io_uring/rsrc: split io_kiocb node type assignments

Currently the io_rsrc_node assignment in io_kiocb is an array of two
pointers, as two nodes may be assigned to a request - one file node,
and one buffer node. However, the buffer node can co-exist with the
provided buffers, as currently it's not supported to use both provided
and registered buffers at the same time.

This crucially brings struct io_kiocb down to 4 cache lines again, as
before it spilled into the 5th cacheline.

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

include/linux/io_uring_types.h

@@ -475,6 +475,7 @@ enum {
 	REQ_F_BL_EMPTY_BIT,
 	REQ_F_BL_NO_RECYCLE_BIT,
 	REQ_F_BUFFERS_COMMIT_BIT,
+	REQ_F_BUF_NODE_BIT,
 
 	/* not a real bit, just to check we're not overflowing the space */
 	__REQ_F_LAST_BIT,
@@ -553,6 +554,8 @@ enum {
 	REQ_F_BL_NO_RECYCLE	= IO_REQ_FLAG(REQ_F_BL_NO_RECYCLE_BIT),
 	/* buffer ring head needs incrementing on put */
 	REQ_F_BUFFERS_COMMIT	= IO_REQ_FLAG(REQ_F_BUFFERS_COMMIT_BIT),
+	/* buf node is valid */
+	REQ_F_BUF_NODE		= IO_REQ_FLAG(REQ_F_BUF_NODE_BIT),
 };
 
 typedef void (*io_req_tw_func_t)(struct io_kiocb *req, struct io_tw_state *ts);
@@ -633,6 +636,8 @@ struct io_kiocb {
 		 * REQ_F_BUFFER_RING is set.
 		 */
 		struct io_buffer_list	*buf_list;
+
+		struct io_rsrc_node	*buf_node;
 	};
 
 	union {
@@ -642,7 +647,7 @@ struct io_kiocb {
 		__poll_t apoll_events;
 	};
 
-	struct io_rsrc_node		*rsrc_nodes[2];
+	struct io_rsrc_node		*file_node;
 
 	atomic_t			refs;
 	bool				cancel_seq_set;

io_uring/io_uring.c

@@ -948,8 +948,8 @@ void io_req_defer_failed(struct io_kiocb *req, s32 res)
 static void io_preinit_req(struct io_kiocb *req, struct io_ring_ctx *ctx)
 {
 	req->ctx = ctx;
-	req->rsrc_nodes[IORING_RSRC_FILE] = NULL;
-	req->rsrc_nodes[IORING_RSRC_BUFFER] = NULL;
+	req->buf_node = NULL;
+	req->file_node = NULL;
 	req->link = NULL;
 	req->async_data = NULL;
 	/* not necessary, but safer to zero */
@@ -1882,7 +1882,7 @@ inline struct file *io_file_get_fixed(struct io_kiocb *req, int fd,
 	io_ring_submit_lock(ctx, issue_flags);
 	node = io_rsrc_node_lookup(&ctx->file_table.data, fd);
 	if (node) {
-		io_req_assign_rsrc_node(req, node);
+		io_req_assign_rsrc_node(&req->file_node, node);
 		req->flags |= io_slot_flags(node);
 		file = io_slot_file(node);
 	}

io_uring/net.c

@@ -1348,7 +1348,8 @@ static int io_send_zc_import(struct io_kiocb *req, unsigned int issue_flags)
 		io_ring_submit_lock(ctx, issue_flags);
 		node = io_rsrc_node_lookup(&ctx->buf_table, sr->buf_index);
 		if (node) {
-			io_req_assign_rsrc_node(sr->notif, node);
+			io_req_assign_rsrc_node(&sr->notif->buf_node, node);
+			sr->notif->flags |= REQ_F_BUF_NODE;
 			ret = 0;
 		}
 		io_ring_submit_unlock(ctx, issue_flags);

