Re: Btrfs disk layout question

["Austin S. Hemmelgarn" <ahferroin7@gmail.com>]

On 2017-04-12 00:18, Chris Murphy wrote:
> On Tue, Apr 11, 2017 at 3:00 PM, Adam Borowski <kilobyte@angband.pl> 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.