@@ -286,9 +286,11 @@ static struct p9_fid *v9fs_fid_clone_with_uid(struct dentry *dentry, uid_t uid)
struct p9_fid *v9fs_writeback_fid(struct dentry *dentry)
{
- int err;
+ int err, flags;
struct p9_fid *fid;
+ struct v9fs_session_info *v9ses;
+ v9ses = v9fs_inode2v9ses(dentry->d_inode);
fid = v9fs_fid_clone_with_uid(dentry, 0);
if (IS_ERR(fid))
goto error_out;
@@ -297,8 +299,17 @@ struct p9_fid *v9fs_writeback_fid(struct dentry *dentry)
* dirty pages. We always request for the open fid in read-write
* mode so that a partial page write which result in page
* read can work.
+ *
+ * we don't have a tsyncfs operation for older version
+ * of protocol. So make sure the write back fid is
+ * opened in O_SYNC mode.
*/
- err = p9_client_open(fid, O_RDWR);
+ if (!v9fs_proto_dotl(v9ses))
+ flags = O_RDWR | O_SYNC;
+ else
+ flags = O_RDWR;
+
+ err = p9_client_open(fid, flags);
if (err < 0) {
p9_client_clunk(fid);
fid = ERR_PTR(err);