adding log descriptors to the log, the log descriptors including a first plurality of descriptors that specify changes in respective, individual blocks and a second plurality of descriptors that specify changes in respective extents, each extent including multiple blocks having contiguous LBAs (logical block addresses);

creating a working set of descriptors that includes both a first set of descriptors selected from the first plurality of descriptors and a second set of descriptors selected from the second plurality of descriptors; and

flushing, in a single flush cycle, the working set to persistent structures to implement the changes specified by the first set of descriptors and the second set of descriptors.