linux-kernel - [PATCH 2/2] io_uring: optimise sqe-to-req flags translation

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Date:   Sat, 18 Jan 2020 01:22:31 +0300
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Jens Axboe <axboe@...nel.dk>, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] io_uring: optimise sqe-to-req flags translation

For each IOSQE_* flag there is a corresponding REQ_F_* flag. And there
is a repetitive pattern of their translation:
e.g. if (sqe->flags & SQE_FLAG*) req->flags |= REQ_F_FLAG*

Use the same numeric value/bit for them, so this could be optimised to
check-less copy.

Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
---
 fs/io_uring.c | 58 +++++++++++++++++++++++++--------------------------
 1 file changed, 29 insertions(+), 29 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 163707ac9e76..859243ae74eb 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -452,6 +452,28 @@ struct io_async_ctx {
 	};
 };
 
+enum {
+	/* correspond one-to-one to IOSQE_IO_* flags*/
+	REQ_F_FIXED_FILE	= IOSQE_FIXED_FILE,	/* ctx owns file */
+	REQ_F_IO_DRAIN		= IOSQE_IO_DRAIN,	/* drain existing IO first */
+	REQ_F_LINK		= IOSQE_IO_LINK,	/* linked sqes */
+	REQ_F_HARDLINK		= IOSQE_IO_HARDLINK,	/* doesn't sever on completion < 0 */
+	REQ_F_FORCE_ASYNC	= IOSQE_ASYNC,		/* IOSQE_ASYNC */
+
+	REQ_F_LINK_NEXT		= 1 << 5,	/* already grabbed next link */
+	REQ_F_FAIL_LINK		= 1 << 6,	/* fail rest of links */
+	REQ_F_INFLIGHT		= 1 << 7,	/* on inflight list */
+	REQ_F_CUR_POS		= 1 << 8,	/* read/write uses file position */
+	REQ_F_NOWAIT		= 1 << 9,	/* must not punt to workers */
+	REQ_F_IOPOLL_COMPLETED	= 1 << 10,	/* polled IO has completed */
+	REQ_F_LINK_TIMEOUT	= 1 << 11,	/* has linked timeout */
+	REQ_F_TIMEOUT		= 1 << 12,	/* timeout request */
+	REQ_F_ISREG		= 1 << 13,	/* regular file */
+	REQ_F_MUST_PUNT		= 1 << 14,	/* must be punted even for NONBLOCK */
+	REQ_F_TIMEOUT_NOSEQ	= 1 << 15,	/* no timeout sequence */
+	REQ_F_COMP_LOCKED	= 1 << 16,	/* completion under lock */
+};
+
 /*
  * NOTE! Each of the iocb union members has the file pointer
  * as the first entry in their struct definition. So you can
@@ -494,23 +516,6 @@ struct io_kiocb {
 	struct list_head	link_list;
 	unsigned int		flags;
 	refcount_t		refs;
-#define REQ_F_NOWAIT		1	/* must not punt to workers */
-#define REQ_F_IOPOLL_COMPLETED	2	/* polled IO has completed */
-#define REQ_F_FIXED_FILE	4	/* ctx owns file */
-#define REQ_F_LINK_NEXT		8	/* already grabbed next link */
-#define REQ_F_IO_DRAIN		16	/* drain existing IO first */
-#define REQ_F_LINK		64	/* linked sqes */
-#define REQ_F_LINK_TIMEOUT	128	/* has linked timeout */
-#define REQ_F_FAIL_LINK		256	/* fail rest of links */
-#define REQ_F_TIMEOUT		1024	/* timeout request */
-#define REQ_F_ISREG		2048	/* regular file */
-#define REQ_F_MUST_PUNT		4096	/* must be punted even for NONBLOCK */
-#define REQ_F_TIMEOUT_NOSEQ	8192	/* no timeout sequence */
-#define REQ_F_INFLIGHT		16384	/* on inflight list */
-#define REQ_F_COMP_LOCKED	32768	/* completion under lock */
-#define REQ_F_HARDLINK		65536	/* doesn't sever on completion < 0 */
-#define REQ_F_FORCE_ASYNC	131072	/* IOSQE_ASYNC */
-#define REQ_F_CUR_POS		262144	/* read/write uses file position */
 	u64			user_data;
 	u32			result;
 	u32			sequence;
@@ -4342,9 +4347,6 @@ static int io_req_set_file(struct io_submit_state *state, struct io_kiocb *req,
 	flags = READ_ONCE(sqe->flags);
 	fd = READ_ONCE(sqe->fd);
 
-	if (flags & IOSQE_IO_DRAIN)
-		req->flags |= REQ_F_IO_DRAIN;
-
 	if (!io_req_needs_file(req, fd))
 		return 0;
 
@@ -4566,6 +4568,12 @@ static inline void io_queue_link_head(struct io_kiocb *req)
 #define SQE_VALID_FLAGS	(IOSQE_FIXED_FILE|IOSQE_IO_DRAIN|IOSQE_IO_LINK|	\
 				IOSQE_IO_HARDLINK | IOSQE_ASYNC)
 
+/*
+ * This should be equal to bitmask of corresponding REQ_F_* flags,
+ * i.e. REQ_F_IO_DRAIN|REQ_F_HARDLINK|REQ_F_FORCE_ASYNC
+ */
+#define SQE_INHERITED_FLAGS (IOSQE_IO_DRAIN|IOSQE_IO_HARDLINK|IOSQE_ASYNC)
+
 static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 			  struct io_submit_state *state, struct io_kiocb **link)
 {
@@ -4580,8 +4588,7 @@ static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 		ret = -EINVAL;
 		goto err_req;
 	}
-	if (sqe_flags & IOSQE_ASYNC)
-		req->flags |= REQ_F_FORCE_ASYNC;
+	req->flags |= sqe_flags & SQE_INHERITED_FLAGS;
 
 	ret = io_req_set_file(state, req, sqe);
 	if (unlikely(ret)) {
@@ -4605,10 +4612,6 @@ static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 			head->flags |= REQ_F_IO_DRAIN;
 			ctx->drain_next = 1;
 		}
-
-		if (sqe_flags & IOSQE_IO_HARDLINK)
-			req->flags |= REQ_F_HARDLINK;
-
 		if (io_alloc_async_ctx(req)) {
 			ret = -EAGAIN;
 			goto err_req;
@@ -4635,9 +4638,6 @@ static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 		}
 		if (sqe_flags & (IOSQE_IO_LINK|IOSQE_IO_HARDLINK)) {
 			req->flags |= REQ_F_LINK;
-			if (sqe_flags & IOSQE_IO_HARDLINK)
-				req->flags |= REQ_F_HARDLINK;
-
 			INIT_LIST_HEAD(&req->link_list);
 			ret = io_req_defer_prep(req, sqe);
 			if (ret)
-- 
2.24.0