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         loff_t *opos;                   /* sendfile: output 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 populated pages in map */
  56         unsigned int nr_pages_max;      /* pages[] & partial[] arrays size */
  57         unsigned int flags;             /* splice flags */
  58         const struct pipe_buf_operations *ops;/* ops associated with output pipe */
  59         void (*spd_release)(struct splice_pipe_desc *, unsigned int);
  60 };
  61
  62 typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
  63                            struct splice_desc *);
  64 typedef int (splice_direct_actor)(struct pipe_inode_info *,
  65                                   struct splice_desc *);
  66
  67 extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
  68                                 loff_t *, size_t, unsigned int,
  69                                 splice_actor *);
  70 extern ssize_t __splice_from_pipe(struct pipe_inode_info *,
  71                                   struct splice_desc *, splice_actor *);
  72 extern int splice_from_pipe_feed(struct pipe_inode_info *, struct splice_desc *,
  73                                  splice_actor *);
  74 extern int splice_from_pipe_next(struct pipe_inode_info *,
  75                                  struct splice_desc *);
  76 extern void splice_from_pipe_begin(struct splice_desc *);
  77 extern void splice_from_pipe_end(struct pipe_inode_info *,
  78                                  struct splice_desc *);
  79 extern int pipe_to_file(struct pipe_inode_info *, struct pipe_buffer *,
  80                         struct splice_desc *);
  81
  82 extern ssize_t splice_to_pipe(struct pipe_inode_info *,
  83                               struct splice_pipe_desc *);
  84 extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
  85                                       splice_direct_actor *);
  86
  87 /*
  88  * for dynamic pipe sizing
  89  */
  90 extern int splice_grow_spd(const struct pipe_inode_info *, struct splice_pipe_desc *);
  91 extern void splice_shrink_spd(struct splice_pipe_desc *);
  92 extern void spd_release_page(struct splice_pipe_desc *, unsigned int);
  93
  94 extern const struct pipe_buf_operations page_cache_pipe_buf_ops;
  95 #endif