[PATCH v6 02/18] s390/dasd: Propagate partial completion length across ERP recovery

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

dasd_default_erp_postaction() copies the timing and device state from
the finished ERP request back to the original request but drops
proc_bytes. A request that was partially completed, an ESE read of a
not-yet-allocated track returns fewer bytes than requested, and then
recovered through the ERP chain loses its partial-completion length.
__dasd_cleanup_cqr() then sees proc_bytes == 0 and completes the whole
request instead of requeueing the remainder, silently returning zeroed
data for the part that was never read.

Carry proc_bytes over to the original request like the other
per-request state.

Fixes: 5e6bdd37c552 ("s390/dasd: fix data corruption for thin provisioned devices")
Cc: stable@vger.kernel.org
Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
---
 drivers/s390/block/dasd_erp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/s390/block/dasd_erp.c b/drivers/s390/block/dasd_erp.c
index 89d7516b9ec8..468f0b2cc342 100644
--- a/drivers/s390/block/dasd_erp.c
+++ b/drivers/s390/block/dasd_erp.c
@@ -123,6 +123,7 @@ struct dasd_ccw_req *dasd_default_erp_postaction(struct dasd_ccw_req *cqr)
 	int success;
 	unsigned long startclk, stopclk;
 	struct dasd_device *startdev;
+	unsigned int proc_bytes;
 
 	BUG_ON(cqr->refers == NULL || cqr->function == NULL);
 
@@ -130,6 +131,7 @@ struct dasd_ccw_req *dasd_default_erp_postaction(struct dasd_ccw_req *cqr)
 	startclk = cqr->startclk;
 	stopclk = cqr->stopclk;
 	startdev = cqr->startdev;
+	proc_bytes = cqr->proc_bytes;
 
 	/* free all ERPs - but NOT the original cqr */
 	while (cqr->refers != NULL) {
@@ -147,6 +149,7 @@ struct dasd_ccw_req *dasd_default_erp_postaction(struct dasd_ccw_req *cqr)
 	cqr->startclk = startclk;
 	cqr->stopclk = stopclk;
 	cqr->startdev = startdev;
+	cqr->proc_bytes = proc_bytes;
 	if (success)
 		cqr->status = DASD_CQR_DONE;
 	else {
-- 
2.53.0