linux-stable/drivers/s390/scsi/zfcp_unit.c
Steffen Maier ef4021fe5f scsi: zfcp: fix to prevent port_remove with pure auto scan LUNs (only sdevs)
When the user tries to remove a zfcp port via sysfs, we only rejected it if
there are zfcp unit children under the port. With purely automatically
scanned LUNs there are no zfcp units but only SCSI devices. In such cases,
the port_remove erroneously continued. We close the port and this
implicitly closes all LUNs under the port. The SCSI devices survive with
their private zfcp_scsi_dev still holding a reference to the "removed"
zfcp_port (still allocated but invisible in sysfs) [zfcp_get_port_by_wwpn
in zfcp_scsi_slave_alloc]. This is not a problem as long as the fc_rport
stays blocked. Once (auto) port scan brings back the removed port, we
unblock its fc_rport again by design.  However, there is no mechanism that
would recover (open) the LUNs under the port (no "ersfs_3" without
zfcp_unit [zfcp_erp_strategy_followup_success]).  Any pending or new I/O to
such LUN leads to repeated:

  Done: NEEDS_RETRY Result: hostbyte=DID_IMM_RETRY driverbyte=DRIVER_OK

See also v4.10 commit 6f2ce1c6af ("scsi: zfcp: fix rport unblock race
with LUN recovery"). Even a manual LUN recovery
(echo 0 > /sys/bus/scsi/devices/H:C:T:L/zfcp_failed)
does not help, as the LUN links to the old "removed" port which remains
to lack ZFCP_STATUS_COMMON_RUNNING [zfcp_erp_required_act].
The only workaround is to first ensure that the fc_rport is blocked
(e.g. port_remove again in case it was re-discovered by (auto) port scan),
then delete the SCSI devices, and finally re-discover by (auto) port scan.
The port scan includes an fc_rport unblock, which in turn triggers
a new scan on the scsi target to freshly get new pure auto scan LUNs.

Fix this by rejecting port_remove also if there are SCSI devices
(even without any zfcp_unit) under this port. Re-use mechanics from v3.7
commit d99b601b63 ("[SCSI] zfcp: restore refcount check on port_remove").
However, we have to give up zfcp_sysfs_port_units_mutex earlier in unit_add
to prevent a deadlock with scsi_host scan taking shost->scan_mutex first
and then zfcp_sysfs_port_units_mutex now in our zfcp_scsi_slave_alloc().

Signed-off-by: Steffen Maier <maier@linux.ibm.com>
Fixes: b62a8d9b45 ("[SCSI] zfcp: Use SCSI device data zfcp scsi dev instead of zfcp unit")
Fixes: f8210e3488 ("[SCSI] zfcp: Allow midlayer to scan for LUNs when running in NPIV mode")
Cc: <stable@vger.kernel.org> #2.6.37+
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-05-29 21:52:31 -04:00

