[SCSI] scsi error: have scsi-ml call change_queue_depth to handle QUEUE_FULL

This has scsi-ml call the change_queue_depth functions when
we get a QUEUE_FULL. It will only change the queue depth if
change_queue_depth is set because the LLD may have to
modify some internal resources, so I thought this would
be the safest route.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>

-v2
Limits change_queue_depth to only all luns of target by adding
channel check while iterating for all luns of Scsi_Host. This is
same as currently qla2xxx FC HBA does on QUEUE_FULL event.
Signed-off-by: Vasu Dev <vasu.dev@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/scsi/scsi_error.c

@@ -331,6 +331,28 @@ static int scsi_check_sense(struct scsi_cmnd *scmd)
 	}
 }
 
+static void scsi_handle_queue_full(struct scsi_device *sdev)
+{
+	struct scsi_host_template *sht = sdev->host->hostt;
+	struct scsi_device *tmp_sdev;
+
+	if (!sht->change_queue_depth)
+		return;
+
+	shost_for_each_device(tmp_sdev, sdev->host) {
+		if (tmp_sdev->channel != sdev->channel ||
+		    tmp_sdev->id != sdev->id)
+			continue;
+		/*
+		 * We do not know the number of commands that were at
+		 * the device when we got the queue full so we start
+		 * from the highest possible value and work our way down.
+		 */
+		sht->change_queue_depth(tmp_sdev, tmp_sdev->queue_depth - 1,
+					SCSI_QDEPTH_QFULL);
+	}
+}
+
 /**
  * scsi_eh_completed_normally - Disposition a eh cmd on return from LLD.
  * @scmd:	SCSI cmd to examine.
@@ -387,8 +409,10 @@ static int scsi_eh_completed_normally(struct scsi_cmnd *scmd)
 		 * let issuer deal with this, it could be just fine
 		 */
 		return SUCCESS;
-	case BUSY:
 	case QUEUE_FULL:
+		scsi_handle_queue_full(scmd->device);
+		/* fall through */
+	case BUSY:
 	default:
 		return FAILED;
 	}
@@ -1387,6 +1411,7 @@ int scsi_decide_disposition(struct scsi_cmnd *scmd)
 	 */
 	switch (status_byte(scmd->result)) {
 	case QUEUE_FULL:
+		scsi_handle_queue_full(scmd->device);
 		/*
 		 * the case of trying to send too many commands to a
 		 * tagged queueing device.