ALUA device handler update, part 1

index e7649ed..54d446c 100644
@@ -153,76 +153,11 @@ static void scsi_dh_handler_detach(struct scsi_device *sdev)
 	module_put(sdev->handler->module);
 }
 
-/*
- * Functions for sysfs attribute 'dh_state'
- */
-static ssize_t
-store_dh_state(struct device *dev, struct device_attribute *attr,
-	       const char *buf, size_t count)
-{
-	struct scsi_device *sdev = to_scsi_device(dev);
-	struct scsi_device_handler *scsi_dh;
-	int err = -EINVAL;
-
-	if (sdev->sdev_state == SDEV_CANCEL ||
-	    sdev->sdev_state == SDEV_DEL)
-		return -ENODEV;
-
-	if (!sdev->handler) {
-		/*
-		 * Attach to a device handler
-		 */
-		scsi_dh = scsi_dh_lookup(buf);
-		if (!scsi_dh)
-			return err;
-		err = scsi_dh_handler_attach(sdev, scsi_dh);
-	} else {
-		if (!strncmp(buf, "detach", 6)) {
-			/*
-			 * Detach from a device handler
-			 */
-			sdev_printk(KERN_WARNING, sdev,
-				    "can't detach handler %s.\n",
-				    sdev->handler->name);
-			err = -EINVAL;
-		} else if (!strncmp(buf, "activate", 8)) {
-			/*
-			 * Activate a device handler
-			 */
-			if (sdev->handler->activate)
-				err = sdev->handler->activate(sdev, NULL, NULL);
-			else
-				err = 0;
-		}
-	}
-
-	return err<0?err:count;
-}
-
-static ssize_t
-show_dh_state(struct device *dev, struct device_attribute *attr, char *buf)
-{
-	struct scsi_device *sdev = to_scsi_device(dev);
-
-	if (!sdev->handler)
-		return snprintf(buf, 20, "detached\n");
-
-	return snprintf(buf, 20, "%s\n", sdev->handler->name);
-}
-
-static struct device_attribute scsi_dh_state_attr =
-	__ATTR(dh_state, S_IRUGO | S_IWUSR, show_dh_state,
-	       store_dh_state);
-
 int scsi_dh_add_device(struct scsi_device *sdev)
 {
 	struct scsi_device_handler *devinfo = NULL;
 	const char *drv;
-	int err;
-
-	err = device_create_file(&sdev->sdev_gendev, &scsi_dh_state_attr);
-	if (err)
-		return err;
+	int err = 0;
 
 	drv = scsi_dh_find_driver(sdev);
 	if (drv)

@@ -238,11 +173,6 @@ void scsi_dh_release_device(struct scsi_device *sdev)
 		scsi_dh_handler_detach(sdev);
 }
 
-void scsi_dh_remove_device(struct scsi_device *sdev)
-{
-	device_remove_file(&sdev->sdev_gendev, &scsi_dh_state_attr);
-}
-
 /*
  * scsi_register_device_handler - register a device handler personality
  *      module.

index 4d01cdb1..27b4d0a 100644
@@ -174,12 +174,11 @@ extern struct async_domain scsi_sd_probe_domain;
 #ifdef CONFIG_SCSI_DH
 int scsi_dh_add_device(struct scsi_device *sdev);
 void scsi_dh_release_device(struct scsi_device *sdev);
-void scsi_dh_remove_device(struct scsi_device *sdev);
 #else
 static inline int scsi_dh_add_device(struct scsi_device *sdev) { return 0; }
 static inline void scsi_dh_release_device(struct scsi_device *sdev) { }
-static inline void scsi_dh_remove_device(struct scsi_device *sdev) { }
 #endif
+static inline void scsi_dh_remove_device(struct scsi_device *sdev) { }
 
 /* 
  * internal scsi timeout functions: for use by mid-layer and transport

76 lines not on this page · raw message

index fc3cd26..d015374 100644
@@ -1120,11 +1120,12 @@ int scsi_sysfs_add_sdev(struct scsi_device *sdev)
 	}
 
 	error = scsi_dh_add_device(sdev);
-	if (error) {
+	if (error)
+		/*
+		 * device_handler is optional, so any error can be ignored
+		 */
 		sdev_printk(KERN_INFO, sdev,
 				"failed to add device handler: %d\n", error);
-		return error;
-	}
 
 	device_enable_async_suspend(&sdev->sdev_dev);
 	error = device_add(&sdev->sdev_dev);

index cc2773b..7d01ef0 100644
@@ -320,6 +320,18 @@ static int alua_check_tpgs(struct scsi_device *sdev, struct alua_dh_data *h)
 {
 	int err = SCSI_DH_OK;
 
+	/*
+	 * ALUA support for non-disk devices is fraught with
+	 * difficulties, so disable it for now.
+	 */
+	if (sdev->type != TYPE_DISK) {
+		h->tpgs = TPGS_MODE_NONE;
+		sdev_printk(KERN_INFO, sdev,
+			    "%s: disable for non-disk devices\n",
+			    ALUA_DH_NAME);
+		return SCSI_DH_DEV_UNSUPP;
+	}
+
 	h->tpgs = scsi_device_tpgs(sdev);
 	switch (h->tpgs) {
 	case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT:

index 7d01ef0..9b3b2f7 100644
@@ -131,43 +131,6 @@ static struct request *get_alua_req(struct scsi_device *sdev,
 }
 
