dm: sysfs add suspended attribute

Add a file named 'suspended' to each device-mapper device directory in
sysfs.  It holds the value 1 while the device is suspended.  Otherwise
it holds 0.

Signed-off-by: Peter Rajnoha <prajnoha@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

drivers/md/dm-sysfs.c

@@ -57,12 +57,21 @@ static ssize_t dm_attr_uuid_show(struct mapped_device *md, char *buf)
 	return strlen(buf);
 }
 
+static ssize_t dm_attr_suspended_show(struct mapped_device *md, char *buf)
+{
+	sprintf(buf, "%d\n", dm_suspended(md));
+
+	return strlen(buf);
+}
+
 static DM_ATTR_RO(name);
 static DM_ATTR_RO(uuid);
+static DM_ATTR_RO(suspended);
 
 static struct attribute *dm_attrs[] = {
 	&dm_attr_name.attr,
 	&dm_attr_uuid.attr,
+	&dm_attr_suspended.attr,
 	NULL,
 };