[SCSI] Update the SCSI state model to allow blocking in the created state

Brian King <brking@linux.vnet.ibm.com> reported that fibre channel
devices can oops during scanning if their ports block (because the
device goes from CREATED -> BLOCK -> RUNNING rather than CREATED ->
BLOCK -> CREATED).

Fix this by adding a new state: CREATED_BLOCK which can only transition
back to CREATED and disallow the CREATED -> BLOCK transition.  Now both
the created and blocked states that the mid-layer recognises can include
CREATED_BLOCK.
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/scsi_lib.c

@@ -1251,6 +1251,7 @@ int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
 			break;
 		case SDEV_QUIESCE:
 		case SDEV_BLOCK:
+		case SDEV_CREATED_BLOCK:
 			/*
 			 * If the devices is blocked we defer normal commands.
 			 */
@@ -2064,10 +2065,13 @@ scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
 
 	switch (state) {
 	case SDEV_CREATED:
-		/* There are no legal states that come back to
-		 * created.  This is the manually initialised start
-		 * state */
-		goto illegal;
+		switch (oldstate) {
+		case SDEV_CREATED_BLOCK:
+			break;
+		default:
+			goto illegal;
+		}
+		break;
 			
 	case SDEV_RUNNING:
 		switch (oldstate) {
@@ -2105,8 +2109,17 @@ scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
 
 	case SDEV_BLOCK:
 		switch (oldstate) {
-		case SDEV_CREATED:
 		case SDEV_RUNNING:
+		case SDEV_CREATED_BLOCK:
+			break;
+		default:
+			goto illegal;
+		}
+		break;
+
+	case SDEV_CREATED_BLOCK:
+		switch (oldstate) {
+		case SDEV_CREATED:
 			break;
 		default:
 			goto illegal;
@@ -2394,8 +2407,12 @@ scsi_internal_device_block(struct scsi_device *sdev)
 	int err = 0;
 
 	err = scsi_device_set_state(sdev, SDEV_BLOCK);
-	if (err)
-		return err;
+	if (err) {
+		err = scsi_device_set_state(sdev, SDEV_CREATED_BLOCK);
+
+		if (err)
+			return err;
+	}
 
 	/* 
 	 * The device has transitioned to SDEV_BLOCK.  Stop the
@@ -2438,8 +2455,12 @@ scsi_internal_device_unblock(struct scsi_device *sdev)
 	 * and goose the device queue if successful.  
 	 */
 	err = scsi_device_set_state(sdev, SDEV_RUNNING);
-	if (err)
-		return err;
+	if (err) {
+		err = scsi_device_set_state(sdev, SDEV_CREATED);
+
+		if (err)
+			return err;
+	}
 
 	spin_lock_irqsave(q->queue_lock, flags);
 	blk_start_queue(q);

drivers/scsi/scsi_scan.c

@@ -730,6 +730,8 @@ static int scsi_probe_lun(struct scsi_device *sdev, unsigned char *inq_result,
 static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
 		int *bflags, int async)
 {
+	int ret;
+
 	/*
 	 * XXX do not save the inquiry, since it can change underneath us,
 	 * save just vendor/model/rev.
@@ -885,7 +887,17 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
 
 	/* set the device running here so that slave configure
 	 * may do I/O */
-	scsi_device_set_state(sdev, SDEV_RUNNING);
+	ret = scsi_device_set_state(sdev, SDEV_RUNNING);
+	if (ret) {
+		ret = scsi_device_set_state(sdev, SDEV_BLOCK);
+
+		if (ret) {
+			sdev_printk(KERN_ERR, sdev,
+				    "in wrong state %s to complete scan\n",
+				    scsi_device_state_name(sdev->sdev_state));
+			return SCSI_SCAN_NO_RESPONSE;
+		}
+	}
 
 	if (*bflags & BLIST_MS_192_BYTES_FOR_3F)
 		sdev->use_192_bytes_for_3f = 1;
@@ -899,7 +911,7 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
 	transport_configure_device(&sdev->sdev_gendev);
 
 	if (sdev->host->hostt->slave_configure) {
-		int ret = sdev->host->hostt->slave_configure(sdev);
+		ret = sdev->host->hostt->slave_configure(sdev);
 		if (ret) {
 			/*
 			 * if LLDD reports slave not present, don't clutter

drivers/scsi/scsi_sysfs.c

@@ -34,6 +34,7 @@ static const struct {
 	{ SDEV_QUIESCE, "quiesce" },
 	{ SDEV_OFFLINE,	"offline" },
 	{ SDEV_BLOCK,	"blocked" },
+	{ SDEV_CREATED_BLOCK, "created-blocked" },
 };
 
 const char *scsi_device_state_name(enum scsi_device_state state)

include/scsi/scsi_device.h

@@ -42,9 +42,11 @@ enum scsi_device_state {
 				 * originate in the mid-layer) */
 	SDEV_OFFLINE,		/* Device offlined (by error handling or
 				 * user request */
-	SDEV_BLOCK,		/* Device blocked by scsi lld.  No scsi 
-				 * commands from user or midlayer should be issued
-				 * to the scsi lld. */
+	SDEV_BLOCK,		/* Device blocked by scsi lld.  No
+				 * scsi commands from user or midlayer
+				 * should be issued to the scsi
+				 * lld. */
+	SDEV_CREATED_BLOCK,	/* same as above but for created devices */
 };
 
 enum scsi_device_event {
@@ -393,11 +395,13 @@ static inline int scsi_device_online(struct scsi_device *sdev)
 }
 static inline int scsi_device_blocked(struct scsi_device *sdev)
 {
-	return sdev->sdev_state == SDEV_BLOCK;
+	return sdev->sdev_state == SDEV_BLOCK ||
+		sdev->sdev_state == SDEV_CREATED_BLOCK;
 }
 static inline int scsi_device_created(struct scsi_device *sdev)
 {
-	return sdev->sdev_state == SDEV_CREATED;
+	return sdev->sdev_state == SDEV_CREATED ||
+		sdev->sdev_state == SDEV_CREATED_BLOCK;
 }
 
 /* accessor functions for the SCSI parameters */