From: Pavel Begunkov <asml.silence@gmail.com>
To: Jens Axboe <axboe@kernel.dk>,
io-uring@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2 1/8] io_uring: leave a comment for drain_next
Date: Sat, 25 Jan 2020 22:53:38 +0300 [thread overview]
Message-ID: <fba3559e833b7d220cf6a12ecbf9ac3856154979.1579981749.git.asml.silence@gmail.com> (raw)
In-Reply-To: <cover.1579981749.git.asml.silence@gmail.com>
Draining the middle of a link is tricky, so leave a comment there
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
fs/io_uring.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index e79d6e47dc7b..bc1cab6a256a 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4702,6 +4702,13 @@ 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;
--
2.24.0
next prev parent reply other threads:[~2020-01-25 19:54 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-24 21:40 [PATCH 0/8] add persistent submission state Pavel Begunkov
2020-01-24 21:40 ` [PATCH 1/8] io_uring: add comment for drain_next Pavel Begunkov
2020-01-24 21:40 ` [PATCH 2/8] io_uring: always pass non-null io_submit_state Pavel Begunkov
2020-01-24 21:40 ` [PATCH 3/8] io_uring: place io_submit_state into ctx Pavel Begunkov
2020-01-24 21:40 ` [PATCH 4/8] io_uring: move ring_fd into io_submit_state Pavel Begunkov
2020-01-24 21:40 ` [PATCH 5/8] io_uring: move cur_mm " Pavel Begunkov
2020-01-24 21:40 ` [PATCH 6/8] io_uring: move *link " Pavel Begunkov
2020-01-24 21:40 ` [PATCH 7/8] io_uring: persistent req bulk allocation cache Pavel Begunkov
2020-01-24 21:40 ` [PATCH 8/8] io_uring: optimise " Pavel Begunkov
2020-01-25 19:53 ` [PATCH v2 0/8] add persistent submission state Pavel Begunkov
2020-01-25 19:53 ` Pavel Begunkov [this message]
2020-01-25 19:53 ` [PATCH v2 2/8] io_uring: always pass non-null io_submit_state Pavel Begunkov
2020-01-25 19:53 ` [PATCH v2 3/8] io_uring: place io_submit_state into ctx Pavel Begunkov
2020-01-25 19:53 ` [PATCH v2 4/8] io_uring: move ring_fd into io_submit_state Pavel Begunkov
2020-01-25 19:53 ` [PATCH v2 5/8] io_uring: move cur_mm " Pavel Begunkov
2020-01-25 19:53 ` [PATCH v2 6/8] io_uring: move *link " Pavel Begunkov
2020-01-25 19:53 ` [PATCH v2 7/8] io_uring: persistent req bulk allocation cache Pavel Begunkov
2020-01-25 19:53 ` [PATCH v2 8/8] io_uring: optimise " Pavel Begunkov
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