From: Mike Christie <mchristi@redhat.com>
Date: Thu, 3 Dec 2009 05:18:53 -0500
Subject: [scsi] add emc clariion support to scsi_dh modules
Message-id: <1259817533-12064-1-git-send-email-mchristi@redhat.com>
Patchwork-id: 21661
O-Subject: [PATCH RHEL 5.5]: scsi_dh_emc: add EMC clariion support to scsi_dh
	modules
Bugzilla: 437107
RH-Acked-by: Rob Evers <revers@redhat.com>

From: Mike Christie <mchristi@redhat.com>

This is for BZ 437107.

We have basic EMC clariion support with the dm-emc module,
and EMC is requesting that we add follow-over support.
Follow-over is basically just being able to tell which
controller (service processor in EMC terminology) should
own the device. This prevents scenarios where we can
bounce back and forth between controllers because each
one things they own the device.

Upstream has moved from dm hw handlers, like dm-emc, to the
scsi_dh modules, so follow over is only in the newer scsi_dh_emc
module. In 5.3 we added a couple scsi_dh modules
but did not add scsi_dh_emc because of some issues upstream
like how to support both clariion boxes that support
both ALUA or EMC's tresspass command and to how have userspace
pass in settings and boot.

This patch includes the drivers/scsi/device_handler/scsi_dh_emc
module from upstream, and these dm-mpath changes to support
passing in scsi_dh settings and supporting both modes:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=2bfd2e1337f0d8bb6ff45ce12934c45b83d70ee0
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=a0cf7ea9549ec60988369f90e5c0f855f08abac9

Differences from upstream:
- clariion_check_sense returns different error values. This is due to our
scsi layer using different error codes.
- parse_hw_handler's has compat code for dm hw handlers so the
hw_handler_params change is in a different place.
- While testing we hit some issues and I sent a patch upstream here:
http://marc.info/?l=linux-scsi&m=125978574800618&w=2

I have only compile tested the patch. EMC did some basic tests to
check that failover and failback and follow-over worked
and is going to do some more in depth testing.

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 653e544..5add1e2 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -66,6 +66,7 @@ struct multipath {
 
 	struct hw_handler hw_handler;
 	const char *hw_handler_name;
+	char *hw_handler_params;
 	unsigned nr_priority_groups;
 	struct list_head priority_groups;
 	unsigned pg_init_required;	/* pg_init needs calling? */
@@ -219,6 +220,7 @@ static void free_multipath(struct multipath *m)
 		dm_put_hw_handler(hwh->type);
 	}
 	kfree(m->hw_handler_name);
+	kfree(m->hw_handler_params);
 	mempool_destroy(m->mpio_pool);
 	kfree(m);
 }
@@ -588,12 +590,34 @@ static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps,
 	}
 
 	if (m->hw_handler_name) {
-		r = scsi_dh_attach(bdev_get_queue(p->path.dev->bdev),
-				   m->hw_handler_name);
+		struct request_queue *q = bdev_get_queue(p->path.dev->bdev);
+
+		r = scsi_dh_attach(q, m->hw_handler_name);
+		if (r == -EBUSY) {
+			/*
+			 * Already attached to different hw_handler,
+			 * try to reattach with correct one.
+			 */
+			scsi_dh_detach(q);
+			r = scsi_dh_attach(q, m->hw_handler_name);
+		}
+
 		if (r < 0) {
+			ti->error = "error attaching hardware handler";
 			dm_put_device(ti, p->path.dev);
 			goto bad;
 		}
+
+		if (m->hw_handler_params) {
+			r = scsi_dh_set_params(q, m->hw_handler_params);
+			if (r < 0) {
+				ti->error = "unable to set hardware "
+							"handler parameters";
+				scsi_dh_detach(q);
+				dm_put_device(ti, p->path.dev);
+				goto bad;
+			}
+		}
 	}
 
