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/*
* iobuf.h
*
* Defines the structures used to track abstract kernel-space io buffers.
*
*/
#ifndef __LINUX_IOBUF_H
#define __LINUX_IOBUF_H
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/wait.h>
#include <asm/atomic.h>
/*
* The kiobuf structure describes a physical set of pages reserved
* locked for IO. The reference counts on each page will have been
* incremented, and the flags field will indicate whether or not we have
* pre-locked all of the pages for IO.
*
* kiobufs may be passed in arrays to form a kiovec, but we must
* preserve the property that no page is present more than once over the
* entire iovec.
*/
#define KIO_MAX_ATOMIC_IO 64 /* in kb */
#define KIO_MAX_ATOMIC_BYTES (64 * 1024)
#define KIO_STATIC_PAGES (KIO_MAX_ATOMIC_IO / (PAGE_SIZE >> 10) + 1)
#define KIO_MAX_SECTORS (KIO_MAX_ATOMIC_IO * 2)
/* The main kiobuf struct used for all our IO! */
struct kiobuf
{
int nr_pages; /* Pages actually referenced */
int array_len; /* Space in the allocated lists */
int offset; /* Offset to start of valid data */
int length; /* Number of valid bytes of data */
/* Keep separate track of the physical addresses and page
* structs involved. If we do IO to a memory-mapped device
* region, there won't necessarily be page structs defined for
* every address. */
struct page ** maplist;
unsigned int locked : 1; /* If set, pages has been locked */
/* Always embed enough struct pages for 64k of IO */
struct page * map_array[KIO_STATIC_PAGES];
/* Dynamic state for IO completion: */
atomic_t io_count; /* IOs still in progress */
int errno; /* Status of completed IO */
void (*end_io) (struct kiobuf *); /* Completion callback */
wait_queue_head_t wait_queue;
};
/* mm/memory.c */
int map_user_kiobuf(int rw, struct kiobuf *, unsigned long va, size_t len);
void unmap_kiobuf(struct kiobuf *iobuf);
int lock_kiovec(int nr, struct kiobuf *iovec[], int wait);
int unlock_kiovec(int nr, struct kiobuf *iovec[]);
/* fs/iobuf.c */
void __init kiobuf_setup(void);
void kiobuf_init(struct kiobuf *);
void end_kio_request(struct kiobuf *, int);
void simple_wakeup_kiobuf(struct kiobuf *);
int alloc_kiovec(int nr, struct kiobuf **);
void free_kiovec(int nr, struct kiobuf **);
int expand_kiobuf(struct kiobuf *, int);
void kiobuf_wait_for_io(struct kiobuf *);
/* fs/buffer.c */
int brw_kiovec(int rw, int nr, struct kiobuf *iovec[],
kdev_t dev, unsigned long b[], int size);
#endif /* __LINUX_IOBUF_H */
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