5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Stefan Haberland <sth@linux.ibm.com>
commit 6fb5ba2e7e43173a3761e46f091070a8185efa14 upstream.
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: <redacted>
Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Link: https://patch.msgid.link/20260805111612.1285190-3-sth@linux.ibm.com (local)
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/s390/block/dasd_erp.c | 3 +++
1 file changed, 3 insertions(+)
--- a/drivers/s390/block/dasd_erp.c
+++ b/drivers/s390/block/dasd_erp.c
@@ -127,6 +127,7 @@ struct dasd_ccw_req *dasd_default_erp_po
int success;
unsigned long startclk, stopclk;
struct dasd_device *startdev;
+ unsigned int proc_bytes;
BUG_ON(cqr->refers == NULL || cqr->function == NULL);
@@ -134,6 +135,7 @@ struct dasd_ccw_req *dasd_default_erp_po
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) {@@ -151,6 +153,7 @@ struct dasd_ccw_req *dasd_default_erp_po
cqr->startclk = startclk;
cqr->stopclk = stopclk;
cqr->startdev = startdev;
+ cqr->proc_bytes = proc_bytes;
if (success)
cqr->status = DASD_CQR_DONE;
else {