On Tue, Mar 04, 2025 at 10:47:48PM +0000, Pavel Begunkov wrote: > Are you only concerned about the size being too restrictive or do you > see any other problems? You can't know the size beforehand. A stacking block driver can split the I/O for absolutely any reason it wants, and there is no requirement to propagate that up to the queue limits. That's why we need to be able to synchronously return the wouldblock error to get this right.