[SCSI] Log msg when getting Unit Attention

If the user accidentally changes LUN mappings or it occurs
due to a bug, then it can cause data corruption that can take
months and months to track down. This patch adds a log
message when getting REPORT_LUNS_DATA_CHANGED and it adds
a generic message for other Unit Attentions with asc == 0x3f.

We are working on adding support for handling of these errors,
but I think until then we should at least log a message so
tracking down problems as a result of one of these changes
is a little easier.
Signed-off-by: NMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: NJames Bottomley <James.Bottomley@suse.de>

drivers/scsi/scsi_error.c

@@ -307,6 +307,19 @@ static int scsi_check_sense(struct scsi_cmnd *scmd)
 		    (sshdr.asc == 0x04) && (sshdr.ascq == 0x02))
 			return FAILED;
 
+		if (sshdr.asc == 0x3f && sshdr.ascq == 0x0e)
+			scmd_printk(KERN_WARNING, scmd,
+				    "Warning! Received an indication that the "
+				    "LUN assignments on this target have "
+				    "changed. The Linux SCSI layer does not "
+				    "automatically remap LUN assignments.\n");
+		else if (sshdr.asc == 0x3f)
+			scmd_printk(KERN_WARNING, scmd,
+				    "Warning! Received an indication that the "
+				    "operating parameters on this target have "
+				    "changed. The Linux SCSI layer does not "
+				    "automatically adjust these parameters.\n");
+
 		if (blk_barrier_rq(scmd->request))
 			/*
 			 * barrier requests should always retry on UA