CephFS delayed deletion

When you delete a file, the data is not immediately removed. Eachobject in the file needs to be removed independently, and sendingsize_of_file / stripe_size * replication_count messages would slowthe client down too much, and use a too much of the clientsbandwidth. Additionally, snapshots may mean some objects should not bedeleted.

Instead, the file is marked as deleted on the MDS, and deleted lazily.