[PATCH] libata: implement ata_dev_disable()

This patch implements ata_dev_disable() which prints a warning message
and takes @dev offline.  Currently, this is done by explicitly
incrementing dev->class with case-by-case warning messages.  Giving
user clear indication when libata gives up will be more important as
libata will be doing more retries.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/scsi/libata-core.c

@@ -394,6 +394,15 @@ static const char *ata_mode_string(unsigned int xfer_mask)
 	return "<n/a>";
 }
 
+static void ata_dev_disable(struct ata_port *ap, struct ata_device *dev)
+{
+	if (ata_dev_present(dev)) {
+		printk(KERN_WARNING "ata%u: dev %u disabled\n",
+		       ap->id, dev->devno);
+		dev->class++;
+	}
+}
+
 /**
  *	ata_pio_devchk - PATA device presence detection
  *	@ap: ATA channel to examine