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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 	size_t total_len;		/* remaining length */
28 	unsigned int len;		/* current length */
29 	unsigned int flags;		/* splice flags */
30 	/*
31 	 * actor() private data
32 	 */
33 	union {
34 		void __user *userptr;	/* memory to write to */
35 		struct file *file;	/* file to read/write */
36 		void *data;		/* cookie */
37 	} u;
38 	loff_t pos;			/* file position */
39 	loff_t *opos;			/* sendfile: output position */
40 	size_t num_spliced;		/* number of bytes already spliced */
41 	bool need_wakeup;		/* need to wake up writer */
42 };
43 
44 struct partial_page {
45 	unsigned int offset;
46 	unsigned int len;
47 	unsigned long private;
48 };
49 
50 /*
51  * Passed to splice_to_pipe
52  */
53 struct splice_pipe_desc {
54 	struct page **pages;		/* page map */
55 	struct partial_page *partial;	/* pages[] may not be contig */
56 	int nr_pages;			/* number of populated pages in map */
57 	unsigned int nr_pages_max;	/* pages[] & partial[] arrays size */
58 	unsigned int flags;		/* splice flags */
59 	const struct pipe_buf_operations *ops;/* ops associated with output pipe */
60 	void (*spd_release)(struct splice_pipe_desc *, unsigned int);
61 };
62 
63 typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
64 			   struct splice_desc *);
65 typedef int (splice_direct_actor)(struct pipe_inode_info *,
66 				  struct splice_desc *);
67 
68 extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
69 				loff_t *, size_t, unsigned int,
70 				splice_actor *);
71 extern ssize_t __splice_from_pipe(struct pipe_inode_info *,
72 				  struct splice_desc *, splice_actor *);
73 extern ssize_t splice_to_pipe(struct pipe_inode_info *,
74 			      struct splice_pipe_desc *);
75 extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
76 				      splice_direct_actor *);
77 
78 /*
79  * for dynamic pipe sizing
80  */
81 extern int splice_grow_spd(const struct pipe_inode_info *, struct splice_pipe_desc *);
82 extern void splice_shrink_spd(struct splice_pipe_desc *);
83 extern void spd_release_page(struct splice_pipe_desc *, unsigned int);
84 
85 extern const struct pipe_buf_operations page_cache_pipe_buf_ops;
86 #endif
87