diff --git a/lang/en/error.php b/lang/en/error.php
index 371cf469fd3..b40859b4e18 100644
--- a/lang/en/error.php
+++ b/lang/en/error.php
@@ -324,6 +324,7 @@ $string['invalidsection'] = 'Course module record contains invalid section';
 $string['invalidsesskey'] = 'Incorrect sesskey submitted, form not accepted!';
 $string['invalidshortname'] = 'That\'s an invalid short course name';
 $string['invalidstatedetected'] = 'Something has gone wrong: {$a}. This should never normally happen.';
+$string['invalidsourcefield'] = 'Draft file\'s source field is invalid';
 $string['invalidurl'] = 'Invalid URL';
 $string['invaliduser'] = 'Invalid user';
 $string['invaliduserid'] = 'Invalid user id';
diff --git a/lib/filelib.php b/lib/filelib.php
index 11cba0fac86..8d8faf4db96 100644
--- a/lib/filelib.php
+++ b/lib/filelib.php
@@ -375,7 +375,7 @@ function file_prepare_draft_area(&$draftitemid, $contextid, $component, $fileare
                     continue;
                 }
                 $draftfile = $fs->create_file_from_storedfile($file_record, $file);
-                // XXX: This is a hack for file manager
+                // XXX: This is a hack for file manager (MDL-28666)
                 // File manager needs to know the original file information before copying
                 // to draft area, so we append these information in mdl_files.source field
                 // {@link file_storage::search_references()}
@@ -679,9 +679,13 @@ function file_get_submitted_draft_itemid($elname) {
  */
 function file_restore_source_field_from_draft_file($storedfile) {
     $source = unserialize($storedfile->get_source());
-    if (!empty($source) && is_object($source)) {
-        $restoredsource = $source->source;
-        $storedfile->set_source($restoredsource);
+    if (!empty($source)) {
+        if (is_object($source)) {
+            $restoredsource = $source->source;
+            $storedfile->set_source($restoredsource);
+        } else {
+            throw new moodle_exception('invalidsourcefield', 'error');
+        }
     }
     return $storedfile;
 }
@@ -813,6 +817,11 @@ function file_save_draft_area_files($draftitemid, $contextid, $component, $filea
                 $oldfile->set_sortorder($newfile->get_sortorder());
             }
 
+            // Update file size
+            if ($oldfile->get_filesize() != $newfile->get_filesize()) {
+                $oldfile->set_filesize($newfile->get_filesize());
+            }
+
             // unchanged file or directory - we keep it as is
             unset($newhashes[$oldhash]);
             if (!$oldfile->is_directory()) {
diff --git a/lib/filestorage/stored_file.php b/lib/filestorage/stored_file.php
index f20a528700b..5141c61caa2 100644
--- a/lib/filestorage/stored_file.php
+++ b/lib/filestorage/stored_file.php
@@ -191,15 +191,27 @@ class stored_file {
      */
     public function delete_reference() {
         global $DB;
+
         // Remove repository info.
         $this->repository = null;
+
+        // Remove reference info from DB.
+        $DB->delete_records('files_reference', array('id'=>$this->file_record->referencefileid));
+
+        // Must refresh $this->file_record form DB
+        $filerecord = $DB->get_record('files', array('id'=>$this->get_id()));
+        // Update DB
+        $filerecord->referencelastsync = null;
+        $filerecord->referencelifetime = null;
+        $filerecord->referencefileid = null;
+        $this->update($filerecord);
+
+        // unset object variable
         unset($this->file_record->repositoryid);
         unset($this->file_record->reference);
         unset($this->file_record->referencelastsync);
         unset($this->file_record->referencelifetime);
-
-        // Remove reference info from DB.
-        $DB->delete_records('files_reference', array('id'=>$this->file_record->referencefileid));
+        unset($this->file_record->referencefileid);
     }
 
     /**
@@ -560,6 +572,17 @@ class stored_file {
         return $this->file_record->filesize;
     }
 
