initial commit of add_pool - disk role filter rockstor#1494

By examining the role of a disk we can rule it out as
a prospective pool member, or include it in the case of
an openLUKS device.

src/rockstor/storageadmin/static/storageadmin/js/views/add_pool.js

@@ -57,7 +57,10 @@ AddPoolView = Backbone.View.extend({
         $(this.el).empty();
         var _this = this;
         this.filteredCollection = _.reject(this.collection.models, function (disk) {
-            return _.isNull(disk.get('pool')) && !disk.get('parted') && !disk.get('offline') && _.isNull(disk.get('btrfs_uuid')) && isSerialUsable(disk.get('serial'));
+            return _.isNull(disk.get('pool')) && !disk.get('parted') &&
+                !disk.get('offline') && _.isNull(disk.get('btrfs_uuid')) &&
+                isSerialUsable(disk.get('serial')) &&
+                isRoleUsable(disk.get('role'));
         });
 
         // N.B. the isSerialUsable() code below is now duplicated in the
@@ -80,6 +83,40 @@ AddPoolView = Backbone.View.extend({
             return true;
         }
 
+        // Using the disk.role system we can filter drives on their usability.
+        // Roles for inclusion: openLUKS containers
+        // Roles to dismiss: LUKS containers, mdraid members, the 'root' role,
+        // and partitioned.
+        // Defaults to reject (return false)
+        function isRoleUsable(role) {
+            // check if our role is null = db default
+            // A drive with no role shouldn't present a problem for use.
+            if (role == null) {
+                console.log("add_pool ACCEPTING ROLE OF null")
+                return true;
+            }
+            // try json conversion and return false if it fails
+            // @todo not sure if this is redundant?
+            try {
+                var roleAsJson = JSON.parse(role);
+            } catch (e) {
+                // as we can't read this drives role we play save and exclude
+                // it's isRoleUsable status by false
+                return false;
+            }
+            // We have a json object, look for acceptable roles in the keys
+            //
+            // Accept use of 'openLUKS' device
+            if (roleAsJson.hasOwnProperty('openLUKS')) {
+                console.log("add_pool ACCEPTING ROLE OF openLUKS json = " + role);
+                return true;
+            }
+            // In all other cases return false, ie:
+            // reject roles of for example root, mdraid, LUKS, partitioned etc
+            console.log("add_pool REJECTING ROLE with json = " + role);
+            return false;
+        }
+
         this.collection.remove(this.filteredCollection);
         $(_this.el).append(_this.template({
             disks: this.collection.toJSON(),