Check if a given ZFS attribute is already set on the filesystem befor…

…e calling 'zfs set ...'. This is necessary because zfs set will attempt to set, for example, mountpoint even if the filesystem is already mounted at the correct location.

resources/default.rb

@@ -89,6 +89,21 @@ def zfs_get_properties(name)
   cmd.stdout
 end
 
+# Helper method to check if a filesystem property is already set
+# so that we don't call zfs set when it's unnecessary.
+# @param [String] ZFS Name
+# @param [Hash] ZFS Property => value
+# @return [Boolean]
+def zfs_property_already_set?(fs, property)
+  key = property.keys[0]
+  new_value = property[property.keys[0]]
+  cmd = Mixlib::ShellOut.new('zfs', 'get', key.to_s, fs)
+  cmd.run_command
+  existing_property = parse_zfs_properties(cmd.stdout)[0]
+  existing_value = existing_property[existing_property.keys[0]]
+  existing_value == new_value ? true : false
+end
+
 # TODO: Add support for setting inheritance from parent filesystems.
 # @param [String] ZFS Name
 # @param [Hash] ZFS Property => value
@@ -102,6 +117,7 @@ def zfs_set_properties(fs, properties)
 
   configurable_properties.each do |setting|
     next if PROPERTIES_VALID_ONLY_AT_CREATE.include?(setting.keys[0])
+    next if zfs_property_already_set?(fs, setting)
     cmd = Mixlib::ShellOut.new('zfs', 'set', "#{setting.keys[0]}=#{setting[setting.keys[0]]}", fs)
     cmd.environment['PATH'] = "/usr/sbin:#{ENV['PATH']}" if platform_family?('solaris2')
     cmd.run_command