io_uring: keep unlock_post inlined in hot path

This partially reverts

6c16fe3c ("io_uring: kill io_cqring_ev_posted() and __io_cq_unlock_post()")

The redundancy of __io_cq_unlock_post() was always to keep it inlined
into __io_submit_flush_completions(). Inline it back and rename with
hope of clarifying the intention behind it.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/372a16c485fca44c069be2e92fc5e7332a1d7fd7.1669310258.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/io_uring.c

@@ -582,7 +582,8 @@ void __io_commit_cqring_flush(struct io_ring_ctx *ctx)
 		io_eventfd_flush_signal(ctx);
 }
 
-void io_cq_unlock_post(struct io_ring_ctx *ctx)
+/* keep it inlined for io_submit_flush_completions() */
+static inline void io_cq_unlock_post_inline(struct io_ring_ctx *ctx)
 	__releases(ctx->completion_lock)
 {
 	io_commit_cqring(ctx);
@@ -592,6 +593,12 @@ void io_cq_unlock_post(struct io_ring_ctx *ctx)
 	io_cqring_wake(ctx);
 }
 
+void io_cq_unlock_post(struct io_ring_ctx *ctx)
+	__releases(ctx->completion_lock)
+{
+	io_cq_unlock_post_inline(ctx);
+}
+
 /* Returns true if there are no backlogged entries after the flush */
 static bool __io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force)
 {
@@ -1389,7 +1396,7 @@ static void __io_submit_flush_completions(struct io_ring_ctx *ctx)
 		if (!(req->flags & REQ_F_CQE_SKIP))
 			__io_fill_cqe_req(ctx, req);
 	}
-	io_cq_unlock_post(ctx);
+	io_cq_unlock_post_inline(ctx);
 
 	if (!wq_list_empty(&ctx->submit_state.compl_reqs)) {
 		io_free_batch_list(ctx, state->compl_reqs.first);