[S390] dasd: add device attribute to disable blocking on lost paths
When the connection between host and storage server is lost, the
dasd device driver usually blocks all I/O on affected devices and
waits for them to reappear. In some setups however it would be
better if the I/O is returned as error so that device can be
recovered by some other means, eg. in a raid or multipath setup.
Signed-off-by: Holger Smolinski <Holger.Smolinski@de.ibm.com>
Signed-off-by: Stefan Weinhuber <wein@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/block/dasd_devmap.c b/drivers/s390/block/dasd_devmap.c
index 2ef2573..300e28a 100644
--- a/drivers/s390/block/dasd_devmap.c
+++ b/drivers/s390/block/dasd_devmap.c
@@ -206,6 +206,8 @@
features |= DASD_FEATURE_USEDIAG;
else if (len == 6 && !strncmp(str, "erplog", 6))
features |= DASD_FEATURE_ERPLOG;
+ else if (len == 8 && !strncmp(str, "failfast", 8))
+ features |= DASD_FEATURE_FAILFAST;
else {
MESSAGE(KERN_WARNING,
"unsupported feature: %*s, "
@@ -667,6 +669,51 @@
*/
/*
+ * failfast controls the behaviour, if no path is available
+ */
+static ssize_t dasd_ff_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct dasd_devmap *devmap;
+ int ff_flag;
+
+ devmap = dasd_find_busid(dev->bus_id);
+ if (!IS_ERR(devmap))
+ ff_flag = (devmap->features & DASD_FEATURE_FAILFAST) != 0;
+ else
+ ff_flag = (DASD_FEATURE_DEFAULT & DASD_FEATURE_FAILFAST) != 0;
+ return snprintf(buf, PAGE_SIZE, ff_flag ? "1\n" : "0\n");
+}
+
+static ssize_t dasd_ff_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct dasd_devmap *devmap;
+ int val;
+ char *endp;
+
+ devmap = dasd_devmap_from_cdev(to_ccwdev(dev));
+ if (IS_ERR(devmap))
+ return PTR_ERR(devmap);
+
+ val = simple_strtoul(buf, &endp, 0);
+ if (((endp + 1) < (buf + count)) || (val > 1))
+ return -EINVAL;
+
+ spin_lock(&dasd_devmap_lock);
+ if (val)
+ devmap->features |= DASD_FEATURE_FAILFAST;
+ else
+ devmap->features &= ~DASD_FEATURE_FAILFAST;
+ if (devmap->device)
+ devmap->device->features = devmap->features;
+ spin_unlock(&dasd_devmap_lock);
+ return count;
+}
+
+static DEVICE_ATTR(failfast, 0644, dasd_ff_show, dasd_ff_store);
+
+/*
* readonly controls the readonly status of a dasd
*/
static ssize_t
@@ -1020,6 +1067,7 @@
&dev_attr_use_diag.attr,
&dev_attr_eer_enabled.attr,
&dev_attr_erplog.attr,
+ &dev_attr_failfast.attr,
NULL,
};