io_uring: Create a helper to return the SQE size

Create a simple helper that returns the size of the SQE. The SQE could
have two size, depending of the flags.

If IO_URING_SETUP_SQE128 flag is set, then return a double SQE,
otherwise returns the sizeof of io_uring_sqe (64 bytes).

Signed-off-by: Breno Leitao <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Pavel Begunkov <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

Author: leitao

io_uring/io_uring.h

@@ -394,4 +394,14 @@ static inline void io_req_queue_tw_complete(struct io_kiocb *req, s32 res)
 	io_req_task_work_add(req);
 }
 
+/*
+ * IORING_SETUP_SQE128 contexts allocate twice the normal SQE size for each
+ * slot.
+ */
+static inline size_t uring_sqe_size(struct io_ring_ctx *ctx)
+{
+	if (ctx->flags & IORING_SETUP_SQE128)
+		return 2 * sizeof(struct io_uring_sqe);
+	return sizeof(struct io_uring_sqe);
+}
 #endif