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/cmservice.c b/fs/afs/cmservice.c
index a3bcec7..1c8c6cc 100644
--- a/fs/afs/cmservice.c
+++ b/fs/afs/cmservice.c
@@ -289,7 +289,7 @@
 	call->server = server;
 
 	INIT_WORK(&call->work, SRXAFSCB_CallBack);
-	schedule_work(&call->work);
+	queue_work(afs_wq, &call->work);
 	return 0;
 }
 
@@ -336,7 +336,7 @@
 	call->server = server;
 
 	INIT_WORK(&call->work, SRXAFSCB_InitCallBackState);
-	schedule_work(&call->work);
+	queue_work(afs_wq, &call->work);
 	return 0;
 }
 
@@ -367,7 +367,7 @@
 	call->server = server;
 
 	INIT_WORK(&call->work, SRXAFSCB_InitCallBackState);
-	schedule_work(&call->work);
+	queue_work(afs_wq, &call->work);
 	return 0;
 }
 
@@ -400,7 +400,7 @@
 	call->state = AFS_CALL_REPLYING;
 
 	INIT_WORK(&call->work, SRXAFSCB_Probe);
-	schedule_work(&call->work);
+	queue_work(afs_wq, &call->work);
 	return 0;
 }
 
@@ -496,7 +496,7 @@
 	call->state = AFS_CALL_REPLYING;
 
 	INIT_WORK(&call->work, SRXAFSCB_ProbeUuid);
-	schedule_work(&call->work);
+	queue_work(afs_wq, &call->work);
 	return 0;
 }
 
@@ -580,6 +580,6 @@
 	call->state = AFS_CALL_REPLYING;
 
 	INIT_WORK(&call->work, SRXAFSCB_TellMeAboutYourself);
-	schedule_work(&call->work);
+	queue_work(afs_wq, &call->work);
 	return 0;
 }