gnbd_kern.h

openGFS , a kind of file system.

/*
 *
 *    Copyright 1999 Regents of the University of Minnesota
 *    Portions Copyright 1999-2001 Sistina Software, Inc.
 *    Portions Copyright 2001 The OpenGFS Project
 *
 *    This is free software released under the GNU General Public License.
 *    There is no warranty for this software.  See the file COPYING for
 *    details.
 *
 *    See the file AUTHORS for a list of contributors.
 *
 */
#ifndef _GNBD_GNBD_KERN_H
#define _GNBD_GNBD_KERN_H

struct request_queue;

/*
 * The piece of the pending message queue that is used to match received
 * replies with the request that generated them.
 */
typedef struct sdQ {
	theader_t hdr;		/* we this for any possible resends */
	struct request *req;	/* request this cam from */
	struct sdQ *next;
} transferQ_t;

/*
 * This structure defines the, umm, shape of this device.  We'll have one
 * of these for each device that can exist.
 *
 * ok, here I'll try to describe the possible states that each device in
 * the gnbd can be in.
 * OPEN or CLOSED 
 *    Open is usage != 0, otherwise Closed.
 * PENDING or CLEAR
 *    If Rhead == NULL then Clear, otherwise Pending.
 * CONNECTED or DISCONNECTED
 *    Connected if the socket is connected. Otherwise disconnected.
 *    Also, in the disconnected state, the transiod thread should be
 *    distroyed. That way it can be recreated on connect again.
 *    If recvd_run is false, this is Disconnected.
 * 
 * If ISgnbdDisConnected, all new reads and writes will immeaditily
 * block. (unless opened nonblocking then returns EAGAIN). This stops the
 * generation of new io requests. Since when that thread is dead, we cannot
 * process IO. And we'd flood the request queues if we didn't block things
 * off at the read&write commands. Hence the wait queue, gassed.
 */
#define ISgnbdOpened(x)		((x)->usage != 0)
#define ISgnbdConnected(x)	((x)->recvd_run != 0)
#define ISgnbdDisConnected(x)	(!ISgnbdConnected(x))
#define ISgnbdPending(x)	((x)->Rhead != NULL)
typedef struct gnbd_s {
	u64 size;
	int usage;

	int readonly:1;
	int recvd_run:1;
	int good_connect:1;

	u32 servip;
	u16 servport;

	wait_queue_head_t gassed;
	struct socket *sock;
	struct semaphore sender;
	struct semaphore tiodmux;
	struct semaphore tqmux;
	transferQ_t *Rhead;
} gnbd_t;

extern int gnbd_major;

extern void my_end_request(struct request *req);
extern void gnbd_request(struct request_queue *q);
extern int trans_start_up(gnbd_t * tio);
extern void trans_shutdown(gnbd_t * tio, int complete);
extern void cmd_RW(gnbd_t * tio, struct request *req, u32 len, u64 offset);

#endif /* _GNBD_GNBD_KERN_H */