s390/dasd: fix data corruption for thin provisioned devices

Devices are formatted in multiple of tracks.
For an Extent Space Efficient (ESE) volume we get errors when accessing
unformatted tracks. In this case the driver either formats the track on
the flight for write requests or returns zero data for read requests.

In case a request spans multiple tracks, the indication of an unformatted
track presented for the first track is incorrectly applied to all tracks
covered by the request. As a result, tracks containing data will be handled
as empty, resulting in zero data being returned on read, or overwriting
existing data with zero on write.

Fix by determining the track that gets the NRF error.
For write requests only format the track that is surely not formatted.
For Read requests all tracks before have returned valid data and should not
be touched.
All tracks after the unformatted track might be formatted or not. Those are
returned to the blocklayer to build a new request.

When using alias devices there is a chance that multiple write requests
trigger a format of the same track which might lead to data loss. Ensure
that a track is formatted only once by maintaining a list of currently
processed tracks.

Fixes: 5e2b17e712cf ("s390/dasd: Add dynamic formatting support for ESE volumes")
Cc: stable@vger.kernel.org # 5.3+
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 24 insertions, 3 deletions

diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index 6cca72782af6..cf87eb27879f 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -178,6 +178,8 @@ struct dasd_block *dasd_alloc_block(void)
 		     (unsigned long) block);
 	INIT_LIST_HEAD(&block->ccw_queue);
 	spin_lock_init(&block->queue_lock);
+	INIT_LIST_HEAD(&block->format_list);
+	spin_lock_init(&block->format_lock);
 	timer_setup(&block->timer, dasd_block_timeout, 0);
 	spin_lock_init(&block->profile.lock);
 
@@ -1779,20 +1781,26 @@ void dasd_int_handler(struct ccw_device *cdev, unsigned long intparm,
 
 	if (dasd_ese_needs_format(cqr->block, irb)) {
 		if (rq_data_dir((struct request *)cqr->callback_data) == READ) {
-			device->discipline->ese_read(cqr);
+			device->discipline->ese_read(cqr, irb);
 			cqr->status = DASD_CQR_SUCCESS;
 			cqr->stopclk = now;
 			dasd_device_clear_timer(device);
 			dasd_schedule_device_bh(device);
 			return;
 		}
-		fcqr = device->discipline->ese_format(device, cqr);
+		fcqr = device->discipline->ese_format(device, cqr, irb);
 		if (IS_ERR(fcqr)) {
+			if (PTR_ERR(fcqr) == -EINVAL) {
+				cqr->status = DASD_CQR_ERROR;
+				return;
+			}
 			/*
 			 * If we can't format now, let the request go
 			 * one extra round. Maybe we can format later.
 			 */
 			cqr->status = DASD_CQR_QUEUED;
+			dasd_schedule_device_bh(device);
+			return;
 		} else {
 			fcqr->status = DASD_CQR_QUEUED;
 			cqr->status = DASD_CQR_QUEUED;
@@ -2748,11 +2756,13 @@ static void __dasd_cleanup_cqr(struct dasd_ccw_req *cqr)
 {
 	struct request *req;
 	blk_status_t error = BLK_STS_OK;
+	unsigned int proc_bytes;
 	int status;
 
 	req = (struct request *) cqr->callback_data;
 	dasd_profile_end(cqr->block, cqr, req);
 
+	proc_bytes = cqr->proc_bytes;
 	status = cqr->block->base->discipline->free_cp(cqr, req);
 	if (status < 0)
 		error = errno_to_blk_status(status);
@@ -2783,7 +2793,18 @@ static void __dasd_cleanup_cqr(struct dasd_ccw_req *cqr)
 		blk_mq_end_request(req, error);
 		blk_mq_run_hw_queues(req->q, true);
 	} else {
-		blk_mq_complete_request(req);
+		/*
+		 * Partial completed requests can happen with ESE devices.
+		 * During read we might have gotten a NRF error and have to
+		 * complete a request partially.
+		 */
+		if (proc_bytes) {
+			blk_update_request(req, BLK_STS_OK,
+					   blk_rq_bytes(req) - proc_bytes);
+			blk_mq_requeue_request(req, true);
+		} else {
+			blk_mq_complete_request(req);
+		}
 	}
 }