 	r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
@@ -704,9 +728,24 @@ static int parse_hw_handler(struct arg_set *as, struct multipath *m,
 	if (scsi_dh_handler_exist(m->hw_handler_name)) {
 		DMINFO("Using scsi_dh module scsi_dh_%s for failover/failback "
 		       "and device management.", m->hw_handler_name);
-		if (hw_argc > 1)
-			DMWARN("No arguments accepted for this hardware "
-			       "handler");
+
+		if (hw_argc > 1) {
+			char *p;
+			int i, j, len = 4;
+
+			for (i = 0; i <= hw_argc - 2; i++)
+				len += strlen(as->argv[i]) + 1;
+			p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
+			if (!p) {
+				ti->error = "memory allocation failed";
+				r = -ENOMEM;
+				goto done;
+			}
+			j = sprintf(p, "%d", hw_argc - 1);
+			for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
+				j = sprintf(p, "%s", as->argv[i]);
+		}
+
 		goto done;
 	}
 
diff --git a/drivers/scsi/device_handler/Kconfig b/drivers/scsi/device_handler/Kconfig
index da8207b..2543b31 100644
--- a/drivers/scsi/device_handler/Kconfig
+++ b/drivers/scsi/device_handler/Kconfig
@@ -11,6 +11,12 @@ menuconfig SCSI_DH
 	  devices utilized in multipath configurations. Say Y here to
 	  select support for specific hardware.
 
+config SCSI_DH_EMC
+	tristate "EMC CLARiiON Device Handler"
+	depends on SCSI_DH
+	help
+	If you have a EMC CLARiiON select y. Otherwise, say N.
+
 config SCSI_DH_RDAC
 	tristate "LSI RDAC Device Handler"
 	depends on SCSI_DH
diff --git a/drivers/scsi/device_handler/Makefile b/drivers/scsi/device_handler/Makefile
index 5e8aebc..d6bd0d6 100644
--- a/drivers/scsi/device_handler/Makefile
+++ b/drivers/scsi/device_handler/Makefile
@@ -3,4 +3,5 @@
 #
 obj-$(CONFIG_SCSI_DH)		+= scsi_dh.o
 obj-$(CONFIG_SCSI_DH_RDAC)	+= scsi_dh_rdac.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.c b/drivers/scsi/device_handler/scsi_dh.c
index fcbf552..1db3b4a 100644
--- a/drivers/scsi/device_handler/scsi_dh.c
+++ b/drivers/scsi/device_handler/scsi_dh.c
@@ -446,6 +446,44 @@ int scsi_dh_activate(struct request_queue *q)
 EXPORT_SYMBOL_GPL(scsi_dh_activate);
 