 /*
- * submit_vpd_inquiry - Issue an INQUIRY VPD page 0x83 command
- * @sdev: sdev the command should be sent to
- */
-static int submit_vpd_inquiry(struct scsi_device *sdev, struct alua_dh_data *h)
-{
-	struct request *rq;
-	int err = SCSI_DH_RES_TEMP_UNAVAIL;
-
-	rq = get_alua_req(sdev, h->buff, h->bufflen, READ);
-	if (!rq)
-		goto done;
-
-	/* Prepare the command. */
-	rq->cmd[0] = INQUIRY;
-	rq->cmd[1] = 1;
-	rq->cmd[2] = 0x83;
-	rq->cmd[4] = h->bufflen;
-	rq->cmd_len = COMMAND_SIZE(INQUIRY);
-
-	rq->sense = h->sense;
-	memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
-	rq->sense_len = h->senselen = 0;
-
-	err = blk_execute_rq(rq->q, NULL, rq, 1);
-	if (err == -EIO) {
-		sdev_printk(KERN_INFO, sdev,
-			    "%s: evpd inquiry failed with %x\n",
-			    ALUA_DH_NAME, rq->errors);
-		h->senselen = rq->sense_len;
-		err = SCSI_DH_IO;
-	}
-	blk_put_request(rq);
-done:
-	return err;
-}
-
-/*
  * submit_rtpg - Issue a REPORT TARGET GROUP STATES command
  * @sdev: sdev the command should be sent to
  */

@@ -359,43 +322,29 @@ static int alua_check_tpgs(struct scsi_device *sdev, struct alua_dh_data *h)
 }
 
 /*
- * alua_vpd_inquiry - Evaluate INQUIRY vpd page 0x83
+ * 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_vpd_inquiry(struct scsi_device *sdev, struct alua_dh_data *h)
+static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h)
 {
-	int len;
-	unsigned err;
 	unsigned char *d;
+	unsigned char __rcu *vpd_pg83;
 
- retry:
-	err = submit_vpd_inquiry(sdev, h);
-
-	if (err != SCSI_DH_OK)
-		return err;
-
-	/* Check if vpd page exceeds initial buffer */
-	len = (h->buff[2] << 8) + h->buff[3] + 4;
-	if (len > h->bufflen) {
-		/* Resubmit with the correct length */
-		if (realloc_buffer(h, len)) {
-			sdev_printk(KERN_WARNING, sdev,
-				    "%s: kmalloc buffer failed\n",
-				    ALUA_DH_NAME);
-			/* Temporary failure, bypass */
-			return SCSI_DH_DEV_TEMP_BUSY;
-		}
-		goto retry;
+	rcu_read_lock();
+	if (!rcu_dereference(sdev->vpd_pg83)){
+		rcu_read_unlock();
+		return SCSI_DH_DEV_UNSUPP;
 	}
 
 	/*
-	 * Now look for the correct descriptor.
+	 * Look for the correct descriptor.
 	 */
-	d = h->buff + 4;
-	while (d < h->buff + len) {
+	vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
+	d = vpd_pg83 + 4;
+	while (d < vpd_pg83 + sdev->vpd_pg83_len) {
 		switch (d[1] & 0xf) {
 		case 0x4:
 			/* Relative target port */

@@ -410,6 +359,7 @@ static int alua_vpd_inquiry(struct scsi_device *sdev, struct alua_dh_data *h)
 		}
 		d += d[3] + 4;
 	}
+	rcu_read_unlock();
 
 	if (h->group_id == -1) {
 		/*

@@ -422,14 +372,13 @@ static int alua_vpd_inquiry(struct scsi_device *sdev, struct alua_dh_data *h)
 			    ALUA_DH_NAME);
 		h->state = TPGS_STATE_OPTIMIZED;
 		h->tpgs = TPGS_MODE_NONE;
-		err = SCSI_DH_DEV_UNSUPP;
-	} else {
-		sdev_printk(KERN_INFO, sdev,
-			    "%s: port group %02x rel port %02x\n",
-			    ALUA_DH_NAME, h->group_id, h->rel_port);
+		return SCSI_DH_DEV_UNSUPP;
 	}
+	sdev_printk(KERN_INFO, sdev,
+		    "%s: port group %02x rel port %02x\n",
+		    ALUA_DH_NAME, h->group_id, h->rel_port);
 
-	return err;
+	return 0;
 }
 
 static char print_alua_state(int state)

@@ -692,7 +641,7 @@ static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h)
 	if (err != SCSI_DH_OK)
 		goto out;
 
