[PATCH V10 09/12] io_uring: add callback to 'io_mapped_buffer' for giving back kernel buffer

[Ming Lei <ming.lei@xxxxxxxxxx>]

Add one callback to 'io_mapped_buffer' for giving back kernel buffer
after the buffer is used.

Meantime move 'io_rsrc_node' into public header, and it will become
part of kernel buffer API.

Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
 include/linux/io_uring_types.h | 20 +++++++++++++++++++-
 io_uring/rsrc.c                | 14 +++++++++++++-
 io_uring/rsrc.h                | 13 +------------
 3 files changed, 33 insertions(+), 14 deletions(-)

diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
index 03abaeef4a67..7de0d4c0ed6b 100644
--- a/include/linux/io_uring_types.h
+++ b/include/linux/io_uring_types.h
@@ -40,8 +40,26 @@ enum io_uring_cmd_flags {
 	IO_URING_F_COMPAT		= (1 << 12),
 };
 
+struct io_rsrc_node {
+	unsigned char			type;
+	unsigned char			flags;
+	int				refs;
+
+	u64 tag;
+	union {
+		unsigned long file_ptr;
+		struct io_mapped_buf *buf;
+	};
+};
+
+typedef void (io_uring_kbuf_ack_t) (struct io_rsrc_node *);
+
 struct io_mapped_buf {
-	u64		addr;
+	/* 'addr' is always 0 for kernel buffer */
+	union {
+		u64			addr;
+		io_uring_kbuf_ack_t	*kbuf_ack;
+	};
 	unsigned int	len;
 	unsigned int	nr_bvecs;
 	refcount_t	refs;
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index b0b60ae0456a..327bc1a83e4b 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -441,6 +441,18 @@ int io_files_update(struct io_kiocb *req, unsigned int issue_flags)
 	return IOU_OK;
 }
 
+static void __io_free_buf_node(struct io_ring_ctx *ctx, struct io_rsrc_node *node)
+{
+	struct io_mapped_buf *buf = node->buf;
+
+	if (node->flags & IORING_RSRC_F_BUF_KERNEL) {
+		if (buf->kbuf_ack)
+			buf->kbuf_ack(node);
+	} else {
+		io_buffer_unmap(ctx, node);
+	}
+}
+
 void io_free_rsrc_node(struct io_ring_ctx *ctx, struct io_rsrc_node *node)
 {
 	bool need_free = node->flags & IORING_RSRC_F_NEED_FREE;
@@ -457,7 +469,7 @@ void io_free_rsrc_node(struct io_ring_ctx *ctx, struct io_rsrc_node *node)
 		break;
 	case IORING_RSRC_BUFFER:
 		if (node->buf)
-			io_buffer_unmap(ctx, node);
+			__io_free_buf_node(ctx, node);
 		break;
 	default:
 		WARN_ON_ONCE(1);
diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
index 3bc3a484fbba..f45a26c3b79d 100644
--- a/io_uring/rsrc.h
+++ b/io_uring/rsrc.h
@@ -14,18 +14,7 @@ enum {
 	__IORING_RSRC_LAST_TYPE,
 
 	IORING_RSRC_F_NEED_FREE		= 1 << 0,
-};
-
-struct io_rsrc_node {
-	unsigned char			type;
-	unsigned char			flags;
-	int				refs;
-
-	u64 tag;
-	union {
-		unsigned long file_ptr;
-		struct io_mapped_buf *buf;
-	};
+	IORING_RSRC_F_BUF_KERNEL	= 1 << 1,
 };
 
 struct io_imu_folio_data {
-- 
2.47.0