Actually, a good chunk of that is available via memfd + linkat. - Unit files: memfd, fdatasync, linkat, fsync(dir) - Temporary files. memfd, preferably within

Actually, a good chunk of that is available via memfd + linkat. - Unit files: memfd, fdatasync, linkat, fsync(dir) - Temporary files. memfd, preferably within /tmp to avoid any disk I/O unless you have a particularly large file to buffer - Log files. This is trickier. Probably requires running on a fs that supports reflinks and creating a new memfd that’s a true clone of the original file, appending, & then replacing it. The one piece that is incompatible with this is that other file descriptors are stale and you have to reopen to see new data but that’s at odds with APIs available today - either readers can see partial writes or you have to have a new file. There have been proposals to allow buffering writes but delaying publishing the metadata acking the data but that hasn’t gone anywhere unfortunately. - Managed files. I’m not sure that completions are the right contract here because technically the kernel could defer that completion indefinitely whereas databases typical need some kind of latency bounds of “OK - I really want this to commit to disk nowish”.