uring_cmd currently copies the full SQE at prep time, just in case it needs it to be stable. However, for inline completions or requests that get queued up on the device side, there's no need to ever copy the SQE. This is particularly important, as various use cases of uring_cmd will be using 128b sized SQEs. Opt in to using ->sqe_copy() to let the core of io_uring decide when to copy SQEs. This callback will only be called if it is safe to do so. Reviewed-by: Caleb Sander Mateos <csander@purestorage.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>