Patch "scsi: zfcp: fix queuecommand for scsi_eh commands when DIX enabled" has been added to the 3.18-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    scsi: zfcp: fix queuecommand for scsi_eh commands when DIX enabled

to the 3.18-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     scsi-zfcp-fix-queuecommand-for-scsi_eh-commands-when-dix-enabled.patch
and it can be found in the queue-3.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 71b8e45da51a7b64a23378221c0a5868bd79da4f Mon Sep 17 00:00:00 2001
From: Steffen Maier <maier@linux.vnet.ibm.com>
Date: Fri, 28 Jul 2017 12:30:51 +0200
Subject: scsi: zfcp: fix queuecommand for scsi_eh commands when DIX enabled

From: Steffen Maier <maier@linux.vnet.ibm.com>

commit 71b8e45da51a7b64a23378221c0a5868bd79da4f upstream.

Since commit db007fc5e20c ("[SCSI] Command protection operation"),
scsi_eh_prep_cmnd() saves scmd->prot_op and temporarily resets it to
SCSI_PROT_NORMAL.
Other FCP LLDDs such as qla2xxx and lpfc shield their queuecommand()
to only access any of scsi_prot_sg...() if
(scsi_get_prot_op(cmd) != SCSI_PROT_NORMAL).

Do the same thing for zfcp, which introduced DIX support with
commit ef3eb71d8ba4 ("[SCSI] zfcp: Introduce experimental support for
DIF/DIX").

Otherwise, TUR SCSI commands as part of scsi_eh likely fail in zfcp,
because the regular SCSI command with DIX protection data, that scsi_eh
re-uses in scsi_send_eh_cmnd(), of course still has
(scsi_prot_sg_count() != 0) and so zfcp sends down bogus requests to the
FCP channel hardware.

This causes scsi_eh_test_devices() to have (finish_cmds == 0)
[not SCSI device is online or not scsi_eh_tur() failed]
so regular SCSI commands, that caused / were affected by scsi_eh,
are moved to work_q and scsi_eh_test_devices() itself returns false.
In turn, it unnecessarily escalates in our case in scsi_eh_ready_devs()
beyond host reset to finally scsi_eh_offline_sdevs()
which sets affected SCSI devices offline with the following kernel message:

"kernel: sd H:0:T:L: Device offlined - not ready after error recovery"

Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
Fixes: ef3eb71d8ba4 ("[SCSI] zfcp: Introduce experimental support for DIF/DIX")
Reviewed-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Signed-off-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/s390/scsi/zfcp_fsf.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/s390/scsi/zfcp_fsf.c
+++ b/drivers/s390/scsi/zfcp_fsf.c
@@ -2247,7 +2247,8 @@ int zfcp_fsf_fcp_cmnd(struct scsi_cmnd *
 	fcp_cmnd = (struct fcp_cmnd *) &req->qtcb->bottom.io.fcp_cmnd;
 	zfcp_fc_scsi_to_fcp(fcp_cmnd, scsi_cmnd, 0);
 
-	if (scsi_prot_sg_count(scsi_cmnd)) {
+	if ((scsi_get_prot_op(scsi_cmnd) != SCSI_PROT_NORMAL) &&
+	    scsi_prot_sg_count(scsi_cmnd)) {
 		zfcp_qdio_set_data_div(qdio, &req->qdio_req,
 				       scsi_prot_sg_count(scsi_cmnd));
 		retval = zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req,


Patches currently in stable-queue which might be from maier@linux.vnet.ibm.com are

queue-3.18/scsi-zfcp-add-handling-for-fcp_resid_over-to-the-fcp-ingress-path.patch
queue-3.18/scsi-zfcp-trace-high-part-of-new-64-bit-scsi-lun.patch
queue-3.18/scsi-zfcp-fix-queuecommand-for-scsi_eh-commands-when-dix-enabled.patch
queue-3.18/scsi-zfcp-fix-payload-with-full-fcp_rsp-iu-in-scsi-trace-records.patch
queue-3.18/scsi-zfcp-trace-hba-fsf-response-by-default-on-dismiss-or-timedout-late-response.patch
queue-3.18/scsi-zfcp-fix-missing-trace-records-for-early-returns-in-tmf-eh-handlers.patch