From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f171.google.com ([209.85.223.171]:33260 "EHLO mail-io0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753846AbdDLLUZ (ORCPT ); Wed, 12 Apr 2017 07:20:25 -0400 Received: by mail-io0-f171.google.com with SMTP id k87so21868233ioi.0 for ; Wed, 12 Apr 2017 04:20:25 -0700 (PDT) Subject: Re: Btrfs disk layout question To: Chris Murphy , Adam Borowski References: <20170411210023.vfqck3h6nepdow3z@angband.pl> Cc: Amin Hassani , Btrfs BTRFS From: "Austin S. Hemmelgarn" Message-ID: Date: Wed, 12 Apr 2017 07:20:13 -0400 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 2017-04-12 00:18, Chris Murphy wrote: > On Tue, Apr 11, 2017 at 3:00 PM, Adam Borowski wrote: >> On Tue, Apr 11, 2017 at 12:15:32PM -0700, Amin Hassani wrote: >>> I am working on a project with Btrfs and I was wondering if there is >>> any way to see the disk layout of the btrfs image. Let's assume I have >>> a read-only btrfs image with compression on and only using one disk >>> (no raid or anything). Is it possible to get a set of offset-lengths >>> for each file >> >> While btrfs-specific ioctls give more information, you might want to look at >> FIEMAP (Documentation/filesystems/fiemap.txt) as it works on most >> filesystems, not just btrfs. One interface to FIEMAP is provided in >> "/usr/sbin/filefrag -v". > > Good idea. Although, on Btrfs I'm pretty sure it reports the Btrfs > (internal) logical addressing; not the actual physical sector address > on the drive. So it depends on what the original poster is trying to > discover. > That said, there is a tool to translate that back, and depending on how detailed you want to get, that may be more efficient than debug tree.