Shorten snapshots names in CephFS drivers

The name set to snapshots in the CephFS drivers
is generated appending the snapshot id with the
snapshot instance id.

This is a problem because Ceph has a limitation
in the name of the subvolumes (shares) being created.

What happens then is, when trying to create a snapshot,
the snapshot gets created with a truncated name and it cannot
be accessed later.

This change drops the snapshot instance id from the
assigned name in order to avoid this limitation.

Closes-Bug: #1967760

Change-Id: Ifab3ec9de2abeb1af8e6499feca0236e1ee22fcf

manila/share/drivers/cephfs/driver.py

@@ -595,7 +595,7 @@ class CephFSDriver(driver.ExecuteMixin, driver.GaneshaMixin,
         argdict = {
             "vol_name": self.volname,
             "sub_name": snapshot["share_id"],
-            "snap_name": "_".join([snapshot["snapshot_id"], snapshot["id"]]),
+            "snap_name": snapshot["snapshot_id"],
         }
 
         rados_command(
@@ -605,13 +605,24 @@ class CephFSDriver(driver.ExecuteMixin, driver.GaneshaMixin,
         # delete a FS snapshot
         LOG.debug("[%(be)s]: delete_snapshot: snapshot=%(id)s.",
                   {"be": self.backend_name, "id": snapshot['id']})
-        argdict = {
+
+        # FIXME(vkmc) remove this in CC (next tick) release.
+        legacy_snap_name = "_".join([snapshot["snapshot_id"], snapshot["id"]])
+
+        argdict_legacy = {
             "vol_name": self.volname,
             "sub_name": snapshot["share_id"],
-            "snap_name": '_'.join([snapshot['snapshot_id'], snapshot['id']]),
+            "snap_name": legacy_snap_name,
             "force": True,
         }
 
+        # try removing snapshot using legacy naming
+        rados_command(
+            self.rados_client, "fs subvolume snapshot rm", argdict_legacy)
+
+        # in case it's a snapshot with new naming, retry remove with new name
+        argdict = argdict_legacy.copy()
+        argdict.update({"snap_name": snapshot["snapshot_id"]})
         rados_command(self.rados_client, "fs subvolume snapshot rm", argdict)
 
     def create_share_group(self, context, sg_dict, share_server=None):
@@ -734,7 +745,7 @@ class CephFSDriver(driver.ExecuteMixin, driver.GaneshaMixin,
         argdict = {
             "vol_name": self.volname,
             "sub_name": parent_share["id"],
-            "snap_name": '_'.join([snapshot["snapshot_id"], snapshot["id"]]),
+            "snap_name": snapshot["snapshot_id"],
             "target_sub_name": share["id"]
         }
         if share['share_group_id'] is not None:

manila/tests/share/drivers/cephfs/test_driver.py

@@ -364,8 +364,7 @@ class CephFSDriverTestCase(test.TestCase):
         snapshot_create_dict = {
             "vol_name": self._driver.volname,
             "sub_name": self._snapshot["share_id"],
-            "snap_name": "_".join([
-                self._snapshot["snapshot_id"], self._snapshot["id"]]),
+            "snap_name": self._snapshot["snapshot_id"]
         }
 
         self._driver.create_snapshot(self._context, self._snapshot, None)
@@ -375,23 +374,35 @@ class CephFSDriverTestCase(test.TestCase):
             snapshot_create_prefix, snapshot_create_dict)
 
     def test_delete_snapshot(self):
+        legacy_snap_name = "_".join(
+            [self._snapshot["snapshot_id"], self._snapshot["id"]])
+
         snapshot_remove_prefix = "fs subvolume snapshot rm"
 
         snapshot_remove_dict = {
             "vol_name": self._driver.volname,
             "sub_name": self._snapshot["share_id"],
-            "snap_name": "_".join([
-                self._snapshot["snapshot_id"], self._snapshot["id"]]),
-            "force": True,
+            "snap_name": legacy_snap_name,
+            "force": True
         }
 
+        snapshot_remove_dict_2 = snapshot_remove_dict.copy()
+        snapshot_remove_dict_2.update(
+            {"snap_name": self._snapshot["snapshot_id"]})
+
         self._driver.delete_snapshot(self._context,
                                      self._snapshot,
                                      None)
 
-        driver.rados_command.assert_called_once_with(
-            self._driver.rados_client,
-            snapshot_remove_prefix, snapshot_remove_dict)
+        driver.rados_command.assert_has_calls([
+            mock.call(self._driver.rados_client,
+                      snapshot_remove_prefix,
+                      snapshot_remove_dict),
+            mock.call(self._driver.rados_client,
+                      snapshot_remove_prefix,
+                      snapshot_remove_dict_2)])
+
+        self.assertEqual(2, driver.rados_command.call_count)
 
     def test_create_share_group(self):
         group_create_prefix = "fs subvolumegroup create"
@@ -465,8 +476,7 @@ class CephFSDriverTestCase(test.TestCase):
         create_share_from_snapshot_dict = {
             "vol_name": self._driver.volname,
             "sub_name": parent_share["id"],
-            "snap_name": "_".join([
-                self._snapshot["snapshot_id"], self._snapshot["id"]]),
+            "snap_name": self._snapshot["snapshot_id"],
             "target_sub_name": self._share["id"]
         }
 

releasenotes/notes/bug-1967760-shorten-snapshot-names-cephfs-a220e2b9f7ba5739.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Make snapshot names in CephFS drivers shorter to
+    avoid limitation in Ceph clusters which truncates
+    the subvolume name and makes the snapshots inaccesible.