To restate my previous NAK: A low-level protocol detail like RWF_ZONE_APPEND has absolutely no business being exposed in the Linux file system interface. And as mentioned before I think the idea of returning the actual position written for O_APPEND writes totally makes sense, and actually is generalizable to all files. Together with zonefs that gives you a perfect interface for zone append. On Thu, Jun 25, 2020 at 10:45:48PM +0530, Kanchan Joshi wrote: > Introduce RWF_ZONE_APPEND flag to represent zone-append. And no one but us select few even know what zone append is, nevermind what the detailed semantics are. If you add a userspace API you need to very clearly document the semantics inluding errors and corner cases.