18.104.22.168.3 Handling the SMB2_CREATE_ALLOCATION_SIZE Create Context
The client is requesting that a specific allocation size be set for the file that is being created. The server SHOULD support this create context request.<261> If the server does not support it, the SMB2_CREATE_ALLOCATION_SIZE create context request MUST be ignored.
The processing changes involved for this create context are:
In the "Open Execution" phase, the server MUST pass the received allocation size to the underlying object store to reserve the requested space for the created file.<262> If the object store does not have sufficient space available to hold a file of the requested size, the server MUST fail the open request with STATUS_DISK_FULL.