splice: divorce the splice structure/function definitions from the pipe header

We need to move even more stuff into the header so that folks can use
the splice_to_pipe() implementation instead of open-coding a lot of
pipe knowledge (see relay implementation), so move to our own header
file finally.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

include/linux/splice.h

@@ -0,0 +1,72 @@
+/*
+ * Function declerations and data structures related to the splice
+ * implementation.
+ *
+ * Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com>
+ *
+ */
+#ifndef SPLICE_H
+#define SPLICE_H
+
+#include <linux/pipe_fs_i.h>
+
+/*
+ * splice is tied to pipes as a transport (at least for now), so we'll just
+ * add the splice flags here.
+ */
+#define SPLICE_F_MOVE	(0x01)	/* move pages instead of copying */
+#define SPLICE_F_NONBLOCK (0x02) /* don't block on the pipe splicing (but */
+				 /* we may still block on the fd we splice */
+				 /* from/to, of course */
+#define SPLICE_F_MORE	(0x04)	/* expect more data */
+#define SPLICE_F_GIFT	(0x08)	/* pages passed in are a gift */
+
+/*
+ * Passed to the actors
+ */
+struct splice_desc {
+	unsigned int len, total_len;	/* current and remaining length */
+	unsigned int flags;		/* splice flags */
+	/*
+	 * actor() private data
+	 */
+	union {
+		void __user *userptr;	/* memory to write to */
+		struct file *file;	/* file to read/write */
+		void *data;		/* cookie */
+	} u;
+	loff_t pos;			/* file position */
+};
+
+struct partial_page {
+	unsigned int offset;
+	unsigned int len;
+};
+
+/*
+ * Passed to splice_to_pipe
+ */
+struct splice_pipe_desc {
+	struct page **pages;		/* page map */
+	struct partial_page *partial;	/* pages[] may not be contig */
+	int nr_pages;			/* number of pages in map */
+	unsigned int flags;		/* splice flags */
+	const struct pipe_buf_operations *ops;/* ops associated with output pipe */
+};
+
+typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
+			   struct splice_desc *);
+typedef int (splice_direct_actor)(struct pipe_inode_info *,
+				  struct splice_desc *);
+
+extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
+				loff_t *, size_t, unsigned int,
+				splice_actor *);
+extern ssize_t __splice_from_pipe(struct pipe_inode_info *,
+				  struct splice_desc *, splice_actor *);
+extern ssize_t splice_to_pipe(struct pipe_inode_info *,
+			      struct splice_pipe_desc *);
+extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
+				      splice_direct_actor *);
+
+#endif