nfs: have nfs_mount fake up a auth_flavs list when the server didn't provide it

Instead of handling this as a special case in the auth-selection code,
we can simply fake up an auth_flavs list when the server doesn't
provide it.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/mount_clnt.c

@@ -139,7 +139,10 @@ struct mnt_fhstatus {
  * nfs_mount - Obtain an NFS file handle for the given host and path
  * @info: pointer to mount request arguments
  *
- * Uses default timeout parameters specified by underlying transport.
+ * Uses default timeout parameters specified by underlying transport. On
+ * successful return, the auth_flavs list and auth_flav_len will be populated
+ * with the list from the server or a faked-up list if the server didn't
+ * provide one.
  */
 int nfs_mount(struct nfs_mount_request *info)
 {
@@ -195,6 +198,15 @@ int nfs_mount(struct nfs_mount_request *info)
 	dprintk("NFS: MNT request succeeded\n");
 	status = 0;
 
+	/*
+	 * If the server didn't provide a flavor list, allow the
+	 * client to try any flavor.
+	 */
+	if (info->version != NFS_MNT3_VERSION || *info->auth_flav_len == 0) {
+		dprintk("NFS: Faking up auth_flavs list\n");
+		info->auth_flavs[0] = RPC_AUTH_NULL;
+		*info->auth_flav_len = 1;
+	}
 out:
 	return status;
 

fs/nfs/super.c

@@ -1619,19 +1619,6 @@ static int nfs_select_flavor(struct nfs_parsed_mount_data *args,
 	unsigned int i, count = *(request->auth_flav_len);
 	rpc_authflavor_t flavor;
 
-	/*
-	 * The NFSv2 MNT operation does not return a flavor list.
-	 */
-	if (args->mount_server.version != NFS_MNT3_VERSION)
-		goto out_default;
-
-	/*
-	 * Certain releases of Linux's mountd return an empty
-	 * flavor list in some cases.
-	 */
-	if (count == 0)
-		goto out_default;
-
 	/*
 	 * If the sec= mount option is used, the specified flavor or AUTH_NULL
 	 * must be in the list returned by the server.