From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ee0-f45.google.com ([74.125.83.45]:61258 "EHLO mail-ee0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751110AbaDQPjt (ORCPT ); Thu, 17 Apr 2014 11:39:49 -0400 Received: by mail-ee0-f45.google.com with SMTP id d17so822460eek.32 for ; Thu, 17 Apr 2014 08:39:48 -0700 (PDT) Received: from [192.168.178.21] (p549C5CB6.dip0.t-ipconnect.de. [84.156.92.182]) by mx.google.com with ESMTPSA id o7sm68352178eew.25.2014.04.17.08.39.46 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 17 Apr 2014 08:39:47 -0700 (PDT) Message-ID: <534FF5C1.8070404@gmail.com> Date: Thu, 17 Apr 2014 17:39:45 +0200 From: "Oliver O." MIME-Version: 1.0 To: linux-btrfs@vger.kernel.org Subject: File changing in snapshot Content-Type: text/plain; charset=ISO-8859-15; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: I seem to have observed a file on a (writable) snapshot changing although there were no writes occuring on the snapshot itself. This is not supposed to happen, right? Sequence of events: 1. A (writable) snapshot @home-2014-04-16 is taken on a @home subvolume mounted at /home. 2. The current subvolume (@home) is used (via /home) for continued write access, no writes are supposed to occur on the snapshot. 3. The snapshot @home-2014-04-16 is backed up (using rdiff-backup) to a different disk. 4. As the backup is compared to the snapshot @home-2014-04-16, one file differs. Further analysis: The file in @home-2014-04-16 changed its contents (but not mtime or other metadata) after being backup up from that snapshot. 5 bytes differ. The previous snapshot @home-2014-04-10 contains the file in its original form, which is identical to the backup just taken from @home-2014-04-16. The file change appears identically - on the last snapshot @home-2014-04-16 and - on the current subvolume used for writing (@home). btrfs scrub reports 0 errors. At the time the snapshot @home-2014-04-16 was taken, the file (an Excel file) was probably accessed through Samba, which supposedly uses kernel oplocks (if that makes a difference). Versions: - Kernel 3.11.0-19-generic (Ubuntu 13.10) - btrfs-tools 0.19+20130705-1 - Samba 3.6.18 Any ideas?