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    Subject[PATCH 4.9 35/77] scsi: zfcp: fix queuecommand for scsi_eh commands when DIX enabled
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    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
    @@ -2258,7 +2258,8 @@ 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,

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