Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

6 files changed, 2977 insertions, 0 deletions

diff --git a/drivers/scsi/device_handler/Kconfig b/drivers/scsi/device_handler/Kconfig
new file mode 100644
index 000000000..368eb94c2
--- /dev/null
+++ b/drivers/scsi/device_handler/Kconfig
@@ -0,0 +1,41 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# SCSI Device Handler configuration
+#
+
+menuconfig SCSI_DH
+	bool "SCSI Device Handlers"
+	depends on SCSI
+	default n
+	help
+	  SCSI Device Handlers provide device specific support for
+	  devices utilized in multipath configurations. Say Y here to
+	  select support for specific hardware.
+
+config SCSI_DH_RDAC
+	tristate "LSI RDAC Device Handler"
+	depends on SCSI_DH && SCSI
+	help
+	If you have a LSI RDAC select y. Otherwise, say N.
+
+config SCSI_DH_HP_SW
+	tristate "HP/COMPAQ MSA Device Handler"
+	depends on SCSI_DH && SCSI
+	help
+	If you have a HP/COMPAQ MSA device that requires START_STOP to
+	be sent to start it and cannot upgrade the firmware then select y.
+	Otherwise, say N.
+
+config SCSI_DH_EMC
+	tristate "EMC CLARiiON Device Handler"
+	depends on SCSI_DH && SCSI
+	help
+	If you have a EMC CLARiiON select y. Otherwise, say N.
+
+config SCSI_DH_ALUA
+	tristate "SPC-3 ALUA Device Handler"
+	depends on SCSI_DH && SCSI
+	help
+	  SCSI Device handler for generic SPC-3 Asymmetric Logical Unit
+	  Access (ALUA).
+
diff --git a/drivers/scsi/device_handler/Makefile b/drivers/scsi/device_handler/Makefile
new file mode 100644
index 000000000..0a603aefd
--- /dev/null
+++ b/drivers/scsi/device_handler/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# SCSI Device Handler
+#
+obj-$(CONFIG_SCSI_DH_RDAC)	+= scsi_dh_rdac.o
+obj-$(CONFIG_SCSI_DH_HP_SW)	+= scsi_dh_hp_sw.o
+obj-$(CONFIG_SCSI_DH_EMC)	+= scsi_dh_emc.o
+obj-$(CONFIG_SCSI_DH_ALUA)	+= scsi_dh_alua.o
diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
new file mode 100644
index 000000000..0781f991e
--- /dev/null
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -0,0 +1,1287 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Generic SCSI-3 ALUA SCSI Device Handler
+ *
+ * Copyright (C) 2007-2010 Hannes Reinecke, SUSE Linux Products GmbH.
+ * All rights reserved.
+ */
+#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
+#define ALUA_RTPG_RETRY_DELAY		2
+
+/* 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;
+	bool			disabled;
+};
+
+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];
+	blk_opf_t 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(sdev, cdb, DMA_FROM_DEVICE, buff, bufflen, NULL,
+			sshdr, ALUA_FAILOVER_TIMEOUT * HZ,
+			ALUA_FAILOVER_RETRIES, req_flags, 0, NULL);
+}
+
+/*
+ * submit_stpg - Issue a SET TARGET PORT GROUP command
+ *
+ * Currently we're only setting the current target port group state
+ * to 'active/optimized' and let the array firmware figure out
+ * the states of the remaining groups.
+ */
+static int submit_stpg(struct scsi_device *sdev, int group_id,
+		       struct scsi_sense_hdr *sshdr)
+{
+	u8 cdb[MAX_COMMAND_SIZE];
+	unsigned char stpg_data[8];
+	int stpg_len = 8;
+	blk_opf_t req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
+		REQ_FAILFAST_DRIVER;
+
+	/* Prepare the data buffer */
+	memset(stpg_data, 0, stpg_len);
+	stpg_data[4] = SCSI_ACCESS_STATE_OPTIMAL;
+	put_unaligned_be16(group_id, &stpg_data[6]);
+
+	/* Prepare the command. */
+	memset(cdb, 0x0, MAX_COMMAND_SIZE);
+	cdb[0] = MAINTENANCE_OUT;
+	cdb[1] = MO_SET_TARGET_PGS;
+	put_unaligned_be32(stpg_len, &cdb[6]);
+
+	return scsi_execute(sdev, cdb, DMA_TO_DEVICE, stpg_data, stpg_len, NULL,
+			sshdr, ALUA_FAILOVER_TIMEOUT * HZ,
+			ALUA_FAILOVER_RETRIES, req_flags, 0, NULL);
+}
+
+static struct alua_port_group *alua_find_get_pg(char *id_str, size_t id_size,
+						int group_id)
+{
+	struct alua_port_group *pg;
+
+	if (!id_str || !id_size || !strlen(id_str))
+		return NULL;
+
+	list_for_each_entry(pg, &port_group_list, node) {
+		if (pg->group_id != group_id)
+			continue;
+		if (!pg->device_id_len || pg->device_id_len != id_size)
+			continue;
+		if (strncmp(pg->device_id_str, id_str, id_size))
+			continue;
+		if (!kref_get_unless_zero(&pg->kref))
+			continue;
+		return pg;
+	}
+
+	return NULL;
+}
+
+/*
+ * alua_alloc_pg - Allocate a new port_group structure
+ * @sdev: scsi device
+ * @group_id: port group id
+ * @tpgs: target port group settings
+ *
+ * Allocate a new port_group structure for a given
+ * device.
+ */
+static struct alua_port_group *alua_alloc_pg(struct scsi_device *sdev,
+					     int group_id, int tpgs)
+{
+	struct alua_port_group *pg, *tmp_pg;
+
+	pg = kzalloc(sizeof(struct alua_port_group), GFP_KERNEL);
+	if (!pg)
+		return ERR_PTR(-ENOMEM);
+
+	pg->device_id_len = scsi_vpd_lun_id(sdev, pg->device_id_str,
+					    sizeof(pg->device_id_str));
+	if (pg->device_id_len <= 0) {
+		/*
+		 * TPGS supported but no device identification found.
+		 * Generate private device identification.
+		 */
+		sdev_printk(KERN_INFO, sdev,
+			    "%s: No device descriptors found\n",
+			    ALUA_DH_NAME);
+		pg->device_id_str[0] = '\0';
+		pg->device_id_len = 0;
+	}
+	pg->group_id = group_id;
+	pg->tpgs = tpgs;
+	pg->state = SCSI_ACCESS_STATE_OPTIMAL;
+	pg->valid_states = TPGS_SUPPORT_ALL;
+	if (optimize_stpg)
+		pg->flags |= ALUA_OPTIMIZE_STPG;
+	kref_init(&pg->kref);
+	INIT_DELAYED_WORK(&pg->rtpg_work, alua_rtpg_work);
+	INIT_LIST_HEAD(&pg->rtpg_list);
+	INIT_LIST_HEAD(&pg->node);
+	INIT_LIST_HEAD(&pg->dh_list);
+	spin_lock_init(&pg->lock);
+
+	spin_lock(&port_group_lock);
+	tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len,
+				  group_id);
+	if (tmp_pg) {
+		spin_unlock(&port_group_lock);
+		kfree(pg);
+		return tmp_pg;
+	}
+
+	list_add(&pg->node, &port_group_list);
+	spin_unlock(&port_group_lock);
+
+	return pg;
+}
+
+/*
+ * alua_check_tpgs - Evaluate TPGS setting
+ * @sdev: device to be checked
+ *
+ * Examine the TPGS setting of the sdev to find out if ALUA
+ * is supported.
+ */
+static int alua_check_tpgs(struct scsi_device *sdev)
+{
+	int tpgs = TPGS_MODE_NONE;
+
+	/*
+	 * ALUA support for non-disk devices is fraught with
+	 * difficulties, so disable it for now.
+	 */
+	if (sdev->type != TYPE_DISK) {
+		sdev_printk(KERN_INFO, sdev,
+			    "%s: disable for non-disk devices\n",
+			    ALUA_DH_NAME);
+		return tpgs;
+	}
+
+	tpgs = scsi_device_tpgs(sdev);
+	switch (tpgs) {
+	case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT:
+		sdev_printk(KERN_INFO, sdev,
+			    "%s: supports implicit and explicit TPGS\n",
+			    ALUA_DH_NAME);
+		break;
+	case TPGS_MODE_EXPLICIT:
+		sdev_printk(KERN_INFO, sdev, "%s: supports explicit TPGS\n",
+			    ALUA_DH_NAME);
+		break;
+	case TPGS_MODE_IMPLICIT:
+		sdev_printk(KERN_INFO, sdev, "%s: supports implicit TPGS\n",
+			    ALUA_DH_NAME);
+		break;
+	case TPGS_MODE_NONE:
+		sdev_printk(KERN_INFO, sdev, "%s: not supported\n",
+			    ALUA_DH_NAME);
+		break;
+	default:
+		sdev_printk(KERN_INFO, sdev,
+			    "%s: unsupported TPGS setting %d\n",
+			    ALUA_DH_NAME, tpgs);
+		tpgs = TPGS_MODE_NONE;
+		break;
+	}
+
+	return tpgs;
+}
+
+/*
+ * alua_check_vpd - Evaluate INQUIRY vpd page 0x83
+ * @sdev: device to be checked
+ *
+ * Extract the relative target port and the target port group
+ * descriptor from the list of identificators.
+ */
+static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h,
+			  int tpgs)
+{
+	int rel_port = -1, group_id;
+	struct alua_port_group *pg, *old_pg = NULL;
+	bool pg_updated = false;
+	unsigned long flags;
+
+	group_id = scsi_vpd_tpg_id(sdev, &rel_port);
+	if (group_id < 0) {
+		/*
+		 * Internal error; TPGS supported but required
+		 * VPD identification descriptors not present.
+		 * Disable ALUA support
+		 */
+		sdev_printk(KERN_INFO, sdev,
+			    "%s: No target port descriptors found\n",
+			    ALUA_DH_NAME);
+		return SCSI_DH_DEV_UNSUPP;
+	}
+
+	pg = alua_alloc_pg(sdev, group_id, tpgs);
+	if (IS_ERR(pg)) {
+		if (PTR_ERR(pg) == -ENOMEM)
+			return SCSI_DH_NOMEM;
+		return SCSI_DH_DEV_UNSUPP;
+	}
+	if (pg->device_id_len)
+		sdev_printk(KERN_INFO, sdev,
+			    "%s: device %s port group %x rel port %x\n",
+			    ALUA_DH_NAME, pg->device_id_str,
+			    group_id, rel_port);
+	else
+		sdev_printk(KERN_INFO, sdev,
+			    "%s: port group %x rel port %x\n",
+			    ALUA_DH_NAME, group_id, rel_port);
+
+	/* Check for existing port group references */
+	spin_lock(&h->pg_lock);
+	old_pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock));
+	if (old_pg != pg) {
+		/* port group has changed. Update to new port group */
+		if (h->pg) {
+			spin_lock_irqsave(&old_pg->lock, flags);
+			list_del_rcu(&h->node);
+			spin_unlock_irqrestore(&old_pg->lock, flags);
+		}
+		rcu_assign_pointer(h->pg, pg);
+		pg_updated = true;
+	}
+
+	spin_lock_irqsave(&pg->lock, flags);
+	if (pg_updated)
+		list_add_rcu(&h->node, &pg->dh_list);
+	spin_unlock_irqrestore(&pg->lock, flags);
+
+	alua_rtpg_queue(rcu_dereference_protected(h->pg,
+						  lockdep_is_held(&h->pg_lock)),
+			sdev, NULL, true);
+	spin_unlock(&h->pg_lock);
+
+	if (old_pg)
+		kref_put(&old_pg->kref, release_port_group);
+
+	return SCSI_DH_OK;
+}
+
+static char print_alua_state(unsigned char state)
+{
+	switch (state) {
+	case SCSI_ACCESS_STATE_OPTIMAL:
+		return 'A';
+	case SCSI_ACCESS_STATE_ACTIVE:
+		return 'N';
+	case SCSI_ACCESS_STATE_STANDBY:
+		return 'S';
+	case SCSI_ACCESS_STATE_UNAVAILABLE:
+		return 'U';
+	case SCSI_ACCESS_STATE_LBA:
+		return 'L';
+	case SCSI_ACCESS_STATE_OFFLINE:
+		return 'O';
+	case SCSI_ACCESS_STATE_TRANSITIONING:
+		return 'T';
+	default:
+		return 'X';
+	}
+}
+
+static enum scsi_disposition alua_check_sense(struct scsi_device *sdev,
+					      struct scsi_sense_hdr *sense_hdr)
+{
+	struct alua_dh_data *h = sdev->handler_data;
+	struct alua_port_group *pg;
+
+	switch (sense_hdr->sense_key) {
+	case NOT_READY:
+		if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) {
+			/*
+			 * LUN Not Accessible - ALUA state transition
+			 */
+			rcu_read_lock();
+			pg = rcu_dereference(h->pg);
+			if (pg)
+				pg->state = SCSI_ACCESS_STATE_TRANSITIONING;
+			rcu_read_unlock();
+			alua_check(sdev, false);
+			return NEEDS_RETRY;
+		}
+		break;
+	case UNIT_ATTENTION:
+		if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00) {
+			/*
+			 * Power On, Reset, or Bus Device Reset.
