While I have your attention, assuming SSD with typical 128k erase blocks, do you do anything special to avoid write amplification at the disk level when reusing pages? My understanding is that those are in-place updates from the filesystem's POV, so writing over 32k of old pages will cause 128-256k actual writes. One could avoid this somewhat with trim support, fallocate + hole punch (not portable) but you have to think carefully about alignments and grouping free pages into contiguous erase block multiples. That never struck me as being very practical. Have you thought about that problem before or tried anything there?