Commit 8cdf2193 authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring: add comment for drain_next 



Draining the middle of a link is tricky, so leave a comment there

Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 980ad263

fs/io_uring.c

+7 −0
Original line number Diff line number Diff line
@@ -4629,6 +4629,13 @@ static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe, 
	if (*link) {

		struct io_kiocb *head = *link;



		/*

		 * Taking sequential execution of a link, draining both sides

		 * of the link also fullfils IOSQE_IO_DRAIN semantics for all

		 * requests in the link. So, it drains the head and the

		 * next after the link request. The last one is done via

		 * drain_next flag to persist the effect across calls.

		 */

		if (sqe_flags & IOSQE_IO_DRAIN) {

			head->flags |= REQ_F_IO_DRAIN;

			ctx->drain_next = 1;