/* * Manager for various I/O types. * (C) 2004 - 2005 FUJITA Tomonori <tomof@acm.org> * This code is licenced under the GPL. */#include "iscsi.h"#include "iotype.h"#include "iscsi_dbg.h"static LIST_HEAD(iotypes);static rwlock_t iotypes_lock = RW_LOCK_UNLOCKED;static struct iotype *find_iotype(const char *name){	struct iotype *iot = NULL;	list_for_each_entry(iot, &iotypes, iot_list) {		if (strcmp(iot->name, name) == 0)			return iot;	}	return NULL;}struct iotype *get_iotype(const char *name){	struct iotype *iot;	read_lock(&iotypes_lock);	iot = find_iotype(name);	read_unlock(&iotypes_lock);	return iot;}void put_iotype(struct iotype *iot){	if (!iot)		return;	return;}static int register_iotype(struct iotype *iot){	int err = 0;	struct iotype *p;	write_lock(&iotypes_lock);	p = find_iotype(iot->name);	if (p)		err = -EBUSY;	else		list_add_tail(&iot->iot_list, &iotypes);	write_unlock(&iotypes_lock);	return err;}static int unregister_iotype(struct iotype *iot){	int err = 0;	struct iotype *p;	write_lock(&iotypes_lock);	p = find_iotype(iot->name);	if (p && p == iot)		list_del_init(&iot->iot_list);	else		err = -EINVAL;	write_unlock(&iotypes_lock);	return err;}struct iotype *iotype_array[] = {	&fileio,	&blockio,	&nullio,};int iotype_init(void){	int i, err;	for (i = 0; i < ARRAY_SIZE(iotype_array); i++) {		if (!(err = register_iotype(iotype_array[i])))			iprintk("Registered io type %s\n",						iotype_array[i]->name);		else {			eprintk("Failed to register io type %s\n",						iotype_array[i]->name);			break;		}	}	return err;}void iotype_exit(void){	int i;	for (i = 0; i < ARRAY_SIZE(iotype_array); i++)		unregister_iotype(iotype_array[i]);}