[gpderetta]

Forget about consumer FD, unless you are explicitly doing O_DIRECT, why would you expect that a notification that your IO has completed would mean that it has reached the disk at all? The data might still be just in the kernel page buffer and not gotten close to the disk at all.

You mention you need to wait for the compilation record to be written. But how do you do that without fsync or O_DIRECT? A notification that the write is completed is not that.

Edit: maybe you are using RWF_SYNC in your write call. That could work.