-	err = alua_vpd_inquiry(sdev, h);
+	err = alua_check_vpd(sdev, h);
 	if (err != SCSI_DH_OK)
 		goto out;
 

index 9b3b2f7..c63f304 100644
@@ -310,12 +310,18 @@ static int alua_check_tpgs(struct scsi_device *sdev, struct alua_dh_data *h)
 		sdev_printk(KERN_INFO, sdev, "%s: supports implicit TPGS\n",
 			    ALUA_DH_NAME);
 		break;
-	default:
-		h->tpgs = TPGS_MODE_NONE;
+	case TPGS_MODE_NONE:
 		sdev_printk(KERN_INFO, sdev, "%s: not supported\n",
 			    ALUA_DH_NAME);
 		err = SCSI_DH_DEV_UNSUPP;
 		break;
+	default:
+		sdev_printk(KERN_INFO, sdev,
+			    "%s: unsupported TPGS setting %d\n",
+			    ALUA_DH_NAME, h->tpgs);
+		h->tpgs = TPGS_MODE_NONE;
+		err = SCSI_DH_DEV_UNSUPP;
+		break;
 	}
 
 	return err;

index c63f304..240a5dc 100644
@@ -73,7 +73,6 @@ struct alua_dh_data {
 	int			bufflen;
 	unsigned char		transition_tmo;
 	unsigned char		sense[SCSI_SENSE_BUFFERSIZE];
-	int			senselen;
 	struct scsi_device	*sdev;
 	activate_complete	callback_fn;
 	void			*callback_data;

@@ -158,14 +157,13 @@ static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data *h,
 
 	rq->sense = h->sense;
 	memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
-	rq->sense_len = h->senselen = 0;
+	rq->sense_len = 0;
 
 	err = blk_execute_rq(rq->q, NULL, rq, 1);
 	if (err == -EIO) {
 		sdev_printk(KERN_INFO, sdev,
 			    "%s: rtpg failed with %x\n",
 			    ALUA_DH_NAME, rq->errors);
-		h->senselen = rq->sense_len;
 		err = SCSI_DH_IO;
 	}
 	blk_put_request(rq);

@@ -194,9 +192,8 @@ static void stpg_endio(struct request *req, int error)
 		goto done;
 	}
 
-	if (req->sense_len > 0) {
-		err = scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE,
-					   &sense_hdr);
+	if (scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE,
+				 &sense_hdr)) {
 		if (!err) {
 			err = SCSI_DH_IO;
 			goto done;

@@ -265,7 +262,7 @@ static unsigned submit_stpg(struct alua_dh_data *h)
 
 	rq->sense = h->sense;
 	memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
-	rq->sense_len = h->senselen = 0;
+	rq->sense_len = 0;
 	rq->end_io_data = h;
 
 	blk_execute_rq_nowait(rq->q, NULL, rq, 1, stpg_endio);

@@ -514,10 +511,9 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h, int wait_
  retry:
 	err = submit_rtpg(sdev, h, rtpg_ext_hdr_req);
 
-	if (err == SCSI_DH_IO && h->senselen > 0) {
-		err = scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE,
-					   &sense_hdr);
-		if (!err)
+	if (err == SCSI_DH_IO) {
+		if (!scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE,
+					  &sense_hdr))
 			return SCSI_DH_IO;
 
 		/*

index 240a5dc..b817963 100644
@@ -23,6 +23,7 @@
 #include <linux/delay.h>
 #include <linux/module.h>
 #include <scsi/scsi.h>
+#include <scsi/scsi_dbg.h>
 #include <scsi/scsi_eh.h>
 #include <scsi/scsi_dh.h>
 

@@ -194,19 +195,14 @@ static void stpg_endio(struct request *req, int error)
 
 	if (scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE,
 				 &sense_hdr)) {
-		if (!err) {
-			err = SCSI_DH_IO;
-			goto done;
-		}
 		err = alua_check_sense(h->sdev, &sense_hdr);
 		if (err == ADD_TO_MLQUEUE) {
 			err = SCSI_DH_RETRY;
 			goto done;
 		}
-		sdev_printk(KERN_INFO, h->sdev,
-			    "%s: stpg sense code: %02x/%02x/%02x\n",
-			    ALUA_DH_NAME, sense_hdr.sense_key,
-			    sense_hdr.asc, sense_hdr.ascq);
+		sdev_printk(KERN_INFO, h->sdev, "%s: stpg failed\n",
+			    ALUA_DH_NAME);
+		scsi_print_sense_hdr(h->sdev, ALUA_DH_NAME, &sense_hdr);
 		err = SCSI_DH_IO;
 	} else if (error)
 		err = SCSI_DH_IO;

@@ -532,13 +528,16 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h, int wait_
 		}
 
 		err = alua_check_sense(sdev, &sense_hdr);
-		if (err == ADD_TO_MLQUEUE && time_before(jiffies, expiry))
+		if (err == ADD_TO_MLQUEUE && time_before(jiffies, expiry)) {
+			sdev_printk(KERN_ERR, sdev, "%s: rtpg retry\n",
+				    ALUA_DH_NAME);
+			scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 			goto retry;
-		sdev_printk(KERN_INFO, sdev,
-			    "%s: rtpg sense code %02x/%02x/%02x\n",
-			    ALUA_DH_NAME, sense_hdr.sense_key,
-			    sense_hdr.asc, sense_hdr.ascq);
-		err = SCSI_DH_IO;
+		}
+		sdev_printk(KERN_ERR, sdev, "%s: rtpg failed\n",
+			    ALUA_DH_NAME);
+		scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
+		return SCSI_DH_IO;
 	}
 	if (err != SCSI_DH_OK)
 		return err;

index b817963..50fe87c 100644
@@ -138,11 +138,13 @@ static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data *h,
 			    bool rtpg_ext_hdr_req)
 {
 	struct request *rq;
-	int err = SCSI_DH_RES_TEMP_UNAVAIL;
+	int err = 0;
 
 	rq = get_alua_req(sdev, h->buff, h->bufflen, READ);
-	if (!rq)
+	if (!rq) {
+		err = DRIVER_BUSY << 24;
 		goto done;
+	}
 
