1 /*
2  * Function declerations and data structures related to the splice
3  * implementation.
4  *
5  * Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com>
6  *
7  */
8 #ifndef SPLICE_H
9 #define SPLICE_H
10 
11 #include <linux/pipe_fs_i.h>
12 
13 /*
14  * Flags passed in from splice/tee/vmsplice
15  */
16 #define SPLICE_F_MOVE	(0x01)	/* move pages instead of copying */
17 #define SPLICE_F_NONBLOCK (0x02) /* don't block on the pipe splicing (but */
18 				 /* we may still block on the fd we splice */
19 				 /* from/to, of course */
20 #define SPLICE_F_MORE	(0x04)	/* expect more data */
21 #define SPLICE_F_GIFT	(0x08)	/* pages passed in are a gift */
22 
23 /*
24  * Passed to the actors
25  */
26 struct splice_desc {
27 	unsigned int len, total_len;	/* current and remaining length */
28 	unsigned int flags;		/* splice flags */
29 	/*
30 	 * actor() private data
31 	 */
32 	union {
33 		void __user *userptr;	/* memory to write to */
34 		struct file *file;	/* file to read/write */
35 		void *data;		/* cookie */
36 	} u;
37 	loff_t pos;			/* file position */
38 	size_t num_spliced;		/* number of bytes already spliced */
39 	bool need_wakeup;		/* need to wake up writer */
40 };
41 
42 struct partial_page {
43 	unsigned int offset;
44 	unsigned int len;
45 	unsigned long private;
46 };
47 
48 /*
49  * Passed to splice_to_pipe
50  */
51 struct splice_pipe_desc {
52 	struct page **pages;		/* page map */
53 	struct partial_page *partial;	/* pages[] may not be contig */
54 	int nr_pages;			/* number of populated pages in map */
55 	unsigned int nr_pages_max;	/* pages[] & partial[] arrays size */
56 	unsigned int flags;		/* splice flags */
57 	const struct pipe_buf_operations *ops;/* ops associated with output pipe */
58 	void (*spd_release)(struct splice_pipe_desc *, unsigned int);
59 };
60 
61 typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
62 			   struct splice_desc *);
63 typedef int (splice_direct_actor)(struct pipe_inode_info *,
64 				  struct splice_desc *);
65 
66 extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
67 				loff_t *, size_t, unsigned int,
68 				splice_actor *);
69 extern ssize_t __splice_from_pipe(struct pipe_inode_info *,
70 				  struct splice_desc *, splice_actor *);
71 extern int splice_from_pipe_feed(struct pipe_inode_info *, struct splice_desc *,
72 				 splice_actor *);
73 extern int splice_from_pipe_next(struct pipe_inode_info *,
74 				 struct splice_desc *);
75 extern void splice_from_pipe_begin(struct splice_desc *);
76 extern void splice_from_pipe_end(struct pipe_inode_info *,
77 				 struct splice_desc *);
78 extern int pipe_to_file(struct pipe_inode_info *, struct pipe_buffer *,
79 			struct splice_desc *);
80 
81 extern ssize_t splice_to_pipe(struct pipe_inode_info *,
82 			      struct splice_pipe_desc *);
83 extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
84 				      splice_direct_actor *);
85 
86 /*
87  * for dynamic pipe sizing
88  */
89 extern int splice_grow_spd(const struct pipe_inode_info *, struct splice_pipe_desc *);
90 extern void splice_shrink_spd(struct splice_pipe_desc *);
91 extern void spd_release_page(struct splice_pipe_desc *, unsigned int);
92 
93 extern const struct pipe_buf_operations page_cache_pipe_buf_ops;
94 #endif
95