From: NeilBrown <neilb@suse.com>
Date: Wed, 8 Aug 2018 09:20:02 +1000
Subject: [PATCH] NFS: Use an appropriate work queue for direct-write
 completion
Git-commit: 46483c2ea4664679130d6489112f180c2bfc801d
Patch-mainline: v4.19-rc1
References: bsc#1082519

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.

Signed-off-by: Neil Brown <neilb@suse.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Acked-by: NeilBrown <neilb@suse.com>

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

--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -758,7 +758,7 @@ static void nfs_direct_write_schedule_wo
 
 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)