NFS: Use an appropriate work queue for direct-write completion

When a direct-write completes, a work_struct is schedule to handle the completion.
When NFS is being used for swap, the direct write might be a swap-out, so memory allocation can block until the write completes. The work queue currently used is not WQ_MEM_RECLAIM, so tasks can block waiting for memory - this leads to deadlock.

So use nfsiod_workqueue instead. This will always have a running thread, and work items should never block waiting for memory.

---
 fs/nfs/direct.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 621c517b325c..aa12c3063bae 100644
@@ -758,7 +758,7 @@ static void nfs_direct_write_schedule_work(struct work_struct *work)
 
 static void nfs_direct_write_complete(struct nfs_direct_req *dreq)
 {
-	schedule_work(&dreq->work); /* Calls nfs_direct_write_schedule_work */
+	queue_work(nfsiod_workqueue, &dreq->work); /* Calls nfs_direct_write_schedule_work */
 }
 
 static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)

2.14.0.rc0.dirty