From: Trond Myklebust <trond.myklebust@primarydata.com>
Date: Mon, 18 Dec 2017 14:39:13 -0500
Subject: [PATCH] NFS: Add a cond_resched() to nfs_commit_release_pages()
Git-commit: 7f1bda447c9bd48b415acedba6b830f61591601f
Patch-mainline: v4.16-rc1
References: bsc#1077779

The commit list can get very large, and so we need a cond_resched()
in nfs_commit_release_pages() in order to ensure we don't hog the CPU
for excessive periods of time.

Reported-by: Mike Galbraith <efault@gmx.de>
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Acked-by: NeilBrown <neilb@suse.com>

---
 fs/nfs/write.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1754,6 +1754,8 @@ static void nfs_commit_release_pages(str
 		set_bit(NFS_CONTEXT_RESEND_WRITES, &req->wb_context->flags);
 	next:
 		nfs_unlock_and_release_request(req);
+		/* Latency breaker */
+		cond_resched();
 	}
 	nfss = NFS_SERVER(data->inode);
 	if (atomic_long_read(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)