saveconfig: dump control string containing control=value tuples
saveconfig: dump control string containing control=value tuples

Problem:
-------
$ targetcli /backstores/user:glfs create blockX1 1073741824 \
  test@192.168.124.227/block-store/e59309bb-d591-4121-a891-e98ff3416446,max_data_area_mb=32

$ targetcli / saveconfig

$ cat /etc/target/saveconfig.json
{
  "storage_objects": [
    {
      "alua_tpgs": [],
      "attributes": {
        ...
      },
      "config": "glfs/test@192.168.124.227/block-store/e59309bb-d591-4121-a891-e98ff3416446",
      "hw_max_sectors": 128,
      "name": "blockX1",
      "plugin": "user",
      "size": 1073741824,
      "wwn": "3aa072d6-a007-45a3-8eac-e85b53655515"
    }
  ],
  "targets": []
}

Note max_data_area_mb is not dumped into the configfile and hence on restart of
target service or node reboot this storageObject property is lost.

Fix:
----
This patch make sure to dump control string containing control=value tuples, like:
$ cat /etc/target/saveconfig.json
{
  ...
  "config": "glfs/test@192.168.124.227/block-store/e59309bb-d591-4121-a891-e98ff3416446",
  "control": "max_data_area_mb=32",
  ...
}

Signed-off-by: Prasanna Kumar Kalever <a78d8f98557446023f5b3ba9944d7be259a978a3@redhat.com>

cvubrugier/rtslib-fb