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From:   Pavel Begunkov <asml.silence@gmail.com>
To:     Jens Axboe <axboe@kernel.dk>, io-uring@vger.kernel.org,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2 2/2] io_uring: io_queue_link*() right after submit
Date:   Wed,  6 Nov 2019 00:22:15 +0300
Message-Id: <85a316b577e1b5204d27a96a7ce452ed6be3c2ae.1572988512.git.asml.silence@gmail.com>
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After a call to io_submit_sqe(), it's already known whether it needs
to queue a link or not. Do it there, as it's simplier and doesn't keep
an extra variable across the loop.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 fs/io_uring.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index ebe2a4edd644..82c2da99cb5c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2687,7 +2687,6 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
 	struct io_submit_state state, *statep = NULL;
 	struct io_kiocb *link = NULL;
 	struct io_kiocb *shadow_req = NULL;
-	bool prev_was_link = false;
 	int i, submitted = 0;
 	bool mm_fault = false;
 
@@ -2710,17 +2709,6 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
 			}
 		}
 
-		/*
-		 * If previous wasn't linked and we have a linked command,
-		 * that's the end of the chain. Submit the previous link.
-		 */
-		if (!prev_was_link && link) {
-			io_queue_link_head(ctx, link, &link->submit, shadow_req);
-			link = NULL;
-			shadow_req = NULL;
-		}
-		prev_was_link = (s.sqe->flags & IOSQE_IO_LINK) != 0;
-
 		if (link && (s.sqe->flags & IOSQE_IO_DRAIN)) {
 			if (!shadow_req) {
 				shadow_req = io_get_req(ctx, NULL);
@@ -2741,6 +2729,16 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
 		trace_io_uring_submit_sqe(ctx, s.sqe->user_data, true, async);
 		io_submit_sqe(ctx, &s, statep, &link);
 		submitted++;
+
+		/*
+		 * If previous wasn't linked and we have a linked command,
+		 * that's the end of the chain. Submit the previous link.
+		 */
+		if (!(s.sqe->flags & IOSQE_IO_LINK) && link) {
+			io_queue_link_head(ctx, link, &link->submit, shadow_req);
+			link = NULL;
+			shadow_req = NULL;
+		}
 	}
 
 	if (link)
-- 
2.23.0