root/include/linux/splice.h

INCLUDED FROM

/*
 * Function declerations and data structures related to the splice
 * implementation.
 *
 * Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com>
 *
 */
#ifndef SPLICE_H
#define SPLICE_H

#include <linux/pipe_fs_i.h>

/*
 * splice is tied to pipes as a transport (at least for now), so we'll just
 * add the splice flags here.
 */
#define SPLICE_F_MOVE   (0x01)  /* move pages instead of copying */
#define SPLICE_F_NONBLOCK (0x02) /* don't block on the pipe splicing (but */
                                 /* we may still block on the fd we splice */
                                 /* from/to, of course */
#define SPLICE_F_MORE   (0x04)  /* expect more data */
#define SPLICE_F_GIFT   (0x08)  /* pages passed in are a gift */

/*
 * Passed to the actors
 */
struct splice_desc {
        unsigned int len, total_len;    /* current and remaining length */
        unsigned int flags;             /* splice flags */
        /*
         * actor() private data
         */
        union {
                void __user *userptr;   /* memory to write to */
                struct file *file;      /* file to read/write */
                void *data;             /* cookie */
        } u;
        loff_t pos;                     /* file position */
};

struct partial_page {
        unsigned int offset;
        unsigned int len;
        unsigned long private;
};

/*
 * Passed to splice_to_pipe
 */
struct splice_pipe_desc {
        struct page **pages;            /* page map */
        struct partial_page *partial;   /* pages[] may not be contig */
        int nr_pages;                   /* number of pages in map */
        unsigned int flags;             /* splice flags */
        const struct pipe_buf_operations *ops;/* ops associated with output pipe */
        void (*spd_release)(struct splice_pipe_desc *, unsigned int);
};

typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
                           struct splice_desc *);
typedef int (splice_direct_actor)(struct pipe_inode_info *,
                                  struct splice_desc *);

extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
                                loff_t *, size_t, unsigned int,
                                splice_actor *);
extern ssize_t __splice_from_pipe(struct pipe_inode_info *,
                                  struct splice_desc *, splice_actor *);
extern ssize_t splice_to_pipe(struct pipe_inode_info *,
                              struct splice_pipe_desc *);
extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
                                      splice_direct_actor *);

#endif