From: Marcos Mello Subject: Re: Kernel does not respect tune2fs -E mount_opts=foo Date: Tue, 23 Aug 2016 13:01:53 -0300 Message-ID: References: <20160823154849.GA15892@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: linux-ext4@vger.kernel.org To: tytso@mit.edu Return-path: Received: from mail-yb0-f179.google.com ([209.85.213.179]:36555 "EHLO mail-yb0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753370AbcHWQI6 (ORCPT ); Tue, 23 Aug 2016 12:08:58 -0400 Received: by mail-yb0-f179.google.com with SMTP id e31so52150693ybi.3 for ; Tue, 23 Aug 2016 09:08:14 -0700 (PDT) In-Reply-To: <20160823154849.GA15892@thunk.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: 2016-08-23 12:48 GMT-03:00 : > The problem you are running into is not something we can fix, > unfortunately, or at least not in a full and general way. The problem > is that there are certain mount options which are parsed by the mount > command (in userspace) and then translated to a mount flag, which is > then passed to the mount command as a bitmask, and which is > interpreted by the VFS layer before calling the file system. > > The mount options field in the superblock is parsed by the ext4 file > system along with options that were not parsed by the mount binary, > passed to the VFS, which then passed it to ext4 file system driver. > > In theory, we could interpret relatime in ext4 and replicate its > effects. For relatime, this is trivial to do. There may be other > mount options which are interepted by the mount userspace program, and > implemented in the VFS, where this would be much less easy to do. > >> Other options like noacl, nouser_xattr, are ignored too. This >> filesystem is not listed in fstab. > > This is exactly the same issue. > Thanks for the explanation. A hint about this limitation in tune2fs man page would help. Marcos