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