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 * 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        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
  44struct partial_page {
  45        unsigned int offset;
  46        unsigned int len;
  47        unsigned long private;
  48};
  49
  50/*
  51 * Passed to splice_to_pipe
  52 */
  53struct 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
  63typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
  64                           struct splice_desc *);
  65typedef int (splice_direct_actor)(struct pipe_inode_info *,
  66                                  struct splice_desc *);
  67
  68extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
  69                                loff_t *, size_t, unsigned int,
  70                                splice_actor *);
  71extern ssize_t __splice_from_pipe(struct pipe_inode_info *,
  72                                  struct splice_desc *, splice_actor *);
  73extern ssize_t splice_to_pipe(struct pipe_inode_info *,
  74                              struct splice_pipe_desc *);
  75extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
  76                                      splice_direct_actor *);
  77
  78/*
  79 * for dynamic pipe sizing
  80 */
  81extern int splice_grow_spd(const struct pipe_inode_info *, struct splice_pipe_desc *);
  82extern void splice_shrink_spd(struct splice_pipe_desc *);
  83extern void spd_release_page(struct splice_pipe_desc *, unsigned int);
  84
  85extern const struct pipe_buf_operations page_cache_pipe_buf_ops;
  86#endif
  87