Actually, these systemcalls or inode operations were introduced in linux-2.6.17.
But I don't think there exists an application issuces such new systemcalls,
and aufs decided not to support them in linux-2.6.17.
In linux-2.6.23, sendfile inode operation was removed and aufs becomes having to
support splice oprations.

In other words, this patch is for linux-2.6.23 and later. Aufs doesn't support
splice related systemcalls before 2.6.23.

diff --git a/fs/splice.c b/fs/splice.c
index 6bdcb61..cdcb4f6 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -893,8 +893,13 @@ EXPORT_SYMBOL(generic_splice_sendpage);
 /*
  * Attempt to initiate a splice from pipe to file.
  */
+#ifdef CONFIG_AUFS_SPLICE_PATCH
+long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
+			   loff_t *ppos, size_t len, unsigned int flags)
+#else
 static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
 			   loff_t *ppos, size_t len, unsigned int flags)
+#endif
 {
 	int ret;
 
@@ -914,13 +919,22 @@ static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
 
 	return out->f_op->splice_write(pipe, out, ppos, len, flags);
 }
+#ifdef CONFIG_AUFS_SPLICE_PATCH
+EXPORT_SYMBOL(do_splice_from);
+#endif
 
 /*
  * Attempt to initiate a splice from a file to a pipe.
  */
+#ifdef CONFIG_AUFS_SPLICE_PATCH
+long do_splice_to(struct file *in, loff_t *ppos,
+			 struct pipe_inode_info *pipe, size_t len,
+			 unsigned int flags)
+#else
 static long do_splice_to(struct file *in, loff_t *ppos,
 			 struct pipe_inode_info *pipe, size_t len,
 			 unsigned int flags)
+#endif
 {
 	int ret;
 
@@ -940,6 +954,9 @@ static long do_splice_to(struct file *in, loff_t *ppos,
 
 	return in->f_op->splice_read(in, ppos, pipe, len, flags);
 }
+#ifdef CONFIG_AUFS_SPLICE_PATCH
+EXPORT_SYMBOL(do_splice_to);
+#endif
 
 /**
  * splice_direct_to_actor - splices data directly between two non-pipes
diff --git a/include/linux/splice.h b/include/linux/splice.h
index 33e447f..7846e83 100644
--- a/include/linux/splice.h
+++ b/include/linux/splice.h
@@ -70,4 +70,11 @@ extern ssize_t splice_to_pipe(struct pipe_inode_info *,
 extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
 				      splice_direct_actor *);
 
+#ifdef CONFIG_AUFS_SPLICE_PATCH
+extern long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
+			   loff_t *ppos, size_t len, unsigned int flags);
+extern long do_splice_to(struct file *in, loff_t *ppos,
+			 struct pipe_inode_info *pipe, size_t len,
+			 unsigned int flags);
+#endif
 #endif