NFS: Ensure we only call set_page_writeback() under the page lock

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 3de334c7..0496306 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -438,6 +438,7 @@
 extern int nfs_sync_mapping_range(struct address_space *, loff_t, loff_t, int);
 extern int nfs_wb_all(struct inode *inode);
 extern int nfs_wb_page(struct inode *inode, struct page* page);
+extern int nfs_wb_page_priority(struct inode *inode, struct page* page, int how);
 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 extern int  nfs_commit_inode(struct inode *, int);
 extern struct nfs_write_data *nfs_commit_alloc(void);