nfs4 use mandatory attribute file type in nfs4_get_root

S_ISDIR(fsinfo.fattr->mode) checks the file type rather than the mode bits,
so we should be checking for the NFS_ATTR_FATTR_TYPE fattr property.
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@kernel.org

fs/nfs/getroot.c

@@ -146,7 +146,7 @@ int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh)
 		goto out;
 	}
 
-	if (!(fsinfo.fattr->valid & NFS_ATTR_FATTR_MODE)
+	if (!(fsinfo.fattr->valid & NFS_ATTR_FATTR_TYPE)
 			|| !S_ISDIR(fsinfo.fattr->mode)) {
 		printk(KERN_ERR "nfs4_get_rootfh:"
 		       " getroot encountered non-directory\n");