Share server for one neovim session

[ray-x]

I found in some cases, efm will startup multiple server instances:

LspInfo:

 
 Language client log: /Users/ray/.cache/nvim/lsp.log
 Detected filetype:   lua
 
 2 client(s) attached to this buffer: 
 
 Client: sumneko_lua (id: 1, pid: 77948, bufnr: [1, 1, 2])
 ...
 
 Client: efm (id: 3, pid: 77957, bufnr: [2])
 	filetypes:       javascript, javascriptreact, typescript, typescriptreact, html, css, go, lua, sql, json, markdown, scss, yaml, javascript.jsx, less, graphql, vue, svelte
 	autostart:       true
 	root directory:  /Users/ray/github/navigator.lua/lua/navigator
 	cmd:             efm-langserver -loglevel 1 -logfile /Users/ray/tmp/efm.log
 
 1 active client(s) not attached to this buffer: 
 
 Client: efm (id: 2, pid: 77949, bufnr: [1, 1])
 	filetypes:       javascript, javascriptreact, typescript, typescriptreact, html, css, go, lua, sql, json, markdown, scss, yaml, javascript.jsx, less, graphql, vue, svelte
 	autostart:       true
 	root directory:  /Users/ray/github/navigator.lua/lua
 	cmd:             efm-langserver -loglevel 1 -logfile /Users/ray/tmp/efm.log

And efm setup:

  local efm_cfg = {
    flags = {debounce_text_changes = 2000},
    cmd = {'efm-langserver', '-loglevel', '1', '-logfile', vim.fn.expand("$HOME") .. '/tmp/efm.log'}, -- 1~10
    init_options = {documentFormatting = true, codeAction = false, document_formatting = true},
    root_dir = require'lspconfig'.util.root_pattern({'.git/', 'package.json', '.'}),
    on_attach = function(client)
      client.resolved_capabilities.document_formatting = true
      client.resolved_capabilities.goto_definition = false
      vim.cmd([[autocmd BufWritePre <buffer> lua vim.lsp.buf.formatting()]])
    end,
    filetypes = {
       'go', 'lua','sql',
    },

    settings = {
      rootMarkers = {".git/", 'package.json', 'Makefile', 'go.mod'},
      lintDebounce = "1s",
      formatDebounce = "1000ms",
      languages = {
        go = {
          {
            formatCommand = "golines --max-len=120  --base-formatter=gofumpt",
            formatStdin = true,
            lintCommand = "golangci-lint run",
            LintSeverity = 3
          }
        },
        lua = {
          {
            formatCommand = "lua-format --indent-width 2 --tab-width 2 --no-use-tab --column-limit 120 --column-table-limit 100 --no-keep-simple-function-one-line --no-chop-down-table --chop-down-kv-table --no-keep-simple-control-block-one-line --no-keep-simple-function-one-line --no-break-after-functioncall-lp --no-break-after-operator",
            formatStdin = true
          }
        },
      }
    }
  }

require'lspconfig'.efm.setup(efm_cfg)

step to reproduce:

Suppose I am in root dir of repo navigator.lua

neovim -u vimrc   lua/navigator.lua lua/navigator/cclshierarchy.lua

And switch between buffer with :bn, :bp
Run LspInfo and saw efm started two instances.

Expected behavior:
As the rootMarker is .git and both file are lua. It should use one instance of efm-language-server