patch-2.3.12 linux/include/linux/iobuf.h

• Lines: 81
• Date: Wed Jul 28 13:56:48 1999
• Orig file: v2.3.11/linux/include/linux/iobuf.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.11/linux/include/linux/iobuf.h linux/include/linux/iobuf.h
@@ -0,0 +1,80 @@
+/*
+ * 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)
+
+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. */
+
+	unsigned long *	pagelist;
+	struct page **	maplist;
+
+	unsigned int	locked : 1;	/* If set, pages has been locked */
+	
+	/* Always embed enough struct pages for 64k of IO */
+	unsigned long	page_array[KIO_STATIC_PAGES];
+	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);
+
+/* fs/iobuf.c */
+
+void __init kiobuf_init(void);
+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, int bmap);
+
+#endif /* __LINUX_IOBUF_H */