv_io(struct smbdirect_socket *sc)
 	return msg;
 }
 
+__maybe_unused /* this is temporary while this file is included in orders */
+static void smbdirect_connection_negotiate_rdma_resources(struct smbdirect_socket *sc,
+							  u8 peer_initiator_depth,
+							  u8 peer_responder_resources,
+							  const struct rdma_conn_param *param)
+{
+	struct smbdirect_socket_parameters *sp = &sc->parameters;
+
+	if (rdma_protocol_iwarp(sc->ib.dev, sc->rdma.cm_id->port_num) &&
+	    param->private_data_len == 8) {
+		/*
+		 * Legacy clients with only iWarp MPA v1 support
+		 * need a private blob in order to negotiate
+		 * the IRD/ORD values.
+		 */
+		const __be32 *ird_ord_hdr = param->private_data;
+		u32 ird32 = be32_to_cpu(ird_ord_hdr[0]);
+		u32 ord32 = be32_to_cpu(ird_ord_hdr[1]);
+
+		/*
+		 * cifs.ko sends the legacy IRD/ORD negotiation
+		 * event if iWarp MPA v2 was used.
+		 *
+		 * Here we check that the values match and only
+		 * mark the client as legacy if they don't match.
+		 */
+		if ((u32)param->initiator_depth != ird32 ||
+		    (u32)param->responder_resources != ord32) {
+			/*
+			 * There are broken clients (old cifs.ko)
+			 * using little endian and also
+			 * struct rdma_conn_param only uses u8
+			 * for initiator_depth and responder_resources,
+			 * so we truncate the value to U8_MAX.
+			 *
+			 * smb_direct_accept_client() will then
+			 * do the real negotiation in order to
+			 * select the minimum between client and
+			 * server.
+			 */
+			ird32 = min_t(u32, ird32, U8_MAX);
+			ord32 = min_t(u32, ord32, U8_MAX);
+
+			sc->rdma.legacy_iwarp = true;
+			peer_initiator_depth = (u8)ird32;
+			peer_responder_resources = (u8)ord32;
+		}
+	}
+
+	/*
+	 * negotiate the value by using the minimum
+	 * between client and server if the client provided
+	 * non 0 values.
+	 */
+	if (peer_initiator_depth != 0)
+		sp->initiator_depth = min_t(u8, sp->initiator_depth,
+					    peer_initiator_depth);
+	if (peer_responder_resources != 0)
+		sp->responder_resources = min_t(u8, sp->responder_resources,
+						peer_responder_resources);
+}
+
 static void smbdirect_connection_schedule_disconnect(struct smbdirect_socket *sc,
 						     int error)
 {
-- 
2.43.0