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 #define SPLICE_F_ALL (SPLICE_F_MOVE|SPLICE_F_NONBLOCK|SPLICE_F_MORE|SPLICE_F_GIFT)
  24
  25 /*
  26  * Passed to the actors
  27  */
  28 struct splice_desc {
  29         size_t total_len;               /* remaining length */
  30         unsigned int len;               /* current length */
  31         unsigned int flags;             /* splice flags */
  32         /*
  33          * actor() private data
  34          */
  35         union {
  36                 void __user *userptr;   /* memory to write to */
  37                 struct file *file;      /* file to read/write */
  38                 void *data;             /* cookie */
  39         } u;
  40         loff_t pos;                     /* file position */
  41         loff_t *opos;                   /* sendfile: output position */
  42         size_t num_spliced;             /* number of bytes already spliced */
  43         bool need_wakeup;               /* need to wake up writer */
  44 };
  45
  46 struct partial_page {
  47         unsigned int offset;
  48         unsigned int len;
  49         unsigned long private;
  50 };
  51
  52 /*
  53  * Passed to splice_to_pipe
  54  */
  55 struct splice_pipe_desc {
  56         struct page **pages;            /* page map */
  57         struct partial_page *partial;   /* pages[] may not be contig */
  58         int nr_pages;                   /* number of populated pages in map */
  59         unsigned int nr_pages_max;      /* pages[] & partial[] arrays size */
  60         const struct pipe_buf_operations *ops;/* ops associated with output pipe */
  61         void (*spd_release)(struct splice_pipe_desc *, unsigned int);
  62 };
  63
  64 typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
  65                            struct splice_desc *);
  66 typedef int (splice_direct_actor)(struct pipe_inode_info *,
  67                                   struct splice_desc *);
  68
  69 extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
  70                                 loff_t *, size_t, unsigned int,
  71                                 splice_actor *);
  72 extern ssize_t __splice_from_pipe(struct pipe_inode_info *,
  73                                   struct splice_desc *, splice_actor *);
  74 extern ssize_t splice_to_pipe(struct pipe_inode_info *,
  75                               struct splice_pipe_desc *);
  76 extern ssize_t add_to_pipe(struct pipe_inode_info *,
  77                               struct pipe_buffer *);
  78 extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
  79                                       splice_direct_actor *);
  80
  81 /*
  82  * for dynamic pipe sizing
  83  */
  84 extern int splice_grow_spd(const struct pipe_inode_info *, struct splice_pipe_desc *);
  85 extern void splice_shrink_spd(struct splice_pipe_desc *);
  86
  87 extern const struct pipe_buf_operations page_cache_pipe_buf_ops;
  88 extern const struct pipe_buf_operations default_pipe_buf_ops;
  89 #endif