afs: add afs_wq and use it instead of the system workqueue

flush_scheduled_work() is going away.  afs needs to make sure all the
works it has queued have finished before being unloaded and there can
be arbitrary number of pending works.  Add afs_wq and use it as the
flush domain instead of the system workqueue.

Also, convert cancel_delayed_work() + flush_scheduled_work() to
cancel_delayed_work_sync() in afs_mntpt_kill_timer().

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: linux-afs@lists.infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/afs/main.c b/fs/afs/main.c
index cfd1cbe..42dd2e4 100644
--- a/fs/afs/main.c
+++ b/fs/afs/main.c
@@ -30,6 +30,7 @@
 MODULE_PARM_DESC(rootcell, "root AFS cell name and VL server IP addr list");
 
 struct afs_uuid afs_uuid;
+struct workqueue_struct *afs_wq;
 
 /*
  * get a client UUID
@@ -87,10 +88,16 @@
 	if (ret < 0)
 		return ret;
 
+	/* create workqueue */
+	ret = -ENOMEM;
+	afs_wq = alloc_workqueue("afs", 0, 0);
+	if (!afs_wq)
+		return ret;
+
 	/* register the /proc stuff */
 	ret = afs_proc_init();
 	if (ret < 0)
-		return ret;
+		goto error_proc;
 
 #ifdef CONFIG_AFS_FSCACHE
 	/* we want to be able to cache */
@@ -140,6 +147,8 @@
 error_cache:
 #endif
 	afs_proc_cleanup();
+error_proc:
+	destroy_workqueue(afs_wq);
 	rcu_barrier();
 	printk(KERN_ERR "kAFS: failed to register: %d\n", ret);
 	return ret;
@@ -163,7 +172,7 @@
 	afs_purge_servers();
 	afs_callback_update_kill();
 	afs_vlocation_purge();
-	flush_scheduled_work();
+	destroy_workqueue(afs_wq);
 	afs_cell_purge();
 #ifdef CONFIG_AFS_FSCACHE
 	fscache_unregister_netfs(&afs_cache_netfs);