linux/include/linux/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 <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 */
  26struct 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
  42struct partial_page {
  43        unsigned int offset;
  44        unsigned int len;
  45        unsigned long private;
  46};
  47
  48/*
  49 * Passed to splice_to_pipe
  50 */
  51struct 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
  61typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
  62                           struct splice_desc *);
  63typedef int (splice_direct_actor)(struct pipe_inode_info *,
  64                                  struct splice_desc *);
  65
  66extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
  67                                loff_t *, size_t, unsigned int,
  68                                splice_actor *);
  69extern ssize_t __splice_from_pipe(struct pipe_inode_info *,
  70                                  struct splice_desc *, splice_actor *);
  71extern int splice_from_pipe_feed(struct pipe_inode_info *, struct splice_desc *,
  72                                 splice_actor *);
  73extern int splice_from_pipe_next(struct pipe_inode_info *,
  74                                 struct splice_desc *);
  75extern void splice_from_pipe_begin(struct splice_desc *);
  76extern void splice_from_pipe_end(struct pipe_inode_info *,
  77                                 struct splice_desc *);
  78extern int pipe_to_file(struct pipe_inode_info *, struct pipe_buffer *,
  79                        struct splice_desc *);
  80
  81extern ssize_t splice_to_pipe(struct pipe_inode_info *,
  82                              struct splice_pipe_desc *);
  83extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
  84                                      splice_direct_actor *);
  85
  86/*
  87 * for dynamic pipe sizing
  88 */
  89extern int splice_grow_spd(const struct pipe_inode_info *, struct splice_pipe_desc *);
  90extern void splice_shrink_spd(struct splice_pipe_desc *);
  91extern void spd_release_page(struct splice_pipe_desc *, unsigned int);
  92
  93extern const struct pipe_buf_operations page_cache_pipe_buf_ops;
  94#endif
  95
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