 	/* Prepare the command. */
 	rq->cmd[0] = MAINTENANCE_IN;

@@ -160,13 +162,9 @@ static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data *h,
 	memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
 	rq->sense_len = 0;
 
-	err = blk_execute_rq(rq->q, NULL, rq, 1);
-	if (err == -EIO) {
-		sdev_printk(KERN_INFO, sdev,
-			    "%s: rtpg failed with %x\n",
-			    ALUA_DH_NAME, rq->errors);
-		err = SCSI_DH_IO;
-	}
+	blk_execute_rq(rq->q, NULL, rq, 1);
+	if (rq->errors)
+		err = rq->errors;
 	blk_put_request(rq);
 done:
 	return err;

@@ -493,7 +491,7 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h, int wait_
 	struct scsi_sense_hdr sense_hdr;
 	int len, k, off, valid_states = 0;
 	unsigned char *ucp;
-	unsigned err;
+	unsigned err, retval;
 	bool rtpg_ext_hdr_req = 1;
 	unsigned long expiry, interval = 0;
 	unsigned int tpg_desc_tbl_off;

@@ -505,12 +503,17 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h, int wait_
 		expiry = round_jiffies_up(jiffies + h->transition_tmo * HZ);
 
  retry:
-	err = submit_rtpg(sdev, h, rtpg_ext_hdr_req);
-
-	if (err == SCSI_DH_IO) {
+	retval = submit_rtpg(sdev, h, rtpg_ext_hdr_req);
+	if (retval) {
 		if (!scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE,
-					  &sense_hdr))
+					  &sense_hdr)) {
+			sdev_printk(KERN_INFO, sdev,
+				    "%s: rtpg failed, result %d\n",
+				    ALUA_DH_NAME, retval);
+			if (driver_byte(retval) == DRIVER_BUSY)
+				return SCSI_DH_DEV_TEMP_BUSY;
 			return SCSI_DH_IO;
+		}
 
 		/*
 		 * submit_rtpg() has failed on existing arrays

@@ -539,8 +542,6 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h, int wait_
 		scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 		return SCSI_DH_IO;
 	}
-	if (err != SCSI_DH_OK)
-		return err;
 
 	len = (h->buff[0] << 24) + (h->buff[1] << 16) +
 		(h->buff[2] << 8) + h->buff[3] + 4;

index 50fe87c..ea626732 100644
@@ -171,13 +171,11 @@ done:
 }
 
 /*
- * alua_stpg - Evaluate SET TARGET GROUP STATES
+ * stpg_endio - Evaluate SET TARGET GROUP STATES
  * @sdev: the device to be evaluated
  * @state: the new target group state
  *
- * Send a SET TARGET GROUP STATES command to the device.
- * We only have to test here if we should resubmit the command;
- * any other error is assumed as a failure.
+ * Evaluate a SET TARGET GROUP STATES command response.
  */
 static void stpg_endio(struct request *req, int error)
 {

index f8170e9..56710e0 100644
@@ -12,8 +12,6 @@ extern size_t __scsi_format_command(char *, size_t,
 				   const unsigned char *, size_t);
 extern void scsi_show_extd_sense(const struct scsi_device *, const char *,
 				 unsigned char, unsigned char);
-extern void scsi_show_sense_hdr(const struct scsi_device *, const char *,
-				const struct scsi_sense_hdr *);
 extern void scsi_print_sense_hdr(const struct scsi_device *, const char *,
 				 const struct scsi_sense_hdr *);
 extern void scsi_print_sense(const struct scsi_cmnd *);

index ea626732..03f8190 100644
@@ -59,8 +59,9 @@
 #define ALUA_FAILOVER_TIMEOUT		60
 #define ALUA_FAILOVER_RETRIES		5
 
-/* flags passed from user level */
+/* device handler flags */
 #define ALUA_OPTIMIZE_STPG		1
+#define ALUA_RTPG_EXT_HDR_UNSUPP	2
 
 struct alua_dh_data {
 	int			group_id;

@@ -134,8 +135,7 @@ static struct request *get_alua_req(struct scsi_device *sdev,
  * submit_rtpg - Issue a REPORT TARGET GROUP STATES command
  * @sdev: sdev the command should be sent to
  */
-static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data *h,
-			    bool rtpg_ext_hdr_req)
+static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
 {
 	struct request *rq;
 	int err = 0;

@@ -148,7 +148,7 @@ static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data *h,
 
 	/* Prepare the command. */
 	rq->cmd[0] = MAINTENANCE_IN;
-	if (rtpg_ext_hdr_req)
+	if (!(h->flags & ALUA_RTPG_EXT_HDR_UNSUPP))
 		rq->cmd[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT;
 	else
 		rq->cmd[1] = MI_REPORT_TARGET_PGS;