263 lines
6.5 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* zfcp device driver
*
* Tracking of manually configured LUNs and helper functions to
* register the LUNs with the SCSI midlayer.
*
* Copyright IBM Corp. 2010
*/
#include "zfcp_def.h"
#include "zfcp_ext.h"
/**
* zfcp_unit_scsi_scan - Register LUN with SCSI midlayer
* @unit: The zfcp LUN/unit to register
*
* When the SCSI midlayer is not allowed to automatically scan and
* attach SCSI devices, zfcp has to register the single devices with
* the SCSI midlayer.
*/
void zfcp_unit_scsi_scan(struct zfcp_unit *unit)
{
struct fc_rport *rport = unit->port->rport;
u64 lun;
lun = scsilun_to_int((struct scsi_lun *) &unit->fcp_lun);
if (rport && rport->port_state == FC_PORTSTATE_ONLINE)
scsi_scan_target(&rport->dev, 0, rport->scsi_target_id, lun,
SCSI_SCAN_MANUAL);
}
static void zfcp_unit_scsi_scan_work(struct work_struct *work)
{
struct zfcp_unit *unit = container_of(work, struct zfcp_unit,
scsi_work);
zfcp_unit_scsi_scan(unit);
put_device(&unit->dev);
}
/**
* zfcp_unit_queue_scsi_scan - Register configured units on port
* @port: The zfcp_port where to register units
*
* After opening a port, all units configured on this port have to be
* registered with the SCSI midlayer. This function should be called
* after calling fc_remote_port_add, so that the fc_rport is already
* ONLINE and the call to scsi_scan_target runs the same way as the
* call in the FC transport class.
*/
void zfcp_unit_queue_scsi_scan(struct zfcp_port *port)
{
struct zfcp_unit *unit;
read_lock_irq(&port->unit_list_lock);
list_for_each_entry(unit, &port->unit_list, list) {
get_device(&unit->dev);
if (scsi_queue_work(port->adapter->scsi_host,
&unit->scsi_work) <= 0)
put_device(&unit->dev);
}
read_unlock_irq(&port->unit_list_lock);
}
static struct zfcp_unit *_zfcp_unit_find(struct zfcp_port *port, u64 fcp_lun)
{
struct zfcp_unit *unit;
list_for_each_entry(unit, &port->unit_list, list)
if (unit->fcp_lun == fcp_lun) {
get_device(&unit->dev);
return unit;
}
return NULL;
}
/**
* zfcp_unit_find - Find and return zfcp_unit with specified FCP LUN
* @port: zfcp_port where to look for the unit
* @fcp_lun: 64 Bit FCP LUN used to identify the zfcp_unit
*
* If zfcp_unit is found, a reference is acquired that has to be
* released later.
*
* Returns: Pointer to the zfcp_unit, or NULL if there is no zfcp_unit
* with the specified FCP LUN.
*/
struct zfcp_unit *zfcp_unit_find(struct zfcp_port *port, u64 fcp_lun)
{
struct zfcp_unit *unit;
read_lock_irq(&port->unit_list_lock);
unit = _zfcp_unit_find(port, fcp_lun);
read_unlock_irq(&port->unit_list_lock);
return unit;
}
/**
* zfcp_unit_release - Drop reference to zfcp_port and free memory of zfcp_unit.
* @dev: pointer to device in zfcp_unit
*/
static void zfcp_unit_release(struct device *dev)
{
struct zfcp_unit *unit = container_of(dev, struct zfcp_unit, dev);
atomic_dec(&unit->port->units);
kfree(unit);
}
/**
* zfcp_unit_enqueue - enqueue unit to unit list of a port.
* @port: pointer to port where unit is added
* @fcp_lun: FCP LUN of unit to be enqueued
* Returns: 0 success
*
* Sets up some unit internal structures and creates sysfs entry.
*/
int zfcp_unit_add(struct zfcp_port *port, u64 fcp_lun)
{
struct zfcp_unit *unit;
int retval = 0;
mutex_lock(&zfcp_sysfs_port_units_mutex);
if (zfcp_sysfs_port_is_removing(port)) {
/* port is already gone */
retval = -ENODEV;
goto out;
}
unit = zfcp_unit_find(port, fcp_lun);
if (unit) {
put_device(&unit->dev);
retval = -EEXIST;
goto out;
}
unit = kzalloc(sizeof(struct zfcp_unit), GFP_KERNEL);
if (!unit) {
retval = -ENOMEM;
goto out;
}
unit->port = port;
unit->fcp_lun = fcp_lun;
unit->dev.parent = &port->dev;
unit->dev.release = zfcp_unit_release;
unit->dev.groups = zfcp_unit_attr_groups;
INIT_WORK(&unit->scsi_work, zfcp_unit_scsi_scan_work);
if (dev_set_name(&unit->dev, "0x%016llx",
(unsigned long long) fcp_lun)) {
kfree(unit);
retval = -ENOMEM;
goto out;
}
if (device_register(&unit->dev)) {
put_device(&unit->dev);
retval = -ENOMEM;
goto out;
}
atomic_inc(&port->units); /* under zfcp_sysfs_port_units_mutex ! */
write_lock_irq(&port->unit_list_lock);
list_add_tail(&unit->list, &port->unit_list);
write_unlock_irq(&port->unit_list_lock);
/*
* lock order: shost->scan_mutex before zfcp_sysfs_port_units_mutex
* due to zfcp_unit_scsi_scan() => zfcp_scsi_slave_alloc()
*/
mutex_unlock(&zfcp_sysfs_port_units_mutex);
zfcp_unit_scsi_scan(unit);
return retval;
out:
mutex_unlock(&zfcp_sysfs_port_units_mutex);
return retval;
}
/**
* zfcp_unit_sdev - Return SCSI device for zfcp_unit
* @unit: The zfcp_unit where to get the SCSI device for
*
* Returns: scsi_device pointer on success, NULL if there is no SCSI
* device for this zfcp_unit
*
* On success, the caller also holds a reference to the SCSI device
* that must be released with scsi_device_put.
*/
struct scsi_device *zfcp_unit_sdev(struct zfcp_unit *unit)
{
struct Scsi_Host *shost;
struct zfcp_port *port;
u64 lun;
lun = scsilun_to_int((struct scsi_lun *) &unit->fcp_lun);
port = unit->port;
shost = port->adapter->scsi_host;
return scsi_device_lookup(shost, 0, port->starget_id, lun);
}
/**
* zfcp_unit_sdev_status - Return zfcp LUN status for SCSI device
* @unit: The unit to lookup the SCSI device for
*
* Returns the zfcp LUN status field of the SCSI device if the SCSI device
* for the zfcp_unit exists, 0 otherwise.
*/
unsigned int zfcp_unit_sdev_status(struct zfcp_unit *unit)
{
unsigned int status = 0;
struct scsi_device *sdev;
struct zfcp_scsi_dev *zfcp_sdev;
sdev = zfcp_unit_sdev(unit);
if (sdev) {
zfcp_sdev = sdev_to_zfcp(sdev);
status = atomic_read(&zfcp_sdev->status);
scsi_device_put(sdev);
}
return status;
}
/**
* zfcp_unit_remove - Remove entry from list of configured units
* @port: The port where to remove the unit from the configuration
* @fcp_lun: The 64 bit LUN of the unit to remove
*
* Returns: -EINVAL if a unit with the specified LUN does not exist,
* 0 on success.
*/
int zfcp_unit_remove(struct zfcp_port *port, u64 fcp_lun)
{
struct zfcp_unit *unit;
struct scsi_device *sdev;
write_lock_irq(&port->unit_list_lock);
unit = _zfcp_unit_find(port, fcp_lun);
if (unit)
list_del(&unit->list);
write_unlock_irq(&port->unit_list_lock);
if (!unit)
return -EINVAL;
sdev = zfcp_unit_sdev(unit);
if (sdev) {
scsi_remove_device(sdev);
scsi_device_put(sdev);
}
put_device(&unit->dev);
device_unregister(&unit->dev);
return 0;
}