LXR linux/include/linux/splice.h

   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 * splice is tied to pipes as a transport (at least for now), so we'll just
  15 * add the splice flags here.
  16 */
  17#define SPLICE_F_MOVE   (0x01)  /* move pages instead of copying */
  18#define SPLICE_F_NONBLOCK (0x02) /* don't block on the pipe splicing (but */
  19                                 /* we may still block on the fd we splice */
  20                                 /* from/to, of course */
  21#define SPLICE_F_MORE   (0x04)  /* expect more data */
  22#define SPLICE_F_GIFT   (0x08)  /* pages passed in are a gift */
  23
  24/*
  25 * Passed to the actors
  26 */
  27struct splice_desc {
  28        unsigned int len, total_len;    /* current and remaining 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        size_t num_spliced;             /* number of bytes already spliced */
  40        bool need_wakeup;               /* need to wake up writer */
  41};
  42
  43struct partial_page {
  44        unsigned int offset;
  45        unsigned int len;
  46        unsigned long private;
  47};
  48
  49/*
  50 * Passed to splice_to_pipe
  51 */
  52struct splice_pipe_desc {
  53        struct page **pages;            /* page map */
  54        struct partial_page *partial;   /* pages[] may not be contig */
  55        int nr_pages;                   /* number of pages in map */
  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#endif
  87