io_uring: move req->poll_refs into previous struct hole

This serves two purposes:

- We now have the last cacheline mostly unused for generic workloads,
  instead of having to pull in the poll refs explicitly for workloads
  that rely on poll arming.

- It shrinks the io_kiocb from 232 to 224 bytes.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index b17cf54..fa4e2cb 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -908,6 +908,7 @@ struct io_kiocb {
        /* used by request caches, completion batching and iopoll */
        struct io_wq_work_node          comp_list;
        atomic_t                        refs;
+       atomic_t                        poll_refs;
        struct io_kiocb                 *link;
        struct io_task_work             io_task_work;
        /* for polled requests, i.e. IORING_OP_POLL_ADD and async armed poll */
@@ -916,12 +917,11 @@ struct io_kiocb {
        struct async_poll               *apoll;
        /* opcode allocated if it needs to store data for async defer */
        void                            *async_data;
-       struct io_wq_work               work;
        /* custom credentials, valid IFF REQ_F_CREDS is set */
-       const struct cred               *creds;
        /* stores selected buf, valid IFF REQ_F_BUFFER_SELECTED is set */
        struct io_buffer                *kbuf;
-       atomic_t                        poll_refs;
+       const struct cred               *creds;
+       struct io_wq_work               work;
 };
 
 struct io_tctx_node {