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splice.h
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1 /*
2  * Function declerations and data structures related to the splice
3  * implementation.
4  *
5  * Copyright (C) 2007 Jens Axboe <[email protected]>
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
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