[SPLICE]: Don't assume regular pages in splice_to_pipe()

Allow caller to pass in a release function, there might be
other resources that need releasing as well. Needed for
network receive.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/splice.h

@@ -53,6 +53,7 @@ struct splice_pipe_desc {
 	int nr_pages;			/* number of pages in map */
 	unsigned int flags;		/* splice flags */
 	const struct pipe_buf_operations *ops;/* ops associated with output pipe */
+	void (*spd_release)(struct splice_pipe_desc *, unsigned int);
 };
 
 typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,