[PATCH RESEND] io_uring: a small optimization for REQ_F_DRAIN_LINK

[Jackie Liu <jackieliu@byteisland.com>]

From: Jackie Liu <liuyun01@kylinos.cn>

We don't need to set drain_next every time, make a small judgment
and add unlikely, it looks like there will be a little optimization.

Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
---
 resend that patch, because reject by mail-list.

 fs/io_uring.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 013e5ed..f4ec44a 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2938,12 +2938,14 @@ static void __io_queue_sqe(struct io_kiocb *req)
 static void io_queue_sqe(struct io_kiocb *req)
 {
 	int ret;
+	bool drain_link = req->flags & REQ_F_DRAIN_LINK;
 
-	if (unlikely(req->ctx->drain_next)) {
+	if (unlikely(req->ctx->drain_next && !drain_link)) {
 		req->flags |= REQ_F_IO_DRAIN;
 		req->ctx->drain_next = false;
+	} else if (unlikely(drain_link)) {
+		req->ctx->drain_next = true;
 	}
-	req->ctx->drain_next = (req->flags & REQ_F_DRAIN_LINK);
 
 	ret = io_req_defer(req);
 	if (ret) {
-- 
2.7.4