diff --git a/common/send-stream.c b/common/send-stream.c
index b7e1eaeb..e51b973d 100644
--- a/common/send-stream.c
+++ b/common/send-stream.c
@@ -44,7 +44,7 @@ struct btrfs_send_stream {
 	int fd;
 
 	int cmd;
-	struct btrfs_send_attribute cmd_attrs[BTRFS_SEND_A_MAX + 1];
+	struct btrfs_send_attribute cmd_attrs[__BTRFS_SEND_A_MAX + 1];
 	u32 version;
 
 	/*
@@ -183,7 +183,7 @@ static int read_cmd(struct btrfs_send_stream *sctx)
 		}
 		tlv_type = le16_to_cpu(*(__le16 *)data);
 
-		if (tlv_type == 0 || tlv_type > BTRFS_SEND_A_MAX) {
+		if (tlv_type == 0 || tlv_type > __BTRFS_SEND_A_MAX) {
 			error("invalid tlv in cmd tlv_type = %hu", tlv_type);
 			ret = -EINVAL;
 			goto out;
@@ -228,7 +228,7 @@ static int tlv_get(struct btrfs_send_stream *sctx, int attr, void **data, int *l
 	int ret;
 	struct btrfs_send_attribute *send_attr;
 
-	if (attr <= 0 || attr > BTRFS_SEND_A_MAX) {
+	if (attr <= 0 || attr > __BTRFS_SEND_A_MAX) {
 		error("invalid attribute requested, attr = %d", attr);
 		ret = -EINVAL;
 		goto out;
diff --git a/kernel-shared/send.h b/kernel-shared/send.h
index db1bec19..34de60ff 100644
--- a/kernel-shared/send.h
+++ b/kernel-shared/send.h
@@ -20,16 +20,27 @@
 #ifndef __BTRFS_SEND_H__
 #define __BTRFS_SEND_H__
 
+#include "kernel-lib/sizes.h"
 #include "kernel-shared/ctree.h"
 
 #define BTRFS_SEND_STREAM_MAGIC "btrfs-stream"
+/* Conditional support for the upcoming protocol version. */
+#ifdef CONFIG_BTRFS_DEBUG
+#define BTRFS_SEND_STREAM_VERSION 3
+#else
 #define BTRFS_SEND_STREAM_VERSION 2
+#endif
 
 /*
- * In send stream v1, no command is larger than 64KiB. In send stream v2, no limit
- * should be assumed.
+ * In send stream v1, no command is larger than 64K. In send stream v2, no
+ * limit should be assumed, the buffer size is set to be a header with
+ * compressed extent size.
  */
-#define BTRFS_SEND_BUF_SIZE_V1				(64 * 1024)
+#define BTRFS_SEND_BUF_SIZE_V1				SZ_64K
+#define BTRFS_SEND_BUF_SIZE_V2	ALIGN(SZ_16K + BTRFS_MAX_COMPRESSED, PAGE_SIZE)
+
+struct inode;
+struct btrfs_ioctl_send_args;
 
 enum btrfs_tlv_type {
 	BTRFS_TLV_U8,
@@ -102,6 +113,7 @@ enum btrfs_send_cmd {
 	BTRFS_SEND_C_ENCODED_WRITE	= 25,
 	BTRFS_SEND_C_MAX_V2		= 25,
 
+	/* Version 3 */
 	BTRFS_SEND_C_ENABLE_VERITY	= 26,
 	BTRFS_SEND_C_MAX_V3		= 26,
 	/* End */
@@ -179,8 +191,9 @@ enum {
 	BTRFS_SEND_A_VERITY_SIG_DATA	= 35,
 	BTRFS_SEND_A_MAX_V3		= 35,
 
-	/* End */
-	BTRFS_SEND_A_MAX		= 35,
+	__BTRFS_SEND_A_MAX		= 35,
 };
 
+long btrfs_ioctl_send(struct inode *inode, struct btrfs_ioctl_send_args *arg);
+
 #endif