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s390/dasd: add device ping attribute

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Add a function to check if a device is accessible.
This makes mostly sense for copy pair secondary devices but it will work
for all devices.

The sysfs attribute ping is a write only attribute and will issue a NOP
CCW to the device.
In case of success it will return zero. If the device is not accessible
it will return an error code.

Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
Link: https://lore.kernel.org/r/20220920192616.808070-8-sth@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Stefan Haberland
2022-09-20 21:26:16 +02:00
committed by Jens Axboe
parent 1fca631a11
commit 32ff8ce08b
4 changed files with 81 additions and 0 deletions
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35
drivers/s390/block/dasd_devmap.c
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@@ -2234,6 +2234,40 @@ out:
}
static DEVICE_ATTR(copy_role, 0444, dasd_copy_role_show, NULL);
static ssize_t dasd_device_ping(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct dasd_device *device;
size_t rc;
device = dasd_device_from_cdev(to_ccwdev(dev));
if (IS_ERR(device))
return -ENODEV;
/*
* do not try during offline processing
* early check only
* the sleep_on function itself checks for offline
* processing again
*/
if (test_bit(DASD_FLAG_OFFLINE, &device->flags)) {
rc = -EBUSY;
goto out;
}
if (!device->discipline || !device->discipline->device_ping) {
rc = -EOPNOTSUPP;
goto out;
}
rc = device->discipline->device_ping(device);
if (!rc)
rc = count;
out:
dasd_put_device(device);
return rc;
}
static DEVICE_ATTR(ping, 0200, NULL, dasd_device_ping);
#define DASD_DEFINE_ATTR(_name, _func) \
static ssize_t dasd_##_name##_show(struct device *dev, \
struct device_attribute *attr, \
@@ -2292,6 +2326,7 @@ static struct attribute * dasd_attrs[] = {
&dev_attr_fc_security.attr,
&dev_attr_copy_pair.attr,
&dev_attr_copy_role.attr,
&dev_attr_ping.attr,
NULL,
};