Konstantin, >> The corresponding exported primitive is called >> blkdev_issue_assign_range(). > > What exact semantics of that? REQ_OP_ALLOCATE will be used to compel a device to allocate a block range. What a given block contains after successful allocation is undefined (depends on the device implementation). For block allocation with deterministic zeroing, one must keep using REQ_OP_WRITE_ZEROES with the NOUNMAP flag set. -- Martin K. Petersen Oracle Linux Engineering