Defensively check that an inode is deleted before trying to do something with it.  Moreover, consider an inode a candidate for deletion if its deletion_in_progress flag is set (as an alternative to its link count reaching zero).
Defensively check that an inode is deleted before trying to do something
with it.  Moreover, consider an inode a candidate for deletion if its
deletion_in_progress flag is set (as an alternative to its link count
reaching zero).

jcnelson/fskit,jcnelson/fskit