[PATCH 2/3] io_uring: mark requests that will go async with REQ_F_ASYNC_ISSUE

[Jens Axboe <axboe@kernel.dk>]

REQ_F_ASYNC_ISSUE is flagged in a request, if the core parts of io_uring
either knows that it will be issued from an out-of-line context, or if
there's a risk that it will. As REQ_F_FORCE_ASYNC will similarly force
async issue of a request, add a io_req_will_async_issue() helper that
callers can use without needing to worry about the internal details.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 include/linux/io_uring_types.h | 3 +++
 io_uring/io_uring.c            | 1 +
 io_uring/io_uring.h            | 5 +++++
 3 files changed, 9 insertions(+)

diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
index 2922635986f5..3b17c1da1ab0 100644
--- a/include/linux/io_uring_types.h
+++ b/include/linux/io_uring_types.h
@@ -502,6 +502,7 @@ enum {
 	REQ_F_BUF_NODE_BIT,
 	REQ_F_HAS_METADATA_BIT,
 	REQ_F_IMPORT_BUFFER_BIT,
+	REQ_F_ASYNC_ISSUE_BIT,
 
 	/* not a real bit, just to check we're not overflowing the space */
 	__REQ_F_LAST_BIT,
@@ -591,6 +592,8 @@ enum {
 	 * For SEND_ZC, whether to import buffers (i.e. the first issue).
 	 */
 	REQ_F_IMPORT_BUFFER	= IO_REQ_FLAG(REQ_F_IMPORT_BUFFER_BIT),
+	/* request will be issued async */
+	REQ_F_ASYNC_ISSUE	= IO_REQ_FLAG(REQ_F_ASYNC_ISSUE_BIT),
 };
 
 typedef void (*io_req_tw_func_t)(struct io_kiocb *req, io_tw_token_t tw);
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index cf759c172083..8f431a9a7812 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2197,6 +2197,7 @@ static inline int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
 		trace_io_uring_link(req, link->last);
 		link->last->link = req;
 		link->last = req;
+		req->flags |= REQ_F_ASYNC_ISSUE;
 
 		if (req->flags & IO_REQ_LINK_FLAGS)
 			return 0;
diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h
index d59c12277d58..ff6b577c18f5 100644
--- a/io_uring/io_uring.h
+++ b/io_uring/io_uring.h
@@ -524,4 +524,9 @@ static inline bool io_has_work(struct io_ring_ctx *ctx)
 	return test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq) ||
 	       io_local_work_pending(ctx);
 }
+
+static inline bool io_req_will_async_issue(struct io_kiocb *req)
+{
+	return (req->flags & (REQ_F_FORCE_ASYNC | REQ_F_ASYNC_ISSUE));
+}
 #endif
-- 
2.49.0