Use 32-bit integer for NFS fsuid for older kernels [GH-1127]

CHANGELOG.md

@@ -8,6 +8,8 @@ BUG FIXES:
   - NFS exports with improper casing on Mac OS X work properly. [GH-1202]
   - Shared folders overriding '/vagrant' in multi-VM environments no
     longer all just use the last value. [GH-1935]
+  - NFS export fsid's are now 32-bit integers, rather than UUIDs. This
+    lets NFS exports work with Linux kernels older than 2.6.20. [GH-1127]
 
 ## 1.2.4 (July 16, 2013)
 

lib/vagrant/action/builtin/nfs.rb

@@ -1,6 +1,6 @@
-require 'digest/md5'
 require 'fileutils'
 require 'pathname'
+require 'zlib'
 
 require "log4r"
 
@@ -95,11 +95,9 @@ module Vagrant
           opts[:map_gid] = prepare_permission(:gid, opts)
           opts[:nfs_version] ||= 3
 
-          # The poor man's UUID. An MD5 hash here is sufficient since
-          # we need a 32 character "uuid" to represent the filesystem
-          # of an export. Hashing the host path is safe because two of
-          # the same host path will hash to the same fsid.
-          opts[:uuid]    = Digest::MD5.hexdigest(opts[:hostpath])
+          # We use a CRC32 to generate a 32-bit checksum so that the
+          # fsid is compatible with both old and new kernels.
+          opts[:uuid] = Zlib.crc32(opts[:hostpath]).to_s
         end
 
         # Prepares the UID/GID settings for a single folder.