+			 * Might have obscured a state transition,
+			 * so schedule a recheck.
+			 */
+			alua_check(sdev, true);
+			return ADD_TO_MLQUEUE;
+		}
+		if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x04)
+			/*
+			 * Device internal reset
+			 */
+			return ADD_TO_MLQUEUE;
+		if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x01)
+			/*
+			 * Mode Parameters Changed
+			 */
+			return ADD_TO_MLQUEUE;
+		if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06) {
+			/*
+			 * ALUA state changed
+			 */
+			alua_check(sdev, true);
+			return ADD_TO_MLQUEUE;
+		}
+		if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07) {
+			/*
+			 * Implicit ALUA state transition failed
+			 */
+			alua_check(sdev, true);
+			return ADD_TO_MLQUEUE;
+		}
+		if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x03)
+			/*
+			 * Inquiry data has changed
+			 */
+			return ADD_TO_MLQUEUE;
+		if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x0e)
+			/*
+			 * REPORTED_LUNS_DATA_HAS_CHANGED is reported
+			 * when switching controllers on targets like
+			 * Intel Multi-Flex. We can just retry.
+			 */
+			return ADD_TO_MLQUEUE;
+		break;
+	}
+
+	return SCSI_RETURN_NOT_HANDLED;
+}
+
+/*
+ * alua_tur - Send a TEST UNIT READY
+ * @sdev: device to which the TEST UNIT READY command should be send
+ *
+ * Send a TEST UNIT READY to @sdev to figure out the device state
+ * Returns SCSI_DH_RETRY if the sense code is NOT READY/ALUA TRANSITIONING,
+ * SCSI_DH_OK if no error occurred, and SCSI_DH_IO otherwise.
+ */
+static int alua_tur(struct scsi_device *sdev)
+{
+	struct scsi_sense_hdr sense_hdr;
+	int retval;
+
+	retval = scsi_test_unit_ready(sdev, ALUA_FAILOVER_TIMEOUT * HZ,
+				      ALUA_FAILOVER_RETRIES, &sense_hdr);
+	if (sense_hdr.sense_key == NOT_READY &&
+	    sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a)
+		return SCSI_DH_RETRY;
+	else if (retval)
+		return SCSI_DH_IO;
+	else
+		return SCSI_DH_OK;
+}
+
+/*
+ * alua_rtpg - Evaluate REPORT TARGET GROUP STATES
+ * @sdev: the device to be evaluated.
+ *
+ * Evaluate the Target Port Group State.
+ * Returns SCSI_DH_DEV_OFFLINED if the path is
+ * found to be unusable.
+ */
+static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
+{
+	struct scsi_sense_hdr sense_hdr;
+	struct alua_port_group *tmp_pg;
+	int len, k, off, bufflen = ALUA_RTPG_SIZE;
+	int group_id_old, state_old, pref_old, valid_states_old;
+	unsigned char *desc, *buff;
+	unsigned err;
+	int retval;
+	unsigned int tpg_desc_tbl_off;
+	unsigned char orig_transition_tmo;
+	unsigned long flags;
+	bool transitioning_sense = false;
+
+	group_id_old = pg->group_id;
+	state_old = pg->state;
+	pref_old = pg->pref;
+	valid_states_old = pg->valid_states;
+
+	if (!pg->expiry) {
+		unsigned long transition_tmo = ALUA_FAILOVER_TIMEOUT * HZ;
+
+		if (pg->transition_tmo)
+			transition_tmo = pg->transition_tmo * HZ;
+
+		pg->expiry = round_jiffies_up(jiffies + transition_tmo);
+	}
+
+	buff = kzalloc(bufflen, GFP_KERNEL);
+	if (!buff)
+		return SCSI_DH_DEV_TEMP_BUSY;
+
+ retry:
+	err = 0;
+	retval = submit_rtpg(sdev, buff, bufflen, &sense_hdr, pg->flags);
+
+	if (retval) {
+		/*
+		 * Some (broken) implementations have a habit of returning
+		 * an error during things like firmware update etc.
+		 * But if the target only supports active/optimized there's
+		 * not much we can do; it's not that we can switch paths
+		 * or anything.
+		 * So ignore any errors to avoid spurious failures during
+		 * path failover.
+		 */
+		if ((pg->valid_states & ~TPGS_SUPPORT_OPTIMIZED) == 0) {
+			sdev_printk(KERN_INFO, sdev,
+				    "%s: ignoring rtpg result %d\n",
+				    ALUA_DH_NAME, retval);
+			kfree(buff);
+			return SCSI_DH_OK;
+		}
+		if (retval < 0 || !scsi_sense_valid(&sense_hdr)) {
+			sdev_printk(KERN_INFO, sdev,
+				    "%s: rtpg failed, result %d\n",
+				    ALUA_DH_NAME, retval);
+			kfree(buff);
+			if (retval < 0)
+				return SCSI_DH_DEV_TEMP_BUSY;
+			if (host_byte(retval) == DID_NO_CONNECT)
+				return SCSI_DH_RES_TEMP_UNAVAIL;
+			return SCSI_DH_IO;
+		}
+
+		/*
+		 * submit_rtpg() has failed on existing arrays
+		 * when requesting extended header info, and
+		 * the array doesn't support extended headers,
+		 * even though it shouldn't according to T10.
+		 * The retry without rtpg_ext_hdr_req set
+		 * handles this.
+		 * Note:  some arrays return a sense key of ILLEGAL_REQUEST
+		 * with ASC 00h if they don't support the extended header.
+		 */
+		if (!(pg->flags & ALUA_RTPG_EXT_HDR_UNSUPP) &&
+		    sense_hdr.sense_key == ILLEGAL_REQUEST) {
+			pg->flags |= ALUA_RTPG_EXT_HDR_UNSUPP;
+			goto retry;
+		}
+		/*
+		 * If the array returns with 'ALUA state transition'
+		 * sense code here it cannot return RTPG data during
+		 * transition. So set the state to 'transitioning' directly.
+		 */
+		if (sense_hdr.sense_key == NOT_READY &&
+		    sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) {
+			transitioning_sense = true;
+			goto skip_rtpg;
+		}
+		/*
+		 * Retry on any other UNIT ATTENTION occurred.
+		 */
+		if (sense_hdr.sense_key == UNIT_ATTENTION)
+			err = SCSI_DH_RETRY;
+		if (err == SCSI_DH_RETRY &&
+		    pg->expiry != 0 && time_before(jiffies, pg->expiry)) {
+			sdev_printk(KERN_ERR, sdev, "%s: rtpg retry\n",
+				    ALUA_DH_NAME);
+			scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
+			kfree(buff);
+			return err;
+		}
+		sdev_printk(KERN_ERR, sdev, "%s: rtpg failed\n",
+			    ALUA_DH_NAME);
+		scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
+		kfree(buff);
+		pg->expiry = 0;
+		return SCSI_DH_IO;
+	}
+
+	len = get_unaligned_be32(&buff[0]) + 4;
+
+	if (len > bufflen) {
+		/* Resubmit with the correct length */
+		kfree(buff);
+		bufflen = len;
+		buff = kmalloc(bufflen, GFP_KERNEL);
+		if (!buff) {
+			sdev_printk(KERN_WARNING, sdev,
+				    "%s: kmalloc buffer failed\n",__func__);
+			/* Temporary failure, bypass */
+			pg->expiry = 0;
+			return SCSI_DH_DEV_TEMP_BUSY;
+		}
+		goto retry;
+	}
+
+	orig_transition_tmo = pg->transition_tmo;
+	if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR && buff[5] != 0)
+		pg->transition_tmo = buff[5];
+	else
+		pg->transition_tmo = ALUA_FAILOVER_TIMEOUT;
+
+	if (orig_transition_tmo != pg->transition_tmo) {
+		sdev_printk(KERN_INFO, sdev,
+			    "%s: transition timeout set to %d seconds\n",
+			    ALUA_DH_NAME, pg->transition_tmo);
+		pg->expiry = jiffies + pg->transition_tmo * HZ;
+	}
+
+	if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR)
+		tpg_desc_tbl_off = 8;
+	else
+		tpg_desc_tbl_off = 4;
+
+	for (k = tpg_desc_tbl_off, desc = buff + tpg_desc_tbl_off;
+	     k < len;
+	     k += off, desc += off) {
+		u16 group_id = get_unaligned_be16(&desc[2]);
+
+		spin_lock_irqsave(&port_group_lock, flags);
+		tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len,
+					  group_id);
+		spin_unlock_irqrestore(&port_group_lock, flags);
+		if (tmp_pg) {
+			if (spin_trylock_irqsave(&tmp_pg->lock, flags)) {
+				if ((tmp_pg == pg) ||
+				    !(tmp_pg->flags & ALUA_PG_RUNNING)) {
+					struct alua_dh_data *h;
+
+					tmp_pg->state = desc[0] & 0x0f;
+					tmp_pg->pref = desc[0] >> 7;
+					rcu_read_lock();
+					list_for_each_entry_rcu(h,
+						&tmp_pg->dh_list, node) {
+						if (!h->sdev)
+							continue;
+						h->sdev->access_state = desc[0];
+					}
+					rcu_read_unlock();
+				}
+				if (tmp_pg == pg)
+					tmp_pg->valid_states = desc[1];
+				spin_unlock_irqrestore(&tmp_pg->lock, flags);
+			}
+			kref_put(&tmp_pg->kref, release_port_group);
+		}
+		off = 8 + (desc[7] * 4);
+	}
+
+ skip_rtpg:
+	spin_lock_irqsave(&pg->lock, flags);
+	if (transitioning_sense)
+		pg->state = SCSI_ACCESS_STATE_TRANSITIONING;
+
+	if (group_id_old != pg->group_id || state_old != pg->state ||
+		pref_old != pg->pref || valid_states_old != pg->valid_states)
+		sdev_printk(KERN_INFO, sdev,
+			"%s: port group %02x state %c %s supports %c%c%c%c%c%c%c\n",
+			ALUA_DH_NAME, pg->group_id, print_alua_state(pg->state),
+			pg->pref ? "preferred" : "non-preferred",
+			pg->valid_states&TPGS_SUPPORT_TRANSITION?'T':'t',
+			pg->valid_states&TPGS_SUPPORT_OFFLINE?'O':'o',
+			pg->valid_states&TPGS_SUPPORT_LBA_DEPENDENT?'L':'l',
+			pg->valid_states&TPGS_SUPPORT_UNAVAILABLE?'U':'u',
+			pg->valid_states&TPGS_SUPPORT_STANDBY?'S':'s',
+			pg->valid_states&TPGS_SUPPORT_NONOPTIMIZED?'N':'n',
+			pg->valid_states&TPGS_SUPPORT_OPTIMIZED?'A':'a');
+
+	switch (pg->state) {
+	case SCSI_ACCESS_STATE_TRANSITIONING:
+		if (time_before(jiffies, pg->expiry)) {
+			/* State transition, retry */
+			pg->interval = ALUA_RTPG_RETRY_DELAY;
+			err = SCSI_DH_RETRY;
+		} else {
+			struct alua_dh_data *h;
+
+			/* Transitioning time exceeded, set port to standby */
+			err = SCSI_DH_IO;
+			pg->state = SCSI_ACCESS_STATE_STANDBY;
+			pg->expiry = 0;
+			rcu_read_lock();
+			list_for_each_entry_rcu(h, &pg->dh_list, node) {
+				if (!h->sdev)
+					continue;
+				h->sdev->access_state =
+					(pg->state & SCSI_ACCESS_STATE_MASK);
+				if (pg->pref)
+					h->sdev->access_state |=
+						SCSI_ACCESS_STATE_PREFERRED;
+			}
+			rcu_read_unlock();
+		}
+		break;
+	case SCSI_ACCESS_STATE_OFFLINE:
+		/* Path unusable */
+		err = SCSI_DH_DEV_OFFLINED;
+		pg->expiry = 0;
+		break;
+	default:
+		/* Useable path if active */
+		err = SCSI_DH_OK;
+		pg->expiry = 0;
+		break;
+	}
+	spin_unlock_irqrestore(&pg->lock, flags);
+	kfree(buff);
+	return err;
+}
+
+/*
+ * alua_stpg - Issue a SET TARGET PORT GROUP command
+ *
+ * Issue a SET TARGET PORT GROUP command and evaluate the
+ * response. Returns SCSI_DH_RETRY per default to trigger
+ * a re-evaluation of the target group state or SCSI_DH_OK
+ * if no further action needs to be taken.