@@ -490,7 +490,6 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h, int wait_
 	int len, k, off, valid_states = 0;
 	unsigned char *ucp;
 	unsigned err, retval;
-	bool rtpg_ext_hdr_req = 1;
 	unsigned long expiry, interval = 0;
 	unsigned int tpg_desc_tbl_off;
 	unsigned char orig_transition_tmo;

@@ -501,7 +500,7 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h, int wait_
 		expiry = round_jiffies_up(jiffies + h->transition_tmo * HZ);
 
  retry:
-	retval = submit_rtpg(sdev, h, rtpg_ext_hdr_req);
+	retval = submit_rtpg(sdev, h);
 	if (retval) {
 		if (!scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE,
 					  &sense_hdr)) {

@@ -521,10 +520,10 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h, int wait_
 		 * The retry without rtpg_ext_hdr_req set
 		 * handles this.
 		 */
-		if (rtpg_ext_hdr_req == 1 &&
+		if (!(h->flags & ALUA_RTPG_EXT_HDR_UNSUPP) &&
 		    sense_hdr.sense_key == ILLEGAL_REQUEST &&
 		    sense_hdr.asc == 0x24 && sense_hdr.ascq == 0) {
-			rtpg_ext_hdr_req = 0;
+			h->flags |= ALUA_RTPG_EXT_HDR_UNSUPP;
 			goto retry;
 		}
 

index 03f8190..d54f42e 100644
@@ -22,6 +22,7 @@
 #include <linux/slab.h>
 #include <linux/delay.h>
 #include <linux/module.h>
+#include <asm/unaligned.h>
 #include <scsi/scsi.h>
 #include <scsi/scsi_dbg.h>
 #include <scsi/scsi_eh.h>

@@ -152,10 +153,7 @@ static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
 		rq->cmd[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT;
 	else
 		rq->cmd[1] = MI_REPORT_TARGET_PGS;
-	rq->cmd[6] = (h->bufflen >> 24) & 0xff;
-	rq->cmd[7] = (h->bufflen >> 16) & 0xff;
-	rq->cmd[8] = (h->bufflen >>  8) & 0xff;
-	rq->cmd[9] = h->bufflen & 0xff;
+	put_unaligned_be32(h->bufflen, &rq->cmd[6]);
 	rq->cmd_len = COMMAND_SIZE(MAINTENANCE_IN);
 
 	rq->sense = h->sense;

@@ -236,8 +234,7 @@ static unsigned submit_stpg(struct alua_dh_data *h)
 	/* Prepare the data buffer */
 	memset(h->buff, 0, stpg_len);
 	h->buff[4] = TPGS_STATE_OPTIMIZED & 0x0f;
-	h->buff[6] = (h->group_id >> 8) & 0xff;
-	h->buff[7] = h->group_id & 0xff;
+	put_unaligned_be16(h->group_id, &h->buff[6]);
 
 	rq = get_alua_req(sdev, h->buff, stpg_len, WRITE);
 	if (!rq)

@@ -246,10 +243,7 @@ static unsigned submit_stpg(struct alua_dh_data *h)
 	/* Prepare the command. */
 	rq->cmd[0] = MAINTENANCE_OUT;
 	rq->cmd[1] = MO_SET_TARGET_PGS;
-	rq->cmd[6] = (stpg_len >> 24) & 0xff;
-	rq->cmd[7] = (stpg_len >> 16) & 0xff;
-	rq->cmd[8] = (stpg_len >>  8) & 0xff;
-	rq->cmd[9] = stpg_len & 0xff;
+	put_unaligned_be32(stpg_len, &rq->cmd[6]);
 	rq->cmd_len = COMMAND_SIZE(MAINTENANCE_OUT);
 
 	rq->sense = h->sense;

@@ -343,11 +337,11 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h)
 		switch (d[1] & 0xf) {
 		case 0x4:
 			/* Relative target port */
-			h->rel_port = (d[6] << 8) + d[7];
+			h->rel_port = get_unaligned_be16(&d[6]);
 			break;
 		case 0x5:
 			/* Target port group */
-			h->group_id = (d[6] << 8) + d[7];
+			h->group_id = get_unaligned_be16(&d[6]);
 			break;
 		default:
 			break;

@@ -540,8 +534,7 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h, int wait_
 		return SCSI_DH_IO;
 	}
 
-	len = (h->buff[0] << 24) + (h->buff[1] << 16) +
-		(h->buff[2] << 8) + h->buff[3] + 4;
+	len = get_unaligned_be32(&h->buff[0]) + 4;
 
 	if (len > h->bufflen) {
 		/* Resubmit with the correct length */

@@ -576,7 +569,7 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h, int wait_
 	     k < len;
 	     k += off, ucp += off) {
 
