NFSv4: Fix Oops in nfs4_create_referral_server

The filehandle that is passed into nfs4_create_referral_server is
not initialised. The expectation is that nfs4_create_referral_server will
initialise it, and return it to the caller.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/client.c

@@ -1030,7 +1030,7 @@ error:
  * Create an NFS4 referral server record
  */
 struct nfs_server *nfs4_create_referral_server(struct nfs_clone_mount *data,
-					       struct nfs_fh *fh)
+					       struct nfs_fh *mntfh)
 {
 	struct nfs_client *parent_client;
 	struct nfs_server *server, *parent_server;
@@ -1069,8 +1069,13 @@ struct nfs_server *nfs4_create_referral_server(struct nfs_clone_mount *data,
 	BUG_ON(!server->nfs_client->rpc_ops);
 	BUG_ON(!server->nfs_client->rpc_ops->file_inode_ops);
 
+	/* Probe the root fh to retrieve its FSID and filehandle */
+	error = nfs4_path_walk(server, mntfh, data->mnt_path);
+	if (error < 0)
+		goto error;
+
 	/* probe the filesystem info for this server filesystem */
-	error = nfs_probe_fsinfo(server, fh, &fattr);
+	error = nfs_probe_fsinfo(server, mntfh, &fattr);
 	if (error < 0)
 		goto error;
 

fs/nfs/super.c

@@ -1044,7 +1044,7 @@ static int nfs4_referral_get_sb(struct file_system_type *fs_type, int flags,
 		nfs4_fill_super(s);
 	}
 
-	mntroot = nfs4_get_root(s, data->fh);
+	mntroot = nfs4_get_root(s, &mntfh);
 	if (IS_ERR(mntroot)) {
 		error = PTR_ERR(mntroot);
 		goto error_splat_super;