• Steffen Maier's avatar
    zfcp: close window with unblocked rport during rport gone · 4eeaa4f3
    Steffen Maier authored
    On a successful end of reopen port forced,
    zfcp_erp_strategy_followup_success() re-uses the port erp_action
    and the subsequent zfcp_erp_action_cleanup() now
    sees ZFCP_ERP_SUCCEEDED with
    erp_action->action==ZFCP_ERP_ACTION_REOPEN_PORT
    instead of ZFCP_ERP_ACTION_REOPEN_PORT_FORCED
    but must not perform zfcp_scsi_schedule_rport_register().
    
    We can detect this because the fresh port reopen erp_action
    is in its very first step ZFCP_ERP_STEP_UNINITIALIZED.
    
    Otherwise this opens a time window with unblocked rport
    (until the followup port reopen recovery would block it again).
    If a scsi_cmnd timeout occurs during this time window
    fc_timed_out() cannot work as desired and such command
    would indeed time out and trigger scsi_eh. This prevents
    a clean and timely path failover.
    This should not happen if the path issue can be recovered
    on FC transport layer such as path issues involving RSCNs.
    
    Also, unnecessary and repeated DID_IMM_RETRY for pending and
    undesired new requests occur because internally zfcp still
    has its zfcp_port blocked.
    
    As follow-on errors with scsi_eh, it can cause,
    in the worst case, permanently lost paths due to one of:
    sd <scsidev>: [<scsidisk>] Medium access timeout failure. Offlining disk!
    sd <scsidev>: Device offlined - not ready after error recovery
    
    For fix validation and to aid future debugging with other recoveries
    we now also trace (un)blocking of rports.
    Signed-off-by: default avatarSteffen Maier <maier@linux.vnet.ibm.com>
    Fixes: 5767620c ("[SCSI] zfcp: Do not unblock rport from REOPEN_PORT_FORCED")
    Fixes: a2fa0aed ("[SCSI] zfcp: Block FC transport rports early on errors")
    Fixes: 5f852be9 ("[SCSI] zfcp: Fix deadlock between zfcp ERP and SCSI")
    Fixes: 338151e0 ("[SCSI] zfcp: make use of fc_remote_port_delete when target port is unavailable")
    Fixes: 3859f6a2 ("[PATCH] zfcp: add rports to enable scsi_add_device to work again")
    Cc: <stable@vger.kernel.org> #2.6.32+
    Reviewed-by: default avatarBenjamin Block <bblock@linux.vnet.ibm.com>
    Reviewed-by: default avatarHannes Reinecke <hare@suse.com>
    Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
    4eeaa4f3
zfcp_scsi.c 20.7 KB