NFS: Fix an f_mode/f_flags confusion in fs/nfs/write.c

O_SYNC is stored in filp->f_flags.
Thanks to Al Viro for pointing out the bug.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/write.c

@@ -734,7 +734,7 @@ int nfs_updatepage(struct file *file, struct page *page,
 	 */
 	if (nfs_write_pageuptodate(page, inode) &&
 			inode->i_flock == NULL &&
-			!(file->f_mode & O_SYNC)) {
+			!(file->f_flags & O_SYNC)) {
 		count = max(count + offset, nfs_page_length(page));
 		offset = 0;
 	}