+ */
+static unsigned alua_stpg(struct scsi_device *sdev, struct alua_port_group *pg)
+{
+	int retval;
+	struct scsi_sense_hdr sense_hdr;
+
+	if (!(pg->tpgs & TPGS_MODE_EXPLICIT)) {
+		/* Only implicit ALUA supported, retry */
+		return SCSI_DH_RETRY;
+	}
+	switch (pg->state) {
+	case SCSI_ACCESS_STATE_OPTIMAL:
+		return SCSI_DH_OK;
+	case SCSI_ACCESS_STATE_ACTIVE:
+		if ((pg->flags & ALUA_OPTIMIZE_STPG) &&
+		    !pg->pref &&
+		    (pg->tpgs & TPGS_MODE_IMPLICIT))
+			return SCSI_DH_OK;
+		break;
+	case SCSI_ACCESS_STATE_STANDBY:
+	case SCSI_ACCESS_STATE_UNAVAILABLE:
+		break;
+	case SCSI_ACCESS_STATE_OFFLINE:
+		return SCSI_DH_IO;
+	case SCSI_ACCESS_STATE_TRANSITIONING:
+		break;
+	default:
+		sdev_printk(KERN_INFO, sdev,
+			    "%s: stpg failed, unhandled TPGS state %d",
+			    ALUA_DH_NAME, pg->state);
+		return SCSI_DH_NOSYS;
+	}
+	retval = submit_stpg(sdev, pg->group_id, &sense_hdr);
+
+	if (retval) {
+		if (retval < 0 || !scsi_sense_valid(&sense_hdr)) {
+			sdev_printk(KERN_INFO, sdev,
+				    "%s: stpg failed, result %d",
+				    ALUA_DH_NAME, retval);
+			if (retval < 0)
+				return SCSI_DH_DEV_TEMP_BUSY;
+		} else {
+			sdev_printk(KERN_INFO, sdev, "%s: stpg failed\n",
+				    ALUA_DH_NAME);
+			scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
+		}
+	}
+	/* Retry RTPG */
+	return SCSI_DH_RETRY;
+}
+
+static bool alua_rtpg_select_sdev(struct alua_port_group *pg)
+{
+	struct alua_dh_data *h;
+	struct scsi_device *sdev = NULL;
+
+	lockdep_assert_held(&pg->lock);
+	if (WARN_ON(!pg->rtpg_sdev))
+		return false;
+
+	/*
+	 * RCU protection isn't necessary for dh_list here
+	 * as we hold pg->lock, but for access to h->pg.
+	 */
+	rcu_read_lock();
+	list_for_each_entry_rcu(h, &pg->dh_list, node) {
+		if (!h->sdev)
+			continue;
+		if (h->sdev == pg->rtpg_sdev) {
+			h->disabled = true;
+			continue;
+		}
+		if (rcu_dereference(h->pg) == pg &&
+		    !h->disabled &&
+		    !scsi_device_get(h->sdev)) {
+			sdev = h->sdev;
+			break;
+		}
+	}
+	rcu_read_unlock();
+
+	if (!sdev) {
+		pr_warn("%s: no device found for rtpg\n",
+			(pg->device_id_len ?
+			 (char *)pg->device_id_str : "(nameless PG)"));
+		return false;
+	}
+
+	sdev_printk(KERN_INFO, sdev, "rtpg retry on different device\n");
+
+	scsi_device_put(pg->rtpg_sdev);
+	pg->rtpg_sdev = sdev;
+
+	return true;
+}
+
+static void alua_rtpg_work(struct work_struct *work)
+{
+	struct alua_port_group *pg =
+		container_of(work, struct alua_port_group, rtpg_work.work);
+	struct scsi_device *sdev;
+	LIST_HEAD(qdata_list);
+	int err = SCSI_DH_OK;
+	struct alua_queue_data *qdata, *tmp;
+	struct alua_dh_data *h;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pg->lock, flags);
+	sdev = pg->rtpg_sdev;
+	if (!sdev) {
+		WARN_ON(pg->flags & ALUA_PG_RUN_RTPG);
+		WARN_ON(pg->flags & ALUA_PG_RUN_STPG);
+		spin_unlock_irqrestore(&pg->lock, flags);
+		kref_put(&pg->kref, release_port_group);
+		return;
+	}
+	pg->flags |= ALUA_PG_RUNNING;
+	if (pg->flags & ALUA_PG_RUN_RTPG) {
+		int state = pg->state;
+
+		pg->flags &= ~ALUA_PG_RUN_RTPG;
+		spin_unlock_irqrestore(&pg->lock, flags);
+		if (state == SCSI_ACCESS_STATE_TRANSITIONING) {
+			if (alua_tur(sdev) == SCSI_DH_RETRY) {
+				spin_lock_irqsave(&pg->lock, flags);
+				pg->flags &= ~ALUA_PG_RUNNING;
+				pg->flags |= ALUA_PG_RUN_RTPG;
+				if (!pg->interval)
+					pg->interval = ALUA_RTPG_RETRY_DELAY;
+				spin_unlock_irqrestore(&pg->lock, flags);
+				queue_delayed_work(kaluad_wq, &pg->rtpg_work,
+						   pg->interval * HZ);
+				return;
+			}
+			/* Send RTPG on failure or if TUR indicates SUCCESS */
+		}
+		err = alua_rtpg(sdev, pg);
+		spin_lock_irqsave(&pg->lock, flags);
+
+		/* If RTPG failed on the current device, try using another */
+		if (err == SCSI_DH_RES_TEMP_UNAVAIL &&
+		    alua_rtpg_select_sdev(pg))
+			err = SCSI_DH_IMM_RETRY;
+
+		if (err == SCSI_DH_RETRY || err == SCSI_DH_IMM_RETRY ||
+		    pg->flags & ALUA_PG_RUN_RTPG) {
+			pg->flags &= ~ALUA_PG_RUNNING;
+			if (err == SCSI_DH_IMM_RETRY)
+				pg->interval = 0;
+			else if (!pg->interval && !(pg->flags & ALUA_PG_RUN_RTPG))
+				pg->interval = ALUA_RTPG_RETRY_DELAY;
+			pg->flags |= ALUA_PG_RUN_RTPG;
+			spin_unlock_irqrestore(&pg->lock, flags);
+			queue_delayed_work(kaluad_wq, &pg->rtpg_work,
+					   pg->interval * HZ);
+			return;
+		}
+		if (err != SCSI_DH_OK)
+			pg->flags &= ~ALUA_PG_RUN_STPG;
+	}
+	if (pg->flags & ALUA_PG_RUN_STPG) {
+		pg->flags &= ~ALUA_PG_RUN_STPG;
+		spin_unlock_irqrestore(&pg->lock, flags);
+		err = alua_stpg(sdev, pg);
+		spin_lock_irqsave(&pg->lock, flags);
+		if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) {
+			pg->flags |= ALUA_PG_RUN_RTPG;
+			pg->interval = 0;
+			pg->flags &= ~ALUA_PG_RUNNING;
+			spin_unlock_irqrestore(&pg->lock, flags);
+			queue_delayed_work(kaluad_wq, &pg->rtpg_work,
+					   pg->interval * HZ);
+			return;
+		}
+	}
+
+	list_splice_init(&pg->rtpg_list, &qdata_list);
+	/*
+	 * We went through an RTPG, for good or bad.
+	 * Re-enable all devices for the next attempt.
+	 */
+	list_for_each_entry(h, &pg->dh_list, node)
+		h->disabled = false;
+	pg->rtpg_sdev = NULL;
+	spin_unlock_irqrestore(&pg->lock, flags);
+
+	list_for_each_entry_safe(qdata, tmp, &qdata_list, entry) {
+		list_del(&qdata->entry);
+		if (qdata->callback_fn)
+			qdata->callback_fn(qdata->callback_data, err);
+		kfree(qdata);
+	}
+	spin_lock_irqsave(&pg->lock, flags);
+	pg->flags &= ~ALUA_PG_RUNNING;
+	spin_unlock_irqrestore(&pg->lock, flags);
+	scsi_device_put(sdev);
+	kref_put(&pg->kref, release_port_group);
+}
+
+/**
+ * alua_rtpg_queue() - cause RTPG to be submitted asynchronously
+ * @pg: ALUA port group associated with @sdev.
+ * @sdev: SCSI device for which to submit an RTPG.
+ * @qdata: Information about the callback to invoke after the RTPG.
+ * @force: Whether or not to submit an RTPG if a work item that will submit an
+ *         RTPG already has been scheduled.
+ *
+ * Returns true if and only if alua_rtpg_work() will be called asynchronously.
+ * That function is responsible for calling @qdata->fn().
+ */
+static bool alua_rtpg_queue(struct alua_port_group *pg,
+			    struct scsi_device *sdev,
+			    struct alua_queue_data *qdata, bool force)
+{
+	int start_queue = 0;
+	unsigned long flags;
+	if (WARN_ON_ONCE(!pg) || scsi_device_get(sdev))
+		return false;
+
+	spin_lock_irqsave(&pg->lock, flags);
+	if (qdata) {
+		list_add_tail(&qdata->entry, &pg->rtpg_list);
+		pg->flags |= ALUA_PG_RUN_STPG;
+		force = true;
+	}
+	if (pg->rtpg_sdev == NULL) {
+		pg->interval = 0;
+		pg->flags |= ALUA_PG_RUN_RTPG;
+		kref_get(&pg->kref);
+		pg->rtpg_sdev = sdev;
+		start_queue = 1;
+	} else if (!(pg->flags & ALUA_PG_RUN_RTPG) && force) {
+		pg->flags |= ALUA_PG_RUN_RTPG;
+		/* Do not queue if the worker is already running */
+		if (!(pg->flags & ALUA_PG_RUNNING)) {
+			kref_get(&pg->kref);
+			start_queue = 1;
+		}
+	}
+
+	spin_unlock_irqrestore(&pg->lock, flags);
+
+	if (start_queue) {
+		if (queue_delayed_work(kaluad_wq, &pg->rtpg_work,
+				msecs_to_jiffies(ALUA_RTPG_DELAY_MSECS)))
+			sdev = NULL;
+		else
+			kref_put(&pg->kref, release_port_group);
+	}
+	if (sdev)
+		scsi_device_put(sdev);
+
+	return true;
+}
+
+/*
+ * alua_initialize - Initialize ALUA state
+ * @sdev: the device to be initialized
+ *
+ * For the prep_fn to work correctly we have
+ * to initialize the ALUA state for the device.
+ */
+static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h)
+{
+	int err = SCSI_DH_DEV_UNSUPP, tpgs;
+
+	mutex_lock(&h->init_mutex);
+	h->disabled = false;
+	tpgs = alua_check_tpgs(sdev);
+	if (tpgs != TPGS_MODE_NONE)
+		err = alua_check_vpd(sdev, h, tpgs);
+	h->init_error = err;
+	mutex_unlock(&h->init_mutex);
+	return err;
+}
+/*
+ * alua_set_params - set/unset the optimize flag
+ * @sdev: device on the path to be activated
+ * params - parameters in the following format
+ *      "no_of_params\0param1\0param2\0param3\0...\0"
+ * For example, to set the flag pass the following parameters
+ * from multipath.conf
+ *     hardware_handler        "2 alua 1"
+ */
+static int alua_set_params(struct scsi_device *sdev, const char *params)
+{
+	struct alua_dh_data *h = sdev->handler_data;
+	struct alua_port_group *pg = NULL;
+	unsigned int optimize = 0, argc;
+	const char *p = params;
+	int result = SCSI_DH_OK;
+	unsigned long flags;
+
+	if ((sscanf(params, "%u", &argc) != 1) || (argc != 1))
+		return -EINVAL;
+
+	while (*p++)
+		;
+	if ((sscanf(p, "%u", &optimize) != 1) || (optimize > 1))
+		return -EINVAL;
+
+	rcu_read_lock();
+	pg = rcu_dereference(h->pg);
+	if (!pg) {
+		rcu_read_unlock();
+		return -ENXIO;
+	}
+	spin_lock_irqsave(&pg->lock, flags);
+	if (optimize)
+		pg->flags |= ALUA_OPTIMIZE_STPG;
+	else
+		pg->flags &= ~ALUA_OPTIMIZE_STPG;
+	spin_unlock_irqrestore(&pg->lock, flags);
+	rcu_read_unlock();
+
+	return result;
+}
+
+/*
+ * alua_activate - activate a path
+ * @sdev: device on the path to be activated
+ *
+ * We're currently switching the port group to be activated only and
+ * let the array figure out the rest.
+ * There may be other arrays which require us to switch all port groups
+ * based on a certain policy. But until we actually encounter them it
+ * should be okay.
