/*
* 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 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
#define ALUA_SYNC_STPG 0x04
/* 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;
static struct workqueue_struct *kaluad_sync_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;
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 *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 void 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