s390/dasd: add aq_requeue sysfs attribute

Add a sysfs attribute to control if all IO requests will be requeued to
the blocklayer in case of an autoquiesce event or not.

A value of 1 means that in case of an autoquiesce event all IO requests
will be requeued to the blocklayer.

A value of 0 means that the device will only be stopped.
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Link: https://lore.kernel.org/r/20230405142017.2446986-5-sth@linux.ibm.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/s390/block/dasd_devmap.c

@@ -1517,6 +1517,41 @@ static ssize_t dasd_aq_mask_store(struct device *dev, struct device_attribute *a
 
 static DEVICE_ATTR(aq_mask, 0644, dasd_aq_mask_show, dasd_aq_mask_store);
 
+/*
+ * aq_requeue controls if requests are returned to the blocklayer on quiesce
+ * or if requests are only not started
+ */
+static ssize_t dasd_aqr_show(struct device *dev, struct device_attribute *attr,
+			     char *buf)
+{
+	struct dasd_devmap *devmap;
+	int flag;
+
+	devmap = dasd_find_busid(dev_name(dev));
+	if (!IS_ERR(devmap))
+		flag = (devmap->features & DASD_FEATURE_REQUEUEQUIESCE) != 0;
+	else
+		flag = (DASD_FEATURE_DEFAULT &
+			DASD_FEATURE_REQUEUEQUIESCE) != 0;
+	return sysfs_emit(buf, "%d\n", flag);
+}
+
+static ssize_t dasd_aqr_store(struct device *dev, struct device_attribute *attr,
+			      const char *buf, size_t count)
+{
+	bool val;
+	int rc;
+
+	if (kstrtobool(buf, &val))
+		return -EINVAL;
+
+	rc = dasd_set_feature(to_ccwdev(dev), DASD_FEATURE_REQUEUEQUIESCE, val);
+
+	return rc ? : count;
+}
+
+static DEVICE_ATTR(aq_requeue, 0644, dasd_aqr_show, dasd_aqr_store);
+
 /*
  * expiration time for default requests
  */
@@ -2367,6 +2402,7 @@ static struct attribute * dasd_attrs[] = {
 	&dev_attr_copy_role.attr,
 	&dev_attr_ping.attr,
 	&dev_attr_aq_mask.attr,
+	&dev_attr_aq_requeue.attr,
 	NULL,
 };