========================= CephFS delayed deletion

The deletion of a file does not immediately remove its data. Each of the file's underlying objects must be removed independently. If these objects were removed immediately, the client would have to send size_of_file / stripe_size * replication_count messages. This would consume significant bandwith and would slow the client unacceptably. If snapshots exist, their existence can prevent the deletion of objects associated with them.

In these cases, such files are (1) marked as deleted on the MDS and (2) deleted lazily.