-		if (h->group_id == (ucp[2] << 8) + ucp[3]) {
+		if (h->group_id == get_unaligned_be16(&ucp[2])) {
 			h->state = ucp[0] & 0x0f;
 			h->pref = ucp[0] >> 7;
 			valid_states = ucp[1];

index d54f42e..c9751c9 100644
@@ -262,24 +262,23 @@ static unsigned submit_stpg(struct alua_dh_data *h)
  * Examine the TPGS setting of the sdev to find out if ALUA
  * is supported.
  */
-static int alua_check_tpgs(struct scsi_device *sdev, struct alua_dh_data *h)
+static int alua_check_tpgs(struct scsi_device *sdev)
 {
-	int err = SCSI_DH_OK;
+	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) {
-		h->tpgs = TPGS_MODE_NONE;
 		sdev_printk(KERN_INFO, sdev,
 			    "%s: disable for non-disk devices\n",
 			    ALUA_DH_NAME);
-		return SCSI_DH_DEV_UNSUPP;
+		return tpgs;
 	}
 
-	h->tpgs = scsi_device_tpgs(sdev);
-	switch (h->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",

@@ -296,18 +295,16 @@ static int alua_check_tpgs(struct scsi_device *sdev, struct alua_dh_data *h)
 	case TPGS_MODE_NONE:
 		sdev_printk(KERN_INFO, sdev, "%s: not supported\n",
 			    ALUA_DH_NAME);
-		err = SCSI_DH_DEV_UNSUPP;
 		break;
 	default:
 		sdev_printk(KERN_INFO, sdev,
 			    "%s: unsupported TPGS setting %d\n",
-			    ALUA_DH_NAME, h->tpgs);
-		h->tpgs = TPGS_MODE_NONE;
-		err = SCSI_DH_DEV_UNSUPP;
+			    ALUA_DH_NAME, tpgs);
+		tpgs = TPGS_MODE_NONE;
 		break;
 	}
 
-	return err;
+	return tpgs;
 }
 
 /*

@@ -627,10 +624,10 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h, int wait_
  */
 static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h)
 {
-	int err;
+	int err = SCSI_DH_DEV_UNSUPP;
 
-	err = alua_check_tpgs(sdev, h);
-	if (err != SCSI_DH_OK)
+	h->tpgs = alua_check_tpgs(sdev);
+	if (h->tpgs == TPGS_MODE_NONE)
 		goto out;
 
 	err = alua_check_vpd(sdev, h);

index c9751c9..abf05b4 100644
@@ -85,7 +85,6 @@ struct alua_dh_data {
 #define ALUA_POLICY_SWITCH_ALL		1
 
 static char print_alua_state(int);
-static int alua_check_sense(struct scsi_device *, struct scsi_sense_hdr *);
 
 static int realloc_buffer(struct alua_dh_data *h, unsigned len)
 {

@@ -189,8 +188,13 @@ static void stpg_endio(struct request *req, int error)
 
 	if (scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE,
 				 &sense_hdr)) {
-		err = alua_check_sense(h->sdev, &sense_hdr);
-		if (err == ADD_TO_MLQUEUE) {
+		if (sense_hdr.sense_key == NOT_READY &&
+		    sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) {
+			/* ALUA state transition already in progress */
+			err = SCSI_DH_OK;
+			goto done;
+		}
+		if (sense_hdr.sense_key == UNIT_ATTENTION) {
 			err = SCSI_DH_RETRY;
 			goto done;
 		}

@@ -399,28 +403,6 @@ static int alua_check_sense(struct scsi_device *sdev,
 			 * LUN Not Accessible - ALUA state transition
 			 */
 			return ADD_TO_MLQUEUE;
-		if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0b)
-			/*
-			 * LUN Not Accessible -- Target port in standby state
-			 */
-			return SUCCESS;
-		if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0c)
-			/*
-			 * LUN Not Accessible -- Target port in unavailable state
-			 */
-			return SUCCESS;
-		if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x12)
-			/*
-			 * LUN Not Ready -- Offline
-			 */
-			return SUCCESS;
-		if (sdev->allow_restart &&
-		    sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x02)
-			/*
-			 * if the device is not started, we need to wake
-			 * the error handler to start the motor
-			 */
-			return FAILED;
 		break;
 	case UNIT_ATTENTION:
 		if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00)

@@ -517,9 +499,16 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h, int wait_
 			h->flags |= ALUA_RTPG_EXT_HDR_UNSUPP;
 			goto retry;
 		}
-
-		err = alua_check_sense(sdev, &sense_hdr);
-		if (err == ADD_TO_MLQUEUE && time_before(jiffies, expiry)) {
+		/*
+		 * Retry on ALUA state transition or if any
+		 * UNIT ATTENTION occurred.
+		 */
+		if (sense_hdr.sense_key == NOT_READY &&
+		    sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a)
+			err = SCSI_DH_RETRY;
+		else if (sense_hdr.sense_key == UNIT_ATTENTION)
+			err = SCSI_DH_RETRY;
+		if (err == SCSI_DH_RETRY && time_before(jiffies, expiry)) {
 			sdev_printk(KERN_ERR, sdev, "%s: rtpg retry\n",
 				    ALUA_DH_NAME);
 			scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);

