On Mon, Dec 11, 2017 at 05:04:05PM +1100, NeilBrown wrote: > @@ -385,7 +385,9 @@ int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid, > { > const struct export_operations *nop = inode->i_sb->s_export_op; > > - if (nop && nop->encode_fh) > + if (nop) > + return FILEID_INVALID; > + if (nop->encode_fh) > return nop->encode_fh(inode, fid->raw, max_len, parent); This might as well have been if (nop) return FILEID_INVALID; BUG(); Have you ever tested that?