io_uring: don't reinit submit state every time

As now submit_state is retained across syscalls, we can save ourself
from initialising it from ground up for each io_submit_sqes(). Set some
fields during ctx allocation, and just keep them always consistent.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
[axboe: remove unnecessary zeroing of ctx members]
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -1345,6 +1345,7 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	INIT_LIST_HEAD(&ctx->rsrc_ref_list);
 	INIT_DELAYED_WORK(&ctx->rsrc_put_work, io_rsrc_put_work);
 	init_llist_head(&ctx->rsrc_put_llist);
+	INIT_LIST_HEAD(&submit_state->comp.list);
 	return ctx;
 err:
 	if (ctx->fallback_req)
@@ -6661,8 +6662,10 @@ static void io_submit_state_end(struct io_submit_state *state,
 	if (state->plug_started)
 		blk_finish_plug(&state->plug);
 	io_state_file_put(state);
-	if (state->free_reqs)
+	if (state->free_reqs) {
 		kmem_cache_free_bulk(req_cachep, state->free_reqs, state->reqs);
+		state->free_reqs = 0;
+	}
 }
 
 /*
@@ -6672,10 +6675,6 @@ static void io_submit_state_start(struct io_submit_state *state,
 				  unsigned int max_ios)
 {
 	state->plug_started = false;
-	state->comp.nr = 0;
-	INIT_LIST_HEAD(&state->comp.list);
-	state->free_reqs = 0;
-	state->file_refs = 0;
 	state->ios_left = max_ios;
 }