[RFC PATCH v2 06/13] io_uring: Provide driver API for zctap packet buffers.

[Jonathan Lemon <jonathan.lemon@gmail.com>]

Introduce 'struct io_zctap_buf', representing a buffer used by
the network drivers, and a pair of get/put functions which are
used to obtain the buffers.

The code for these will be fleshed out in the next patch.

Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
---
 include/linux/io_uring.h | 35 +++++++++++++++++++++++++++++++++++
 io_uring/zctap.c         | 11 +++++++++++
 2 files changed, 46 insertions(+)

diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h
index 43bc8a2edccf..c27645ce0efc 100644
--- a/include/linux/io_uring.h
+++ b/include/linux/io_uring.h
@@ -32,6 +32,13 @@ struct io_uring_cmd {
 	u8		pdu[32]; /* available inline for free use */
 };
 
+struct io_zctap_buf {
+	dma_addr_t	dma;
+	struct page	*page;
+	atomic_t	refcount;
+	u8		_pad[4];
+};
+
 #if defined(CONFIG_IO_URING)
 int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
 			      struct iov_iter *iter, void *ioucmd);
@@ -44,6 +51,18 @@ void __io_uring_free(struct task_struct *tsk);
 void io_uring_unreg_ringfd(void);
 const char *io_uring_get_opcode(u8 opcode);
 
+struct io_zctap_ifq;
+struct io_zctap_buf *io_zctap_get_buf(struct io_zctap_ifq *ifq);
+void io_zctap_put_buf(struct io_zctap_ifq *ifq, struct io_zctap_buf *buf);
+
+static inline dma_addr_t io_zctap_buf_dma(struct io_zctap_buf *buf)
+{
+	return buf->dma;
+}
+static inline struct page *io_zctap_buf_page(struct io_zctap_buf *buf)
+{
+	return buf->page;
+}
 static inline void io_uring_files_cancel(void)
 {
 	if (current->io_uring) {
@@ -92,6 +111,22 @@ static inline const char *io_uring_get_opcode(u8 opcode)
 {
 	return "";
 }
+static inline dma_addr_t io_zctap_buf_dma(struct io_zctap_buf *buf)
+{
+	return 0;
+}
+static inline struct page *io_zctap_buf_page(struct io_zctap_buf *buf)
+{
+	return NULL;
+}
+static inline struct io_zctap_buf *io_zctap_get_buf(struct io_zctap_ifq *ifq)
+{
+	return NULL;
+}
+void io_zctap_put_buf(struct io_zctap_ifq *ifq, struct io_zctap_buf *buf)
+{
+}
+
 #endif
 
 #endif
diff --git a/io_uring/zctap.c b/io_uring/zctap.c
index af2e871b1b62..46ba0d011250 100644
--- a/io_uring/zctap.c
+++ b/io_uring/zctap.c
@@ -37,6 +37,17 @@ static u64 zctap_mk_page_info(u16 region_id, u16 pgid)
 	return (u64)0xface << 48 | (u64)region_id << 16 | (u64)pgid;
 }
 
+struct io_zctap_buf *io_zctap_get_buf(struct io_zctap_ifq *ifq)
+{
+	return NULL;
+}
+EXPORT_SYMBOL(io_zctap_get_buf);
+
+void io_zctap_put_buf(struct io_zctap_ifq *ifq, struct io_zctap_buf *buf)
+{
+}
+EXPORT_SYMBOL(io_zctap_put_buf);
+
 static void io_remove_ifq_region(struct ifq_region *ifr)
 {
 	struct io_mapped_ubuf *imu;
-- 
2.30.2