diff --git a/manila/share/drivers/generic.py b/manila/share/drivers/generic.py
index e2bcd8f052..72f183396d 100644
--- a/manila/share/drivers/generic.py
+++ b/manila/share/drivers/generic.py
@@ -667,7 +667,7 @@ class GenericShareDriver(driver.ExecuteMixin, driver.ShareDriver):
                 server_details['instance_id'],
                 volume)
 
-        self._resize_filesystem(server_details, volume)
+        self._resize_filesystem(server_details, volume, new_size=new_size)
         self._mount_device(share, server_details, volume)
         helper.restore_access_after_maintenance(server_details,
                                                 share['name'])
diff --git a/releasenotes/notes/bug-1909951-fix-extend-have-wrong-size-7938eaa6591bd2ad.yaml b/releasenotes/notes/bug-1909951-fix-extend-have-wrong-size-7938eaa6591bd2ad.yaml
new file mode 100644
index 0000000000..b83a50d94e
--- /dev/null
+++ b/releasenotes/notes/bug-1909951-fix-extend-have-wrong-size-7938eaa6591bd2ad.yaml
@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    Fixed a bug that if extend a volume after shrink it under generic
+    driver, it may have a wrong real size. Please see
+    `Launchpad bug #1909951 <https://bugs.launchpad.net/manila/+bug/1909951>`_
+    for more details.