 /*
+ * scsi_dh_set_params - set the parameters for the device as per the
+ *      string specified in params.
+ * @q - Request queue that is associated with the scsi_device for
+ *      which the parameters to be set.
+ * @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".
+ */
+int scsi_dh_set_params(struct request_queue *q, const char *params)
+{
+	int err = -SCSI_DH_NOSYS;
+	unsigned long flags;
+	struct scsi_device *sdev;
+	struct scsi_dh_data *scsi_dh_data;
+	struct scsi_device_handler *scsi_dh = NULL;
+
+	spin_lock_irqsave(q->queue_lock, flags);
+	sdev = q->queuedata;
+	if (sdev) {
+		scsi_dh_data = retrieve_scsi_dh_data(sdev);
+		if (scsi_dh_data)
+			scsi_dh = scsi_dh_data->scsi_dh;
+	}
+
+	if (scsi_dh && scsi_dh->set_params && get_device(&sdev->sdev_gendev))
+		err = 0;
+	spin_unlock_irqrestore(q->queue_lock, flags);
+
+	if (err)
+		return err;
+	err = scsi_dh->set_params(sdev, params);
+	put_device(&sdev->sdev_gendev);
+	return err;
+}
+EXPORT_SYMBOL_GPL(scsi_dh_set_params);
+
+/*
  * scsi_dh_handler_exist - Return TRUE(1) if a device handler exists for
  *	the given name. FALSE(0) otherwise.
  * @name - name of the device handler.
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 0000000..c4a7ffb
--- /dev/null
+++ b/drivers/scsi/device_handler/scsi_dh_emc.c
@@ -0,0 +1,734 @@
+/*
+ * 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
+ *
+ * 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, 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; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include <linux/list.h>
+#include <scsi/scsi.h>
+#include <scsi/scsi_eh.h>
+#include <scsi/scsi_dh.h>
+#include <scsi/scsi_cmnd.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];
+	/*
+	 * SCSI sense buffer for commands -- assumes serial issuance
+	 * and completion sequence of all commands for same multipath.
+	 */
+	unsigned char sense[SCSI_SENSE_BUFFERSIZE];
+	unsigned int senselen;
+	/*
+	 * 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;
+};
+
+static inline struct clariion_dh_data
+			*get_clariion_data(struct scsi_device *sdev)
+{
+	struct scsi_dh_data *scsi_dh_data = retrieve_scsi_dh_data(sdev);
+	BUG_ON(scsi_dh_data == NULL);
+	return ((struct clariion_dh_data *) scsi_dh_data->buf);
+}
+
+/*
+ * Parse MODE_SELECT cmd reply.
+ */
+static int trespass_endio(struct scsi_device *sdev, char *sense)
+{
+	int err = SCSI_DH_IO;
+	struct scsi_sense_hdr sshdr;
+
+	if (!scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, &sshdr)) {
+		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;
+	} else {
+		sdev_printk(KERN_INFO, sdev,
+			    "%s: failed to send MODE SELECT, no sense available\n",
+			    CLARIION_NAME);
+	}
+	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];
+
+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;
+}
+
+/*
+ * Get block request for REQ_BLOCK_PC command issued to path.  Currently
+ * limited to MODE_SELECT (trespass) and INQUIRY (VPD page 0xC0) commands.
+ *
+ * Uses data and sense buffers in hardware handler context structure and
+ * assumes serial servicing of commands, both issuance and completion.
+ */
+static struct request *get_req(struct scsi_device *sdev, int cmd,
+				unsigned char *buffer)
+{
+	struct request *rq;
+	int len = 0;
+
+	rq = blk_get_request(sdev->request_queue,
+			(cmd != INQUIRY) ? WRITE : READ, GFP_NOIO);
+	if (!rq) {
+		sdev_printk(KERN_INFO, sdev, "get_req: blk_get_request failed");
+		return NULL;
+	}
+
+	memset(rq->cmd, 0, BLK_MAX_CDB);
+	rq->cmd[0] = cmd;
+	rq->cmd_len = COMMAND_SIZE(cmd);
+
+	switch (cmd) {
+	case MODE_SELECT:
+		len = sizeof(short_trespass);
+		rq->flags |= REQ_RW;
+		rq->cmd[1] = 0x10;
+		rq->cmd[4] = len;
+		break;
+	case MODE_SELECT_10:
+		len = sizeof(long_trespass);
+		rq->flags |= REQ_RW;