index dd8ad2a..5bd8a19 100644
@@ -3154,3 +3154,143 @@ void sdev_enable_disk_events(struct scsi_device *sdev)
 	atomic_dec(&sdev->disk_events_disable_depth);
 }
 EXPORT_SYMBOL(sdev_enable_disk_events);
+
+/*
+ * scsi_vpd_lun_id - return a unique device identification
+ * @sdev: SCSI device
+ * @id:   buffer for the identification
+ * @id_len:  length of the buffer
+ *
+ * Copies a unique device identification into @id based
+ * on the information in the VPD page 0x83 of the device.
+ * The string will be formatted as a SCSI name string.
+ *
+ * Returns the length of the identification or error on failure.
+ * If the identifier is longer than the supplied buffer the actual
+ * identifier length is returned and the buffer is not zero-padded.
+ */
+int scsi_vpd_lun_id(struct scsi_device *sdev, char *id, size_t id_len)
+{
+	u8 cur_id_type = 0xff;
+	u8 cur_id_size = 0;
+	unsigned char *d, *cur_id_str;
+	unsigned char __rcu *vpd_pg83;
+	int id_size = -EINVAL;
+
+	rcu_read_lock();
+	vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
+	if (!vpd_pg83) {
+		rcu_read_unlock();
+		return -ENXIO;
+	}
+
+	/*
+	 * Look for the correct descriptor.
+	 * Order of preference for lun descriptor:
+	 * - SCSI name string
+	 * - NAA IEEE Registered Extended
+	 * - EUI-64 based 16-byte
+	 * - EUI-64 based 12-byte
+	 * - NAA IEEE Registered
+	 * - NAA IEEE Extended
+	 * as longer descriptors reduce the likelyhood
+	 * of identification clashes.
+	 */
+
+	/* The id string must be at least 20 bytes + terminating NULL byte */
+	if (id_len < 21) {
+		rcu_read_unlock();
+		return -EINVAL;
+	}
+
+	memset(id, 0, id_len);
+	d = vpd_pg83 + 4;
+	while (d < vpd_pg83 + sdev->vpd_pg83_len) {
+		/* Skip designators not referring to the LUN */
+		if ((d[1] & 0x30) != 0x00)
+			goto next_desig;
+
+		switch (d[1] & 0xf) {
+		case 0x2:
+			/* EUI-64 */
+			if (cur_id_size > d[3])
+				break;
+			/* Prefer NAA IEEE Registered Extended */
+			if (cur_id_type == 0x3 &&
+			    cur_id_size == d[3])
+				break;
+			cur_id_size = d[3];
+			cur_id_str = d + 4;
+			cur_id_type = d[1] & 0xf;
+			switch (cur_id_size) {
+			case 8:
+				id_size = snprintf(id, id_len,
+						   "eui.%8phN",
+						   cur_id_str);
+				break;
+			case 12:
+				id_size = snprintf(id, id_len,
+						   "eui.%12phN",
+						   cur_id_str);
+				break;
+			case 16:
+				id_size = snprintf(id, id_len,
+						   "eui.%16phN",
+						   cur_id_str);
+				break;
+			default:
+				cur_id_size = 0;
+				break;
+			}
+			break;
+		case 0x3:
+			/* NAA */
+			if (cur_id_size > d[3])
+				break;
+			cur_id_size = d[3];
+			cur_id_str = d + 4;
+			cur_id_type = d[1] & 0xf;
+			switch (cur_id_size) {
+			case 8:
+				id_size = snprintf(id, id_len,
+						   "naa.%8phN",
+						   cur_id_str);
+				break;
+			case 16:
+				id_size = snprintf(id, id_len,
+						   "naa.%16phN",
+						   cur_id_str);
+				break;
+			default:
+				cur_id_size = 0;
+				break;
+			}
+			break;
+		case 0x8:
+			/* SCSI name string */
+			if (cur_id_size + 4 > d[3])
+				break;
+			/* Prefer others for truncated descriptor */
+			if (cur_id_size && d[3] > id_len)
+				break;
+			cur_id_size = id_size = d[3];
+			cur_id_str = d + 4;
+			cur_id_type = d[1] & 0xf;
+			if (cur_id_size >= id_len)
+				cur_id_size = id_len - 1;
+			memcpy(id, cur_id_str, cur_id_size);
+			/* Decrease priority for truncated descriptor */
+			if (cur_id_size != id_size)
+				cur_id_size = 6;
+			break;
+		default:
+			break;
+		}
+next_desig:
+		d += d[3] + 4;
+	}
+	rcu_read_unlock();
+
+	return id_size;
+}
+EXPORT_SYMBOL(scsi_vpd_lun_id);

index bde4077..4c49cfa 100644
@@ -415,6 +415,7 @@ static inline int scsi_execute_req(struct scsi_device *sdev,
 }
 extern void sdev_disable_disk_events(struct scsi_device *sdev);
 extern void sdev_enable_disk_events(struct scsi_device *sdev);
+extern int scsi_vpd_lun_id(struct scsi_device *, char *, size_t);
 
 #ifdef CONFIG_PM
 extern int scsi_autopm_get_device(struct scsi_device *);

index d015374..ef36053 100644
@@ -905,6 +905,22 @@ sdev_show_function(queue_depth, "%d\n");
 static DEVICE_ATTR(queue_depth, S_IRUGO | S_IWUSR, sdev_show_queue_depth,
 		   sdev_store_queue_depth);
 
