path: root/drivers/scsi/device_handler/scsi_dh_alua.c

/*
 * Generic SCSI-3 ALUA SCSI Device Handler
 *
 * Copyright (C) 2007-2010 Hannes Reinecke, SUSE Linux Products GmbH.
 * All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 */
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <asm/unaligned.h>
#include <scsi/scsi.h>
#include <scsi/scsi_proto.h>
#include <scsi/scsi_dbg.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_dh.h>

#define ALUA_DH_NAME "alua"
#define ALUA_DH_VER "2.0"

#define TPGS_SUPPORT_NONE		0x00
#define TPGS_SUPPORT_OPTIMIZED		0x01
#define TPGS_SUPPORT_NONOPTIMIZED	0x02
#define TPGS_SUPPORT_STANDBY		0x04
#define TPGS_SUPPORT_UNAVAILABLE	0x08
#define TPGS_SUPPORT_LBA_DEPENDENT	0x10
#define TPGS_SUPPORT_OFFLINE		0x40
#define TPGS_SUPPORT_TRANSITION		0x80
#define TPGS_SUPPORT_ALL		0xdf

#define RTPG_FMT_MASK			0x70
#define RTPG_FMT_EXT_HDR		0x10

#define TPGS_MODE_UNINITIALIZED		 -1
#define TPGS_MODE_NONE			0x0
#define TPGS_MODE_IMPLICIT		0x1
#define TPGS_MODE_EXPLICIT		0x2

#define ALUA_RTPG_SIZE			128
#define ALUA_FAILOVER_TIMEOUT		60
#define ALUA_FAILOVER_RETRIES		5
#define ALUA_RTPG_DELAY_MSECS		5

/* device handler flags */
#define ALUA_OPTIMIZE_STPG		0x01
#define ALUA_RTPG_EXT_HDR_UNSUPP	0x02
/* State machine flags */
#define ALUA_PG_RUN_RTPG		0x10
#define ALUA_PG_RUN_STPG		0x20
#define ALUA_PG_RUNNING			0x40

static uint optimize_stpg;
module_param(optimize_stpg, uint, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(optimize_stpg, "Allow use of a non-optimized path, rather than sending a STPG, when implicit TPGS is supported (0=No,1=Yes). Default is 0.");

static LIST_HEAD(port_group_list);
static DEFINE_SPINLOCK(port_group_lock);
static struct workqueue_struct *kaluad_wq;

struct alua_port_group {
	struct kref		kref;
	struct rcu_head		rcu;
	struct list_head	node;
	struct list_head	dh_list;
	unsigned char		device_id_str[256];
	int			device_id_len;
	int			group_id;
	int			tpgs;
	int			state;
	int			pref;
	int			valid_states;
	unsigned		flags; /* used for optimizing STPG */
	unsigned char		transition_tmo;
	unsigned long		expiry;
	unsigned long		interval;
	struct delayed_work	rtpg_work;
	spinlock_t		lock;
	struct list_head	rtpg_list;
	struct scsi_device	*rtpg_sdev;
};

struct alua_dh_data {
	struct list_head	node;
	struct alua_port_group __rcu *pg;
	int			group_id;
	spinlock_t		pg_lock;
	struct scsi_device	*sdev;
	int			init_error;
	struct mutex		init_mutex;
};

struct alua_queue_data {
	struct list_head	entry;
	activate_complete	callback_fn;
	void			*callback_data;
};

#define ALUA_POLICY_SWITCH_CURRENT	0
#define ALUA_POLICY_SWITCH_ALL		1

static void alua_rtpg_work(struct work_struct *work);
static bool alua_rtpg_queue(struct alua_port_group *pg,
			    struct scsi_device *sdev,
			    struct alua_queue_data *qdata, bool force);
static void alua_check(struct scsi_device *sdev, bool force);

static void release_port_group(struct kref *kref)
{
	struct alua_port_group *pg;

	pg = container_of(kref, struct alua_port_group, kref);
	if (pg->rtpg_sdev)
		flush_delayed_work(&pg->rtpg_work);
	spin_lock(&port_group_lock);
	list_del(&pg->node);
	spin_unlock(&port_group_lock);
	kfree_rcu(pg, rcu);
}

/*
 * submit_rtpg - Issue a REPORT TARGET GROUP STATES command
 * @sdev: sdev the command should be sent to
 */
static int submit_rtpg(struct scsi_device *sdev, unsigned char *buff,
		       int bufflen, struct scsi_sense_hdr *sshdr, int flags)
{
	u8 cdb[MAX_COMMAND_SIZE];
	int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
		REQ_FAILFAST_DRIVER;

	/* Prepare the command. */
	memset(cdb, 0x0, MAX_COMMAND_SIZE);
	cdb[0] = MAINTENANCE_IN;
	if (!(flags & ALUA_RTPG_EXT_HDR_UNSUPP))
		cdb[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT;
	else
		cdb[1] = MI_REPORT_TARGET_PGS;
	put_unaligned_be32(bufflen, &cdb[6]);

	return scsi_execute(