On 28/05/2019 16:14, David Howells wrote:

+Then there are attributes that convey information about the mount topology:
+
+ *  ``FSINFO_ATTR_MOUNT_INFO``
+
+    This struct-type attribute conveys information about a mount topology node
+    rather than a superblock.  This includes the ID of the superblock mounted
+    there and the ID of the mount node, its parent, group, master and
+    propagation source.  It also contains the attribute flags for the mount and
+    a change notification counter so that it can be quickly determined if that
+    node changed.
+
+ *  ``FSINFO_ATTR_MOUNT_DEVNAME``
+
+    This string-type attribute returns the "device name" that was supplied when
+    the mount object was created.
+
+ *  ``FSINFO_ATTR_MOUNT_CHILDREN``
+
+    This is an array-type attribute that conveys a set of structs, each of
+    which indicates the mount ID of a child and the change counter for that
+    child.  The kernel also tags an extra element on the end that indicates the
+    ID and change counter of the queried object.  This allows a conflicting
+    change to be quickly detected by comparing the before and after counters.
+
+ *  ``FSINFO_ATTR_MOUNT_SUBMOUNT``
+
+    This is a string-type attribute that conveys the pathname of the Nth
+    mountpoint under the target mount, relative to the mount root or the
+    chroot, whichever is closer.  These correspond on a 1:1 basis with the
+    eleemnts in the FSINFO_ATTR_MOUNT_CHROOT list.

FSINFO_ATTR_MOUNT_CHROOT -> FSINFO_ATTR_MOUNT_CHILDREN