[S390] dasd: Improve handling of stolen DASD reservation

If a DASD device has been reserved by a Linux system, and later
this reservation is ‘stolen’ by a second system by means of an
unconditional reserve, then the first system receives a
notification about this fact. With this patch such an event can
be either ignored, as before, or it can be used to let the device
fail all I/O request, so that the device will not block anymore.

Signed-off-by: Stefan Weinhuber <wein@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 99 insertions, 0 deletions

diff --git a/drivers/s390/block/dasd_devmap.c b/drivers/s390/block/dasd_devmap.c
index 0001df8ad3e6..47fc88692494 100644
--- a/drivers/s390/block/dasd_devmap.c
+++ b/drivers/s390/block/dasd_devmap.c
@@ -1127,6 +1127,103 @@ dasd_expires_store(struct device *dev, struct device_attribute *attr,
 
 static DEVICE_ATTR(expires, 0644, dasd_expires_show, dasd_expires_store);
 
+static ssize_t dasd_reservation_policy_show(struct device *dev,
+                                            struct device_attribute *attr,
+                                            char *buf)
+{
+        struct dasd_devmap *devmap;
+        int rc = 0;
+
+        devmap = dasd_find_busid(dev_name(dev));
+        if (IS_ERR(devmap)) {
+                rc = snprintf(buf, PAGE_SIZE, "ignore\n");
+        } else {
+                spin_lock(&dasd_devmap_lock);
+                if (devmap->features & DASD_FEATURE_FAILONSLCK)
+                        rc = snprintf(buf, PAGE_SIZE, "fail\n");
+                else
+                        rc = snprintf(buf, PAGE_SIZE, "ignore\n");
+                spin_unlock(&dasd_devmap_lock);
+        }
+        return rc;
+}
+
+static ssize_t dasd_reservation_policy_store(struct device *dev,
+                                             struct device_attribute *attr,
+                                             const char *buf, size_t count)
+{
+        struct dasd_devmap *devmap;
+        int rc;
+
+        devmap = dasd_devmap_from_cdev(to_ccwdev(dev));
+        if (IS_ERR(devmap))
+                return PTR_ERR(devmap);
+        rc = 0;
+        spin_lock(&dasd_devmap_lock);
+        if (sysfs_streq("ignore", buf))
+                devmap->features &= ~DASD_FEATURE_FAILONSLCK;
+        else if (sysfs_streq("fail", buf))
+                devmap->features |= DASD_FEATURE_FAILONSLCK;
+        else
+                rc = -EINVAL;
+        if (devmap->device)
+                devmap->device->features = devmap->features;
+        spin_unlock(&dasd_devmap_lock);
+        if (rc)
+                return rc;
+        else
+                return count;
+}
+
+static DEVICE_ATTR(reservation_policy, 0644,
+                   dasd_reservation_policy_show, dasd_reservation_policy_store);
+
+static ssize_t dasd_reservation_state_show(struct device *dev,
+                                           struct device_attribute *attr,
+                                           char *buf)
+{
+        struct dasd_device *device;
+        int rc = 0;
+
+        device = dasd_device_from_cdev(to_ccwdev(dev));
+        if (IS_ERR(device))
+                return snprintf(buf, PAGE_SIZE, "none\n");
+
+        if (test_bit(DASD_FLAG_IS_RESERVED, &device->flags))
+                rc = snprintf(buf, PAGE_SIZE, "reserved\n");
+        else if (test_bit(DASD_FLAG_LOCK_STOLEN, &device->flags))
+                rc = snprintf(buf, PAGE_SIZE, "lost\n");
+        else
+                rc = snprintf(buf, PAGE_SIZE, "none\n");
+        dasd_put_device(device);
+        return rc;
+}
+
+static ssize_t dasd_reservation_state_store(struct device *dev,
+                                            struct device_attribute *attr,
+                                            const char *buf, size_t count)
+{
+        struct dasd_device *device;
+        int rc = 0;
+
+        device = dasd_device_from_cdev(to_ccwdev(dev));
+        if (IS_ERR(device))
+                return -ENODEV;
+        if (sysfs_streq("reset", buf))
+                clear_bit(DASD_FLAG_LOCK_STOLEN, &device->flags);
+        else
+                rc = -EINVAL;
+        dasd_put_device(device);
+
+        if (rc)
+                return rc;
+        else
+                return count;
+}
+
+static DEVICE_ATTR(last_known_reservation_state, 0644,
+                   dasd_reservation_state_show, dasd_reservation_state_store);
+
 static struct attribute * dasd_attrs[] = {
         &dev_attr_readonly.attr,
         &dev_attr_discipline.attr,
@@ -1139,6 +1236,8 @@ static struct attribute * dasd_attrs[] = {
         &dev_attr_erplog.attr,
         &dev_attr_failfast.attr,
         &dev_attr_expires.attr,
+        &dev_attr_reservation_policy.attr,
+        &dev_attr_last_known_reservation_state.attr,
         NULL,
 };