+    /**
+     * Returns the size of file in bytes.
+     *
+     * @param int $filesize bytes
+     */
+    public function set_filesize($filesize) {
+        $filerecord = new stdClass;
+        $filerecord->filesize = $filesize;
+        $this->update($filerecord);
+    }
+
     /**
      * Returns mime type of file.
      *
diff --git a/lib/filestorage/tests/file_storage_test.php b/lib/filestorage/tests/file_storage_test.php
index 9685e3f401a..5f70959c17d 100644
--- a/lib/filestorage/tests/file_storage_test.php
+++ b/lib/filestorage/tests/file_storage_test.php
@@ -109,15 +109,17 @@ class filestoragelib_testcase extends advanced_testcase {
         $contenthash = $originalfile->get_contenthash();
         $newpath = '/test/';
         $newname = 'newtest.txt';
-        // try break it
-        $this->setExpectedException('file_exception');
-        // this shall throw exception
-        $originalfile->rename($filepath, $filename);
+
         // this should work
         $originalfile->rename($newpath, $newname);
         $file = $fs->get_file($syscontext->id, $component, $filearea, $itemid, $newpath, $newname);
         $this->assertInstanceOf('stored_file', $file);
         $this->assertEquals($contenthash, $file->get_contenthash());
+
+        // try break it
+        $this->setExpectedException('file_exception');
+        // this shall throw exception
+        $originalfile->rename($newpath, $newname);
     }
 
     /**
diff --git a/lib/tests/filelib_test.php b/lib/tests/filelib_test.php
index 9a419de243a..ee743e8055e 100644
--- a/lib/tests/filelib_test.php
+++ b/lib/tests/filelib_test.php
@@ -195,4 +195,78 @@ class filelib_testcase extends advanced_testcase {
         $this->assertEquals($license, $file->get_license());
         $this->assertEquals($newsourcefield, $file->get_source());
     }
+
+    /**
+     * Testing deleting original files
+     *
+     * @copyright 2012 Dongsheng Cai {@link http://dongsheng.org}
+     * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+     */
+    public function test_delete_original_file_from_draft() {
+        global $USER, $DB;
+
+        $this->resetAfterTest(true);
+
+        $generator = $this->getDataGenerator();
+        $user = $generator->create_user();
+        $usercontext = context_user::instance($user->id);
+        $USER = $DB->get_record('user', array('id'=>$user->id));
+
+        $repositorypluginname = 'user';
+
+        $args = array();
+        $args['type'] = $repositorypluginname;
+        $repos = repository::get_instances($args);
+        $userrepository = reset($repos);
+        $this->assertInstanceOf('repository', $userrepository);
+
+        $fs = get_file_storage();
+        $syscontext = context_system::instance();
+
+        $filecontent = 'User file content';
+
+        // create a user private file
+        $userfilerecord = new stdClass;
+        $userfilerecord->contextid = $usercontext->id;
+        $userfilerecord->component = 'user';
+        $userfilerecord->filearea  = 'private';
+        $userfilerecord->itemid    = 0;
+        $userfilerecord->filepath  = '/';
+        $userfilerecord->filename  = 'userfile.txt';
+        $userfilerecord->source    = 'test';
+        $userfile = $fs->create_file_from_string($userfilerecord, $filecontent);
+        $userfileref = $fs->pack_reference($userfilerecord);
+        $contenthash = $userfile->get_contenthash();
+
+        $filerecord = array(
+            'contextid' => $syscontext->id,
+            'component' => 'core',
+            'filearea'  => 'phpunit',
+            'itemid'    => 0,
+            'filepath'  => '/',
+            'filename'  => 'test.txt',
+        );
+        // create a file reference
+        $fileref = $fs->create_file_from_reference($filerecord, $userrepository->id, $userfileref);
+        $this->assertInstanceOf('stored_file', $fileref);
+        $this->assertEquals($userrepository->id, $fileref->repository->id);
+        $this->assertEquals($userfile->get_contenthash(), $fileref->get_contenthash());
+        $this->assertEquals($userfile->get_filesize(), $fileref->get_filesize());
+        $this->assertRegExp('#' . $userfile->get_filename(). '$#', $fileref->get_reference_details());
+
+        $draftitemid = 0;
+        file_prepare_draft_area($draftitemid, $usercontext->id, 'user', 'private', 0);
+        $draftfiles = $fs->get_area_files($usercontext->id, 'user', 'draft', $draftitemid);
+        $this->assertEquals(2, count($draftfiles));
+        $draftfile = $fs->get_file($usercontext->id, 'user', 'draft', $draftitemid, $userfilerecord->filepath, $userfilerecord->filename);
+        $draftfile->delete();
+        // Save changed file
+        file_save_draft_area_files($draftitemid, $usercontext->id, 'user', 'private', 0);
+
+        // The file reference should be a regular moodle file now
+        $fileref = $fs->get_file($syscontext->id, 'core', 'phpunit', 0, '/', 'test.txt');
+        $this->assertEquals(false, $fileref->is_external_file());
+        $this->assertEquals($contenthash, $fileref->get_contenthash());
+        $this->assertEquals($filecontent, $fileref->get_content());
+    }
 }
diff --git a/repository/coursefiles/lib.php b/repository/coursefiles/lib.php
index 06d75f689da..64fb1a0c60a 100644
--- a/repository/coursefiles/lib.php
+++ b/repository/coursefiles/lib.php
@@ -279,6 +279,17 @@ class repository_coursefiles extends repository {
         return $coursename . ': ' . $params['filepath'] . $params['filename'];
     }
 
