[PATCH 1/3] zfcp: fix rport unblock if deleted SCSI devices on Scsi_Host

[PATCH 1/3] zfcp: fix rport unblock if deleted SCSI devices on Scsi_Host

[Steffen Maier]

An already deleted SCSI device can exist on the Scsi_Host and remain
there because something still holds a reference.
A new SCSI device with the same H:C:T:L and FCP device, target port WWPN,
and FCP LUN can be created.
When we try to unblock an rport, we still find the deleted SCSI device
and return early because the zfcp_scsi_dev of that SCSI device is
not ZFCP_STATUS_COMMON_UNBLOCKED. Hence we miss to unblock the rport,
even if the new proper SCSI device would be in good state.

Therefore, skip deleted SCSI devices when iterating the sdevs of the shost.
[cf. __scsi_device_lookup{_by_target}() or scsi_device_get()]

The following abbreviated trace sequence can indicate such problem:

Area           : REC
Tag            : ersfs_3
LUN            : 0x4045400300000000
WWPN           : 0x50050763031bd327
LUN status     : 0x40000000     not ZFCP_STATUS_COMMON_UNBLOCKED
Ready count    : n		not incremented yet
Running count  : 0x00000000
ERP want       : 0x01
ERP need       : 0xc1		ZFCP_ERP_ACTION_NONE

Area           : REC
Tag            : ersfs_3
LUN            : 0x4045400300000000
WWPN           : 0x50050763031bd327
LUN status     : 0x41000000
Ready count    : n+1
Running count  : 0x00000000
ERP want       : 0x01
ERP need       : 0x01

...

Area           : REC
Level          : 4		only with increased trace level
Tag            : ertru_l
LUN            : 0x4045400300000000
WWPN           : 0x50050763031bd327
LUN status     : 0x40000000
Request ID     : 0x0000000000000000
ERP status     : 0x01800000
ERP step       : 0x1000
ERP action     : 0x01
ERP count      : 0x00

NOT followed by a trace record with tag "scpaddy"
for WWPN 0x50050763031bd327.

Signed-off-by: Steffen Maier <maier@linux.ibm.com>
Fixes: 6f2ce1c6af37 ("scsi: zfcp: fix rport unblock race with LUN recovery")
Cc: <stable@vger.kernel.org> #2.6.32+
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
---
 drivers/s390/scsi/zfcp_erp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/s390/scsi/zfcp_erp.c b/drivers/s390/scsi/zfcp_erp.c
index 744a64680d5b..c0b2348d7ce6 100644
--- a/drivers/s390/scsi/zfcp_erp.c
+++ b/drivers/s390/scsi/zfcp_erp.c
@@ -1341,6 +1341,9 @@ static void zfcp_erp_try_rport_unblock(struct zfcp_port *port)
 		struct zfcp_scsi_dev *zsdev = sdev_to_zfcp(sdev);
 		int lun_status;
 
+		if (sdev->sdev_state == SDEV_DEL ||
+		    sdev->sdev_state == SDEV_CANCEL)
+			continue;
 		if (zsdev->port != port)
 			continue;
 		/* LUN under port of interest */
-- 
2.16.4

[PATCH 2/3] zfcp: fix scsi_eh host reset with port_forced ERP for non-NPIV FCP devices

[Steffen Maier]

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")
Cc: <stable@vger.kernel.org> #3.0+
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
---
 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 c0b2348d7ce6..e8fc28dba8df 100644
--- a/drivers/s390/scsi/zfcp_erp.c
+++ b/drivers/s390/scsi/zfcp_erp.c
@@ -624,6 +624,20 @@ 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 *dbftag)
 {
diff --git a/drivers/s390/scsi/zfcp_ext.h b/drivers/s390/scsi/zfcp_ext.h
index 3fce47b0b21b..c6acca521ffe 100644
--- a/drivers/s390/scsi/zfcp_ext.h
+++ b/drivers/s390/scsi/zfcp_ext.h
@@ -70,6 +70,8 @@ extern void zfcp_erp_port_reopen(struct zfcp_port *port, int clear,
 				 char *dbftag);
 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 f4f6a07c5222..221d0dfb8493 100644
--- a/drivers/s390/scsi/zfcp_scsi.c
+++ b/drivers/s390/scsi/zfcp_scsi.c
@@ -368,6 +368,10 @@ 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);
-- 
2.16.4