[GitFiles] List files from project root

autoload/fzf/vim.vim

@@ -328,8 +328,14 @@ endfunction
 " ------------------------------------------------------------------
 
 function! fzf#vim#gitfiles(...)
+  let root = systemlist('git rev-parse --show-toplevel')[0]
+  if v:shell_error
+    call s:warn('Not in git repo')
+    return
+  endif
   call s:fzf({
   \ 'source':  'git ls-tree --name-only -r HEAD',
+  \ 'dir':     root,
   \ 'sink*':   s:function('s:common_sink'),
   \ 'options': '--prompt "GitFiles> " -m'.s:expect(),
   \}, a:000)