diff --git a/bundles/element-web/metadata.py b/bundles/element-web/metadata.py
index 4276549..0ce259a 100644
--- a/bundles/element-web/metadata.py
+++ b/bundles/element-web/metadata.py
@@ -3,6 +3,9 @@ defaults = {
         'datasets': {
             'tank/element-web': {
                 'mountpoint': '/opt/element-web',
+                'needed_by': {
+                    'directory:/opt/element-web',
+                },
             },
         },
     },
diff --git a/bundles/gitea/metadata.py b/bundles/gitea/metadata.py
index d34fa7a..06556a9 100644
--- a/bundles/gitea/metadata.py
+++ b/bundles/gitea/metadata.py
@@ -50,9 +50,15 @@ defaults = {
             'tank/gitea': {},
             'tank/gitea/home': {
                 'mountpoint': '/home/git',
+                'needed_by': {
+                    'directory:/home/git',
+                },
             },
             'tank/gitea/var': {
                 'mountpoint': '/var/lib/gitea',
+                'needed_by': {
+                    'directory:/var/lib/gitea',
+                },
             },
         },
     },
diff --git a/bundles/matrix-media-repo/metadata.py b/bundles/matrix-media-repo/metadata.py
index 835abe5..0b753db 100644
--- a/bundles/matrix-media-repo/metadata.py
+++ b/bundles/matrix-media-repo/metadata.py
@@ -60,10 +60,16 @@ defaults = {
             'tank/matrix-media-repo': {},
             'tank/matrix-media-repo/install': {
                 'mountpoint': '/opt/matrix-media-repo',
+                'needed_by': {
+                    'directory:/opt/matrix-media-repo',
+                },
             },
             'tank/matrix-media-repo/media': {
                 'mountpoint': '/var/matrix/media',
                 'compression': 'on',
+                'needed_by': {
+                    'directory:/var/matrix/media',
+                },
             },
         },
     },
diff --git a/bundles/mautrix-telegram/metadata.py b/bundles/mautrix-telegram/metadata.py
index 2ba91fb..bf2cf22 100644
--- a/bundles/mautrix-telegram/metadata.py
+++ b/bundles/mautrix-telegram/metadata.py
@@ -44,6 +44,9 @@ defaults = {
         'datasets': {
             'tank/mautrix-telegram': {
                 'mountpoint': '/opt/mautrix-telegram',
+                'needed_by': {
+                    'directory:/opt/mautrix-telegram',
+                },
             },
         },
     },
diff --git a/bundles/mautrix-whatsapp/metadata.py b/bundles/mautrix-whatsapp/metadata.py
index 708fa81..f559a65 100644
--- a/bundles/mautrix-whatsapp/metadata.py
+++ b/bundles/mautrix-whatsapp/metadata.py
@@ -51,6 +51,9 @@ defaults = {
         'datasets': {
             'tank/mautrix-whatsapp': {
                 'mountpoint': '/opt/mautrix-whatsapp',
+                'needed_by': {
+                    'directory:/opt/mautrix-whatsapp',
+                },
             },
         },
     },
diff --git a/bundles/mx-puppet-discord/metadata.py b/bundles/mx-puppet-discord/metadata.py
index 30e27bd..b2590e0 100644
--- a/bundles/mx-puppet-discord/metadata.py
+++ b/bundles/mx-puppet-discord/metadata.py
@@ -39,6 +39,9 @@ defaults = {
         'datasets': {
             'tank/mx-puppet-discord': {
                 'mountpoint': '/opt/mx-puppet-discord',
+                'needed_by': {
+                    'directory:/opt/mx-puppet-discord',
+                },
             },
         },
     },
diff --git a/bundles/pleroma/metadata.py b/bundles/pleroma/metadata.py
index 056b72d..44e7a3b 100644
--- a/bundles/pleroma/metadata.py
+++ b/bundles/pleroma/metadata.py
@@ -15,6 +15,9 @@ defaults = {
         'datasets': {
             'tank/pleroma-data': {
                 'mountpoint': '/var/pleroma',
+                'needed_by': {