+		rq->cmd[1] = 0x10;
+		rq->cmd[8] = len;
+		break;
+	case INQUIRY:
+		len = CLARIION_BUFFER_SIZE;
+		rq->cmd[4] = len;
+		memset(buffer, 0, len);
+		break;
+	default:
+		BUG_ON(1);
+		break;
+	}
+
+	rq->flags |= REQ_FAILFAST | REQ_BLOCK_PC;
+	rq->timeout = CLARIION_TIMEOUT;
+	rq->retries = CLARIION_RETRIES;
+
+	if (blk_rq_map_kern(rq->q, rq, buffer, len, GFP_NOIO)) {
+		blk_put_request(rq);
+		return NULL;
+	}
+
+	return rq;
+}
+
+static int send_inquiry_cmd(struct scsi_device *sdev, int page,
+			    struct clariion_dh_data *csdev)
+{
+	struct request *rq = get_req(sdev, INQUIRY, csdev->buffer);
+	int err;
+
+	if (!rq)
+		return SCSI_DH_RES_TEMP_UNAVAIL;
+
+	rq->sense = csdev->sense;
+	memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
+	rq->sense_len = csdev->senselen = 0;
+
+	rq->cmd[0] = INQUIRY;
+	if (page != 0) {
+		rq->cmd[1] = 1;
+		rq->cmd[2] = page;
+	}
+	err = blk_execute_rq(sdev->request_queue, NULL, rq, 1);
+	if (err == -EIO) {
+		sdev_printk(KERN_INFO, sdev,
+			    "%s: failed to send %s INQUIRY: %x\n",
+			    CLARIION_NAME, page?"EVPD":"standard",
+			    rq->errors);
+		csdev->senselen = rq->sense_len;
+		err = SCSI_DH_IO;
+	}
+
+	blk_put_request(rq);
+
+	return err;
+}
+
+static int send_trespass_cmd(struct scsi_device *sdev,
+			    struct clariion_dh_data *csdev)
+{
+	struct request *rq;
+	unsigned char *page22;
+	int err, len, cmd;
+
+	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);
+		cmd = MODE_SELECT;
+	} else {
+		page22 = long_trespass;
+		if (!(csdev->flags & CLARIION_HONOR_RESERVATIONS))
+			/* Set Honor Reservations bit */
+			page22[10] |= 0x80;
+		len = sizeof(long_trespass);
+		cmd = MODE_SELECT_10;
+	}
+	BUG_ON((len > CLARIION_BUFFER_SIZE));
+	memcpy(csdev->buffer, page22, len);
+
+	rq = get_req(sdev, cmd, csdev->buffer);
+	if (!rq)
+		return SCSI_DH_RES_TEMP_UNAVAIL;
+
+	rq->sense = csdev->sense;
+	memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
+	rq->sense_len = csdev->senselen = 0;
+
+	err = blk_execute_rq(sdev->request_queue, NULL, rq, 1);
+	if (err == -EIO) {
+		if (rq->sense_len) {
+			err = trespass_endio(sdev, csdev->sense);
+		} else {
+			sdev_printk(KERN_INFO, sdev,
+				    "%s: failed to send MODE SELECT: %x\n",
+				    CLARIION_NAME, rq->errors);
+		}
+	}
+
+	blk_put_request(rq);
+
+	return err;
+}
+
+static int 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 SCSI_MLQUEUE_DIS_FINISH;
+		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 SCSI_MLQUEUE_DIS_FINISH;
+		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 SCSI_MLQUEUE_IMM_RETRY;
+		break;
+	}
+
+	return 0;
+}
+
+static int clariion_prep_fn(struct scsi_device *sdev, struct request *req)
+{
+	struct clariion_dh_data *h = get_clariion_data(sdev);
+	int ret = BLKPREP_OK;
+
+	if (h->lun_state != CLARIION_LUN_OWNED) {
+		ret = BLKPREP_KILL;
+		req->flags |= REQ_QUIET;
+	}
+	return ret;
+
+}
+
+static int clariion_std_inquiry(struct scsi_device *sdev,
+				struct clariion_dh_data *csdev)
+{
+	int err;
+	char *sp_model;
+
+	err = send_inquiry_cmd(sdev, 0, csdev);
+	if (err != SCSI_DH_OK && csdev->senselen) {
+		struct scsi_sense_hdr sshdr;
+
+		if (scsi_normalize_sense(csdev->sense, SCSI_SENSE_BUFFERSIZE,
+					 &sshdr)) {
+			sdev_printk(KERN_ERR, sdev, "%s: INQUIRY sense code "
+				    "%02x/%02x/%02x\n", CLARIION_NAME,
+				    sshdr.sense_key, sshdr.asc, sshdr.ascq);
+		}
+		err = SCSI_DH_IO;
+		goto out;
+	}
+
+	sp_model = parse_sp_model(sdev, csdev->buffer);
+	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, retry = CLARIION_RETRIES;
+
+retry:
+	err = send_inquiry_cmd(sdev, 0xC0, csdev);
+	if (err != SCSI_DH_OK && csdev->senselen) {
+		struct scsi_sense_hdr sshdr;
+
+		err = scsi_normalize_sense(csdev->sense, SCSI_SENSE_BUFFERSIZE,
+					   &sshdr);
+		if (!err)
+			return SCSI_DH_IO;