io_uring/nop.c

@@ -67,7 +67,8 @@ int io_nop(struct io_kiocb *req, unsigned int issue_flags)
 		io_ring_submit_lock(ctx, issue_flags);
 		node = io_rsrc_node_lookup(&ctx->buf_table, nop->buffer);
 		if (node) {
-			io_req_assign_rsrc_node(req, node);
+			io_req_assign_rsrc_node(&req->buf_node, node);
+			req->flags |= REQ_F_BUF_NODE;
 			ret = 0;
 		}
 		io_ring_submit_unlock(ctx, issue_flags);

io_uring/notif.c

@@ -117,8 +117,8 @@ struct io_kiocb *io_alloc_notif(struct io_ring_ctx *ctx)
 	notif->file = NULL;
 	notif->task = current;
 	io_get_task_refs(1);
-	notif->rsrc_nodes[IORING_RSRC_FILE] = NULL;
-	notif->rsrc_nodes[IORING_RSRC_BUFFER] = NULL;
+	notif->file_node = NULL;
+	notif->buf_node = NULL;
 
 	nd = io_notif_to_data(notif);
 	nd->zc_report = false;

io_uring/rsrc.h

@@ -95,10 +95,14 @@ static inline bool io_reset_rsrc_node(struct io_rsrc_data *data, int index)
 
 static inline void io_req_put_rsrc_nodes(struct io_kiocb *req)
 {
-	io_put_rsrc_node(req->rsrc_nodes[IORING_RSRC_FILE]);
-	io_put_rsrc_node(req->rsrc_nodes[IORING_RSRC_BUFFER]);
-	req->rsrc_nodes[IORING_RSRC_FILE] = NULL;
-	req->rsrc_nodes[IORING_RSRC_BUFFER] = NULL;
+	if (req->file_node) {
+		io_put_rsrc_node(req->file_node);
+		req->file_node = NULL;
+	}
+	if (req->flags & REQ_F_BUF_NODE) {
+		io_put_rsrc_node(req->buf_node);
+		req->buf_node = NULL;
+	}
 }
 
 static inline struct io_ring_ctx *io_rsrc_node_ctx(struct io_rsrc_node *node)
@@ -111,11 +115,11 @@ static inline int io_rsrc_node_type(struct io_rsrc_node *node)
 	return node->ctx_ptr & IORING_RSRC_TYPE_MASK;
 }
 
-static inline void io_req_assign_rsrc_node(struct io_kiocb *req,
+static inline void io_req_assign_rsrc_node(struct io_rsrc_node **dst_node,
 					   struct io_rsrc_node *node)
 {
 	node->refs++;
-	req->rsrc_nodes[io_rsrc_node_type(node)] = node;
+	*dst_node = node;
 }
 
 int io_files_update(struct io_kiocb *req, unsigned int issue_flags);

io_uring/rw.c

@@ -341,7 +341,8 @@ static int io_prep_rw_fixed(struct io_kiocb *req, const struct io_uring_sqe *sqe
 	node = io_rsrc_node_lookup(&ctx->buf_table, req->buf_index);
 	if (!node)
 		return -EFAULT;
-	io_req_assign_rsrc_node(req, node);
+	io_req_assign_rsrc_node(&req->buf_node, node);
+	req->flags |= REQ_F_BUF_NODE;
 
 	io = req->async_data;
 	ret = io_import_fixed(ddir, &io->iter, node->buf, rw->addr, rw->len);

io_uring/uring_cmd.c

@@ -219,7 +219,7 @@ int io_uring_cmd_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		 * being called. This prevents destruction of the mapped buffer
 		 * we'll need at actual import time.
 		 */
-		io_req_assign_rsrc_node(req, node);
+		io_req_assign_rsrc_node(&req->buf_node, node);
 	}
 	ioucmd->cmd_op = READ_ONCE(sqe->cmd_op);
 
@@ -275,7 +275,7 @@ int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
 			      struct iov_iter *iter, void *ioucmd)
 {
 	struct io_kiocb *req = cmd_to_io_kiocb(ioucmd);
-	struct io_rsrc_node *node = req->rsrc_nodes[IORING_RSRC_BUFFER];
+	struct io_rsrc_node *node = req->buf_node;
 
 	/* Must have had rsrc_node assigned at prep time */
 	if (node)