+    /**
+     * Return reference file life time
+     *
+     * @param string $ref
+     * @return int
+     */
+    public function get_reference_file_lifetime($ref) {
+        // this should be realtime
+        return 0;
+    }
+
     /**
      * Repository method to serve file
      *
diff --git a/repository/googledocs/lib.php b/repository/googledocs/lib.php
index 833eee953b5..36648bdb81e 100644
--- a/repository/googledocs/lib.php
+++ b/repository/googledocs/lib.php
@@ -19,7 +19,7 @@
  *
  * @since 2.0
  * @package    repository_googledocs
- * @copyright  2010 Dongsheng Cai {@link http://dongsheng.org}
+ * @copyright  2009 Dan Poltawski <talktodan@gmail.com>
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 require_once($CFG->dirroot . '/repository/lib.php');
diff --git a/repository/lib.php b/repository/lib.php
index 9cea0f8eb39..20849b0eef5 100644
--- a/repository/lib.php
+++ b/repository/lib.php
@@ -1066,6 +1066,7 @@ abstract class repository {
      * @param array $options additional options affecting the file serving
      */
     public function send_file($storedfile, $lifetime=86400 , $filter=0, $forcedownload=false, array $options = null) {
+        throw new coding_exception("Repository plugin must implement send_file() method.");
     }
 
     /**
diff --git a/repository/picasa/lib.php b/repository/picasa/lib.php
index c1cbc3ef8cb..6a83ca08238 100644
--- a/repository/picasa/lib.php
+++ b/repository/picasa/lib.php
@@ -19,7 +19,7 @@
  *
  * @since 2.0
  * @package    repository_picasa
- * @copyright  2010 Dongsheng Cai {@link http://dongsheng.org}
+ * @copyright  2009 Dan Poltawski <talktodan@gmail.com>
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 require_once($CFG->dirroot . '/repository/lib.php');
diff --git a/repository/user/lib.php b/repository/user/lib.php
index 80dc94b6667..9d0537a8a27 100644
--- a/repository/user/lib.php
+++ b/repository/user/lib.php
@@ -225,6 +225,17 @@ class repository_user extends repository {
         return $this->get_name() . ': ' . $params['filepath'] . $params['filename'];
     }
 
+    /**
+     * Return reference file life time
+     *
+     * @param string $ref
+     * @return int
+     */
+    public function get_reference_file_lifetime($ref) {
+        // this should be realtime
+        return 0;
+    }
+
     /**
      * Repository method to serve file
      *