+
+		err = clariion_check_sense(sdev, &sshdr);
+		if (retry > 0 && err == SCSI_MLQUEUE_IMM_RETRY) {
+			retry--;
+			goto retry;
+		}
+		sdev_printk(KERN_ERR, sdev, "%s: INQUIRY sense code "
+			    "%02x/%02x/%02x\n", CLARIION_NAME,
+			      sshdr.sense_key, sshdr.asc, sshdr.ascq);
+		err = SCSI_DH_IO;
+	} else {
+		err = parse_sp_info_reply(sdev, csdev);
+	}
+	return err;
+}
+
+static int clariion_activate(struct scsi_device *sdev)
+{
+	struct clariion_dh_data *csdev = get_clariion_data(sdev);
+	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');
+	return result;
+}
+
+/*
+ * 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 = get_clariion_data(sdev);
+	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 const struct scsi_dh_devlist clariion_dev_list[] = {
+	{"DGC", "RAID"},
+	{"DGC", "DISK"},
+	{"DGC", "VRAID"},
+	{NULL, NULL},
+};
+
+static int clariion_bus_attach(struct scsi_device *sdev);
+static void clariion_bus_detach(struct scsi_device *sdev);
+
+static struct scsi_device_handler clariion_dh = {
+	.name		= CLARIION_NAME,
+	.module		= THIS_MODULE,
+	.devlist	= clariion_dev_list,
+	.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 clariion_bus_attach(struct scsi_device *sdev)
+{
+	struct scsi_dh_data *scsi_dh_data;
+	struct clariion_dh_data *h;
+	unsigned long flags;
+	int err;
+
+	scsi_dh_data = kzalloc(sizeof(struct scsi_device_handler *)
+			       + sizeof(*h) , GFP_KERNEL);
+	if (!scsi_dh_data) {
+		sdev_printk(KERN_ERR, sdev, "%s: Attach failed\n",
+			    CLARIION_NAME);
+		return -ENOMEM;
+	}
+
+	scsi_dh_data->scsi_dh = &clariion_dh;
+	h = (struct clariion_dh_data *) scsi_dh_data->buf;
+	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;
+
+	if (!try_module_get(THIS_MODULE))
+		goto failed;
+
+	spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
+	store_scsi_dh_data(sdev, scsi_dh_data);
+	spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
+
+	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');
+
+	return 0;
+
+failed:
+	kfree(scsi_dh_data);
+	sdev_printk(KERN_ERR, sdev, "%s: not attached\n",
+		    CLARIION_NAME);
+	return -EINVAL;
+}
+
+static void clariion_bus_detach(struct scsi_device *sdev)
+{
+	struct scsi_dh_data *scsi_dh_data;
+	unsigned long flags;
+
+	spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
+	scsi_dh_data = retrieve_scsi_dh_data(sdev);
+	store_scsi_dh_data(sdev, NULL);
+	spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
+
+	sdev_printk(KERN_NOTICE, sdev, "%s: Detached\n",
+		    CLARIION_NAME);
+
+	kfree(scsi_dh_data);
+	module_put(THIS_MODULE);
+}
+
+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/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 34fa94c..fddaf3e 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -190,6 +190,7 @@ struct scsi_device_handler {
 	void (*detach)(struct scsi_device *);
 	int (*activate)(struct scsi_device *);
 	int (*prep_fn)(struct scsi_device *, struct request *);
+	int (*set_params)(struct scsi_device *, const char *);
 };
 
 struct scsi_dh_data {
diff --git a/include/scsi/scsi_dh.h b/include/scsi/scsi_dh.h
index fce4e8b..b3e7da5 100644
--- a/include/scsi/scsi_dh.h
+++ b/include/scsi/scsi_dh.h
@@ -65,6 +65,7 @@ extern int scsi_dh_activate(struct request_queue *);
 extern int scsi_dh_handler_exist(const char *);
 extern int scsi_dh_attach(struct request_queue *, const char *);
 extern void scsi_dh_detach(struct request_queue *);
+extern int scsi_dh_set_params(struct request_queue *, const char *);
 #else
 static inline int scsi_dh_activate(struct request_queue *req)
 {
@@ -82,4 +83,9 @@ static inline void scsi_dh_detach(struct request_queue *q)
 {
 	return;
 }
+
+static inline int scsi_dh_set_params(struct request_queue *req, const char *params)
+{
+	return -SCSI_DH_NOSYS;
+}
 #endif