#sccs	"@(#)uts/kern/sys:iobuf.h	1.1"

/*	Convergent Technologies - System V - May 1983	*/

#ifndef iobuf_h
#define iobuf_h

#include <sys/param.h>
#include <sys/buf.h>

/*
 * Each block device has a iobuf, which contains private state stuff
 * and 2 list heads: the b_forw/b_back list, which is doubly linked
 * and has all the buffers currently associated with that major
 * device; and the d_actf/d_actl list, which is private to the
 * device but in fact is always used for the head and tail
 * of the I/O queue for the device.
 * Various routines in bio.c look at b_forw/b_back
 * (notice they are the same as in the buf structure)
 * but the rest is private to each device driver.
 */
struct iobuf
{
	int	b_flags;		/* see buf.h */
	struct	buf *b_forw;		/* first buffer for this dev */
	struct	buf *b_back;		/* last buffer for this dev */
	struct	buf *b_actf;		/* head of I/O queue */
	struct 	buf *b_actl;		/* tail of I/O queue */
	dev_t	b_dev;			/* major+minor device name */
	char	b_active;		/* busy flag */
	char	b_errcnt;		/* error count (for recovery) */
	int	io_nreg;		/* number of regs to log on errors */
	physadr	io_addr;		/* csr address */
	time_t	io_start;
	int	io_s1;			/* space for drivers to leave things */
	int	io_s2;			/* space for drivers to leave things */
};

#define tabinit(dv,stat)	{0,0,0,0,0,makedev(dv,0),0,0,0,0,0,stat,0,0}
#define NDEVREG	(sizeof(struct device)/sizeof(int))

#define	B_ONCE	01	/* flag for once only driver operations */
#define	B_TAPE	02	/* this is a magtape (no bdwrite) */
#define	B_TIME	04	/* for timeout use */

/*
 * IO statistics are kept for each physical unit of each
 * block device (within the driver). Primary purpose is
 * to establish a guesstimate of error rates during
 * error logging.
 */

struct iostat {
	long	io_ops;		/* number of read/writes */
	long	io_misc;	/* number of "other" operations */
	ushort io_unlog;	/* number of unlogged errors */
};

/*
 * structure for system accounting
 */
struct iotime {
	struct iostat ios;
	long	io_bcnt;	/* total blocks transferred */
	time_t	io_act;		/* total controller active time */
	time_t	io_resp;	/* total block response time */
};
#define	io_cnt	ios.io_ops

#endif