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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  * 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  */
  27 struct 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
  43 struct partial_page {
  44         unsigned int offset;
  45         unsigned int len;
  46         unsigned long private;
  47 };
  48
  49 /*
  50  * Passed to splice_to_pipe
  51  */
  52 struct 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
  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
  79 extern ssize_t splice_to_pipe(struct pipe_inode_info *,
  80                               struct splice_pipe_desc *);
  81 extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
  82                                       splice_direct_actor *);
  83
  84 #endif