io_uring: optimise use of ctx->drain_next

Move setting ctx->drain_next to the only place it could be set, when it
got linked non-head requests. The same for checking it, it's interesting
only for a head of a link or a non-linked request.

No functional changes here. This removes some code from the common path
and also removes REQ_F_DRAIN_LINK flag, as it doesn't need it anymore.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 7715a729271a80724217c653db670a9dcd900601..68843a12300030c5e2101e29ac25ce4b39f28229 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -506,7 +506,6 @@ struct io_kiocb {
 #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_DRAIN_LINK       512     /* link should be fully drained */
 #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 */
@@ -4558,12 +4557,6 @@ static void io_queue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
        int ret;
 
-       if (unlikely(req->ctx->drain_next)) {
-               req->flags |= REQ_F_IO_DRAIN;
-               req->ctx->drain_next = 0;
-       }
-       req->ctx->drain_next = (req->flags & REQ_F_DRAIN_LINK) != 0;
-
        ret = io_req_defer(req, sqe);
        if (ret) {
                if (ret != -EIOCBQUEUED) {
@@ -4630,8 +4623,10 @@ err_req:
        if (*link) {
                struct io_kiocb *head = *link;
 
-               if (sqe_flags & IOSQE_IO_DRAIN)
-                       head->flags |= REQ_F_DRAIN_LINK | REQ_F_IO_DRAIN;
+               if (sqe_flags & IOSQE_IO_DRAIN) {
+                       head->flags |= REQ_F_IO_DRAIN;
+                       ctx->drain_next = 1;
+               }
 
                if (sqe_flags & IOSQE_IO_HARDLINK)
                        req->flags |= REQ_F_HARDLINK;
@@ -4655,18 +4650,24 @@ err_req:
                        io_queue_link_head(head);
                        *link = NULL;
                }
-       } else 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)
-                       req->flags |= REQ_F_FAIL_LINK;
-               *link = req;
        } else {
-               io_queue_sqe(req, sqe);
+               if (unlikely(ctx->drain_next)) {
+                       req->flags |= REQ_F_IO_DRAIN;
+                       req->ctx->drain_next = 0;
+               }
+               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)
+                               req->flags |= REQ_F_FAIL_LINK;
+                       *link = req;
+               } else {
+                       io_queue_sqe(req, sqe);
+               }
        }
 
        return true;