Add mount_options option.

This option can be very useful with the existing enable_nfs option to
choose a different protocol like tcp (udp is the default), and to add
other nfs options like nolock.

README.md

@@ -25,7 +25,14 @@ Vagrant.configure("2") do |config|
   config.vm.box = 'your-box'
   config.cache.auto_detect = true
   # If you are using VirtualBox, you might want to enable NFS for shared folders
+  # This is also very useful for vagrant-libvirt if you want bi-directional sync
   # config.cache.enable_nfs = true
+  # You can now specify mount options if needed, eg:
+  # config.cache.mount_options = ['rw', 'vers=3', 'tcp', 'nolock']
+  # The nolock option can be useful for an NFSv3 client that wants to avoid the
+  # NLM sideband protocol. Without this option, apt-get might hang if it tries
+  # to lock files needed for /var/cache/* operations. All of this can be avoided
+  # by using NFSv4 everywhere. die NFSv3, die! The tcp option is not the default.
 end
 ```
 

lib/vagrant-cachier/config.rb

@@ -1,7 +1,7 @@
 module VagrantPlugins
   module Cachier
     class Config < Vagrant.plugin(2, :config)
-      attr_accessor :scope, :auto_detect, :enable_nfs
+      attr_accessor :scope, :auto_detect, :enable_nfs, :mount_options
       attr_reader   :buckets
 
       ALLOWED_SCOPES = %w( box machine )
@@ -10,6 +10,7 @@ module VagrantPlugins
         @scope         = UNSET_VALUE
         @auto_detect   = UNSET_VALUE
         @enable_nfs    = UNSET_VALUE
+        @mount_options = UNSET_VALUE
       end
 
       def enable(bucket, opts = {})
@@ -34,6 +35,7 @@ module VagrantPlugins
         @scope         = :box  if @scope == UNSET_VALUE
         @auto_detect   = false if @auto_detect == UNSET_VALUE
         @enable_nfs    = false if @enable_nfs == UNSET_VALUE
+        @mount_options = false if @mount_options == UNSET_VALUE
         @buckets       = @buckets ? @buckets.dup : {}
       end
 

lib/vagrant-cachier/provision_ext.rb

@@ -18,7 +18,13 @@ module VagrantPlugins
             FileUtils.mkdir_p(cache_root.to_s) unless cache_root.exist?
 
             nfs_flag = env[:machine].config.cache.enable_nfs
+            mount_options = env[:machine].config.cache.mount_options
+
+            if mount_options
+              env[:machine].config.vm.synced_folder cache_root, '/tmp/vagrant-cache', id: "vagrant-cache", nfs: nfs_flag, mount_options: mount_options
+            else
               env[:machine].config.vm.synced_folder cache_root, '/tmp/vagrant-cache', id: "vagrant-cache", nfs: nfs_flag
+            end
 
             env[:cache_dirs] = []