[SCSI] sd_dif: problem with verify of type 1 protection information (PI)

It appears to me that there is a problem with handling of type 1 protection
information.

It is considering a logical block reference tag of 0xffffffff to be an error,
but it is actually valid any time ((lba & 0xffffffff) == 0xffffffff) [for
example, 2TiB-1, 4TiB-1, 6TiB-1, etc.].

I'm going by what's written in 4.18.3 of SBC3, where there doesn't appear
to be any invalid value for the reference tag.
Signed-off-by: NJeremy Higdon <jeremy@sgi.com>
Acked-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

drivers/scsi/sd_dif.c

@@ -93,14 +93,6 @@ static int sd_dif_type1_verify(struct blk_integrity_exchg *bix, csum_fn *fn)
 		if (sdt->app_tag == 0xffff)
 			return 0;
 
-		/* Bad ref tag received from disk */
-		if (sdt->ref_tag == 0xffffffff) {
-			printk(KERN_ERR
-			       "%s: bad phys ref tag on sector %lu\n",
-			       bix->disk_name, (unsigned long)sector);
-			return -EIO;
-		}
-
 		if (be32_to_cpu(sdt->ref_tag) != (sector & 0xffffffff)) {
 			printk(KERN_ERR
 			       "%s: ref tag error on sector %lu (rcvd %u)\n",