scsi: zfcp: fix scsi_eh host reset with port_forced ERP for non-NPIV FCP devices [Linux 3.16.72]

This Linux kernel change "scsi: zfcp: fix scsi_eh host reset with port_forced ERP for non-NPIV FCP devices" is included in the Linux 3.16.72 release. This change is authored by Steffen Maier <maier [at] linux.ibm.com> on Tue Mar 26 14:36:59 2019 +0100. The commit for this change in Linux stable tree is 7221637 (patch) which is from upstream commit 242ec14. The same Linux upstream change may have been applied to various maintained Linux releases and you can find all Linux releases containing changes from upstream 242ec14.

scsi: zfcp: fix scsi_eh host reset with port_forced ERP for non-NPIV FCP devices

commit 242ec1455151267fe35a0834aa9038e4c4670884 upstream.

Suppose more than one non-NPIV FCP device is active on the same channel.
Send I/O to storage and have some of the pending I/O run into a SCSI
command timeout, e.g. due to bit errors on the fibre. Now the error
situation stops. However, we saw FCP requests continue to timeout in the
channel. The abort will be successful, but the subsequent TUR fails.
Scsi_eh starts. The LUN reset fails. The target reset fails.  The host
reset only did an FCP device recovery. However, for non-NPIV FCP devices,
this does not close and reopen ports on the SAN-side if other non-NPIV FCP
device(s) share the same open ports.

In order to resolve the continuing FCP request timeouts, we need to
explicitly close and reopen ports on the SAN-side.

This was missing since the beginning of zfcp in v2.6.0 history commit
ea127f975424 ("[PATCH] s390 (7/7): zfcp host adapter.").

Note: The FSF requests for forced port reopen could run into FSF request
timeouts due to other reasons. This would trigger an internal FCP device
recovery. Pending forced port reopen recoveries would get dismissed. So
some ports might not get fully reopened during this host reset handler.
However, subsequent I/O would trigger the above described escalation and
eventually all ports would be forced reopen to resolve any continuing FCP
request timeouts due to earlier bit errors.

Signed-off-by: Steffen Maier <maier@linux.ibm.com>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

There are 20 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 drivers/s390/scsi/zfcp_erp.c  | 14 ++++++++++++++
 drivers/s390/scsi/zfcp_ext.h  |  2 ++
 drivers/s390/scsi/zfcp_scsi.c |  4 ++++
 3 files changed, 20 insertions(+)

diff --git a/drivers/s390/scsi/zfcp_erp.c b/drivers/s390/scsi/zfcp_erp.c
index cb3f461..3a62c04 100644
--- a/drivers/s390/scsi/zfcp_erp.c
+++ b/drivers/s390/scsi/zfcp_erp.c
@@ -652,6 +652,20 @@ static void zfcp_erp_strategy_memwait(struct zfcp_erp_action *erp_action)
    add_timer(&erp_action->timer);
 }

+void zfcp_erp_port_forced_reopen_all(struct zfcp_adapter *adapter,
+                    int clear, char *dbftag)
+{
+   unsigned long flags;
+   struct zfcp_port *port;
+
+   write_lock_irqsave(&adapter->erp_lock, flags);
+   read_lock(&adapter->port_list_lock);
+   list_for_each_entry(port, &adapter->port_list, list)
+       _zfcp_erp_port_forced_reopen(port, clear, dbftag);
+   read_unlock(&adapter->port_list_lock);
+   write_unlock_irqrestore(&adapter->erp_lock, flags);
+}
+
 static void _zfcp_erp_port_reopen_all(struct zfcp_adapter *adapter,
                      int clear, char *id)
 {
diff --git a/drivers/s390/scsi/zfcp_ext.h b/drivers/s390/scsi/zfcp_ext.h
index c5023d6..cfe2a3b 100644
--- a/drivers/s390/scsi/zfcp_ext.h
+++ b/drivers/s390/scsi/zfcp_ext.h
@@ -68,6 +68,8 @@ extern void zfcp_erp_port_forced_no_port_dbf(char *id,
 extern int  zfcp_erp_port_reopen(struct zfcp_port *, int, char *);
 extern void zfcp_erp_port_shutdown(struct zfcp_port *, int, char *);
 extern void zfcp_erp_port_forced_reopen(struct zfcp_port *, int, char *);
+extern void zfcp_erp_port_forced_reopen_all(struct zfcp_adapter *adapter,
+                       int clear, char *dbftag);
 extern void zfcp_erp_set_lun_status(struct scsi_device *, u32);
 extern void zfcp_erp_clear_lun_status(struct scsi_device *, u32);
 extern void zfcp_erp_lun_reopen(struct scsi_device *, int, char *);
diff --git a/drivers/s390/scsi/zfcp_scsi.c b/drivers/s390/scsi/zfcp_scsi.c
index f213786..9e9f0ad 100644
--- a/drivers/s390/scsi/zfcp_scsi.c
+++ b/drivers/s390/scsi/zfcp_scsi.c
@@ -347,6 +347,10 @@ static int zfcp_scsi_eh_host_reset_handler(struct scsi_cmnd *scpnt)
    struct zfcp_adapter *adapter = zfcp_sdev->port->adapter;
    int ret = SUCCESS, fc_ret;

+   if (!(adapter->connection_features & FSF_FEATURE_NPIV_MODE)) {
+       zfcp_erp_port_forced_reopen_all(adapter, 0, "schrh_p");
+       zfcp_erp_wait(adapter);
+   }
    zfcp_erp_adapter_reopen(adapter, 0, "schrh_1");
    zfcp_erp_wait(adapter);
    fc_ret = fc_block_scsi_eh(scpnt);

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