mgr/volumes: handling dangling symlinks gracefully

If we come across situations where we encounter dangling
symlinks for clones due to any reason,like older versions
may have produced dangling clone symlinks which remained
post-upgrade, it needs to be handled gracefully by deleting
it, presence of which may not allow deletion of the snapshot.
We are now cleaning those up in the snapshot info command.

Fixes: https://tracker.ceph.com/issues/58090
Signed-off-by: Neeraj Pratap Singh <neesingh@redhat.com>

diff --git a/src/pybind/mgr/volumes/fs/operations/versions/subvolume_v1.py b/src/pybind/mgr/volumes/fs/operations/versions/subvolume_v1.py
index 90f35a4c90b39e6523c9bd816bc8c1d9f7056ddb..05257394a9637cf2c8802fba540ab54a68f0f3a1 100644 (file)
--- a/src/pybind/mgr/volumes/fs/operations/versions/subvolume_v1.py
+++ b/src/pybind/mgr/volumes/fs/operations/versions/subvolume_v1.py
@@ -743,6 +743,20 @@ class SubvolumeV1(SubvolumeBase, SubvolumeTemplate):
                 return False
             raise
 
+    def remove_non_existent_pending_clones(self, path, link_path, track_id):
+        try:
+            self.fs.lstat(link_path)
+        except cephfs.Error as e:
+            if e.args[0] == errno.ENOENT:
+                try:
+                    log.info(f"Cleaning up dangling symlink for the clone: {path}")
+                    self.fs.unlink(path)
+                    self._remove_snap_clone(track_id)
+                except (cephfs.Error, MetadataMgrException) as e:
+                    log.warning(f'Removing of dangling symlink for the clone {path}'
+                                f' failed with the exception:"{e}"')
+                    pass
+    
     def get_pending_clones(self, snapname):
         pending_clones_info: Dict[str, Any] = {"has_pending_clones": "no"}
         pending_track_id_list = []
@@ -768,7 +782,9 @@ class SubvolumeV1(SubvolumeBase, SubvolumeTemplate):
 
         for track_id in pending_track_id_list:
             try:
-                link_path = self.fs.readlink(os.path.join(index_path, track_id), 4096)
+                t_path = os.path.join(index_path, track_id)
+                link_path = self.fs.readlink(t_path, 4096)
+                self.remove_non_existent_pending_clones(t_path, link_path, track_id)
             except cephfs.Error as e:
                 if e.errno != errno.ENOENT:
                     raise VolumeException(-e.args[0], e.args[1])