[PATCH v6 01/18] s390/dasd: Do not complete a failed ESE read as successful

[Stefan Haberland <sth@linux.ibm.com>]

dasd_int_handler() completes an NRF read of an unallocated ESE track by
calling ese_read() and unconditionally marking the request
DASD_CQR_SUCCESS. dasd_eckd_ese_read() can return an error before it has
zeroed the destination buffer: a failed sense-data parse or a current
track outside the requested range both return early, leaving the
destination pages untouched. The request is still completed successfully,
so the block layer is handed stale / uninitialized memory instead of
zeros.

Check the ese_read() return value and fail the request through the normal
error path instead of forcing DASD_CQR_SUCCESS.

Fixes: 5e6bdd37c552 ("s390/dasd: fix data corruption for thin provisioned devices")
Cc: stable@vger.kernel.org
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
---
 drivers/s390/block/dasd.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index dc1c6d5ab3be..e9f0722af104 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -1698,8 +1698,10 @@ void dasd_int_handler(struct ccw_device *cdev, unsigned long intparm,
 			return;
 		}
 		if (rq_data_dir(req) == READ) {
-			device->discipline->ese_read(cqr, irb);
-			cqr->status = DASD_CQR_SUCCESS;
+			if (device->discipline->ese_read(cqr, irb))
+				cqr->status = DASD_CQR_ERROR;
+			else
+				cqr->status = DASD_CQR_SUCCESS;
 			cqr->stopclk = now;
 			dasd_device_clear_timer(device);
 			dasd_schedule_device_bh(device);
-- 
2.53.0