+ */
+static int alua_activate(struct scsi_device *sdev,
+			activate_complete fn, void *data)
+{
+	struct alua_dh_data *h = sdev->handler_data;
+	int err = SCSI_DH_OK;
+	struct alua_queue_data *qdata;
+	struct alua_port_group *pg;
+
+	qdata = kzalloc(sizeof(*qdata), GFP_KERNEL);
+	if (!qdata) {
+		err = SCSI_DH_RES_TEMP_UNAVAIL;
+		goto out;
+	}
+	qdata->callback_fn = fn;
+	qdata->callback_data = data;
+
+	mutex_lock(&h->init_mutex);
+	rcu_read_lock();
+	pg = rcu_dereference(h->pg);
+	if (!pg || !kref_get_unless_zero(&pg->kref)) {
+		rcu_read_unlock();
+		kfree(qdata);
+		err = h->init_error;
+		mutex_unlock(&h->init_mutex);
+		goto out;
+	}
+	rcu_read_unlock();
+	mutex_unlock(&h->init_mutex);
+
+	if (alua_rtpg_queue(pg, sdev, qdata, true)) {
+		fn = NULL;
+	} else {
+		kfree(qdata);
+		err = SCSI_DH_DEV_OFFLINED;
+	}
+	kref_put(&pg->kref, release_port_group);
+out:
+	if (fn)
+		fn(data, err);
+	return 0;
+}
+
+/*
+ * alua_check - check path status
+ * @sdev: device on the path to be checked
+ *
+ * Check the device status
+ */
+static void alua_check(struct scsi_device *sdev, bool force)
+{
+	struct alua_dh_data *h = sdev->handler_data;
+	struct alua_port_group *pg;
+
+	rcu_read_lock();
+	pg = rcu_dereference(h->pg);
+	if (!pg || !kref_get_unless_zero(&pg->kref)) {
+		rcu_read_unlock();
+		return;
+	}
+	rcu_read_unlock();
+	alua_rtpg_queue(pg, sdev, NULL, force);
+	kref_put(&pg->kref, release_port_group);
+}
+
+/*
+ * alua_prep_fn - request callback
+ *
+ * Fail I/O to all paths not in state
+ * active/optimized or active/non-optimized.
+ */
+static blk_status_t alua_prep_fn(struct scsi_device *sdev, struct request *req)
+{
+	struct alua_dh_data *h = sdev->handler_data;
+	struct alua_port_group *pg;
+	unsigned char state = SCSI_ACCESS_STATE_OPTIMAL;
+
+	rcu_read_lock();
+	pg = rcu_dereference(h->pg);
+	if (pg)
+		state = pg->state;
+	rcu_read_unlock();
+
+	switch (state) {
+	case SCSI_ACCESS_STATE_OPTIMAL:
+	case SCSI_ACCESS_STATE_ACTIVE:
+	case SCSI_ACCESS_STATE_LBA:
+	case SCSI_ACCESS_STATE_TRANSITIONING:
+		return BLK_STS_OK;
+	default:
+		req->rq_flags |= RQF_QUIET;
+		return BLK_STS_IOERR;
+	}
+}
+
+static void alua_rescan(struct scsi_device *sdev)
+{
+	struct alua_dh_data *h = sdev->handler_data;
+
+	alua_initialize(sdev, h);
+}
+
+/*
+ * alua_bus_attach - Attach device handler
+ * @sdev: device to be attached to
+ */
+static int alua_bus_attach(struct scsi_device *sdev)
+{
+	struct alua_dh_data *h;
+	int err;
+
+	h = kzalloc(sizeof(*h) , GFP_KERNEL);
+	if (!h)
+		return SCSI_DH_NOMEM;
+	spin_lock_init(&h->pg_lock);
+	rcu_assign_pointer(h->pg, NULL);
+	h->init_error = SCSI_DH_OK;
+	h->sdev = sdev;
+	INIT_LIST_HEAD(&h->node);
+
+	mutex_init(&h->init_mutex);
+	err = alua_initialize(sdev, h);
+	if (err != SCSI_DH_OK && err != SCSI_DH_DEV_OFFLINED)
+		goto failed;
+
+	sdev->handler_data = h;
+	return SCSI_DH_OK;
+failed:
+	kfree(h);
+	return err;
+}
+
+/*
+ * alua_bus_detach - Detach device handler
+ * @sdev: device to be detached from
+ */
+static void alua_bus_detach(struct scsi_device *sdev)
+{
+	struct alua_dh_data *h = sdev->handler_data;
+	struct alua_port_group *pg;
+
+	spin_lock(&h->pg_lock);
+	pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock));
+	rcu_assign_pointer(h->pg, NULL);
+	spin_unlock(&h->pg_lock);
+	if (pg) {
+		spin_lock_irq(&pg->lock);
+		list_del_rcu(&h->node);
+		spin_unlock_irq(&pg->lock);
+		kref_put(&pg->kref, release_port_group);
+	}
+	sdev->handler_data = NULL;
+	synchronize_rcu();
+	kfree(h);
+}
+
+static struct scsi_device_handler alua_dh = {
+	.name = ALUA_DH_NAME,
+	.module = THIS_MODULE,
+	.attach = alua_bus_attach,
+	.detach = alua_bus_detach,
+	.prep_fn = alua_prep_fn,
+	.check_sense = alua_check_sense,
+	.activate = alua_activate,
+	.rescan = alua_rescan,
+	.set_params = alua_set_params,
+};
+
+static int __init alua_init(void)
+{
+	int r;
+
+	kaluad_wq = alloc_workqueue("kaluad", WQ_MEM_RECLAIM, 0);
+	if (!kaluad_wq)
+		return -ENOMEM;
+
+	r = scsi_register_device_handler(&alua_dh);
+	if (r != 0) {
+		printk(KERN_ERR "%s: Failed to register scsi device handler",
+			ALUA_DH_NAME);
+		destroy_workqueue(kaluad_wq);
+	}
+	return r;
+}
+
+static void __exit alua_exit(void)
+{
+	scsi_unregister_device_handler(&alua_dh);
+	destroy_workqueue(kaluad_wq);
+}
+
+module_init(alua_init);
+module_exit(alua_exit);
+
+MODULE_DESCRIPTION("DM Multipath ALUA support");
+MODULE_AUTHOR("Hannes Reinecke <hare@suse.de>");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(ALUA_DH_VER);
diff --git a/drivers/scsi/device_handler/scsi_dh_emc.c b/drivers/scsi/device_handler/scsi_dh_emc.c
new file mode 100644
index 000000000..2e21ab447
--- /dev/null
+++ b/drivers/scsi/device_handler/scsi_dh_emc.c
@@ -0,0 +1,545 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Target driver for EMC CLARiiON AX/CX-series hardware.
+ * Based on code from Lars Marowsky-Bree <lmb@suse.de>
+ * and Ed Goggin <egoggin@emc.com>.
+ *
+ * Copyright (C) 2006 Red Hat, Inc.  All rights reserved.
+ * Copyright (C) 2006 Mike Christie
+ */
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <scsi/scsi.h>
+#include <scsi/scsi_eh.h>
+#include <scsi/scsi_dh.h>
+#include <scsi/scsi_device.h>
+
+#define CLARIION_NAME			"emc"
+
+#define CLARIION_TRESPASS_PAGE		0x22
+#define CLARIION_BUFFER_SIZE		0xFC
+#define CLARIION_TIMEOUT		(60 * HZ)
+#define CLARIION_RETRIES		3
+#define CLARIION_UNBOUND_LU		-1
+#define CLARIION_SP_A			0
+#define CLARIION_SP_B			1
+
+/* Flags */
+#define CLARIION_SHORT_TRESPASS		1
+#define CLARIION_HONOR_RESERVATIONS	2
+
+/* LUN states */
+#define CLARIION_LUN_UNINITIALIZED	-1
+#define CLARIION_LUN_UNBOUND		0
+#define CLARIION_LUN_BOUND		1
+#define CLARIION_LUN_OWNED		2
+
+static unsigned char long_trespass[] = {
+	0, 0, 0, 0, 0, 0, 0, 0,
+	CLARIION_TRESPASS_PAGE,	/* Page code */
+	0x09,			/* Page length - 2 */
+	0x01,			/* Trespass code */
+	0xff, 0xff,		/* Trespass target */
+	0, 0, 0, 0, 0, 0	/* Reserved bytes / unknown */
+};
+
+static unsigned char short_trespass[] = {
+	0, 0, 0, 0,
+	CLARIION_TRESPASS_PAGE,	/* Page code */
+	0x02,			/* Page length - 2 */
+	0x01,			/* Trespass code */
+	0xff,			/* Trespass target */
+};
+
+static const char * lun_state[] =
+{
+    "not bound",
+    "bound",
+    "owned",
+};
+
+struct clariion_dh_data {
+	/*
+	 * Flags:
+	 *  CLARIION_SHORT_TRESPASS
+	 * Use short trespass command (FC-series) or the long version
+	 * (default for AX/CX CLARiiON arrays).
+	 *
+	 *  CLARIION_HONOR_RESERVATIONS
+	 * Whether or not (default) to honor SCSI reservations when
+	 * initiating a switch-over.
+	 */
+	unsigned flags;
+	/*
+	 * I/O buffer for both MODE_SELECT and INQUIRY commands.
+	 */
+	unsigned char buffer[CLARIION_BUFFER_SIZE];
+	/*
+	 * LUN state
+	 */
+	int lun_state;
+	/*
+	 * SP Port number
+	 */
+	int port;
+	/*
+	 * which SP (A=0,B=1,UNBOUND=-1) is the default SP for this
+	 * path's mapped LUN
+	 */
+	int default_sp;
+	/*
+	 * which SP (A=0,B=1,UNBOUND=-1) is the active SP for this
+	 * path's mapped LUN
+	 */
+	int current_sp;
+};
+
+/*
+ * Parse MODE_SELECT cmd reply.
+ */
+static int trespass_endio(struct scsi_device *sdev,
+			  struct scsi_sense_hdr *sshdr)
+{
+	int err = SCSI_DH_IO;
+
+	sdev_printk(KERN_ERR, sdev, "%s: Found valid sense data 0x%2x, "
+		    "0x%2x, 0x%2x while sending CLARiiON trespass "
+		    "command.\n", CLARIION_NAME, sshdr->sense_key,
+		    sshdr->asc, sshdr->ascq);
+
+	if (sshdr->sense_key == 0x05 && sshdr->asc == 0x04 &&
+	    sshdr->ascq == 0x00) {
+		/*
+		 * Array based copy in progress -- do not send
+		 * mode_select or copy will be aborted mid-stream.
+		 */
+		sdev_printk(KERN_INFO, sdev, "%s: Array Based Copy in "
+			    "progress while sending CLARiiON trespass "
+			    "command.\n", CLARIION_NAME);
+		err = SCSI_DH_DEV_TEMP_BUSY;
+	} else if (sshdr->sense_key == 0x02 && sshdr->asc == 0x04 &&
+		   sshdr->ascq == 0x03) {
+		/*
+		 * LUN Not Ready - Manual Intervention Required
+		 * indicates in-progress ucode upgrade (NDU).
