- // If the block has been PUT more recently than -permission_ttl,
- // return success without removing the block. This guards against
- // a race condition where a block is old enough that Data Manager
- // has added it to the trash list, but the user submitted a PUT
- // for the block since then.
+ // If the block has been PUT in the last blob_signature_ttl
+ // seconds, return success without removing the block. This
+ // protects data from garbage collection until it is no longer
+ // possible for clients to retrieve the unreferenced blocks
+ // anyway (because the permission signatures have expired).