gluster:refactor: Refactor GlusterFSConnection class

Gluster volume info is required when validating that gluster volume
is replica 3 and when calculating gluster backup servers option.
volinfo property introduced to save multiple calls to get gluster
volume info.
self._volname and self._volfileserver introduced because they are
used in multiple places in the code.

Change-Id: I3014723e1e3d1164a986f5e04208e199396b21b0
Signed-off-by: Ala Hino <ahino@redhat.com>
Reviewed-on: https://gerrit.ovirt.org/42952
Reviewed-by: Nir Soffer <nsoffer@redhat.com>
Continuous-Integration: Jenkins CI
Reviewed-by: Adam Litke <alitke@redhat.com>

vdsm/storage/storageServer.py

@@ -282,32 +282,39 @@ def __init__(self,
                                                   vfsType=vfsType,
                                                   options=options,
                                                   mountClass=mountClass)
-        self._backup_servers_option = None
+        self._volinfo = None
+        self._volfileserver, volname = self._remotePath.split(":", 1)
+        self._volname = volname.strip('/')
 
     @property
     def options(self):
-        if self._backup_servers_option is None:
-            self._backup_servers_option = self._get_backup_servers_option()
+        backup_servers_option = self._get_backup_servers_option()
         return ",".join(
-            p for p in (self._options, self._backup_servers_option) if p)
+            p for p in (self._options, backup_servers_option) if p)
+
+    @property
+    def volinfo(self):
+        if self._volinfo is None:
+            self._volinfo = self._get_gluster_volinfo()
+        return self._volinfo
 
     def _get_backup_servers_option(self):
         if "backup-volfile-servers" in self._options:
             self.log.warn("Using user specified backup-volfile-servers option")
             return ""
 
-        volfileServer, volname = self._remotePath.split(":", 1)
-        volname = volname.strip('/')
-        volInfo = supervdsm.getProxy().glusterVolumeInfo(volname,
-                                                         volfileServer)
-        servers = [brick.split(":")[0]
-                   for brick in volInfo[volname]['bricks']]
-        servers.remove(volfileServer)
+        servers = [brick.split(":")[0] for brick in self.volinfo['bricks']]
+        servers.remove(self._volfileserver)
         if not servers:
             return ""
 
         return "backup-volfile-servers=" + ":".join(servers)
 
+    def _get_gluster_volinfo(self):
+        volinfo = supervdsm.getProxy().glusterVolumeInfo(self._volname,
+                                                         self._volfileserver)
+        return volinfo[self._volname]
+
 
 class NFSConnection(object):
     DEFAULT_OPTIONS = ["soft", "nosharecache"]