[PATCH 3.16 192/366] s390/dasd: fix IO error for newly defined devices

[Ben Hutchings]

3.16.60-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Stefan Haberland <sth@xxxxxxxxxxxxxxxxxx>

commit 5d27a2bf6e14f5c7d1033ad1e993fcd0eba43e83 upstream.

When a new CKD storage volume is defined at the storage server, Linux
may be relying on outdated information about that volume, which leads to
the following errors:

1. Command Reject Errors for minidisk on z/VM:

dasd-eckd.b3193d: 0.0.XXXX: An error occurred in the DASD device driver,
		  reason=09
dasd(eckd): I/O status report for device 0.0.XXXX:
dasd(eckd): in req: 00000000XXXXXXXX CC:00 FC:04 AC:00 SC:17 DS:02 CS:00
	    RC:0
dasd(eckd): device 0.0.2046: Failing CCW: 00000000XXXXXXXX
dasd(eckd): Sense(hex)  0- 7: 80 00 00 00 00 00 00 00
dasd(eckd): Sense(hex)  8-15: 00 00 00 00 00 00 00 00
dasd(eckd): Sense(hex) 16-23: 00 00 00 00 e1 00 0f 00
dasd(eckd): Sense(hex) 24-31: 00 00 40 e2 00 00 00 00
dasd(eckd): 24 Byte: 0 MSG 0, no MSGb to SYSOP

2. Equipment Check errors on LPAR or for dedicated devices on z/VM:

dasd(eckd): I/O status report for device 0.0.XXXX:
dasd(eckd): in req: 00000000XXXXXXXX CC:00 FC:04 AC:00 SC:17 DS:0E CS:40
	    fcxs:01 schxs:00 RC:0
dasd(eckd): device 0.0.9713: Failing TCW: 00000000XXXXXXXX
dasd(eckd): Sense(hex)  0- 7: 10 00 00 00 13 58 4d 0f
dasd(eckd): Sense(hex)  8-15: 67 00 00 00 00 00 00 04
dasd(eckd): Sense(hex) 16-23: e5 18 05 33 97 01 0f 0f
dasd(eckd): Sense(hex) 24-31: 00 00 40 e2 00 04 58 0d
dasd(eckd): 24 Byte: 0 MSG f, no MSGb to SYSOP

Fix this problem by using the up-to-date information provided during
online processing via the device specific SNEQ to detect the case of
outdated LCU data. If there is a difference, perform a re-read of that
data.

Reviewed-by: Jan Hoeppner <hoeppner@xxxxxxxxxxxxx>
Signed-off-by: Stefan Haberland <sth@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
[bwh: Backported to 3.16:
 - Move up assignment of "private"
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/drivers/s390/block/dasd_alias.c
+++ b/drivers/s390/block/dasd_alias.c
@@ -608,18 +608,26 @@ static int _schedule_lcu_update(struct a
 
 int dasd_alias_add_device(struct dasd_device *device)
 {
-	struct dasd_eckd_private *private;
-	struct alias_lcu *lcu;
+	struct dasd_eckd_private *private = device->private;
+	__u8 uaddr = private->uid.real_unit_addr;
+	struct alias_lcu *lcu = private->lcu;
 	unsigned long flags;
 	int rc;
 
-	private = (struct dasd_eckd_private *) device->private;
-	lcu = private->lcu;
 	rc = 0;
 
 	/* need to take cdev lock before lcu lock */
 	spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 	spin_lock(&lcu->lock);
+	/*
+	 * Check if device and lcu type differ. If so, the uac data may be
+	 * outdated and needs to be updated.
+	 */
+	if (private->uid.type !=  lcu->uac->unit[uaddr].ua_type) {
+		lcu->flags |= UPDATE_PENDING;
+		DBF_DEV_EVENT(DBF_WARNING, device, "%s",
+			      "uid type mismatch - trigger rescan");
+	}
 	if (!(lcu->flags & UPDATE_PENDING)) {
 		rc = _add_device_to_lcu(lcu, device, device);
 		if (rc)