+                    'directory:/var/pleroma',
+                },
             },
         },
     },
diff --git a/bundles/postfixadmin/metadata.py b/bundles/postfixadmin/metadata.py
index ead4bd4..f808e57 100644
--- a/bundles/postfixadmin/metadata.py
+++ b/bundles/postfixadmin/metadata.py
@@ -27,10 +27,16 @@ defaults = {
     'zfs': {
         'datasets': {
             'tank/mail': {
-                'mountpoint': '/var/mail',
+                'mountpoint': '/var/mail/vmail',
+                'needed_by': {
+                    'directory:/var/mail/vmail',
+                },
             },
             'tank/postfixadmin': {
                 'mountpoint': '/opt/postfixadmin',
+                'needed_by': {
+                    'directory:/opt/postfixadmin',
+                },
             },
         },
     },
diff --git a/items/zfs_dataset.py b/items/zfs_dataset.py
index 4adce84..6c38538 100644
--- a/items/zfs_dataset.py
+++ b/items/zfs_dataset.py
@@ -119,13 +119,16 @@ class ZFSDataset(Item):
                 # XXX Could be optimized by finding the "largest"
                 # parent only.
                 yield item.id
-            elif self.attributes.get('mountpoint'):
-                for item_type in ['directory', 'file', 'git_deploy']:
-                    if (
-                        item.ITEM_TYPE_NAME == item_type and
-                        item.name.startswith('{}:{}'.format(item_type, self.attributes['mountpoint']))
-                    ):
-                        yield item.id
+
+            # XXX This populates 'needs', not 'needed_by'. We have opened
+            # an issue: https://github.com/bundlewrap/bundlewrap/issues/648
+#            elif self.attributes.get('mountpoint'):
+#                for item_type in ['directory', 'file', 'git_deploy']:
+#                    if (
+#                        item.ITEM_TYPE_NAME == item_type and
+#                        item.name.startswith('{}:{}'.format(item_type, self.attributes['mountpoint']))
+#                    ):
+#                        yield item.id
 
 
         if not pool_item_found:
diff --git a/nodes/htz-cloud/luther.py b/nodes/htz-cloud/luther.py
index e20b33b..7bc79fd 100644
--- a/nodes/htz-cloud/luther.py
+++ b/nodes/htz-cloud/luther.py
@@ -87,6 +87,9 @@ nodes['htz-cloud.luther'] = {
             'datasets': {
                 'tank/luther-website': {
                     'mountpoint': '/var/www/luther-ps',
+                    'needed_by': {
+                        'directory:/var/www/luther-ps',
+                    },
                 },
             },
         },
diff --git a/nodes/htz-cloud/sewfile.py b/nodes/htz-cloud/sewfile.py
index 4ae4b4f..b187d1b 100644
--- a/nodes/htz-cloud/sewfile.py
+++ b/nodes/htz-cloud/sewfile.py
@@ -79,6 +79,9 @@ nodes['htz-cloud.sewfile'] = {
                 },
                 'tank/seafile-data': {
                     'mountpoint': '/mnt/seafile-data',
+                    'needed_by': {
+                        'bundle:seafile',
+                    },
                 },
             },
         },
diff --git a/nodes/rx300.py b/nodes/rx300.py
index 8960afe..f3b2995 100644
--- a/nodes/rx300.py
+++ b/nodes/rx300.py
@@ -324,9 +324,15 @@ nodes['rx300'] = {
                 'tank/libvirt': {
                     'mountpoint': '/var/lib/libvirt',
                     'compression': 'on',
+                    'needed_by': {
+                        'bundle:vmhost',
+                    },
                 },
                 'tank/home-kunsi': {
                     'mountpoint': '/home/kunsi',
+                    'needed_by': {
+                        'directory:/home/kunsi',
+                    },
                 },
             },
         },