SLOW_WORK: Wait for outstanding work items belonging to a module to clear

Wait for outstanding slow work items belonging to a module to clear when
unregistering that module as a user of the facility.  This prevents the put_ref
code of a work item from being taken away before it returns.

Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/fs/fscache/main.c b/fs/fscache/main.c
index 4de41b5..add6bdb 100644
--- a/fs/fscache/main.c
+++ b/fs/fscache/main.c
@@ -48,7 +48,7 @@
 {
 	int ret;
 
-	ret = slow_work_register_user();
+	ret = slow_work_register_user(THIS_MODULE);
 	if (ret < 0)
 		goto error_slow_work;
 
@@ -80,7 +80,7 @@
 error_cookie_jar:
 	fscache_proc_cleanup();
 error_proc:
-	slow_work_unregister_user();
+	slow_work_unregister_user(THIS_MODULE);
 error_slow_work:
 	return ret;
 }
@@ -97,7 +97,7 @@
 	kobject_put(fscache_root);
 	kmem_cache_destroy(fscache_cookie_jar);
 	fscache_proc_cleanup();
-	slow_work_unregister_user();
+	slow_work_unregister_user(THIS_MODULE);
 	printk(KERN_NOTICE "FS-Cache: Unloaded\n");
 }