+static ssize_t
+sdev_show_wwid(struct device *dev, struct device_attribute *attr,
+		    char *buf)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+	ssize_t count;
+
+	count = scsi_vpd_lun_id(sdev, buf, PAGE_SIZE);
+	if (count > 0) {
+		buf[count] = '\n';
+		count++;
+	}
+	return count;
+}
+static DEVICE_ATTR(wwid, S_IRUGO, sdev_show_wwid, NULL);
+
 #ifdef CONFIG_SCSI_DH
 static ssize_t
 sdev_show_dh_state(struct device *dev, struct device_attribute *attr,

@@ -1028,6 +1044,7 @@ static struct attribute *scsi_sdev_attrs[] = {
 	&dev_attr_modalias.attr,
 	&dev_attr_queue_depth.attr,
 	&dev_attr_queue_type.attr,
+	&dev_attr_wwid.attr,
 #ifdef CONFIG_SCSI_DH
 	&dev_attr_dh_state.attr,
 #endif

index 5bd8a19..99d087b 100644
@@ -23,6 +23,7 @@
 #include <linux/scatterlist.h>
 #include <linux/blk-mq.h>
 #include <linux/ratelimit.h>
+#include <asm/unaligned.h>
 
 #include <scsi/scsi.h>
 #include <scsi/scsi_cmnd.h>

@@ -3294,3 +3295,50 @@ next_desig:
 	return id_size;
 }
 EXPORT_SYMBOL(scsi_vpd_lun_id);
+
+/*
+ * scsi_vpd_tpg_id - return a target port group identifier
+ * @sdev: SCSI device
+ *
+ * Returns the Target Port Group identifier from the information
+ * froom VPD page 0x83 of the device.
+ *
+ * Returns the identifier or error on failure.
+ */
+int scsi_vpd_tpg_id(struct scsi_device *sdev, int *rel_id)
+{
+	unsigned char *d;
+	unsigned char __rcu *vpd_pg83;
+	int group_id = -EAGAIN, rel_port = -1;
+
+	rcu_read_lock();
+	vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
+	if (!vpd_pg83) {
+		rcu_read_unlock();
+		return -ENXIO;
+	}
+
+	d = sdev->vpd_pg83 + 4;
+	while (d < sdev->vpd_pg83 + sdev->vpd_pg83_len) {
+		switch (d[1] & 0xf) {
+		case 0x4:
+			/* Relative target port */
+			rel_port = get_unaligned_be16(&d[6]);
+			break;
+		case 0x5:
+			/* Target port group */
+			group_id = get_unaligned_be16(&d[6]);
+			break;
+		default:
+			break;
+		}
+		d += d[3] + 4;
+	}
+	rcu_read_unlock();
+
+	if (group_id >= 0 && rel_id && rel_port != -1)
+		*rel_id = rel_port;
+
+	return group_id;
+}
+EXPORT_SYMBOL(scsi_vpd_tpg_id);

index 4c49cfa..f63a167 100644
@@ -416,6 +416,7 @@ static inline int scsi_execute_req(struct scsi_device *sdev,
 extern void sdev_disable_disk_events(struct scsi_device *sdev);
 extern void sdev_enable_disk_events(struct scsi_device *sdev);
 extern int scsi_vpd_lun_id(struct scsi_device *, char *, size_t);
+extern int scsi_vpd_tpg_id(struct scsi_device *, int *);
 
 #ifdef CONFIG_PM
 extern int scsi_autopm_get_device(struct scsi_device *);

index abf05b4..20fe981 100644
@@ -320,38 +320,10 @@ static int alua_check_tpgs(struct scsi_device *sdev)
  */
 static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h)
 {
-	unsigned char *d;
-	unsigned char __rcu *vpd_pg83;
+	int rel_port = -1, group_id;
 
-	rcu_read_lock();
-	if (!rcu_dereference(sdev->vpd_pg83)){
-		rcu_read_unlock();
-		return SCSI_DH_DEV_UNSUPP;
-	}
-
-	/*
-	 * Look for the correct descriptor.
-	 */
-	vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
-	d = vpd_pg83 + 4;
-	while (d < vpd_pg83 + sdev->vpd_pg83_len) {
-		switch (d[1] & 0xf) {
-		case 0x4:
-			/* Relative target port */
-			h->rel_port = get_unaligned_be16(&d[6]);
-			break;
-		case 0x5:
-			/* Target port group */
-			h->group_id = get_unaligned_be16(&d[6]);
-			break;
-		default:
-			break;
-		}
-		d += d[3] + 4;
-	}
-	rcu_read_unlock();
-
-	if (h->group_id == -1) {
+	group_id = scsi_vpd_tpg_id(sdev, &rel_port);
+	if (group_id < 0) {
 		/*
 		 * Internal error; TPGS supported but required
 		 * VPD identification descriptors not present.

@@ -360,10 +332,11 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h)
 		sdev_printk(KERN_INFO, sdev,
 			    "%s: No target port descriptors found\n",
 			    ALUA_DH_NAME);
-		h->state = TPGS_STATE_OPTIMIZED;
-		h->tpgs = TPGS_MODE_NONE;
 		return SCSI_DH_DEV_UNSUPP;
 	}
+	h->rel_port = rel_port;
+	h->group_id = group_id;
+
 	sdev_printk(KERN_INFO, sdev,
 		    "%s: port group %02x rel port %02x\n",
 		    ALUA_DH_NAME, h->group_id, h->rel_port);