releases/4.9.52/scsi-zfcp-fix-queuecommand-for-scsi_eh-commands-when-dix-enabled.patch

   1 From 71b8e45da51a7b64a23378221c0a5868bd79da4f Mon Sep 17 00:00:00 2001
   2 From: Steffen Maier <maier@linux.vnet.ibm.com>
   3 Date: Fri, 28 Jul 2017 12:30:51 +0200
   4 Subject: scsi: zfcp: fix queuecommand for scsi_eh commands when DIX enabled
   5
   6 From: Steffen Maier <maier@linux.vnet.ibm.com>
   7
   8 commit 71b8e45da51a7b64a23378221c0a5868bd79da4f upstream.
   9
  10 Since commit db007fc5e20c ("[SCSI] Command protection operation"),
  11 scsi_eh_prep_cmnd() saves scmd->prot_op and temporarily resets it to
  12 SCSI_PROT_NORMAL.
  13 Other FCP LLDDs such as qla2xxx and lpfc shield their queuecommand()
  14 to only access any of scsi_prot_sg...() if
  15 (scsi_get_prot_op(cmd) != SCSI_PROT_NORMAL).
  16
  17 Do the same thing for zfcp, which introduced DIX support with
  18 commit ef3eb71d8ba4 ("[SCSI] zfcp: Introduce experimental support for
  19 DIF/DIX").
  20
  21 Otherwise, TUR SCSI commands as part of scsi_eh likely fail in zfcp,
  22 because the regular SCSI command with DIX protection data, that scsi_eh
  23 re-uses in scsi_send_eh_cmnd(), of course still has
  24 (scsi_prot_sg_count() != 0) and so zfcp sends down bogus requests to the
  25 FCP channel hardware.
  26
  27 This causes scsi_eh_test_devices() to have (finish_cmds == 0)
  28 [not SCSI device is online or not scsi_eh_tur() failed]
  29 so regular SCSI commands, that caused / were affected by scsi_eh,
  30 are moved to work_q and scsi_eh_test_devices() itself returns false.
  31 In turn, it unnecessarily escalates in our case in scsi_eh_ready_devs()
  32 beyond host reset to finally scsi_eh_offline_sdevs()
  33 which sets affected SCSI devices offline with the following kernel message:
  34
  35 "kernel: sd H:0:T:L: Device offlined - not ready after error recovery"
  36
  37 Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
  38 Fixes: ef3eb71d8ba4 ("[SCSI] zfcp: Introduce experimental support for DIF/DIX")
  39 Reviewed-by: Benjamin Block <bblock@linux.vnet.ibm.com>
  40 Signed-off-by: Benjamin Block <bblock@linux.vnet.ibm.com>
  41 Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
  42 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  43
  44 ---
  45  drivers/s390/scsi/zfcp_fsf.c |    3 ++-
  46  1 file changed, 2 insertions(+), 1 deletion(-)
  47
  48 --- a/drivers/s390/scsi/zfcp_fsf.c
  49 +++ b/drivers/s390/scsi/zfcp_fsf.c
  50 @@ -2258,7 +2258,8 @@ int zfcp_fsf_fcp_cmnd(struct scsi_cmnd *
  51         fcp_cmnd = (struct fcp_cmnd *) &req->qtcb->bottom.io.fcp_cmnd;
  52         zfcp_fc_scsi_to_fcp(fcp_cmnd, scsi_cmnd, 0);
  53
  54 -       if (scsi_prot_sg_count(scsi_cmnd)) {
  55 +       if ((scsi_get_prot_op(scsi_cmnd) != SCSI_PROT_NORMAL) &&
  56 +           scsi_prot_sg_count(scsi_cmnd)) {
  57                 zfcp_qdio_set_data_div(qdio, &req->qdio_req,
  58                                        scsi_prot_sg_count(scsi_cmnd));
  59                 retval = zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req,