+		 */
+		sdev_printk(KERN_INFO, sdev, "%s: Detected in-progress "
+			    "ucode upgrade NDU operation while sending "
+			    "CLARiiON trespass command.\n", CLARIION_NAME);
+		err = SCSI_DH_DEV_TEMP_BUSY;
+	} else
+		err = SCSI_DH_DEV_FAILED;
+	return err;
+}
+
+static int parse_sp_info_reply(struct scsi_device *sdev,
+			       struct clariion_dh_data *csdev)
+{
+	int err = SCSI_DH_OK;
+
+	/* check for in-progress ucode upgrade (NDU) */
+	if (csdev->buffer[48] != 0) {
+		sdev_printk(KERN_NOTICE, sdev, "%s: Detected in-progress "
+			    "ucode upgrade NDU operation while finding "
+			    "current active SP.", CLARIION_NAME);
+		err = SCSI_DH_DEV_TEMP_BUSY;
+		goto out;
+	}
+	if (csdev->buffer[4] > 2) {
+		/* Invalid buffer format */
+		sdev_printk(KERN_NOTICE, sdev,
+			    "%s: invalid VPD page 0xC0 format\n",
+			    CLARIION_NAME);
+		err = SCSI_DH_NOSYS;
+		goto out;
+	}
+	switch (csdev->buffer[28] & 0x0f) {
+	case 6:
+		sdev_printk(KERN_NOTICE, sdev,
+			    "%s: ALUA failover mode detected\n",
+			    CLARIION_NAME);
+		break;
+	case 4:
+		/* Linux failover */
+		break;
+	default:
+		sdev_printk(KERN_WARNING, sdev,
+			    "%s: Invalid failover mode %d\n",
+			    CLARIION_NAME, csdev->buffer[28] & 0x0f);
+		err = SCSI_DH_NOSYS;
+		goto out;
+	}
+
+	csdev->default_sp = csdev->buffer[5];
+	csdev->lun_state = csdev->buffer[4];
+	csdev->current_sp = csdev->buffer[8];
+	csdev->port = csdev->buffer[7];
+	if (csdev->lun_state == CLARIION_LUN_OWNED)
+		sdev->access_state = SCSI_ACCESS_STATE_OPTIMAL;
+	else
+		sdev->access_state = SCSI_ACCESS_STATE_STANDBY;
+	if (csdev->default_sp == csdev->current_sp)
+		sdev->access_state |= SCSI_ACCESS_STATE_PREFERRED;
+out:
+	return err;
+}
+
+#define emc_default_str "FC (Legacy)"
+
+static char * parse_sp_model(struct scsi_device *sdev, unsigned char *buffer)
+{
+	unsigned char len = buffer[4] + 5;
+	char *sp_model = NULL;
+	unsigned char sp_len, serial_len;
+
+	if (len < 160) {
+		sdev_printk(KERN_WARNING, sdev,
+			    "%s: Invalid information section length %d\n",
+			    CLARIION_NAME, len);
+		/* Check for old FC arrays */
+		if (!strncmp(buffer + 8, "DGC", 3)) {
+			/* Old FC array, not supporting extended information */
+			sp_model = emc_default_str;
+		}
+		goto out;
+	}
+
+	/*
+	 * Parse extended information for SP model number
+	 */
+	serial_len = buffer[160];
+	if (serial_len == 0 || serial_len + 161 > len) {
+		sdev_printk(KERN_WARNING, sdev,
+			    "%s: Invalid array serial number length %d\n",
+			    CLARIION_NAME, serial_len);
+		goto out;
+	}
+	sp_len = buffer[99];
+	if (sp_len == 0 || serial_len + sp_len + 161 > len) {
+		sdev_printk(KERN_WARNING, sdev,
+			    "%s: Invalid model number length %d\n",
+			    CLARIION_NAME, sp_len);
+		goto out;
+	}
+	sp_model = &buffer[serial_len + 161];
+	/* Strip whitespace at the end */
+	while (sp_len > 1 && sp_model[sp_len - 1] == ' ')
+		sp_len--;
+
+	sp_model[sp_len] = '\0';
+
+out:
+	return sp_model;
+}
+
+static int send_trespass_cmd(struct scsi_device *sdev,
+			    struct clariion_dh_data *csdev)
+{
+	unsigned char *page22;
+	unsigned char cdb[MAX_COMMAND_SIZE];
+	int err, res = SCSI_DH_OK, len;
+	struct scsi_sense_hdr sshdr;
+	blk_opf_t req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
+		REQ_FAILFAST_DRIVER;
+
+	if (csdev->flags & CLARIION_SHORT_TRESPASS) {
+		page22 = short_trespass;
+		if (!(csdev->flags & CLARIION_HONOR_RESERVATIONS))
+			/* Set Honor Reservations bit */
+			page22[6] |= 0x80;
+		len = sizeof(short_trespass);
+		cdb[0] = MODE_SELECT;
+		cdb[1] = 0x10;
+		cdb[4] = len;
+	} else {
+		page22 = long_trespass;
+		if (!(csdev->flags & CLARIION_HONOR_RESERVATIONS))
+			/* Set Honor Reservations bit */
+			page22[10] |= 0x80;
+		len = sizeof(long_trespass);
+		cdb[0] = MODE_SELECT_10;
+		cdb[8] = len;
+	}
+	BUG_ON((len > CLARIION_BUFFER_SIZE));
+	memcpy(csdev->buffer, page22, len);
+
+	err = scsi_execute(sdev, cdb, DMA_TO_DEVICE, csdev->buffer, len, NULL,
+			&sshdr, CLARIION_TIMEOUT * HZ, CLARIION_RETRIES,
+			req_flags, 0, NULL);
+	if (err) {
+		if (scsi_sense_valid(&sshdr))
+			res = trespass_endio(sdev, &sshdr);
+		else {
+			sdev_printk(KERN_INFO, sdev,
+				    "%s: failed to send MODE SELECT: %x\n",
+				    CLARIION_NAME, err);
+			res = SCSI_DH_IO;
+		}
+	}
+
+	return res;
+}
+
+static enum scsi_disposition clariion_check_sense(struct scsi_device *sdev,
+					struct scsi_sense_hdr *sense_hdr)
+{
+	switch (sense_hdr->sense_key) {
+	case NOT_READY:
+		if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x03)
+			/*
+			 * LUN Not Ready - Manual Intervention Required
+			 * indicates this is a passive path.
+			 *
+			 * FIXME: However, if this is seen and EVPD C0
+			 * indicates that this is due to a NDU in
+			 * progress, we should set FAIL_PATH too.
+			 * This indicates we might have to do a SCSI
+			 * inquiry in the end_io path. Ugh.
+			 *
+			 * Can return FAILED only when we want the error
+			 * recovery process to kick in.
+			 */
+			return SUCCESS;
+		break;
+	case ILLEGAL_REQUEST:
+		if (sense_hdr->asc == 0x25 && sense_hdr->ascq == 0x01)
+			/*
+			 * An array based copy is in progress. Do not
+			 * fail the path, do not bypass to another PG,
+			 * do not retry. Fail the IO immediately.
+			 * (Actually this is the same conclusion as in
+			 * the default handler, but lets make sure.)
+			 *
+			 * Can return FAILED only when we want the error
+			 * recovery process to kick in.
+			 */
+			return SUCCESS;
+		break;
+	case UNIT_ATTENTION:
+		if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00)
+			/*
+			 * Unit Attention Code. This is the first IO
+			 * to the new path, so just retry.
+			 */
+			return ADD_TO_MLQUEUE;
+		break;
+	}
+
+	return SCSI_RETURN_NOT_HANDLED;
+}
+
+static blk_status_t clariion_prep_fn(struct scsi_device *sdev,
+		struct request *req)
+{
+	struct clariion_dh_data *h = sdev->handler_data;
+
+	if (h->lun_state != CLARIION_LUN_OWNED) {
+		req->rq_flags |= RQF_QUIET;
+		return BLK_STS_IOERR;
+	}
+
+	return BLK_STS_OK;
+}
+
+static int clariion_std_inquiry(struct scsi_device *sdev,
+				struct clariion_dh_data *csdev)
+{
+	int err = SCSI_DH_OK;
+	char *sp_model;
+
+	sp_model = parse_sp_model(sdev, sdev->inquiry);
+	if (!sp_model) {
+		err = SCSI_DH_DEV_UNSUPP;
+		goto out;
+	}
+
+	/*
+	 * FC Series arrays do not support long trespass
+	 */
+	if (!strlen(sp_model) || !strncmp(sp_model, "FC",2))
+		csdev->flags |= CLARIION_SHORT_TRESPASS;
+
+	sdev_printk(KERN_INFO, sdev,
+		    "%s: detected Clariion %s, flags %x\n",
+		    CLARIION_NAME, sp_model, csdev->flags);
+out:
+	return err;
+}
+
+static int clariion_send_inquiry(struct scsi_device *sdev,
+				 struct clariion_dh_data *csdev)
+{
+	int err = SCSI_DH_IO;
+
+	if (!scsi_get_vpd_page(sdev, 0xC0, csdev->buffer,
+			       CLARIION_BUFFER_SIZE))
+		err = parse_sp_info_reply(sdev, csdev);
+
+	return err;
+}
+
+static int clariion_activate(struct scsi_device *sdev,
+				activate_complete fn, void *data)
+{
+	struct clariion_dh_data *csdev = sdev->handler_data;
+	int result;
+
+	result = clariion_send_inquiry(sdev, csdev);
+	if (result != SCSI_DH_OK)
+		goto done;
+
+	if (csdev->lun_state == CLARIION_LUN_OWNED)
+		goto done;
+
+	result = send_trespass_cmd(sdev, csdev);
+	if (result != SCSI_DH_OK)
+		goto done;
+	sdev_printk(KERN_INFO, sdev,"%s: %s trespass command sent\n",
+		    CLARIION_NAME,
+		    csdev->flags&CLARIION_SHORT_TRESPASS?"short":"long" );
+
+	/* Update status */
+	result = clariion_send_inquiry(sdev, csdev);
+	if (result != SCSI_DH_OK)
+		goto done;
+
+done:
+	sdev_printk(KERN_INFO, sdev,
+		    "%s: at SP %c Port %d (%s, default SP %c)\n",
+		    CLARIION_NAME, csdev->current_sp + 'A',
+		    csdev->port, lun_state[csdev->lun_state],
+		    csdev->default_sp + 'A');
+
+	if (fn)
+		fn(data, result);
+	return 0;
+}
+/*
+ * params - parameters in the following format
+ *      "no_of_params\0param1\0param2\0param3\0...\0"
+ *      for example, string for 2 parameters with value 10 and 21
+ *      is specified as "2\010\021\0".
+ */
+static int clariion_set_params(struct scsi_device *sdev, const char *params)
+{
+	struct clariion_dh_data *csdev = sdev->handler_data;
+	unsigned int hr = 0, st = 0, argc;
+	const char *p = params;
+	int result = SCSI_DH_OK;
+
+	if ((sscanf(params, "%u", &argc) != 1) || (argc != 2))
+		return -EINVAL;
+
+	while (*p++)
+		;
+	if ((sscanf(p, "%u", &st) != 1) || (st > 1))
+		return -EINVAL;
+
+	while (*p++)
+		;
+	if ((sscanf(p, "%u", &hr) != 1) || (hr > 1))
+		return -EINVAL;
+
+	if (st)
+		csdev->flags |= CLARIION_SHORT_TRESPASS;
+	else
+		csdev->flags &= ~CLARIION_SHORT_TRESPASS;
+
+	if (hr)
+		csdev->flags |= CLARIION_HONOR_RESERVATIONS;
+	else
+		csdev->flags &= ~CLARIION_HONOR_RESERVATIONS;
+
+	/*
+	 * If this path is owned, we have to send a trespass command
+	 * with the new parameters. If not, simply return. Next trespass
+	 * command would use the parameters.
+	 */
+	if (csdev->lun_state != CLARIION_LUN_OWNED)
+		goto done;
+
+	csdev->lun_state = CLARIION_LUN_UNINITIALIZED;
+	result = send_trespass_cmd(sdev, csdev);
+	if (result != SCSI_DH_OK)
+		goto done;
+
+	/* Update status */
+	result = clariion_send_inquiry(sdev, csdev);
+
+done:
+	return result;
+}
+
+static int clariion_bus_attach(struct scsi_device *sdev)
+{
+	struct clariion_dh_data *h;
+	int err;
+
+	h = kzalloc(sizeof(*h) , GFP_KERNEL);
+	if (!h)
+		return SCSI_DH_NOMEM;
+	h->lun_state = CLARIION_LUN_UNINITIALIZED;
+	h->default_sp = CLARIION_UNBOUND_LU;
+	h->current_sp = CLARIION_UNBOUND_LU;
+
+	err = clariion_std_inquiry(sdev, h);
+	if (err != SCSI_DH_OK)
+		goto failed;
+
+	err = clariion_send_inquiry(sdev, h);
+	if (err != SCSI_DH_OK)
+		goto failed;
+
+	sdev_printk(KERN_INFO, sdev,
+		    "%s: connected to SP %c Port %d (%s, default SP %c)\n",
+		    CLARIION_NAME, h->current_sp + 'A',
+		    h->port, lun_state[h->lun_state],
+		    h->default_sp + 'A');
+
+	sdev->handler_data = h;
+	return SCSI_DH_OK;
+
+failed:
+	kfree(h);
+	return err;
+}
+
+static void clariion_bus_detach(struct scsi_device *sdev)
+{
+	kfree(sdev->handler_data);
+	sdev->handler_data = NULL;
+}
+
+static struct scsi_device_handler clariion_dh = {
+	.name		= CLARIION_NAME,
+	.module		= THIS_MODULE,
+	.attach		= clariion_bus_attach,
+	.detach		= clariion_bus_detach,
+	.check_sense	= clariion_check_sense,
+	.activate	= clariion_activate,
+	.prep_fn	= clariion_prep_fn,
+	.set_params	= clariion_set_params,
+};
+
+static int __init clariion_init(void)
+{
+	int r;
+
+	r = scsi_register_device_handler(&clariion_dh);
+	if (r != 0)
+		printk(KERN_ERR "%s: Failed to register scsi device handler.",
+			CLARIION_NAME);
+	return r;
+}
+
+static void __exit clariion_exit(void)
+{
+	scsi_unregister_device_handler(&clariion_dh);
+}
+
+module_init(clariion_init);
+module_exit(clariion_exit);
+
+MODULE_DESCRIPTION("EMC CX/AX/FC-family driver");
+MODULE_AUTHOR("Mike Christie <michaelc@cs.wisc.edu>, Chandra Seetharaman <sekharan@us.ibm.com>");
+MODULE_LICENSE("GPL");
diff --git a/drivers/scsi/device_handler/scsi_dh_hp_sw.c b/drivers/scsi/device_handler/scsi_dh_hp_sw.c
new file mode 100644
index 000000000..0d2cfa60a
--- /dev/null
+++ b/drivers/scsi/device_handler/scsi_dh_hp_sw.c
@@ -0,0 +1,261 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Basic HP/COMPAQ MSA 1000 support. This is only needed if your HW cannot be
+ * upgraded.
