1 /*
2  * iobuf.h
3  *
4  * Defines the structures used to track abstract kernel-space io buffers.
5  *
6  */
7 
8 #ifndef __LINUX_IOBUF_H
9 #define __LINUX_IOBUF_H
10 
11 #include <linux/mm.h>
12 #include <linux/init.h>
13 #include <linux/wait.h>
14 #include <asm/atomic.h>
15 
16 /*
17  * The kiobuf structure describes a physical set of pages reserved
18  * locked for IO.  The reference counts on each page will have been
19  * incremented, and the flags field will indicate whether or not we have
20  * pre-locked all of the pages for IO.
21  *
22  * kiobufs may be passed in arrays to form a kiovec, but we must
23  * preserve the property that no page is present more than once over the
24  * entire iovec.
25  */
26 
27 #define KIO_MAX_ATOMIC_IO	512 /* in kb */
28 #define KIO_STATIC_PAGES	(KIO_MAX_ATOMIC_IO / (PAGE_SIZE >> 10) + 1)
29 #define KIO_MAX_SECTORS		(KIO_MAX_ATOMIC_IO * 2)
30 
31 /* The main kiobuf struct used for all our IO! */
32 
33 struct kiobuf
34 {
35 	int		nr_pages;	/* Pages actually referenced */
36 	int		array_len;	/* Space in the allocated lists */
37 	int		offset;		/* Offset to start of valid data */
38 	int		length;		/* Number of valid bytes of data */
39 
40 	unsigned int	locked : 1;	/* If set, pages has been locked */
41 
42 	struct page **  maplist;
43 	struct buffer_head ** bh;
44 	unsigned long * blocks;
45 
46 	/* Dynamic state for IO completion: */
47 	atomic_t	io_count;	/* IOs still in progress */
48 	int		errno;		/* Status of completed IO */
49 	void		(*end_io) (struct kiobuf *); /* Completion callback */
50 	wait_queue_head_t wait_queue;
51 };
52 
53 
54 /* mm/memory.c */
55 
56 int	map_user_kiobuf(int rw, struct kiobuf *, unsigned long va, size_t len);
57 void	unmap_kiobuf(struct kiobuf *iobuf);
58 int	lock_kiovec(int nr, struct kiobuf *iovec[], int wait);
59 int	unlock_kiovec(int nr, struct kiobuf *iovec[]);
60 void	mark_dirty_kiobuf(struct kiobuf *iobuf, int bytes);
61 
62 /* fs/iobuf.c */
63 
64 void	end_kio_request(struct kiobuf *, int);
65 void	simple_wakeup_kiobuf(struct kiobuf *);
66 int	alloc_kiovec(int nr, struct kiobuf **);
67 void	free_kiovec(int nr, struct kiobuf **);
68 int	expand_kiobuf(struct kiobuf *, int);
69 void	kiobuf_wait_for_io(struct kiobuf *);
70 extern int alloc_kiobuf_bhs(struct kiobuf *);
71 extern void free_kiobuf_bhs(struct kiobuf *);
72 
73 /* fs/buffer.c */
74 
75 int	brw_kiovec(int rw, int nr, struct kiobuf *iovec[],
76 		   kdev_t dev, unsigned long b[], int size);
77 
78 #endif /* __LINUX_IOBUF_H */
79