NFS: Make "port=" mount option optional for RDMA mounts

Having to specify "proto=rdma,port=20049" is cumbersome.

RFC 8267 Section 6.3 requires NFSv4 clients to use "the alternative
well-known port number", which is 20049. Make the use of the well-
known port number automatic, just as it is for NFS/TCP and port
2049.

For NFSv2/3, Section 4.2 allows clients to simply choose 20049 as
the default or use rpcbind. I don't know of an NFS/RDMA server
implementation that registers it's NFS/RDMA service with rpcbind,
so automatically choosing 20049 seems like the better choice. The
other widely-deployed NFS/RDMA client, Solaris, also uses 20049
as the default port.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 5ef2c71348bd6f532a1af1e8fdb5b0a2b142f6f4..7c942462d8c62464e08a55564d0b46d718973ebf 100644 (file)
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -2168,7 +2168,10 @@ static int nfs_validate_text_mount_data(void *options,
 
        if (args->version == 4) {
 #if IS_ENABLED(CONFIG_NFS_V4)
-               port = NFS_PORT;
+               if (args->nfs_server.protocol == XPRT_TRANSPORT_RDMA)
+                       port = NFS_RDMA_PORT;
+               else
+                       port = NFS_PORT;
                max_namelen = NFS4_MAXNAMLEN;
                max_pathlen = NFS4_MAXPATHLEN;
                nfs_validate_transport_protocol(args);
@@ -2178,8 +2181,11 @@ static int nfs_validate_text_mount_data(void *options,
 #else
                goto out_v4_not_compiled;
 #endif /* CONFIG_NFS_V4 */
-       } else
+       } else {
                nfs_set_mount_transport_protocol(args);
+               if (args->nfs_server.protocol == XPRT_TRANSPORT_RDMA)
+                       port = NFS_RDMA_PORT;
+       }
 
        nfs_set_port(sap, &args->nfs_server.port, port);