+ *
+ * Copyright (C) 2006 Red Hat, Inc.  All rights reserved.
+ * Copyright (C) 2006 Mike Christie
+ * Copyright (C) 2008 Hannes Reinecke <hare@suse.de>
+ */
+
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <scsi/scsi.h>
+#include <scsi/scsi_dbg.h>
+#include <scsi/scsi_eh.h>
+#include <scsi/scsi_dh.h>
+
+#define HP_SW_NAME			"hp_sw"
+
+#define HP_SW_TIMEOUT			(60 * HZ)
+#define HP_SW_RETRIES			3
+
+#define HP_SW_PATH_UNINITIALIZED	-1
+#define HP_SW_PATH_ACTIVE		0
+#define HP_SW_PATH_PASSIVE		1
+
+struct hp_sw_dh_data {
+	int path_state;
+	int retries;
+	int retry_cnt;
+	struct scsi_device *sdev;
+};
+
+static int hp_sw_start_stop(struct hp_sw_dh_data *);
+
+/*
+ * tur_done - Handle TEST UNIT READY return status
+ * @sdev: sdev the command has been sent to
+ * @errors: blk error code
+ *
+ * Returns SCSI_DH_DEV_OFFLINED if the sdev is on the passive path
+ */
+static int tur_done(struct scsi_device *sdev, struct hp_sw_dh_data *h,
+		    struct scsi_sense_hdr *sshdr)
+{
+	int ret = SCSI_DH_IO;
+
+	switch (sshdr->sense_key) {
+	case UNIT_ATTENTION:
+		ret = SCSI_DH_IMM_RETRY;
+		break;
+	case NOT_READY:
+		if (sshdr->asc == 0x04 && sshdr->ascq == 2) {
+			/*
+			 * LUN not ready - Initialization command required
+			 *
+			 * This is the passive path
+			 */
+			h->path_state = HP_SW_PATH_PASSIVE;
+			ret = SCSI_DH_OK;
+			break;
+		}
+		fallthrough;
+	default:
+		sdev_printk(KERN_WARNING, sdev,
+			   "%s: sending tur failed, sense %x/%x/%x\n",
+			   HP_SW_NAME, sshdr->sense_key, sshdr->asc,
+			   sshdr->ascq);
+		break;
+	}
+	return ret;
+}
+
+/*
+ * hp_sw_tur - Send TEST UNIT READY
+ * @sdev: sdev command should be sent to
+ *
+ * Use the TEST UNIT READY command to determine
+ * the path state.
+ */
+static int hp_sw_tur(struct scsi_device *sdev, struct hp_sw_dh_data *h)
+{
+	unsigned char cmd[6] = { TEST_UNIT_READY };
+	struct scsi_sense_hdr sshdr;
+	int ret = SCSI_DH_OK, res;
+	blk_opf_t req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
+		REQ_FAILFAST_DRIVER;
+
+retry:
+	res = scsi_execute(sdev, cmd, DMA_NONE, NULL, 0, NULL, &sshdr,
+			HP_SW_TIMEOUT, HP_SW_RETRIES, req_flags, 0, NULL);
+	if (res) {
+		if (scsi_sense_valid(&sshdr))
+			ret = tur_done(sdev, h, &sshdr);
+		else {
+			sdev_printk(KERN_WARNING, sdev,
+				    "%s: sending tur failed with %x\n",
+				    HP_SW_NAME, res);
+			ret = SCSI_DH_IO;
+		}
+	} else {
+		h->path_state = HP_SW_PATH_ACTIVE;
+		ret = SCSI_DH_OK;
+	}
+	if (ret == SCSI_DH_IMM_RETRY)
+		goto retry;
+
+	return ret;
+}
+
+/*
+ * hp_sw_start_stop - Send START STOP UNIT command
+ * @sdev: sdev command should be sent to
+ *
+ * Sending START STOP UNIT activates the SP.
+ */
+static int hp_sw_start_stop(struct hp_sw_dh_data *h)
+{
+	unsigned char cmd[6] = { START_STOP, 0, 0, 0, 1, 0 };
+	struct scsi_sense_hdr sshdr;
+	struct scsi_device *sdev = h->sdev;
+	int res, rc = SCSI_DH_OK;
+	int retry_cnt = HP_SW_RETRIES;
+	blk_opf_t req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
+		REQ_FAILFAST_DRIVER;
+
+retry:
+	res = scsi_execute(sdev, cmd, DMA_NONE, NULL, 0, NULL, &sshdr,
+			HP_SW_TIMEOUT, HP_SW_RETRIES, req_flags, 0, NULL);
+	if (res) {
+		if (!scsi_sense_valid(&sshdr)) {
+			sdev_printk(KERN_WARNING, sdev,
+				    "%s: sending start_stop_unit failed, "
+				    "no sense available\n", HP_SW_NAME);
+			return SCSI_DH_IO;
+		}
+		switch (sshdr.sense_key) {
+		case NOT_READY:
+			if (sshdr.asc == 0x04 && sshdr.ascq == 3) {
+				/*
+				 * LUN not ready - manual intervention required
+				 *
+				 * Switch-over in progress, retry.
+				 */
+				if (--retry_cnt)
+					goto retry;
+				rc = SCSI_DH_RETRY;
+				break;
+			}
+			fallthrough;
+		default:
+			sdev_printk(KERN_WARNING, sdev,
+				    "%s: sending start_stop_unit failed, "
+				    "sense %x/%x/%x\n", HP_SW_NAME,
+				    sshdr.sense_key, sshdr.asc, sshdr.ascq);
+			rc = SCSI_DH_IO;
+		}
+	}
+	return rc;
+}
+
+static blk_status_t hp_sw_prep_fn(struct scsi_device *sdev, struct request *req)
+{
+	struct hp_sw_dh_data *h = sdev->handler_data;
+
+	if (h->path_state != HP_SW_PATH_ACTIVE) {
+		req->rq_flags |= RQF_QUIET;
+		return BLK_STS_IOERR;
+	}
+
+	return BLK_STS_OK;
+}
+
+/*
+ * hp_sw_activate - Activate a path
+ * @sdev: sdev on the path to be activated
+ *
+ * The HP Active/Passive firmware is pretty simple;
+ * the passive path reports NOT READY with sense codes
+ * 0x04/0x02; a START STOP UNIT command will then
+ * activate the passive path (and deactivate the
+ * previously active one).
+ */
+static int hp_sw_activate(struct scsi_device *sdev,
+				activate_complete fn, void *data)
+{
+	int ret = SCSI_DH_OK;
+	struct hp_sw_dh_data *h = sdev->handler_data;
+
+	ret = hp_sw_tur(sdev, h);
+
+	if (ret == SCSI_DH_OK && h->path_state == HP_SW_PATH_PASSIVE)
+		ret = hp_sw_start_stop(h);
+
+	if (fn)
+		fn(data, ret);
+	return 0;
+}
+
+static int hp_sw_bus_attach(struct scsi_device *sdev)
+{
+	struct hp_sw_dh_data *h;
+	int ret;
+
+	h = kzalloc(sizeof(*h), GFP_KERNEL);
+	if (!h)
+		return SCSI_DH_NOMEM;
+	h->path_state = HP_SW_PATH_UNINITIALIZED;
+	h->retries = HP_SW_RETRIES;
+	h->sdev = sdev;
+
+	ret = hp_sw_tur(sdev, h);
+	if (ret != SCSI_DH_OK)
+		goto failed;
+	if (h->path_state == HP_SW_PATH_UNINITIALIZED) {
+		ret = SCSI_DH_NOSYS;
+		goto failed;
+	}
+
+	sdev_printk(KERN_INFO, sdev, "%s: attached to %s path\n",
+		    HP_SW_NAME, h->path_state == HP_SW_PATH_ACTIVE?
+		    "active":"passive");
+
+	sdev->handler_data = h;
+	return SCSI_DH_OK;
+failed:
+	kfree(h);
+	return ret;
+}
+
+static void hp_sw_bus_detach( struct scsi_device *sdev )
+{
+	kfree(sdev->handler_data);
+	sdev->handler_data = NULL;
+}
+
+static struct scsi_device_handler hp_sw_dh = {
+	.name		= HP_SW_NAME,
+	.module		= THIS_MODULE,
+	.attach		= hp_sw_bus_attach,
+	.detach		= hp_sw_bus_detach,
+	.activate	= hp_sw_activate,
+	.prep_fn	= hp_sw_prep_fn,
+};
+
+static int __init hp_sw_init(void)
+{
+	return scsi_register_device_handler(&hp_sw_dh);
+}
+
+static void __exit hp_sw_exit(void)
+{
+	scsi_unregister_device_handler(&hp_sw_dh);
+}
+
+module_init(hp_sw_init);
+module_exit(hp_sw_exit);
+
+MODULE_DESCRIPTION("HP Active/Passive driver");
+MODULE_AUTHOR("Mike Christie <michaelc@cs.wisc.edu");
+MODULE_LICENSE("GPL");
diff --git a/drivers/scsi/device_handler/scsi_dh_rdac.c b/drivers/scsi/device_handler/scsi_dh_rdac.c
new file mode 100644
index 000000000..bf8754741
--- /dev/null
+++ b/drivers/scsi/device_handler/scsi_dh_rdac.c
@@ -0,0 +1,835 @@
+/*
+ * LSI/Engenio/NetApp E-Series RDAC SCSI Device Handler
+ *
+ * Copyright (C) 2005 Mike Christie. All rights reserved.
+ * Copyright (C) Chandra Seetharaman, IBM Corp. 2007
+ *
+ * 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 <scsi/scsi.h>
+#include <scsi/scsi_eh.h>
+#include <scsi/scsi_dh.h>
+#include <linux/workqueue.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+
+#define RDAC_NAME "rdac"
+#define RDAC_RETRY_COUNT 5
+
+/*
+ * LSI mode page stuff
+ *
+ * These struct definitions and the forming of the
+ * mode page were taken from the LSI RDAC 2.4 GPL'd
+ * driver, and then converted to Linux conventions.
