From 6af82f7614a2e31e7ef23e5e160697aef31e8edd Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Sun, 3 Nov 2024 08:17:28 -0700
Subject: [PATCH] io_uring/rsrc: encode node type and ctx together

Rather than keep the type field separate rom ctx, use the fact that we
can encode up to 4 types of nodes in the LSB of the ctx pointer. Doesn't
reclaim any space right now on 64-bit archs, but it leaves a full int
for future use.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 io_uring/rsrc.c | 11 +++++------
 io_uring/rsrc.h | 17 ++++++++++++++---
 2 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index 60fa857985cb..2fb1791d7255 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -124,9 +124,8 @@ struct io_rsrc_node *io_rsrc_node_alloc(struct io_ring_ctx *ctx, int type)
 
 	node = kzalloc(sizeof(*node), GFP_KERNEL);
 	if (node) {
-		node->ctx = ctx;
+		node->ctx_ptr = (unsigned long) ctx | type;
 		node->refs = 1;
-		node->type = type;
 	}
 	return node;
 }
@@ -445,21 +444,21 @@ int io_files_update(struct io_kiocb *req, unsigned int issue_flags)
 
 void io_free_rsrc_node(struct io_rsrc_node *node)
 {
-	struct io_ring_ctx *ctx = node->ctx;
+	struct io_ring_ctx *ctx = io_rsrc_node_ctx(node);
 
 	lockdep_assert_held(&ctx->uring_lock);
 
 	if (node->tag)
-		io_post_aux_cqe(node->ctx, node->tag, 0, 0);
+		io_post_aux_cqe(ctx, node->tag, 0, 0);
 
-	switch (node->type) {
+	switch (io_rsrc_node_type(node)) {
 	case IORING_RSRC_FILE:
 		if (io_slot_file(node))
 			fput(io_slot_file(node));
 		break;
 	case IORING_RSRC_BUFFER:
 		if (node->buf)
-			io_buffer_unmap(node->ctx, node);
+			io_buffer_unmap(ctx, node);
 		break;
 	default:
 		WARN_ON_ONCE(1);
diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
index a40fad783a69..9a8fac31fa49 100644
--- a/io_uring/rsrc.h
+++ b/io_uring/rsrc.h
@@ -11,12 +11,13 @@
 enum {
 	IORING_RSRC_FILE		= 0,
 	IORING_RSRC_BUFFER		= 1,
+
+	IORING_RSRC_TYPE_MASK		= 0x3UL,
 };
 
 struct io_rsrc_node {
-	struct io_ring_ctx		*ctx;
+	unsigned long			ctx_ptr;
 	int				refs;
-	u16				type;
 
 	u64 tag;
 	union {
@@ -100,11 +101,21 @@ static inline void io_req_put_rsrc_nodes(struct io_kiocb *req)
 	req->rsrc_nodes[IORING_RSRC_BUFFER] = NULL;
 }
 
+static inline struct io_ring_ctx *io_rsrc_node_ctx(struct io_rsrc_node *node)
+{
+	return (struct io_ring_ctx *) (node->ctx_ptr & ~IORING_RSRC_TYPE_MASK);
+}
+
+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,
 					   struct io_rsrc_node *node)
 {
 	node->refs++;
-	req->rsrc_nodes[node->type] = node;
+	req->rsrc_nodes[io_rsrc_node_type(node)] = node;
 }
 
 int io_files_update(struct io_kiocb *req, unsigned int issue_flags);