diff --git a/apps/files_sharing/lib/cache.php b/apps/files_sharing/lib/cache.php
index e0737834812440b7365b17d3761c785fcda614aa..b71dfb44ab01d4cbca4b0cb4d81e716590315733 100644
--- a/apps/files_sharing/lib/cache.php
+++ b/apps/files_sharing/lib/cache.php
@@ -394,6 +394,28 @@ class Shared_Cache extends Cache {
 		return $result;
 	}
 
+	/**
+	 * update the folder size and the size of all parent folders
+	 *
+	 * @param string|boolean $path
+	 * @param array $data (optional) meta data of the folder
+	 */
+	public function correctFolderSize($path, $data = null) {
+		$this->calculateFolderSize($path, $data);
+		if ($path !== '') {
+			$parent = dirname($path);
+			if ($parent === '.' or $parent === '/') {
+				$parent = '';
+			}
+			$this->correctFolderSize($parent);
+		} else {
+			// bubble up to source cache
+			$sourceCache = $this->getSourceCache($path);
+			$parent = dirname($this->files[$path]);
+			$sourceCache->correctFolderSize($parent);
+		}
+	}
+
 	/**
 	 * get the size of a folder and set it in the cache
 	 *
diff --git a/apps/files_sharing/tests/propagation.php b/apps/files_sharing/tests/propagation.php
new file mode 100644
index 0000000000000000000000000000000000000000..3d5f9985afde8f8e923ca654d29a53b43a7604e4
--- /dev/null
+++ b/apps/files_sharing/tests/propagation.php
@@ -0,0 +1,90 @@
+<?php
+/**
+ * ownCloud
+ *
+ * @author Robin Appelman
+ * @copyright 2015 Robin Appelman <icewind@owncloud.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU AFFERO GENERAL PUBLIC LICENSE for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public
+ * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\Files_sharing\Tests;
+
+use OC\Files\View;
+
+class Propagation extends TestCase {
+
+	public function testSizePropagationWhenOwnerChangesFile() {
+		$this->loginAsUser(self::TEST_FILES_SHARING_API_USER1);
+		$recipientView = new View('/' . self::TEST_FILES_SHARING_API_USER1 . '/files');
+
+		$this->loginAsUser(self::TEST_FILES_SHARING_API_USER2);
+		$ownerView = new View('/' . self::TEST_FILES_SHARING_API_USER2 . '/files');
+		$ownerView->mkdir('/sharedfolder/subfolder');
+		$ownerView->file_put_contents('/sharedfolder/subfolder/foo.txt', 'bar');
+
+		$sharedFolderInfo = $ownerView->getFileInfo('/sharedfolder', false);
+		\OCP\Share::shareItem('folder', $sharedFolderInfo->getId(), \OCP\Share::SHARE_TYPE_USER, self::TEST_FILES_SHARING_API_USER1, 31);
+		$ownerRootInfo = $ownerView->getFileInfo('', false);
+
+		$this->loginAsUser(self::TEST_FILES_SHARING_API_USER1);
+		$this->assertTrue($recipientView->file_exists('/sharedfolder/subfolder/foo.txt'));
+		$recipientRootInfo = $recipientView->getFileInfo('', false);
+
+		// when file changed as owner
+		$this->loginAsUser(self::TEST_FILES_SHARING_API_USER2);
+		$ownerView->file_put_contents('/sharedfolder/subfolder/foo.txt', 'foobar');
+
+		// size of recipient's root stays the same
+		$this->loginAsUser(self::TEST_FILES_SHARING_API_USER1);
+		$newRecipientRootInfo = $recipientView->getFileInfo('', false);
+		$this->assertEquals($recipientRootInfo->getSize(), $newRecipientRootInfo->getSize());
+
+		// size of owner's root increases
+		$this->loginAsUser(self::TEST_FILES_SHARING_API_USER2);
+		$newOwnerRootInfo = $ownerView->getFileInfo('', false);
+		$this->assertEquals($ownerRootInfo->getSize() + 3, $newOwnerRootInfo->getSize());
+	}
+
+	public function testSizePropagationWhenRecipientChangesFile() {
+		$this->loginAsUser(self::TEST_FILES_SHARING_API_USER1);
+		$recipientView = new View('/' . self::TEST_FILES_SHARING_API_USER1 . '/files');
+
+		$this->loginAsUser(self::TEST_FILES_SHARING_API_USER2);
+		$ownerView = new View('/' . self::TEST_FILES_SHARING_API_USER2 . '/files');
+		$ownerView->mkdir('/sharedfolder/subfolder');
+		$ownerView->file_put_contents('/sharedfolder/subfolder/foo.txt', 'bar');
+
+		$sharedFolderInfo = $ownerView->getFileInfo('/sharedfolder', false);
+		\OCP\Share::shareItem('folder', $sharedFolderInfo->getId(), \OCP\Share::SHARE_TYPE_USER, self::TEST_FILES_SHARING_API_USER1, 31);
+		$ownerRootInfo = $ownerView->getFileInfo('', false);
+
+		$this->loginAsUser(self::TEST_FILES_SHARING_API_USER1);
+		$this->assertTrue($recipientView->file_exists('/sharedfolder/subfolder/foo.txt'));
+		$recipientRootInfo = $recipientView->getFileInfo('', false);
+
+		// when file changed as recipient
+		$recipientView->file_put_contents('/sharedfolder/subfolder/foo.txt', 'foobar');
+
+		// size of recipient's root stays the same
+		$newRecipientRootInfo = $recipientView->getFileInfo('', false);
+		$this->assertEquals($recipientRootInfo->getSize(), $newRecipientRootInfo->getSize());
+
+		// size of owner's root increases
+		$this->loginAsUser(self::TEST_FILES_SHARING_API_USER2);
+		$newOwnerRootInfo = $ownerView->getFileInfo('', false);
+		$this->assertEquals($ownerRootInfo->getSize() + 3, $newOwnerRootInfo->getSize());
+	}
+}