+ */
+#define RDAC_QUIESCENCE_TIME 20
+/*
+ * Page Codes
+ */
+#define RDAC_PAGE_CODE_REDUNDANT_CONTROLLER 0x2c
+
+/*
+ * Controller modes definitions
+ */
+#define RDAC_MODE_TRANSFER_SPECIFIED_LUNS	0x02
+
+/*
+ * RDAC Options field
+ */
+#define RDAC_FORCED_QUIESENCE 0x02
+
+#define RDAC_TIMEOUT	(60 * HZ)
+#define RDAC_RETRIES	3
+
+struct rdac_mode_6_hdr {
+	u8	data_len;
+	u8	medium_type;
+	u8	device_params;
+	u8	block_desc_len;
+};
+
+struct rdac_mode_10_hdr {
+	u16	data_len;
+	u8	medium_type;
+	u8	device_params;
+	u16	reserved;
+	u16	block_desc_len;
+};
+
+struct rdac_mode_common {
+	u8	controller_serial[16];
+	u8	alt_controller_serial[16];
+	u8	rdac_mode[2];
+	u8	alt_rdac_mode[2];
+	u8	quiescence_timeout;
+	u8	rdac_options;
+};
+
+struct rdac_pg_legacy {
+	struct rdac_mode_6_hdr hdr;
+	u8	page_code;
+	u8	page_len;
+	struct rdac_mode_common common;
+#define MODE6_MAX_LUN	32
+	u8	lun_table[MODE6_MAX_LUN];
+	u8	reserved2[32];
+	u8	reserved3;
+	u8	reserved4;
+};
+
+struct rdac_pg_expanded {
+	struct rdac_mode_10_hdr hdr;
+	u8	page_code;
+	u8	subpage_code;
+	u8	page_len[2];
+	struct rdac_mode_common common;
+	u8	lun_table[256];
+	u8	reserved3;
+	u8	reserved4;
+};
+
+struct c9_inquiry {
+	u8	peripheral_info;
+	u8	page_code;	/* 0xC9 */
+	u8	reserved1;
+	u8	page_len;
+	u8	page_id[4];	/* "vace" */
+	u8	avte_cvp;
+	u8	path_prio;
+	u8	reserved2[38];
+};
+
+#define SUBSYS_ID_LEN	16
+#define SLOT_ID_LEN	2
+#define ARRAY_LABEL_LEN	31
+
+struct c4_inquiry {
+	u8	peripheral_info;
+	u8	page_code;	/* 0xC4 */
+	u8	reserved1;
+	u8	page_len;
+	u8	page_id[4];	/* "subs" */
+	u8	subsys_id[SUBSYS_ID_LEN];
+	u8	revision[4];
+	u8	slot_id[SLOT_ID_LEN];
+	u8	reserved[2];
+};
+
+#define UNIQUE_ID_LEN 16
+struct c8_inquiry {
+	u8	peripheral_info;
+	u8	page_code; /* 0xC8 */
+	u8	reserved1;
+	u8	page_len;
+	u8	page_id[4]; /* "edid" */
+	u8	reserved2[3];
+	u8	vol_uniq_id_len;
+	u8	vol_uniq_id[16];
+	u8	vol_user_label_len;
+	u8	vol_user_label[60];
+	u8	array_uniq_id_len;
+	u8	array_unique_id[UNIQUE_ID_LEN];
+	u8	array_user_label_len;
+	u8	array_user_label[60];
+	u8	lun[8];
+};
+
+struct rdac_controller {
+	u8			array_id[UNIQUE_ID_LEN];
+	int			use_ms10;
+	struct kref		kref;
+	struct list_head	node; /* list of all controllers */
+	union			{
+		struct rdac_pg_legacy legacy;
+		struct rdac_pg_expanded expanded;
+	} mode_select;
+	u8	index;
+	u8	array_name[ARRAY_LABEL_LEN];
+	struct Scsi_Host	*host;
+	spinlock_t		ms_lock;
+	int			ms_queued;
+	struct work_struct	ms_work;
+	struct scsi_device	*ms_sdev;
+	struct list_head	ms_head;
+	struct list_head	dh_list;
+};
+
+struct c2_inquiry {
+	u8	peripheral_info;
+	u8	page_code;	/* 0xC2 */
+	u8	reserved1;
+	u8	page_len;
+	u8	page_id[4];	/* "swr4" */
+	u8	sw_version[3];
+	u8	sw_date[3];
+	u8	features_enabled;
+	u8	max_lun_supported;
+	u8	partitions[239]; /* Total allocation length should be 0xFF */
+};
+
+struct rdac_dh_data {
+	struct list_head	node;
+	struct rdac_controller	*ctlr;
+	struct scsi_device	*sdev;
+#define UNINITIALIZED_LUN	(1 << 8)
+	unsigned		lun;
+
+#define RDAC_MODE		0
+#define RDAC_MODE_AVT		1
+#define RDAC_MODE_IOSHIP	2
+	unsigned char		mode;
+
+#define RDAC_STATE_ACTIVE	0
+#define RDAC_STATE_PASSIVE	1
+	unsigned char		state;
+
+#define RDAC_LUN_UNOWNED	0
+#define RDAC_LUN_OWNED		1
+	char			lun_state;
+
+#define RDAC_PREFERRED		0
+#define RDAC_NON_PREFERRED	1
+	char			preferred;
+
+	union			{
+		struct c2_inquiry c2;
+		struct c4_inquiry c4;
+		struct c8_inquiry c8;
+		struct c9_inquiry c9;
+	} inq;
+};
+
+static const char *mode[] = {
+	"RDAC",
+	"AVT",
+	"IOSHIP",
+};
+static const char *lun_state[] =
+{
+	"unowned",
+	"owned",
+};
+
+struct rdac_queue_data {
+	struct list_head	entry;
+	struct rdac_dh_data	*h;
+	activate_complete	callback_fn;
+	void			*callback_data;
+};
+
+static LIST_HEAD(ctlr_list);
+static DEFINE_SPINLOCK(list_lock);
+static struct workqueue_struct *kmpath_rdacd;
+static void send_mode_select(struct work_struct *work);
+
+/*
+ * module parameter to enable rdac debug logging.
+ * 2 bits for each type of logging, only two types defined for now
+ * Can be enhanced if required at later point
+ */
+static int rdac_logging = 1;
+module_param(rdac_logging, int, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(rdac_logging, "A bit mask of rdac logging levels, "
+		"Default is 1 - failover logging enabled, "
+		"set it to 0xF to enable all the logs");
+
+#define RDAC_LOG_FAILOVER	0
+#define RDAC_LOG_SENSE		2
+
+#define RDAC_LOG_BITS		2
+
+#define RDAC_LOG_LEVEL(SHIFT)  \
+	((rdac_logging >> (SHIFT)) & ((1 << (RDAC_LOG_BITS)) - 1))
+
+#define RDAC_LOG(SHIFT, sdev, f, arg...) \
+do { \
+	if (unlikely(RDAC_LOG_LEVEL(SHIFT))) \
+		sdev_printk(KERN_INFO, sdev, RDAC_NAME ": " f "\n", ## arg); \
+} while (0);
+
+static unsigned int rdac_failover_get(struct rdac_controller *ctlr,
+				      struct list_head *list,
+				      unsigned char *cdb)
+{
+	struct rdac_mode_common *common;
+	unsigned data_size;
+	struct rdac_queue_data *qdata;
+	u8 *lun_table;
+
+	if (ctlr->use_ms10) {
+		struct rdac_pg_expanded *rdac_pg;
+
+		data_size = sizeof(struct rdac_pg_expanded);
+		rdac_pg = &ctlr->mode_select.expanded;
+		memset(rdac_pg, 0, data_size);
+		common = &rdac_pg->common;
+		rdac_pg->page_code = RDAC_PAGE_CODE_REDUNDANT_CONTROLLER + 0x40;
+		rdac_pg->subpage_code = 0x1;
+		rdac_pg->page_len[0] = 0x01;
+		rdac_pg->page_len[1] = 0x28;
+		lun_table = rdac_pg->lun_table;
+	} else {
+		struct rdac_pg_legacy *rdac_pg;
+
+		data_size = sizeof(struct rdac_pg_legacy);
+		rdac_pg = &ctlr->mode_select.legacy;
+		memset(rdac_pg, 0, data_size);
+		common = &rdac_pg->common;
+		rdac_pg->page_code = RDAC_PAGE_CODE_REDUNDANT_CONTROLLER;
+		rdac_pg->page_len = 0x68;
+		lun_table = rdac_pg->lun_table;
+	}
+	common->rdac_mode[1] = RDAC_MODE_TRANSFER_SPECIFIED_LUNS;
+	common->quiescence_timeout = RDAC_QUIESCENCE_TIME;
+	common->rdac_options = RDAC_FORCED_QUIESENCE;
+
+	list_for_each_entry(qdata, list, entry) {
+		lun_table[qdata->h->lun] = 0x81;
+	}
+
+	/* Prepare the command. */
+	if (ctlr->use_ms10) {
+		cdb[0] = MODE_SELECT_10;
+		cdb[7] = data_size >> 8;
+		cdb[8] = data_size & 0xff;
+	} else {
+		cdb[0] = MODE_SELECT;
+		cdb[4] = data_size;
+	}
+
+	return data_size;
+}
+
+static void release_controller(struct kref *kref)
+{
+	struct rdac_controller *ctlr;
+	ctlr = container_of(kref, struct rdac_controller, kref);
+
+	list_del(&ctlr->node);
+	kfree(ctlr);
+}
+
+static struct rdac_controller *get_controller(int index, char *array_name,
+			u8 *array_id, struct scsi_device *sdev)
+{
+	struct rdac_controller *ctlr, *tmp;
+
+	list_for_each_entry(tmp, &ctlr_list, node) {
+		if ((memcmp(tmp->array_id, array_id, UNIQUE_ID_LEN) == 0) &&
+			  (tmp->index == index) &&
+			  (tmp->host == sdev->host)) {
+			kref_get(&tmp->kref);
+			return tmp;
+		}
+	}
+	ctlr = kmalloc(sizeof(*ctlr), GFP_ATOMIC);
+	if (!ctlr)
+		return NULL;
+
+	/* initialize fields of controller */
+	memcpy(ctlr->array_id, array_id, UNIQUE_ID_LEN);
+	ctlr->index = index;
+	ctlr->host = sdev->host;
+	memcpy(ctlr->array_name, array_name, ARRAY_LABEL_LEN);
+
+	kref_init(&ctlr->kref);
+	ctlr->use_ms10 = -1;
+	ctlr->ms_queued = 0;
+	ctlr->ms_sdev = NULL;
+	spin_lock_init(&ctlr->ms_lock);
+	INIT_WORK(&ctlr->ms_work, send_mode_select);
+	INIT_LIST_HEAD(&ctlr->ms_head);
+	list_add(&ctlr->node, &ctlr_list);
+	INIT_LIST_HEAD(&ctlr->dh_list);
+
+	return ctlr;
+}
+
+static int get_lun_info(struct scsi_device *sdev, struct rdac_dh_data *h,
+			char *array_name, u8 *array_id)
+{
+	int err = SCSI_DH_IO, i;
+	struct c8_inquiry *inqp = &h->inq.c8;
+
+	if (!scsi_get_vpd_page(sdev, 0xC8, (unsigned char *)inqp,
+			       sizeof(struct c8_inquiry))) {
+		if (inqp->page_code != 0xc8)
+			return SCSI_DH_NOSYS;
+		if (inqp->page_id[0] != 'e' || inqp->page_id[1] != 'd' ||
+		    inqp->page_id[2] != 'i' || inqp->page_id[3] != 'd')
+			return SCSI_DH_NOSYS;
+		h->lun = inqp->lun[7]; /* Uses only the last byte */
+
+		for(i=0; i<ARRAY_LABEL_LEN-1; ++i)
+			*(array_name+i) = inqp->array_user_label[(2*i)+1];
+
+		*(array_name+ARRAY_LABEL_LEN-1) = '\0';
+		memset(array_id, 0, UNIQUE_ID_LEN);
+		memcpy(array_id, inqp->array_unique_id, inqp->array_uniq_id_len);
+		err = SCSI_DH_OK;
+	}
+	return err;
+}
+
+static int check_ownership(struct scsi_device *sdev, struct rdac_dh_data *h)
+{
+	int err = SCSI_DH_IO, access_state;
+	struct rdac_dh_data *tmp;
+	struct c9_inquiry *inqp = &h->inq.c9;
+
+	h->state = RDAC_STATE_ACTIVE;
+	if (!scsi_get_vpd_page(sdev, 0xC9, (unsigned char *)inqp,
+			       sizeof(struct c9_inquiry))) {
+		/* detect the operating mode */
+		if ((inqp->avte_cvp >> 5) & 0x1)
+			h->mode = RDAC_MODE_IOSHIP; /* LUN in IOSHIP mode */
+		else if (inqp->avte_cvp >> 7)
+			h->mode = RDAC_MODE_AVT; /* LUN in AVT mode */
+		else
+			h->mode = RDAC_MODE; /* LUN in RDAC mode */
+
+		/* Update ownership */
+		if (inqp->avte_cvp & 0x1) {
+			h->lun_state = RDAC_LUN_OWNED;
+			access_state = SCSI_ACCESS_STATE_OPTIMAL;
+		} else {
+			h->lun_state = RDAC_LUN_UNOWNED;
+			if (h->mode == RDAC_MODE) {
+				h->state = RDAC_STATE_PASSIVE;
+				access_state = SCSI_ACCESS_STATE_STANDBY;
+			} else
+				access_state = SCSI_ACCESS_STATE_ACTIVE;
+		}
+
+		/* Update path prio*/
+		if (inqp->path_prio & 0x1) {
+			h->preferred = RDAC_PREFERRED;
+			access_state |= SCSI_ACCESS_STATE_PREFERRED;
+		} else
+			h->preferred = RDAC_NON_PREFERRED;
+		rcu_read_lock();
+		list_for_each_entry_rcu(tmp, &h->ctlr->dh_list, node) {
+			/* h->sdev should always be valid */
+			BUG_ON(!tmp->sdev);
+			tmp->sdev->access_state = access_state;
+		}
+		rcu_read_unlock();
+		err = SCSI_DH_OK;
+	}
+
+	return err;
+}
+
+static int initialize_controller(struct scsi_device *sdev,
+		struct rdac_dh_data *h, char *array_name, u8 *array_id)
+{
+	int err = SCSI_DH_IO, index;
+	struct c4_inquiry *inqp = &h->inq.c4;
+
+	if (!scsi_get_vpd_page(sdev, 0xC4, (unsigned char *)inqp,
