path: root/drivers/s390/block/dasd_alias.c

/*
 * PAV alias management for the DASD ECKD discipline
 *
 * Copyright IBM Corporation, 2007
 * Author(s): Stefan Weinhuber <wein@de.ibm.com>
 */

#define KMSG_COMPONENT "dasd-eckd"

#include <linux/list.h>
#include <linux/slab.h>
#include <asm/ebcdic.h>
#include "dasd_int.h"
#include "dasd_eckd.h"

#ifdef PRINTK_HEADER
#undef PRINTK_HEADER
#endif				/* PRINTK_HEADER */
#define PRINTK_HEADER "dasd(eckd):"


/*
 * General concept of alias management:
 * - PAV and DASD alias management is specific to the eckd discipline.
 * - A device is connected to an lcu as long as the device exists.
 *   dasd_alias_make_device_known_to_lcu will be called wenn the
 *   device is checked by the eckd discipline and
 *   dasd_alias_disconnect_device_from_lcu will be called
 *   before the device is deleted.
 * - The dasd_alias_add_device / dasd_alias_remove_device
 *   functions mark the point when a device is 'ready for service'.
 * - A summary unit check is a rare occasion, but it is mandatory to
 *   support it. It requires some complex recovery actions before the
 *   devices can be used again (see dasd_alias_handle_summary_unit_check).
 * - dasd_alias_get_start_dev will find an alias device that can be used
 *   instead of the base device and does some (very simple) load balancing.
 *   This is the function that gets called for each I/O, so when improving
 *   something, this function should get faster or better, the rest has just
 *   to be correct.
 */


static void summary_unit_check_handling_work(struct work_struct *);
static void lcu_update_work(struct work_struct *);
static int _schedule_lcu_update(struct alias_lcu *, struct dasd_device *);

static struct alias_root aliastree = {
	.serverlist = LIST_HEAD_INIT(aliastree.serverlist),
	.lock = __SPIN_LOCK_UNLOCKED(aliastree.lock),
};

static struct alias_server *_find_server(struct dasd_uid *uid)
{
	struct alias_server *pos;
	list_for_each_entry(pos, &aliastree.serverlist, server) {
		if (!strncmp(pos->uid.vendor, uid->vendor,
			     sizeof(uid->vendor))
		    && !strncmp(pos->uid.serial, uid->serial,
				sizeof(uid->serial)))
			return pos;
	};
	return NULL;
}

static struct alias_lcu *_find_lcu(struct alias_server *server,
				   struct dasd_uid *uid)
{
	struct alias_lcu *pos;
	list_for_each_entry(pos, &server->lculist, lcu) {
		if (pos->uid.ssid == uid->ssid)
			return pos;
	};
	return NULL;
}

static struct alias_pav_group *_find_group(struct alias_lcu *lcu,
					   struct dasd_uid *uid)
{
	struct alias_pav_group *pos;
	__u8 search_unit_addr;

	/* for hyper pav there is only one group */
	if (lcu->pav == HYPER_PAV) {
		if (list_empty(&lcu->grouplist))
			return NULL;
		else
			return list_first_entry(&lcu->grouplist,
						struct alias_pav_group, group);
	}

	/* for base pav we have to find the group that matches the base */
	if (uid->type == UA_BASE_DEVICE)
		search_unit_addr = uid->real_unit_addr;
	else
		search_unit_addr = uid->base_unit_addr;
	list_for_each_entry(pos, &lcu->grouplist, group) {
		if (pos->uid.base_unit_addr == search_unit_addr &&
		    !strncmp(pos->uid.vduit, uid->vduit, sizeof(uid->vduit)))
			return pos;
	};
	return NULL;
}

static struct alias_server *_allocate_server(struct dasd_uid *uid)
{
	struct alias_server *server;

	server = kzalloc(sizeof(*server), GFP_KERNEL);
	if (!server)
		return ERR_PTR(-ENOMEM);
	memcpy(server->uid.vendor, uid->vendor, sizeof(uid->vendor));
	memcpy(server->uid.serial, uid->serial, sizeof(uid->serial));
	INIT_LIST_HEAD(&server->server);
	INIT_LIST_HEAD(&server->lculist);
	return server;
}

static void _free_server(struct alias_server *server)
{
	kfree(server);
}

static struct alias_lcu *_allocate_lcu(struct dasd_uid *uid)
{
	struct alias_lcu *lcu;

	lcu = kzalloc(sizeof(*lcu), GFP_KERNEL);
	if (!lcu)
		return ERR_PTR(-ENOMEM);
	lcu->uac = kzalloc(sizeof(*(lcu->uac)), GFP_KERNEL | GFP_DMA);
	if (!lcu->uac)
		goto out_err1;
	lcu->rsu_cqr = kzalloc(sizeof(*lcu->rsu_cqr), GFP_KERNEL | GFP_DMA);
	if (!lcu->rsu_cqr)
		goto out_err2;
	lcu->rsu_cqr