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  */
  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