[SCSI] sr: fix sr_drive_status handling when initialization required

An sr device that reports sense data with SK/ASC/ASCQ of 2/4/2 (Not ready,
Logical unit not ready, Initializing command required) will be handled
in sr_drive_status as (2/4/!1) and assumed to be a 'format in progress'
which returns CDS_DISC_OK.  The drive will not be made ready in this case.

Prior to 210ba1d sr_drive_status would
have returned CDS_TRAY_OPEN and this results in an START_STOP_UNIT to
close the tray, which resolves the initialization requirement.

This patch adds handling for SK/ASC/ASCQ of 2/4/2 where it will return
CDS_TRAY_OPEN as a means of triggering a START_STOP_UNIT.

This issue is seen on the IBM POWER platform when using a file-backed,
virtual optical device.  The device does not support media queries
through the Get Event Status Notification command which could otherwise
trigger a START_STOP_UNIT call to close an open tray.

Signed-off-by: Robert Jennings <rcj@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/scsi/sr_ioctl.c

@@ -324,6 +324,15 @@ int sr_drive_status(struct cdrom_device_info *cdi, int slot)
 			return CDS_NO_DISC;
 	}
 
+	/*
+	 * SK/ASC/ASCQ of 2/4/2 means "initialization required"
+	 * Using CD_TRAY_OPEN results in an START_STOP_UNIT to close
+	 * the tray, which resolves the initialization requirement.
+	 */
+	if (scsi_sense_valid(&sshdr) && sshdr.sense_key == NOT_READY
+			&& sshdr.asc == 0x04 && sshdr.ascq == 0x02)
+		return CDS_TRAY_OPEN;
+
 	/*
 	 * 0x04 is format in progress .. but there must be a disc present!
 	 */