NFS: don't negotiate when user specifies sec flavor

We were always attempting sec flavor negotiation, even if the user
told us a specific sec flavor to use.  If that sec flavor fails,
we should return an error rather than continuing with sec flavor
negotiation.
Signed-off-by: NBryan Schumaker <bjschuma@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4proc.c

@@ -46,6 +46,7 @@
 #include <linux/nfs4.h>
 #include <linux/nfs_fs.h>
 #include <linux/nfs_page.h>
+#include <linux/nfs_mount.h>
 #include <linux/namei.h>
 #include <linux/mount.h>
 #include <linux/module.h>
@@ -2234,7 +2235,7 @@ static int nfs4_proc_get_root(struct nfs_server *server, struct nfs_fh *fhandle,
 			      struct nfs_fsinfo *info)
 {
 	int status = nfs4_lookup_root(server, fhandle, info);
-	if (status == -EPERM)
+	if ((status == -EPERM) && !(server->flags & NFS_MOUNT_SECFLAVOUR))
 		status = nfs4_find_root_sec(server, fhandle, info);
 	if (status == 0)
 		status = nfs4_server_capabilities(server, fhandle);

fs/nfs/super.c

@@ -1004,6 +1004,7 @@ static int nfs_parse_security_flavors(char *value,
 		return 0;
 	}
 
+	mnt->flags |= NFS_MOUNT_SECFLAVOUR;
 	mnt->auth_flavor_len = 1;
 	return 1;
 }