mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-14 21:46:44 +07:00
241699cd72
iov_iter variant for passing data into pipe. copy_to_iter() copies data into page(s) it has allocated and stuffs them into the pipe; copy_page_to_iter() stuffs there a reference to the page given to it. Both will try to coalesce if possible. iov_iter_zero() is similar to copy_to_iter(); iov_iter_get_pages() and friends will do as copy_to_iter() would have and return the pages where the data would've been copied. iov_iter_advance() will truncate everything past the spot it has advanced to. New primitive: iov_iter_pipe(), used for initializing those. pipe should be locked all along. Running out of space acts as fault would for iovec-backed ones; in other words, giving it to ->read_iter() may result in short read if the pipe overflows, or -EFAULT if it happens with nothing copied there. In other words, ->read_iter() on those acts pretty much like ->splice_read(). Moreover, all generic_file_splice_read() users, as well as many other ->splice_read() instances can be switched to that scheme - that'll happen in the next commit. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
90 lines
2.8 KiB
C
90 lines
2.8 KiB
C
/*
|
|
* 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>
|
|
|
|
/*
|
|
* Flags passed in from splice/tee/vmsplice
|
|
*/
|
|
#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 {
|
|
size_t total_len; /* remaining length */
|
|
unsigned int len; /* current 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 */
|
|
loff_t *opos; /* sendfile: output position */
|
|
size_t num_spliced; /* number of bytes already spliced */
|
|
bool need_wakeup; /* need to wake up writer */
|
|
};
|
|
|
|
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 populated pages in map */
|
|
unsigned int nr_pages_max; /* pages[] & partial[] arrays size */
|
|
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 add_to_pipe(struct pipe_inode_info *,
|
|
struct pipe_buffer *);
|
|
extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
|
|
splice_direct_actor *);
|
|
|
|
/*
|
|
* for dynamic pipe sizing
|
|
*/
|
|
extern int splice_grow_spd(const struct pipe_inode_info *, struct splice_pipe_desc *);
|
|
extern void splice_shrink_spd(struct splice_pipe_desc *);
|
|
extern void spd_release_page(struct splice_pipe_desc *, unsigned int);
|
|
|
|
extern const struct pipe_buf_operations page_cache_pipe_buf_ops;
|
|
extern const struct pipe_buf_operations default_pipe_buf_ops;
|
|
#endif
|