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>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 1ade11d1ba07..6d8ace3e3259 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)