From 38def50fabc479dc96ea6bd2cb2526e0dfc36fa4 Mon Sep 17 00:00:00 2001
From: Fred Isaman <iisaman@citi.umich.edu>
Date: Thu, 1 May 2008 20:03:22 +0300
Subject: [PATCH] nfs: fix race in nfs_dirty_request

When called from nfs_flush_incompatible, the req is not locked, so
req->wb_page might be set to NULL before it is used by PageWriteback.

Signed-off-by: Fred Isaman <iisaman@citi.umich.edu>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
---
 fs/nfs/write.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 1ade11d1ba0..6d8ace3e325 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -415,7 +415,7 @@ nfs_dirty_request(struct nfs_page *req)
 
 	if (page == NULL || test_bit(PG_NEED_COMMIT, &req->wb_flags))
 		return 0;
-	return !PageWriteback(req->wb_page);
+	return !PageWriteback(page);
 }
 
 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)