[SCSI] sd: fix USB devices incorrectly reporting DIF support

Some USB devices set the protect bit in the INQUIRY data which
currently causes the DIF code in sd to assume (incorrectly) that they
support READ_CAPACITY(16).  Fix this (only for the time being) by
making sure we only believe the protect bit in the inquiry data if the
device claims conformance to SCSI-3 or above.
Acked-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>

include/scsi/scsi_device.h

@@ -6,6 +6,7 @@
 #include <linux/spinlock.h>
 #include <linux/workqueue.h>
 #include <linux/blkdev.h>
+#include <scsi/scsi.h>
 #include <asm/atomic.h>
 
 struct request_queue;
@@ -426,7 +427,7 @@ static inline int scsi_device_enclosure(struct scsi_device *sdev)
 
 static inline int scsi_device_protection(struct scsi_device *sdev)
 {
-	return sdev->inquiry[5] & (1<<0);
+	return sdev->scsi_level > SCSI_2 && sdev->inquiry[5] & (1<<0);
 }
 
 #define MODULE_ALIAS_SCSI_DEVICE(type) \