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s390/dasd: add safe offline interface

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The regular behavior of the DASD device driver when setting a device
offline is to return all outstanding I/O as failed. This behavior is
different from that of other System z operating systems and may lead
to unexpected data loss. Adding an explicit 'safe' offline function
will allow customers to use DASDs in the way they expect them to work.

Signed-off-by: Stefan Haberland <stefan.haberland@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Stefan Haberland
2012-11-28 13:43:38 +01:00
committed by Martin Schwidefsky
parent 55d3a85cd2
commit d07dc5d8ab
3 changed files with 116 additions and 17 deletions
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34
drivers/s390/block/dasd_devmap.c
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@@ -951,6 +951,39 @@ dasd_use_raw_store(struct device *dev, struct device_attribute *attr,
static DEVICE_ATTR(raw_track_access, 0644, dasd_use_raw_show,
dasd_use_raw_store);
static ssize_t
dasd_safe_offline_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct ccw_device *cdev = to_ccwdev(dev);
struct dasd_device *device;
int rc;
device = dasd_device_from_cdev(cdev);
if (IS_ERR(device)) {
rc = PTR_ERR(device);
goto out;
}
if (test_bit(DASD_FLAG_OFFLINE, &device->flags) ||
test_bit(DASD_FLAG_SAFE_OFFLINE_RUNNING, &device->flags)) {
/* Already doing offline processing */
dasd_put_device(device);
rc = -EBUSY;
goto out;
}
set_bit(DASD_FLAG_SAFE_OFFLINE, &device->flags);
dasd_put_device(device);
rc = ccw_device_set_offline(cdev);
out:
return rc ? rc : count;
}
static DEVICE_ATTR(safe_offline, 0200, NULL, dasd_safe_offline_store);
static ssize_t
dasd_discipline_show(struct device *dev, struct device_attribute *attr,
char *buf)
@@ -1320,6 +1353,7 @@ static struct attribute * dasd_attrs[] = {
&dev_attr_expires.attr,
&dev_attr_reservation_policy.attr,
&dev_attr_last_known_reservation_state.attr,
&dev_attr_safe_offline.attr,
NULL,
};