libata: Report zeroed read after TRIM and max discard size

Our current TRIM payload is a single sector that can accommodate 64 *
65535 blocks being unmapped.  Report this value in the Block Limits
Maximum Unmap LBA count field.

If a storage device supports TRIM and the DRAT and RZAT bits are set,
report TPRZ=1 in Read Capacity(16).

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 340a616..e1e186b 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2115,8 +2115,10 @@
 	 * that we support some form of unmap - in thise case via WRITE SAME
 	 * with the unmap bit set.
 	 */
-	if (ata_id_has_trim(args->id))
+	if (ata_id_has_trim(args->id)) {
+		put_unaligned_be32(65535 * 512 / 8, &rbuf[20]);
 		put_unaligned_be32(1, &rbuf[28]);
+	}
 
 	return 0;
 }
@@ -2411,8 +2413,12 @@
 		rbuf[14] = (lowest_aligned >> 8) & 0x3f;
 		rbuf[15] = lowest_aligned;
 
-		if (ata_id_has_trim(args->id))
-			rbuf[14] |= 0x80;
+		if (ata_id_has_trim(args->id)) {
+			rbuf[14] |= 0x80; /* TPE */
+
+			if (ata_id_has_zero_after_trim(args->id))
+				rbuf[14] |= 0x40; /* TPRZ */
+		}
 	}
 
 	return 0;