Hi, If we end up needing to split a bio that is marked with REQ_NOWAIT, it's entirely possible that any part of the split bio will hit a failure trying to get submitted. If this happens, then the entire request ends up being errored with BLK_STS_AGAIN, even if any parts of this bio has been read or written to the device/file. Rather than end up in this odd state, disallow splitting with REQ_NOWAIT. If we end the entire request upfront with EAGAIN, then we don't end up with a partially written IO that still returns EAGAIN. -- Jens Axboe