+			       sizeof(struct c4_inquiry))) {
+		/* get the controller index */
+		if (inqp->slot_id[1] == 0x31)
+			index = 0;
+		else
+			index = 1;
+
+		spin_lock(&list_lock);
+		h->ctlr = get_controller(index, array_name, array_id, sdev);
+		if (!h->ctlr)
+			err = SCSI_DH_RES_TEMP_UNAVAIL;
+		else {
+			h->sdev = sdev;
+			list_add_rcu(&h->node, &h->ctlr->dh_list);
+		}
+		spin_unlock(&list_lock);
+		err = SCSI_DH_OK;
+	}
+	return err;
+}
+
+static int set_mode_select(struct scsi_device *sdev, struct rdac_dh_data *h)
+{
+	int err = SCSI_DH_IO;
+	struct c2_inquiry *inqp = &h->inq.c2;
+
+	if (!scsi_get_vpd_page(sdev, 0xC2, (unsigned char *)inqp,
+			       sizeof(struct c2_inquiry))) {
+		/*
+		 * If more than MODE6_MAX_LUN luns are supported, use
+		 * mode select 10
+		 */
+		if (inqp->max_lun_supported >= MODE6_MAX_LUN)
+			h->ctlr->use_ms10 = 1;
+		else
+			h->ctlr->use_ms10 = 0;
+		err = SCSI_DH_OK;
+	}
+	return err;
+}
+
+static int mode_select_handle_sense(struct scsi_device *sdev,
+				    struct scsi_sense_hdr *sense_hdr)
+{
+	int err = SCSI_DH_IO;
+	struct rdac_dh_data *h = sdev->handler_data;
+
+	if (!scsi_sense_valid(sense_hdr))
+		goto done;
+
+	switch (sense_hdr->sense_key) {
+	case NO_SENSE:
+	case ABORTED_COMMAND:
+	case UNIT_ATTENTION:
+		err = SCSI_DH_RETRY;
+		break;
+	case NOT_READY:
+		if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x01)
+			/* LUN Not Ready and is in the Process of Becoming
+			 * Ready
+			 */
+			err = SCSI_DH_RETRY;
+		break;
+	case ILLEGAL_REQUEST:
+		if (sense_hdr->asc == 0x91 && sense_hdr->ascq == 0x36)
+			/*
+			 * Command Lock contention
+			 */
+			err = SCSI_DH_IMM_RETRY;
+		break;
+	default:
+		break;
+	}
+
+	RDAC_LOG(RDAC_LOG_FAILOVER, sdev, "array %s, ctlr %d, "
+		"MODE_SELECT returned with sense %02x/%02x/%02x",
+		(char *) h->ctlr->array_name, h->ctlr->index,
+		sense_hdr->sense_key, sense_hdr->asc, sense_hdr->ascq);
+
+done:
+	return err;
+}
+
+static void send_mode_select(struct work_struct *work)
+{
+	struct rdac_controller *ctlr =
+		container_of(work, struct rdac_controller, ms_work);
+	struct scsi_device *sdev = ctlr->ms_sdev;
+	struct rdac_dh_data *h = sdev->handler_data;
+	int err = SCSI_DH_OK, retry_cnt = RDAC_RETRY_COUNT;
+	struct rdac_queue_data *tmp, *qdata;
+	LIST_HEAD(list);
+	unsigned char cdb[MAX_COMMAND_SIZE];
+	struct scsi_sense_hdr sshdr;
+	unsigned int data_size;
+	blk_opf_t req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
+		REQ_FAILFAST_DRIVER;
+
+	spin_lock(&ctlr->ms_lock);
+	list_splice_init(&ctlr->ms_head, &list);
+	ctlr->ms_queued = 0;
+	ctlr->ms_sdev = NULL;
+	spin_unlock(&ctlr->ms_lock);
+
+ retry:
+	memset(cdb, 0, sizeof(cdb));
+
+	data_size = rdac_failover_get(ctlr, &list, cdb);
+
+	RDAC_LOG(RDAC_LOG_FAILOVER, sdev, "array %s, ctlr %d, "
+		"%s MODE_SELECT command",
+		(char *) h->ctlr->array_name, h->ctlr->index,
+		(retry_cnt == RDAC_RETRY_COUNT) ? "queueing" : "retrying");
+
+	if (scsi_execute(sdev, cdb, DMA_TO_DEVICE, &h->ctlr->mode_select,
+			data_size, NULL, &sshdr, RDAC_TIMEOUT * HZ,
+			RDAC_RETRIES, req_flags, 0, NULL)) {
+		err = mode_select_handle_sense(sdev, &sshdr);
+		if (err == SCSI_DH_RETRY && retry_cnt--)
+			goto retry;
+		if (err == SCSI_DH_IMM_RETRY)
+			goto retry;
+	}
+	if (err == SCSI_DH_OK) {
+		h->state = RDAC_STATE_ACTIVE;
+		RDAC_LOG(RDAC_LOG_FAILOVER, sdev, "array %s, ctlr %d, "
+				"MODE_SELECT completed",
+				(char *) h->ctlr->array_name, h->ctlr->index);
+	}
+
+	list_for_each_entry_safe(qdata, tmp, &list, entry) {
+		list_del(&qdata->entry);
+		if (err == SCSI_DH_OK)
+			qdata->h->state = RDAC_STATE_ACTIVE;
+		if (qdata->callback_fn)
+			qdata->callback_fn(qdata->callback_data, err);
+		kfree(qdata);
+	}
+	return;
+}
+
+static int queue_mode_select(struct scsi_device *sdev,
+				activate_complete fn, void *data)
+{
+	struct rdac_queue_data *qdata;
+	struct rdac_controller *ctlr;
+
+	qdata = kzalloc(sizeof(*qdata), GFP_KERNEL);
+	if (!qdata)
+		return SCSI_DH_RETRY;
+
+	qdata->h = sdev->handler_data;
+	qdata->callback_fn = fn;
+	qdata->callback_data = data;
+
+	ctlr = qdata->h->ctlr;
+	spin_lock(&ctlr->ms_lock);
+	list_add_tail(&qdata->entry, &ctlr->ms_head);
+	if (!ctlr->ms_queued) {
+		ctlr->ms_queued = 1;
+		ctlr->ms_sdev = sdev;
+		queue_work(kmpath_rdacd, &ctlr->ms_work);
+	}
+	spin_unlock(&ctlr->ms_lock);
+	return SCSI_DH_OK;
+}
+
+static int rdac_activate(struct scsi_device *sdev,
+			activate_complete fn, void *data)
+{
+	struct rdac_dh_data *h = sdev->handler_data;
+	int err = SCSI_DH_OK;
+	int act = 0;
+
+	err = check_ownership(sdev, h);
+	if (err != SCSI_DH_OK)
+		goto done;
+
+	switch (h->mode) {
+	case RDAC_MODE:
+		if (h->lun_state == RDAC_LUN_UNOWNED)
+			act = 1;
+		break;
+	case RDAC_MODE_IOSHIP:
+		if ((h->lun_state == RDAC_LUN_UNOWNED) &&
+		    (h->preferred == RDAC_PREFERRED))
+			act = 1;
+		break;
+	default:
+		break;
+	}
+
+	if (act) {
+		err = queue_mode_select(sdev, fn, data);
+		if (err == SCSI_DH_OK)
+			return 0;
+	}
+done:
+	if (fn)
+		fn(data, err);
+	return 0;
+}
+
+static blk_status_t rdac_prep_fn(struct scsi_device *sdev, struct request *req)
+{
+	struct rdac_dh_data *h = sdev->handler_data;
+
+	if (h->state != RDAC_STATE_ACTIVE) {
+		req->rq_flags |= RQF_QUIET;
+		return BLK_STS_IOERR;
+	}
+
+	return BLK_STS_OK;
+}
+
+static enum scsi_disposition rdac_check_sense(struct scsi_device *sdev,
+					      struct scsi_sense_hdr *sense_hdr)
+{
+	struct rdac_dh_data *h = sdev->handler_data;
+
+	RDAC_LOG(RDAC_LOG_SENSE, sdev, "array %s, ctlr %d, "
+			"I/O returned with sense %02x/%02x/%02x",
+			(char *) h->ctlr->array_name, h->ctlr->index,
+			sense_hdr->sense_key, sense_hdr->asc, sense_hdr->ascq);
+
+	switch (sense_hdr->sense_key) {
+	case NOT_READY:
+		if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x01)
+			/* LUN Not Ready - Logical Unit Not Ready and is in
+			* the process of becoming ready
+			* Just retry.
+			*/
+			return ADD_TO_MLQUEUE;
+		if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x81)
+			/* LUN Not Ready - Storage firmware incompatible
+			 * Manual code synchonisation required.
+			 *
+			 * Nothing we can do here. Try to bypass the path.
+			 */
+			return SUCCESS;
+		if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0xA1)
+			/* LUN Not Ready - Quiescense in progress
+			 *
+			 * Just retry and wait.
+			 */
+			return ADD_TO_MLQUEUE;
+		if (sense_hdr->asc == 0xA1  && sense_hdr->ascq == 0x02)
+			/* LUN Not Ready - Quiescense in progress
+			 * or has been achieved
+			 * Just retry.
+			 */
+			return ADD_TO_MLQUEUE;
+		break;
+	case ILLEGAL_REQUEST:
+		if (sense_hdr->asc == 0x94 && sense_hdr->ascq == 0x01) {
+			/* Invalid Request - Current Logical Unit Ownership.
+			 * Controller is not the current owner of the LUN,
+			 * Fail the path, so that the other path be used.
+			 */
+			h->state = RDAC_STATE_PASSIVE;
+			return SUCCESS;
+		}
+		break;
+	case UNIT_ATTENTION:
+		if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00)
+			/*
+			 * Power On, Reset, or Bus Device Reset, just retry.
+			 */
+			return ADD_TO_MLQUEUE;
+		if (sense_hdr->asc == 0x8b && sense_hdr->ascq == 0x02)
+			/*
+			 * Quiescence in progress , just retry.
+			 */
+			return ADD_TO_MLQUEUE;
+		break;
+	}
+	/* success just means we do not care what scsi-ml does */
+	return SCSI_RETURN_NOT_HANDLED;
+}
+
+static int rdac_bus_attach(struct scsi_device *sdev)
+{
+	struct rdac_dh_data *h;
+	int err;
+	char array_name[ARRAY_LABEL_LEN];
+	char array_id[UNIQUE_ID_LEN];
+
+	h = kzalloc(sizeof(*h) , GFP_KERNEL);
+	if (!h)
+		return SCSI_DH_NOMEM;
+	h->lun = UNINITIALIZED_LUN;
+	h->state = RDAC_STATE_ACTIVE;
+
+	err = get_lun_info(sdev, h, array_name, array_id);
+	if (err != SCSI_DH_OK)
+		goto failed;
+
+	err = initialize_controller(sdev, h, array_name, array_id);
+	if (err != SCSI_DH_OK)
+		goto failed;
+
+	err = check_ownership(sdev, h);
+	if (err != SCSI_DH_OK)
+		goto clean_ctlr;
+
+	err = set_mode_select(sdev, h);
+	if (err != SCSI_DH_OK)
+		goto clean_ctlr;
+
+	sdev_printk(KERN_NOTICE, sdev,
+		    "%s: LUN %d (%s) (%s)\n",
+		    RDAC_NAME, h->lun, mode[(int)h->mode],
+		    lun_state[(int)h->lun_state]);
+
+	sdev->handler_data = h;
+	return SCSI_DH_OK;
+
+clean_ctlr:
+	spin_lock(&list_lock);
+	kref_put(&h->ctlr->kref, release_controller);
+	spin_unlock(&list_lock);
+
+failed:
+	kfree(h);
+	return err;
+}
+
+static void rdac_bus_detach( struct scsi_device *sdev )
+{
+	struct rdac_dh_data *h = sdev->handler_data;
+
+	if (h->ctlr && h->ctlr->ms_queued)
+		flush_workqueue(kmpath_rdacd);
+
+	spin_lock(&list_lock);
+	if (h->ctlr) {
+		list_del_rcu(&h->node);
+		kref_put(&h->ctlr->kref, release_controller);
+	}
+	spin_unlock(&list_lock);
+	sdev->handler_data = NULL;
+	synchronize_rcu();
+	kfree(h);
+}
+
+static struct scsi_device_handler rdac_dh = {
+	.name = RDAC_NAME,
+	.module = THIS_MODULE,
+	.prep_fn = rdac_prep_fn,
+	.check_sense = rdac_check_sense,
+	.attach = rdac_bus_attach,
+	.detach = rdac_bus_detach,
+	.activate = rdac_activate,
+};
+
+static int __init rdac_init(void)
+{
+	int r;
+
+	r = scsi_register_device_handler(&rdac_dh);
+	if (r != 0) {
+		printk(KERN_ERR "Failed to register scsi device handler.");
+		goto done;
+	}
+
+	/*
+	 * Create workqueue to handle mode selects for rdac
+	 */
+	kmpath_rdacd = create_singlethread_workqueue("kmpath_rdacd");
+	if (!kmpath_rdacd) {
+		scsi_unregister_device_handler(&rdac_dh);
+		printk(KERN_ERR "kmpath_rdacd creation failed.\n");
+
+		r = -EINVAL;
+	}
+done:
+	return r;
+}
+
+static void __exit rdac_exit(void)
+{
+	destroy_workqueue(kmpath_rdacd);
+	scsi_unregister_device_handler(&rdac_dh);
+}
+
+module_init(rdac_init);
+module_exit(rdac_exit);
+
+MODULE_DESCRIPTION("Multipath LSI/Engenio/NetApp E-Series RDAC driver");
+MODULE_AUTHOR("Mike Christie, Chandra Seetharaman");
+MODULE_VERSION("01.00.0000.0000");
+MODULE_LICENSE("GPL");